View Full Version : meg vs inspo



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Simmo
01-11-11, 04:55 PM
ive been looking at both and was wondering if anyone could give me any opinions of each unit. i live near Ap so servicing and repairs would be easy but have heard the meg is alot simpler, im ideally looking for an eccr and i will be using it for pretty much all dives from 10-55m at the moment and hopefully deeper.

thanks in advance
James

humpbackdiving
01-11-11, 05:02 PM
The problem you will get is there will be three types of answers

1. one from inspo users telling how great those units are [me]
2. one from meg users telling how great those units are
3. suggesting that you buy the ccr they use as they will be telling how great those units are

Get in touch with somebody like Richie S and do some try dives before you commit to a purchase. I think your position to apd is a good thing but not a deal breaker.

ATB Greg

Simmo
01-11-11, 05:24 PM
i will definately do a few try dives, my club director does them for the inspo as she dives one along with a few other instructors one on an evolution, ive never heard anything bad about the inspo, and know a reasonable amount about it (as i dive with my club director mainly) i was mainly wondering what advantages the meg has.

any replies are welcome, what do you like about your unit ^

thanks,
James

mala
01-11-11, 06:14 PM
i looked at both and went with the meg.

the nearness of the repair center was something that i didnt want to worry about.

matthewoutram
01-11-11, 07:30 PM
Both are good units. I have a Inspo so fall into Category 1 :-)

The reasons I haven't bought a Meg is nothing really to do with the build, quality or the diving (which those who dive them rave about) but a few little practical things. The main one is the servicing - APD have great service, fast turn-around and are a sizeable outfit based in the UK. This I like, I don't really know what the Meg is like now, they have CE and I suspect things are better than they were when you had to import from the USA.

The other thing I don't like is the tube - it sits out on the boat and leaves the lid and scrubber cannister loose in the cabin. I like to assemble mine in the dry, not outside in the rain/snow/gale force wind.

If you're on a UK boat then it is likely that you'll be able to get Inspo supplies from a fellow diver if in trouble. Supplies abroad are improving also.

The last thing I don't like on the Meg is the on/off switch - it is inside the head. I like to prep my unit the night before - or crack of dawn, when no rushing is needed and I can also drink tea. Once the unit is prepared (takes about 10 minutes) I like to do the pos/neg check and then it is ready to go. I don't mess with it again. I would not be keen on removing the lid again after this without starting over with the checks.

All the above is personal preference, they are both excellent units.

Cheers
Matt.

Rob Dobson
01-11-11, 08:03 PM
I used to own a Meg and I've never owned or dived an Inspo.

As much as I liked the Meg (and there is a lot to really like about them) I found it quite an awkward unit to live with, stuff which took a while to work out:

O2 calibration involves taking the head off, fitting the flow restrictor kit and and an o2 bottle. On a dive boat in the rain...? Really?

Switching the thing on means cracking the head and that means re-doing all your pre-dive checks.

Adjusting the jubilee clips to make config changes was a total PITA.

If you don't happen to be 20+ stone the CLs might not fit you very well.

Positives:

Well supported, flawless build quality, modular design, rugged as anything, great flood recovery and great WOB.

The cross between a Meg and an Inspo would look a lot like a JJ by the way...

humpbackdiving
01-11-11, 08:29 PM
Matt, you forgot the fact that we get to deal with lovely nicky?

matthewoutram
01-11-11, 08:41 PM
O2 calibration involves taking the head off, fitting the flow restrictor kit and and an o2 bottle. On a dive boat in the rain...? Really?

Good point, I'd forgotten about the calibration. I don't think Meg divers calibrate very regularly (well, I don't see them at least). I calibrate before every dive, which gives some confidence that things are not amiss. Some folks say this is a bad idea, but its recommended on an Inspo, perhaps not an issue with a Meg.


Adjusting the jubilee clips to make config changes was a total PITA.

And another point - I run several 3L cylinders for convenience. Normally 2 or 3 O2 bottles and a couple of mixes (say 10/52 and air). I fit what is needed and am not reliant on the skipper to fill them before I can prep. Meg divers have clamps on the cylinders, and sometimes weights, which makes this extra-cylinder usage more awkward.


Matt, you forgot the fact that we get to deal with lovely nicky?

Very true ;-)

Cheers
Matt.

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxessexbloke
01-11-11, 08:42 PM
James
another spanner in the works is who you dive with ,if the group all dive megs look seriously at a meg and so on....as it helps with spares ect

Lee C
01-11-11, 09:16 PM
Just my 2 p,s worth,I have dived a meg for 3+ years & have never had to abort a dive,I cant say that for the other people I have dived with mainly on inspos.

Simmo
01-11-11, 09:36 PM
James
another spanner in the works is who you dive with ,if the group all dive megs look seriously at a meg and so on....as it helps with spares ect

good point and going by that it would have to be an inspo, but decision wont be made untill after a few try dives with both units and ill probably commit next year.

humpbackdiving
01-11-11, 09:43 PM
As rob said look at a JJ. It is designed by Dave T ie same designer as inspo. I always thought of JJs as bit like what inspo could be if apd were bothered in developing their units or after serious dose of botox.

matthewoutram
01-11-11, 09:43 PM
Just my 2 p,s worth,I have dived a meg for 3+ years & have never had to abort a dive,I cant say that for the other people I have dived with mainly on inspos.

Not missed a dive in 9 years with mine.


good point and going by that it would have to be an inspo, but decision wont be made untill after a few try dives with both units and ill probably commit next year.

If you have a mate who you dive with then get the same one as each other.

Cheers
Matt.

matthewoutram
01-11-11, 09:48 PM
As rob said look at a JJ. It is designed by Dave T ie same designer as inspo. I always thought of JJs as bit like what inspo could be if apd were bothered in developing their units or after serious dose of botox.

It's off topic, but which JJ features make it stand-out? I know little of JJ other than it looks like a back-mounted meg with 3rd party electronics (neither of which are bad things, btw).

Matt.

Simmo
01-11-11, 09:52 PM
tbh if i went with the inspo i would be safe in the knowledge that many thousands dive them, matt being a good example (9years!), i like the reputation that Ap have built

humpbackdiving
01-11-11, 09:54 PM
Yep totally right. Off the topic. But I can help it I really like it.

matthewoutram
01-11-11, 10:05 PM
tbh if i went with the inspo i would be safe in the knowledge that many thousands dive them, matt being a good example (9years!), i like the reputation that Ap have built

...and in the last 9 years zero OC dives.

humpbackdiving
01-11-11, 10:15 PM
being honest JJ is a bit of a guilty pleasure but i like and chose the inspo for various reasons:
accessability to training (i live on the isle of man)
accessability to technical service/center
simplicity of built
easy maintenance
spares
huge uk based knowledge base
there was one for sale in a good nick locally

i compared it some time ago to a Hilux among breathers.... a bit ugly but reliable and easily fixed with wd40, hammer and adjustable spanner.

liamm
02-11-11, 01:52 PM
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liamm
02-11-11, 01:53 PM
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Dive Africa
11-11-11, 11:30 AM
I used to dive an Inspo classic - I have been diving a Meg for some time now and I am very bais towards the Meg - actually I'll never touch an Inspo again :D

Meg's build quality is better by some margin (obviously in my subjective and bias opinion). Their radial scrubber is fantastic - Inso a pain to clean - Meg takes apart and cleans very easily. Had various toxic cocktails with the Inspo - almost impossible to happen with Meg. Meg is a lot more versatile: different canisters, scrubbers, lungs - to name but a view.

Try dive the machines - but also assemble and clean.

You cannot forget to put spacers and o-rings into a Meg (yes I know if you do your pre-dive not really an issue) – but this is one design flaw on the Inspo – there is a couple more. You cannot cross thread a Meg.

Points above correct about calibration, but I pre-prepare and calibrate Meg night before and the Meg does really keeps its calibration/set point very well. Switches are inside head - but you actually only have to do negative and get the pp correct again when switching on - not perfect but not that much of an issue - once you get used to it.

Go and have a look at rebreather world - there is a video under the meg forum of Leon Schammehorn doing some interesting things to the Meg - you could never do that to an Inspo.

If you buy an Inspo good to be close to factory as you are going to need their services:rolleyes: (albeit excellent). Meg more reliable/robust/better designed as far as I am concerned. Also there is actually very good support in the UK. Only spares that you are going to need for a Meg is Sorb, battery and O2 Cells - Sorb you can use any, battery (a little more difficult, but they really last long time - I dive plenty and use only about 5 per annum. (there is a little adapter - $10 that allows you to use the standard square 9v battery if you are in a fix) - cells: keep spare and you can use any other r22d equivelent (same as on Inspo/hammerhead and I think rEvo.) - you really will not need any other spares and if you do prep right all issues shoudl be picked up before you go on trip.

I rig all of my cylinders with brackets – so can use multiple cylinders to connect. - Once again not perfect but not really an issue - you can also just sidesling big cylinders and plumb them in or use a cam-band system to attach cylinders. (Meg versatility)

You really can leave the Meg outside in the rain (if assembled off course).

If I was to buy today I’ll look at Meg first, then the JJ and/or Hammerhead and/or rEvo and then only the Inspo – If I was you I might even wait for the Pathfinder to be released early next year – saying this if I had to choose between diving OC or an Inspo, I’ll still dive the Inspo.

Dive Africa
11-11-11, 11:36 AM
O yes and meg does not have that plastic case that cracks, come loose and drifts off into the depths and a meg can stand upright :-)

Suzuki416
11-11-11, 11:44 AM
as a dual inspro user,

buying a 2nd hand inspro classic is the cheapest & easiest way of getting into CCR. The courses are easy to get onto, lots of instructors, everything is known about them - including the faults.

They are a great unit for learning on.
They are the Ford Mondeo of the CCR world.

matthewoutram
11-11-11, 11:53 AM
Go and have a look at rebreather world - there is a video under the meg forum of Leon Schammehorn doing some interesting things to the Meg - you could never do that to an Inspo.

Good post, but here you got carried away, I'm afraid. Not true.


... battery (a little more difficult, but they really last long time - I dive plenty and use only about 5 per annum. (there is a little adapter - $10 that allows you to use the standard square 9v battery if you are in a fix)

I dived with a chap a few years ago, his Meg turned off (completely) after his home-build battery dies on him without notice. Luckily we were at 6m, so the drama was minimised.

Regards
Matt.

steve6690
11-11-11, 11:57 AM
Well I'm chuffed to buggery with my Inspo Vision. Yep, the plastic case is shit and AP really should get that sorted, and one of my hoses seems to want to cross thread itself onto the tee piece so I have to wiggle it around a bit, but other than that I've no real moans with it. It works well and is easy to dive.
I nearly bought a 2nd hand Meg but Mrs Steve insisted I had to have a brand new unit (evil woman). Try and get a new Meg with scrubber monitor (if they even do one), trimix deco software,, fully loaded for £5500 including Mod 1. Cleaning it is a piece of piss - half an hour tops. Prepping it to go diving takes about the same time.
I've seen the video where Leon trashes his Meg underwater and it still dives. You can cut the handset off a vision and chop off the hud and it will still maintain setpoint too. And I'm pretty sure that if you cut off the bottom of the counterlung it would still keep you alive..

Dive Africa
11-11-11, 12:00 PM
Good post, but here you got carried away, I'm afraid. Not true.



I dived with a chap a few years ago, his Meg turned off (completely) after his home-build battery dies on him without notice. Luckily we were at 6m, so the drama was minimised.

Regards
Matt.

I said I was bias :embarassed:- there is a very good reason why I don not build my own batteries - I think you guys can just buy them from CD?

If you where to cut of both primary and secondary on an inspo classic - you would have no idea of PP and the solenoid will not work - this shows the benefit of a Hud (the Narked at 90 - shearwater HUD kit is a must (once again in my opinion) on a inspo classic with the meg even if the HUD is cut off (not that you would ever do it) the solonoid will still work at last set-point.

matthewoutram
11-11-11, 12:04 PM
I said I was bias :embarassed:- there is a very good reason why I don not build my own batteries - I think you guys can just buy them from CD?

If you where to cut of both primary and secondary on an inspo - you would have no idea of PP and the solenoid will not work - this shows the benefit of a Hud (the Narked at 90 - shearwater HUD kit is a must (once again in my opinion) on a inspo with the meg even if the HUD is cut off (not that you would ever do it) the solonoid will still work at last set-point.

True for Classic not for Vision.

Matt.

philsiswick
11-11-11, 12:05 PM
I said I was bias :embarassed:- there is a very good reason why I don not build my own batteries - I think you guys can just buy them from CD?

If you where to cut of both primary and secondary on an inspo - you would have no idea of PP and the solenoid will not work - this shows the benefit of a Hud (the Narked at 90 - shearwater HUD kit is a must (once again in my opinion) on a inspo with the meg even if the HUD is cut off (not that you would ever do it) the solonoid will still work at last set-point.

You (and others) really need to learn to distinguish between the Inspo Classic and the Inspo/Evo Vision when you post stuff like this.

What you say is true for the Classic, though you would have to go some to cut both handsets off.

It is not true for the Vision - as Steve says, you can cut the handset and HUD off and it would still keep setpoint. Both are remote displays (and in the case of the handset, a remote control) for the two controllers. IIRC, deco is calculated on the handset, but the unit will keep SP without it.

steve6690
11-11-11, 12:06 PM
I said I was bias :embarassed:- there is a very good reason why I don not build my own batteries - I think you guys can just buy them from CD?

If you where to cut of both primary and secondary on an inspo - you would have no idea of PP and the solenoid will not work - this shows the benefit of a Hud (the Narked at 90 - shearwater HUD kit is a must (once again in my opinion) on a inspo with the meg even if the HUD is cut off (not that you would ever do it) the solonoid will still work at last set-point.

You're comparing meg to Inspo Classic. The Vision is the newer model and a fairer comparison.

Read all about Vision electronics here :

http://www.rebreatherworld.com/inspiration-and-evolution-rebreather-articles/10514-a-closer-look-at-vision.html

Dive Africa
11-11-11, 12:07 PM
Yes sorry, was referring to classic - already edited my post

Scoop UK
11-11-11, 12:14 PM
Can I ask a side question...

I have heard people refer to Inspo Classics a being dangerous and referred to as YBODs etc and I know a friend of mine blacked out on one underwater. As a result he wont go near one anymore. I don't know the circumstances of that though other than it occured as he went shallower to swim over an obstacle.

Is there really an inherent problem with Inspos or is that a bit of a myth or possibly comes from earlier models? I've heard of electrical problems causing people to can dives but the situations I have heard of have been during testing as opposed to mid dive.

I have searched and cannot find any specific information, only anecdotal accounts.

humpbackdiving
11-11-11, 12:38 PM
Can I ask a side question...

I have heard people refer to Inspo Classics a being dangerous and referred to as YBODs etc and I know a friend of mine blacked out on one underwater. As a result he wont go near one anymore. I don't know the circumstances of that though other than it occured as he went shallower to swim over an obstacle.

Is there really an inherent problem with Inspos or is that a bit of a myth or possibly comes from earlier models? I've heard of electrical problems causing people to can dives but the situations I have heard of have been during testing as opposed to mid dive.

I have searched and cannot find any specific information, only anecdotal accounts.

Be careful when you say things like that unless you are aiming for a Friday ruck….:D

You are saying your friend blacked out swimming over an obstacle… how big was the obstacle, how deep was it, was he working hard against current, was the unit over due for service, was the scrubber packed properly - I assume it was his unit and he prepared it, how pedantic/anal is he in the prep/checks, how old were the cells… all these questions would need thorough answers before any realistic answer can be concluded.

Nobody says they are safer. They definitely need more love and care. You cant throw one in the garage after the dive and take it out from the garage to jump straight in.

They higher attention seeker than any woman I ever met… even mrs H.

All ccrs have problems and I don’t think it is easy to generalise the problems as you don’t know how they had been treated. An incident/failure on a CCR is a end result of an series of issues they may have been knowingly or unknowingly unattended.

Inspos being either clssics or visions form part of so many statistics because there are so many bleeding things. But that also means APD must be doing something right that beeing either productwise or servicewise.

Safest ccr is the one that was not dived yet but there is a separate thread for it.

My 2p

Greg
A happy owner of NSYBOD (not-so-yellow-box-of-DESIRE):D

Scoop UK
11-11-11, 12:45 PM
Just as I suspected. All are potentially dangerous, requiring their own special attention but can be used safely if maintained and operated correctly. I too thought that there is so many of them that there will, of course, be incidents involving that unit.

I don't want to look into things too deeply and cause a ruck! :D

I just wondered if maybe there was a problem that was resolved in the past or something like that. Seems strange that it has a reputation (inlcuding it's own acronym) but no-one can exaplin why! lol

I don't know enough about my friends incident to discuss really.

Thanks,

Sam

humpbackdiving
11-11-11, 12:48 PM
(inlcuding it's own acronym)

YBOD - yellow box of desire... job done

Dive Africa
11-11-11, 12:49 PM
I totally agree with humpbackdiving, and I can only add that it really would not hurt if you want to dive a classic (I did) to install the Narked at 90 Shearwater Hud, as additional safety.

Mark Chase
11-11-11, 01:09 PM
Can I ask a side question...

I have heard people refer to Inspo Classics a being dangerous and referred to as YBODs etc and I know a friend of mine blacked out on one underwater. As a result he wont go near one anymore. I don't know the circumstances of that though other than it occurred as he went shallower to swim over an obstacle.

Is there really an inherent problem with Ins's or is that a bit of a myth or possibly comes from earlier models? I've heard of electrical problems causing people to can dives but the situations I have heard of have been during testing as opposed to mid dive.

I have searched and cannot find any specific information, only anecdotal accounts.

Your friend blacked out either because he has a medical condition or because he screwed up. Not because of the unit.

My 2p would be for him not to go near any CCR till hes sorted the medical condition or learned how to dive one.


More big dives have been carried out on the Inspo Classic than all the other CCR in existence put together.

As a unit it is fairly well designed with a low work of breathing and a simple layout. It still has the best flood recovery and water tolerance of any unit i have ever dived.

The unit suffers from a few inherent problems.

Batter Box design is poor but later models were improved and I believe all serviced units have had theory battery box replaced. Battery box failure could result in intermittent power supply which can result in failure of the hand sets.

Not a problem if your diving it properly

The handsets suffered from the use of inappropriate materials in the construction of the gland where the cable enters. This caused the infamous cracked hand set issue which again would result in hand set failure. The good news is the hand sets are cheep to replace the bad news is they haven't changed the design so expect the hand sets to crack again.

The magnetic switches suffered from corrosion. Again not a big issue but an annoyance, The ferrous magnets needed regular cleaning and maintenance and periodic replacement.

The wiring loom was too exposed inside the head and was again the wrong material so it suffered from corrosion. This caused call errors and required a loom replacement ever second or third service which again wasn't that expensive but I resented paying for a design fault.


There is a critical 0 ring on top of the scrubber which is easily forgotten and can also get kinked. Not a great design feature but it is diver error if its assembled incorrectly. its well covered in mod 1.


Id argue that any unit without a HUD or BOV is a more risky unit to dive and the original classic had neither and APvalves wouldn't support you if you added after market items like i did.


That aside there was little or nothing dangerous about the Inspo Classic. The unit can and did fail but if you were diving it properly you should easily notice the failure modes and self rescue was simple enough.

No point in blaming the unit for diver incompetence. Show me a death on the Classic where the details of the incident are known and the blatant diver error is there for all to see. Not switching on the 02 not switching on the and sets, not doing any pre dive checks, not monitoring the unit and even bashing faulty hand sets against the side of the boat to get them working before jumping in the water. Its all there if you care to read it.


I used to dive a Hammer Head and prior to Dave Shaw's death they used to boast it had a perfect safety record. The inside joke was it had this because it was so bloody unreliable you never had a chance to become complacent. The problem with the Classic was it was too reliable. I did 160+ hours underwater on my Inspo Classic before it tried to kill me. But i was paying attention so it failed to make me a statistic on the day. Had i died when both hand sets shut down id have no one to blame but my self. I would ( and did) have several minutes to notice before i blacked out. And had i been checking my handsets every two mins I would (and did) notice the problem.

For non CCR divers its important to understand that everything on a CCR happens slowly. The only way to kill your self quickly on CCR is dill flush with a hypoxic mix and go shallow or do a rapid ascent on a very low PP02 mix faster than the 02 inject can catch up. Arguably a catastrophic flood would be quick but ll other failure modes are sloooooowwwwww. So its up to you to monitor the unit, understand what your reading and act upon it.

And i am not an APD zealot. I respect them but hate them and id never buy an inspo again because of my personal dislike of how APD do business. Despite my personal feelings I can not bring my self to slag off the units them selves. The new vision seems particularly adept and reliable but id still never buy one.


HTH

ATB

Mark

humpbackdiving
11-11-11, 01:35 PM
... inappropriate materials in the construction of the gland where the cable enters...

this being taken out of the context applies to vision design of tempstick cable. It is not the best design. I think, APD dont agree, it could be designed better as currently it comes up to a 180 turn to come down for storage in distance ring. Because of this it cracks at the point where it is moulded into the tempstick. This should cost me GBP300 if i can be bothered with replacing it.

Greg

DiveImage
11-11-11, 02:46 PM
I’ve owned a couple of AP units. I originally bought a 2nd hand Classic. Yes this did get me into CCR diving ‘cheaply’. However I had to replace so many parts I renamed it, Trigger's broom.
I then got an AP Evolution which was a reliable unit. The yellow box was a pain so I fitted a travel frame. Which also enabled me to use 3ltr cylinders opposed to the original 2ltrs.
I now have a Meg. Which I’m very pleased with.

Simon

matthewoutram
11-11-11, 09:34 PM
Can I ask a side question...

I have heard people refer to Inspo Classics a being dangerous and referred to as YBODs etc and I know a friend of mine blacked out on one underwater. As a result he wont go near one anymore. I don't know the circumstances of that though other than it occured as he went shallower to swim over an obstacle.

Is there really an inherent problem with Inspos or is that a bit of a myth or possibly comes from earlier models? I've heard of electrical problems causing people to can dives but the situations I have heard of have been during testing as opposed to mid dive.

I have searched and cannot find any specific information, only anecdotal accounts.

Classic diver for 9 years, no missed dives, no break-throughs, aborts, floods or bailouts,

Matt.

Dive Africa
15-11-11, 07:08 AM
I used to dive a Hammer Head and prior to Dave Shaw's death they used to boast it had a perfect safety record. The inside joke was it had this because it was so bloody unreliable you never had a chance to become complacent. The problem with the Classic was it was too reliable. I did 160+ hours underwater on my Inspo Classic before it tried to kill me. But i was paying attention so it failed to make me a statistic on the day. Had i died when both hand sets shut down id have no one to blame but my self. I would ( and did) have several minutes to notice before i blacked out. And had i been checking my handsets every two mins I would (and did) notice the problem.


Mark

Hey Mark

Technically you are correct offcourse and I support most of what you said, two small points I want to highlight:

Dave Shaw Dived a Mk15 - albeit with HH controllers;)
I think you are to hard on yourself... although I agree that diver takes 1st and ultimate responsibility, I am of the opinion that techical problems/design faults that the Classic had/has (although most/all would be caught by an alert diver and almost all are well known) combined with a diver having an off day could (to easily) creep on you with potentially bad consequences. I lost a good friend in Dec last year on a classic and it is still unclear if he forgot to switch his machine on or if the handset failed/switched off due to corrosion/battery issues - it actually does not matter as the result is still the same.

I for one will not touch any machine that does not have a HUD so that all relevant info is right in my face (excuse the pun) I would again strongly recommend that a aftermarket HUD is installed on all Classics.

Regards Dries

matthewoutram
15-11-11, 07:57 AM
I would again strongly recommend that a aftermarket HUD is installed on all Classics.

Regards Dries

If you need a HUD don't buy a classic, buy a Vision.

Condolences for your friend.

Matt.

NotDeadYet
15-11-11, 08:24 AM
Cant comment on the quality of the YBOD other than I find handsets off, whether by failure or accident, is a strange thing to blame for blackouts. How can you not spot it? I dont see what a HUD adds other than a fix for poor attention. What worries me more with software driven displays is them telling me shite. I'd rather it was off than that if I could choose a failure mode. Give me a nice simple voltmeter type display any day.

Anyhow, a couple of other points. Dave Shaw was diving a 15.5, not a 15. Small but important differences. And the controller didnt kill him, a combo of doing an ill thought out dive and scrubber failure did that.

Hammerheads have also moved on at least two generations since Mark's unit too. The newer handsets are very stable, the only problem I have had is cold killing standard alkaline batteries which is an easy fix. Other than that it hasnt missed a beat as a controller.

Sent from my GT-I9100 using Tapatalk

Dive Africa
15-11-11, 08:24 AM
Hi Matt

or a Meg or a JJ...:rolleyes:

the reality is that a lot of guys and galls, which now enter the CC arena, are buying Classics because they are available and cheap. it is these newbie rebreather divers which I am more concerned about - you can propably still buy a secondhand classic and install a HUD for cheaper than something with vison electronics (if you exclude deco computer prices)?

matthewoutram
15-11-11, 08:30 AM
Hi Matt

or a Meg or a JJ...:rolleyes:

the reality is that a lot of guys and galls, which now enter the CC arena, are buying Classics because they are available and cheap. it is these newbie rebreather divers which I am more concerned about - you can propably still buy a secondhand classic and install a HUD for cheaper than something with vison electronics (if you exclude deco computer prices)?

It's possible, I'd say. But the price difference isn't going to be much. A good Classic is £2000. It you're paying less then you are getting less. How much is a HUD - about a grand? For £3500 you can be into a second-hand Vision, with Deco Computer. So no real savings.

I agree with your comments about the target market though. IMHO rebreather diving isn't something you "do on a weekend", it takes more than that to make it work.

Cheers
Matt.

Dive Africa
15-11-11, 08:33 AM
Cant comment on the quality of the YBOD other than I find handsets off, whether by failure or accident, is a strange thing to blame for blackouts. How can you not spot it? I dont see what a HUD adds other than a fix for poor attention. What worries me more with software driven displays is them telling me shite. I'd rather it was off than that if I could choose a failure mode. Give me a nice simple voltmeter type display any day.



Sent from my GT-I9100 using Tapatalk

Exactly: an aid for bad concentration and/or poor concentration on a particular day - that is the whole purpose, people are human and they stuff up. My mate was an extremely experiences full trimix CCR and cave diver, he fell over at 6m (at the start of his dive) doing his S-drills. I am not saying that a HUD would have made a difference but it might have had.

I find the smithers code on the Meg quite helpful and if they point out something you can always have a look ate the mV display on the handset

NotDeadYet
15-11-11, 09:16 AM
I think you may be focussing on the wrong things. Good controllers are one thing but equally good practices are required too. I'm a luddite so for me things like being on pure o2 shallow, checking ppo2 regularly and before any depth changes, etc. are just as, if not more, important.

No one sets out to have accidents and no unit should be working against you but equally so many things are avoidable.

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matthewoutram
15-11-11, 10:33 AM
Exactly: an aid for bad concentration and/or poor concentration on a particular day - that is the whole purpose, people are human and they stuff up. My mate was an extremely experiences full trimix CCR and cave diver, he fell over at 6m (at the start of his dive) doing his S-drills. I am not saying that a HUD would have made a difference but it might have had.

I understand that you may not want to discuss this, so feel free to ignore me, Dive Africa. But do you have any more information on how that happened?

I always calibrate before I get in, always. This proves to me that I have O2 (Check O2 -> check gauge is showing 200 bar and push button to show needle does not move OC style). I also make a mental note of the cell end values - this gives me confidence in cell health. I end up with 0.99 in the loop. Pre-breath, first few breaths watch for falling ppO2 and critically watch for climbing ppO2 - this confirms solenoid working and cells responding. Jump-in, check-handsets. I don't do S-drills (actually, what are s-drills?), I do all my checks on the surface. To me this would indicate I have several minutes of breathable mix, certainly I'm confident that if the unit went off as I jumped I would make it to the bottom on breathable gas. You cannot just put a unit on and jump in like you can OC. This, I believe, is where modern-day CCR divers are going wrong - wrong thinking for this type of kit.

Regards
Matt.

humpbackdiving
15-11-11, 10:46 AM
Matt I can't belive anybody would be stupid enough to strap themselves to unit and roll back with no checks. There are some muppets but natural selection by the definition of accesabilty of ccr diving should allow only individuals with common sense into ccr diving.

Dive Africa
15-11-11, 11:42 AM
Unfortunately I was not at the cave site that day - I decided to do a trip down to the coast at the last minute instead - so most of what I know is hearsay and what I know of what he usually did - we will actually never know.

The site has steep stairs into the water and right at the stairs there is a hanging deco platform/grid. His dive team member says that on the day he prepped his machine - did his pre-breaths etc and left the kit up area - telling his team member (which was a little slower in kitting up) - that he will wait for him on the 5m grid - not unusual behavior/practice - it is very hot in SA in December(upper 30's at least) and you do not want to stand around in a dry-suit. When his mate got to the grid about 5 to 7min later, he was gone, but some bubbles were coming up from the bottom - depth there about 40m. He was found on the bottom - loop out of his mouth - and most likely already deceased.

Death was drowning, apparently caused by blackout from a hypoxic loop - all other causes such as heart attack were eliminated.

Planned dive was a level 7 at 68m as this is the only level in his dill range which is capable of exploration - his dill was a 10/50,

His machine was inspected by an extremely experienced/respected instructor trainer on site and immediately after the event. The machine was off.

As I already said my mate was well experienced and from diving with me I believe to be quite fastidious and thorough. What is unclear (and here I am speculating) was whether after doing his pre-breaths/prep he switched the machine off when waiting for his friend; changed his mind; decided to get in the water and just forgot to switch it on or whether the machine was switched on and due to electronic failure switched off. All I know is that his widow send the machine to AP for a service and she got a bill back off just below a 1000GBP - your guess is as good as mine.

He most likely also pre-breathed his machine on the walk down to the water.

We all talk about divers that must concentrate, be aware etc, but here we have a well experienced, fastidious cave and technical diver (also an instructor) who either forget to switch his machine on or failed to noticed that it died - If he can make a mistake like this so could I - this is probably the scariest thing and I would appreciate it that on the one day I make a mistake my machine doesn't do anything other than help me over the edge.

Training was not his issue, experience was not his issue, care (normally not) and he definitely did not stuff up to the extent that a momentary lapse in concentration should have led to his death. My personal believe is that something as simple as a HUD would have made a difference - a pressure switch or wet contact could also have made a difference.

I believe that the inherent (known) issues with the Classics electronics make this machine more susceptible to failure which combined with a lack of concentration/experience/training - on the day makes this machine less than desirable - I know that this machine is widely dived (i used to dive one) but please this post is only my opinion (might be right or wrong) and I would not appreciate being flamed for this. For other reasons I have been diving a Meg for about 4 or 5 years now.

Technical diving is extremely involved - you have a reel, a scooter, a dive light, dry-suit, etc to manage. Forgetting to check your handsets for 5mins should not kill you. This is why I believe that a HUD is a must - you can not miss that bloody blinking or more importantly a lack there-of.

Do I believe that a Classic is more dangerous than an Evolution, Meg, JJ, rEvo or HH, then my answer is yes - it is the one machine that I could never recommend (out of the above list). Do I believe that any of these machines are safer than OC or safe at all, then my answer is a definite no. Training and care is critical with all rebreathers

I trust this makes my somewhat opinionated opinion understandable.

Regards Dries

Dive Africa
15-11-11, 11:53 AM
Oh - S-Drills is a a cave diving/DIR term and stand for safety drills, basically consist of bubble check, gas checks, etc

NotDeadYet
15-11-11, 11:57 AM
Matt I can't belive anybody would be stupid enough to strap themselves to unit and roll back with no checks. There are some muppets but natural selection by the definition of accesabilty of ccr diving should allow only individuals with common sense into ccr diving.

I've seen plenty that do just that. I remember being on a weekend liveaboard where one guy's unit had rattled round the deck (literally, not tied down, just left face down on deck to roll with the boat - everyone fell over it or stood on it at somepoint) for the first day as he didnt dive. On the second day he picked it up, put it on and got in the water with fook all by way of checks. Gas pissing out it.

There are still a lot of clueless people about and they get away with it.

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Suzuki416
15-11-11, 12:04 PM
Sadly thats the real 'problem', With the older Classics, you CANNOT have an off day, you cannot stop monitoring them. Having an OC mindset of I'm breathing so it must be fine can bite you hard.
Both of my Classics have the [email protected] 4/5 cell holder. 1 unit has the SW HUD (can't say I like it though) & SW Pursuit plumbed in & the other unit (my normal use) has a SW GF plumbed in only.

Using an AP Classic without extra monitoring is dumb & I would not recommend that to anyone but when fitted with the SW - thats a different animal..

humpbackdiving
15-11-11, 12:04 PM
I've seen plenty that do just that. I remember being on a weekend liveaboard where one guy's unit had rattled round the deck (literally, not tied down, just left face down on deck to roll with the boat - everyone fell over it or stood on it at somepoint) for the first day as he didnt dive. On the second day he picked it up, put it on and got in the water with fook all by way of checks. Gas pissing out it.

There are still a lot of clueless people about and they get away with it.

Sent from my GT-I9100 using Tapatalk

That just made me cringe! I just hope that they have no luck than sense!

Suzuki416
15-11-11, 12:10 PM
Matt I can't belive anybody would be stupid enough to strap themselves to unit and roll back with no checks. There are some muppets but natural selection by the definition of accesabilty of ccr diving should allow only individuals with common sense into ccr diving.

There are an awful lot of these people about who think that the unit will just work.
They don't do checks, don't do maintanence, jump in with empty cylinders, units turned off, don't change sorb, don't carry bailout..
The list goes on.. & yet in most cases the unit functions enough to keep them alive. Then again sometimes it doesn't.

matthewoutram
15-11-11, 01:42 PM
I believe that the inherent (known) issues with the Classics electronics make this machine more susceptible to failure which combined with a lack of concentration/experience/training - on the day makes this machine less than desirable - I know that this machine is widely dived (i used to dive one) but please this post is only my opinion (might be right or wrong) and I would not appreciate being flamed for this. For other reasons I have been diving a Meg for about 4 or 5 years now.

Technical diving is extremely involved - you have a reel, a scooter, a dive light, dry-suit, etc to manage. Forgetting to check your handsets for 5mins should not kill you. This is why I believe that a HUD is a must - you can not miss that bloody blinking or more importantly a lack there-of.

Do I believe that a Classic is more dangerous than an Evolution, Meg, JJ, rEvo or HH, then my answer is yes - it is the one machine that I could never recommend (out of the above list). Do I believe that any of these machines are safer than OC or safe at all, then my answer is a definite no. Training and care is critical with all rebreathers

I trust this makes my somewhat opinionated opinion understandable.


Thanks for sharing your opinion and the info on this tragic event. I agree, the Classic is an old-design now and it does not have the safety-net that the other, more modern units have. In this regard you do get what you pay for and folks buying second hand Classics don't get HUD's, auto-switch-on's etc. Personal choice at the end of the day.


Oh - S-Drills is a a cave diving/DIR term and stand for safety drills, basically consist of bubble check, gas checks, etc

Ah, that's why it's unfamiliar to me. Bubble check, yes. All other checks are on land (for me).

Regards
Matt.

diveuk
15-11-11, 04:09 PM
S-drills = shut down drills, used when diving manifolded twins to isolate an air leak.

matthewoutram
15-11-11, 04:17 PM
S-drills = shut down drills, used when diving manifolded twins to isolate an air leak.

Oh, I've done lots of them, but never with a rebreather (and not for nearly 10 years!).

Cheers
Matt.

diveuk
15-11-11, 04:27 PM
I would not like to shut down the cylinders on my classic(which does not have a hud or sw or any other add-on, I do my predive checks, monitor my handsets regularly and know my ppO2 at all times, no problem) to isolate a leak.

Dive Africa
16-11-11, 05:53 AM
Oh, I've done lots of them, but never with a rebreather (and not for nearly 10 years!).

Cheers
Matt.

Yes, sort of an adaption of that, check for leaks, do "boom" shutdown of cylinders, check that machine is holding set-point (done out of water as well off-course)(check milivolts on handset to get an idea of cell linearity if you can) etc - in general get everything settled before a bigish dive. I.e no leaks, no other sh!t lets go dive... we tend to do this in a cave environment only - open sea not really as we dive in high current ocean so hitting the bottom fast is a high priority.

Mark Chase
16-11-11, 08:05 AM
Unfortunately I was not at the cave site that day - I decided to do a trip down to the coast at the last minute instead - so most of what I know is hearsay and what I know of what he usually did - we will actually never know.

The site has steep stairs into the water and right at the stairs there is a hanging deco platform/grid. His dive team member says that on the day he prepped his machine - did his pre-breaths etc and left the kit up area - telling his team member (which was a little slower in kitting up) - that he will wait for him on the 5m grid - not unusual behavior/practice - it is very hot in SA in December(upper 30's at least) and you do not want to stand around in a dry-suit. When his mate got to the grid about 5 to 7min later, he was gone, but some bubbles were coming up from the bottom - depth there about 40m. He was found on the bottom - loop out of his mouth - and most likely already deceased.

Death was drowning, apparently caused by blackout from a hypoxic loop - all other causes such as heart attack were eliminated.

Planned dive was a level 7 at 68m as this is the only level in his dill range which is capable of exploration - his dill was a 10/50,

His machine was inspected by an extremely experienced/respected instructor trainer on site and immediately after the event. The machine was off.

As I already said my mate was well experienced and from diving with me I believe to be quite fastidious and thorough. What is unclear (and here I am speculating) was whether after doing his pre-breaths/prep he switched the machine off when waiting for his friend; changed his mind; decided to get in the water and just forgot to switch it on or whether the machine was switched on and due to electronic failure switched off. All I know is that his widow send the machine to AP for a service and she got a bill back off just below a 1000GBP - your guess is as good as mine.

He most likely also pre-breathed his machine on the walk down to the water.

We all talk about divers that must concentrate, be aware etc, but here we have a well experienced, fastidious cave and technical diver (also an instructor) who either forget to switch his machine on or failed to noticed that it died - If he can make a mistake like this so could I - this is probably the scariest thing and I would appreciate it that on the one day I make a mistake my machine doesn't do anything other than help me over the edge.

Training was not his issue, experience was not his issue, care (normally not) and he definitely did not stuff up to the extent that a momentary lapse in concentration should have led to his death. My personal believe is that something as simple as a HUD would have made a difference - a pressure switch or wet contact could also have made a difference.

I believe that the inherent (known) issues with the Classics electronics make this machine more susceptible to failure which combined with a lack of concentration/experience/training - on the day makes this machine less than desirable - I know that this machine is widely dived (i used to dive one) but please this post is only my opinion (might be right or wrong) and I would not appreciate being flamed for this. For other reasons I have been diving a Meg for about 4 or 5 years now.

Technical diving is extremely involved - you have a reel, a scooter, a dive light, dry-suit, etc to manage. Forgetting to check your handsets for 5mins should not kill you. This is why I believe that a HUD is a must - you can not miss that bloody blinking or more importantly a lack there-of.

Do I believe that a Classic is more dangerous than an Evolution, Meg, JJ, rEvo or HH, then my answer is yes - it is the one machine that I could never recommend (out of the above list). Do I believe that any of these machines are safer than OC or safe at all, then my answer is a definite no. Training and care is critical with all rebreathers

I trust this makes my somewhat opinionated opinion understandable.

Regards Dries



By comparison the KISS has no PP02 control No Alarms and No wet switches and no one has ever died from jumping in with the unit switched off.

This is because of the mental attitude of the diver.

Classic divers become complacent due to the alarms and automated secondary control safety features. They expect the automated machine to work so when it doesn't, they die.

The ultimate sin is failing to switch on the hand sets. This not only shows a total lack of pre dive checks but the most basic failing of checking the loop PP02 as soon as you put the loop in your mouth, immediately after jumping in the water, immediately prior to decent, periodically during the dive before and immediately after going shallower for ANY reason.

IE Swim up over a boiler.... check hand sets.

The second reason for a Inspo Classic diver to die is both handsets failing without warning. This happens, I have had it happen to me but it should be caught during the above PP02 checks. If it takes 5mins fro the PP02 to drop from 1.3 down to 0.2 then you must check your hand sets within that time frame.

HUDS are great. I fitted one to my Inspo Classic, but they don't work in good light (usually shallow) or on the surface.

Buzzers are great if theres power to the hand sets

Wet on switches are not so great but they will catch you if you forget ALL the safety checks. Become complacent and even a wet switch wont save you. The handsets need power for the wet switches to work so if theres a power failure you still die.

I had wet switches try and kill me twice. They caused a repeating reboot on my unit which injected 02 across the cells in order to check cell function as part of the boot up route en.

At 70m this spiked my PP02 off the scale

I had a perfectly good passive secondary display which would have let me continue the dive no problem but due to the wet switches it was totally imposable to turn off the Primary Controller.

As for Dave Shaw? He was on a Mk15 and it had Hammer Head controllers. At that time Hammer Head only made controllers. Arguably the new Hammer Head CCR is the same in that it uses a load of bits from Golum and bolts them to a hammer Head controller

My Three Hammer Head units were spanking new latest software in 2007 I also had 05 and 06 spec as i had them upgraded to the 07 Spec.


On the MEG i have witnessed handset failures (internal broken micro switch) on the APex units and total handset failures on the Shearwater units. I have also seen two free flow solinoid failures.

No unit is imune to failure but the ones with the laest toys are the least likley to fail.


ATB

Mark

Mark Chase
16-11-11, 08:12 AM
Cant comment on the quality of the YBOD other than I find handsets off, whether by failure or accident, is a strange thing to blame for blackouts. How can you not spot it? I dont see what a HUD adds other than a fix for poor attention. What worries me more with software driven displays is them telling me shite. I'd rather it was off than that if I could choose a failure mode. Give me a nice simple voltmeter type display any day.

Anyhow, a couple of other points. Dave Shaw was diving a 15.5, not a 15. Small but important differences. And the controller didnt kill him, a combo of doing an ill thought out dive and scrubber failure did that.

Hammerheads have also moved on at least two generations since Mark's unit too. The newer handsets are very stable, the only problem I have had is cold killing standard alkaline batteries which is an easy fix. Other than that it hasnt missed a beat as a controller.

Sent from my GT-I9100 using Tapatalk



Good post but just to point out to my knowladge no one has ever died due to controler failure on ANY CCR.

The sad truth is if an Inspo diver gets in the water without switching on their unit or a KISS diver has a heart attack and is diagnosed with a pre dive heart conditin, its still classified as an Inspo Death and a KISS death.

I pointed this out to Kevin Jurgenson when I was threatened with action should i say it again over on RBW and he had to back down.

Hammer head deaths be they on the MK15 Optima or the Hammer Head CCR are still under the heading of Hammer Head.

ATB

Mark

Mark Chase
16-11-11, 08:17 AM
S-drills = shut down drills, used when diving manifolded twins to isolate an air leak.


Oh, I've done lots of them, but never with a rebreather (and not for nearly 10 years!).

Cheers
Matt.



Not quite:

During CCR Cave diveing training we do a S drill before the dive which includs the usual pre dive CCR checks you would perform at 6m plus a torch check on all torches and an OOA drill with deployment of the long hose bailout bottle to a buddy.

We were given the option at the end f the course to cut this back to personaly breathing off the stage on OC to ensure its working.

ATB

Mark

1693
16-11-11, 08:50 AM
S-drills = shut down drills, used when diving manifolded twins to isolate an air leak.Those are valve drills

S-Drills are gas sharing drills as has already been mentioned

Rob Dobson
16-11-11, 08:58 AM
Those are valve drills

S-Drills are gas sharing drills as has already been mentioned

Doesn't the 'S' in S-drill stand for 'Safety'? The safety drill being gas sharing and the valve drill being a shutdown? (not dived a twinset since 2007 so a little hazy).

matthewoutram
16-11-11, 09:25 AM
Those are valve drills

S-Drills are gas sharing drills as has already been mentioned

Well I never do gas sharing drills. How does a solo diver do them?

I think I'll rephrase my question: What does the "S" is S-drill mean?

Matt.

Scoop UK
16-11-11, 09:25 AM
Doesn't the 'S' in S-drill stand for 'Safety'? The safety drill being gas sharing and the valve drill being a shutdown? (not dived a twinset since 2007 so a little hazy).

The S drill for twinset (or in fact single tank) OC diving (at least for me as a GUE diver) is the donation of the primary reg and deployment of the long hose. Valve drill is seperate from that

Dive Africa
16-11-11, 09:32 AM
Seemingly S has different meanings for different schools/courses. I was tough that S stood for Safety - and depending on environment or whether diving OC or CC would be slightly different.

For solo diving change sharing drills with checking all cylinders are full and regulators are working (yes you have done this on land already) - I tend to do a baby purge (if any at all) and depending of if gas is hypoxic may take a swig of my bottom/main bailout cylinder and check for leaks on all bailout gasses. I would also close all gasses other than the appropriate one to be used at that depth.

NotDeadYet
16-11-11, 09:42 AM
Hammer head deaths be they on the MK15 Optima or the Hammer Head CCR are still under the heading of Hammer Head.

ATB

Mark

I find the whole classification by unit completely pointless. I dont think a properly rigged unit has ever been shown to be at fault.

On the other hand, I dont agree with classifying by add on. When someone has an accident on a JJ will that be a Shearwater accident? I have a Sartek display on my unit, would that be a Sartek accident?

Dave Shaw screwed up his unit whilst doing a stupid dive. There is no official scorecard so any classification is subjective and down to whoever is counting. Depending on your view you could start counting how many DUI users or how many carrying Scubapro kit.

We focus on equipment when you take out preexisting medical conditions 9 times out of 10 someone fucked up or no one knows (but there's a pretty good certainty they fucked up). As long as we keep counting how many Meg divers bought it, how many Inspos, etc then we wont address the issue of people doing stupid things. The only 100% common factor is that there was a human in the loop.



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Clare
16-11-11, 09:42 AM
For solo diving change sharing drills with checking all cylinders are full and regulators are working (yes you have done this on land already) - I tend to do a baby purge (if any at all)

Careful with just purging to check regs. Breathing on the surface and purging in water doesn't check the diaphragm.



Sent from my iPhone using Tapatalk

Dive Africa
16-11-11, 09:45 AM
Yes, thanks for caution, but can't breath of an hypoxic gas so, you hope that you maintained your equipment well and that if there is gas it will work.

matthewoutram
16-11-11, 09:49 AM
The only 100% common factor is that there was a human in the loop.

Better buy an iCCR then ;-)

Matt.

matthewoutram
16-11-11, 09:49 AM
Yes, thanks for caution, but can't breath of an hypoxic gas so, you hope that you maintained your equipment well and that if there is gas it will work.

One breath won't harm you.

philsiswick
16-11-11, 09:51 AM
I find the whole classification by unit completely pointless. I dont think a properly rigged unit has ever been shown to be at fault.

On the other hand, I dont agree with classifying by add on. When someone has an accident on a JJ will that be a Shearwater accident? I have a Sartek display on my unit, would that be a Sartek accident?

Dave Shaw screwed up his unit whilst doing a stupid dive. There is no official scorecard so any classification is subjective and down to whoever is counting. Depending on your view you could start counting how many DUI users or how many carrying Scubapro kit.

We focus on equipment when you take out preexisting medical conditions 9 times out of 10 someone fucked up or no one knows (but there's a pretty good certainty they fucked up). As long as we keep counting how many Meg divers bought it, how many Inspos, etc then we wont address the issue of people doing stupid things. The only 100% common factor is that there was a human in the loop.

I'm with you up to a point. Not taking into account the unit does mean that we may not spot an underlying unit-specifc issue that might be contributing to incidents and deaths. I agree that that would be more likely to be a training issue than a unit one, but as some instructors specialise in certain units, taking the unit into account could still point us at a key risk.

From everything that I have read and heard, I believe that the issues there appear to have been with early Classics were compounded with gaps in the training and habits of their users. With improved training and greater awareness of the issues, I see no reason that those units can be dived as safely as any other CCR.

The problem, as you point out, is that the unit focus drives the wrong behaviours - my unit has zero fatalities therefore I am safe - therefore I skimp on checks/preparation - therefore my unit has a fatality and is no longer safe......

Dive Africa
16-11-11, 09:56 AM
From everything that I have read and heard, I believe that the issues there appear to have been with early Classics were compounded with gaps in the training and habits of their users. With improved training and greater awareness of the issues, I see no reason that those units can be dived as safely as any other CCR.

The problem, as you point out, is that the unit focus drives the wrong behaviours - my unit has zero fatalities therefore I am safe - therefore I skimp on checks/preparation - therefore my unit has a fatality and is no longer safe......

Or maybe to both design/build the units without these bad traits and train the divers better. as an example most good/responsible rebreather manufacturers now use wiring that does not allow water ingress or corrosion.

Clare
16-11-11, 10:00 AM
Yes, thanks for caution, but can't breath of an hypoxic gas so, you hope that you maintained your equipment well and that if there is gas it will work.

I try to avoid 'hope' as a strategy ;)

Most gases on any dive aren't hypoxic. But even if bottom bailout is it is even more important to check this one delivers gas. I'll happily take a breath but if not you can still neg test the reg.


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Brad_Horn
16-11-11, 10:38 AM
I find the whole classification by unit completely pointless. I dont think a properly rigged unit has ever been shown to be at fault.

Shown to be at fault of what and to whom does it need to be proved, might be the question? You might be able to prove a fault on a rebreather though that may not be sufficient to prove it is at fault in any particular incident....

To keep this non political there is a really good accident investigation presentation from NEDU of their EX19 where it was found to be at fault.

Regards
Brad

Mark Chase
16-11-11, 10:42 AM
I find the whole classification by unit completely pointless. I dont think a properly rigged unit has ever been shown to be at fault.

On the other hand, I dont agree with classifying by add on. When someone has an accident on a JJ will that be a Shearwater accident? I have a Sartek display on my unit, would that be a Sartek accident?

Dave Shaw screwed up his unit whilst doing a stupid dive. There is no official scorecard so any classification is subjective and down to whoever is counting. Depending on your view you could start counting how many DUI users or how many carrying Scubapro kit.

We focus on equipment when you take out preexisting medical conditions 9 times out of 10 someone fucked up or no one knows (but there's a pretty good certainty they fucked up). As long as we keep counting how many Meg divers bought it, how many Inspos, etc then we wont address the issue of people doing stupid things. The only 100% common factor is that there was a human in the loop.



Sent from my GT-I9100 using Tapatalk


I see your point but at that time Hammer Head didnt make a whole unit so their claim was bassed on their controlers.

The Shearwater Meg, Shearwater rEvo should be classified seporatly as such because they are option units but ther Shearwater JJ dosen't come any other way so i supose you shoud just call it a JJ?

ATB

Mark

Dive Africa
16-11-11, 10:52 AM
Hey Mark and Chase

PM me your e-mail addresses and I'll send you the official medical reasoning for Dave Shaw's death, not quite as simple as you might think - ever heard of CO2 narcosis?

In any event I am going cave diving now until Sunday, it is a balmy 30 degC over here and the cave site is right in the middle of a game reserve.

Mark Chase
16-11-11, 11:21 AM
Hey Mark and Chase

PM me your e-mail addresses and I'll send you the official medical reasoning for Dave Shaw's death, not quite as simple as you might think - ever heard of CO2 narcosis?

In any event I am going cave diving now until Sunday, it is a balmy 30 degC over here and the cave site is right in the middle of a game reserve.

Thanks for thinking of me but I am well up on this incident with all the official and hypothesized work as well. C02 narcosis and retained C02 issues are two of my pet crusades

I attended Dr Mitchell's lecture and Dave's buddies Don Shirley's talk and i to believe retained C02 due to impaired WOB (asembly fault on Mk15) and a high viscosity gas choice was the cause of the fatality.

ATB

Mark

matthewoutram
16-11-11, 01:06 PM
i to believe retained C02 due to impaired WOB (asembly fault on Mk15) and a high viscosity gas choice was the cause of the fatality.

So not at all related to depth, lack of prolonged experience and ego, then?

Rhetorical.

Matt.

Mark Chase
16-11-11, 03:24 PM
So not at all related to depth, lack of prolonged experience and ego, then?

Rhetorical.

Matt.



No

ATB

Mark

matthewoutram
16-11-11, 03:37 PM
No

ATB

Mark

http://ecx.images-amazon.com/images/I/41vXz478WZL._BO2,204,203,200_PIsitb-sticker-arrow-click,TopRight,35,-76_AA300_SH20_OU02_.jpg

Mark Chase
16-11-11, 07:57 PM
http://ecx.images-amazon.com/images/I/41vXz478WZL._BO2,204,203,200_PIsitb-sticker-arrow-click,TopRight,35,-76_AA300_SH20_OU02_.jpg



And?

I don't think its relevant to what happened.

No one could have survived what happened to him. I also don't believe there was any appreciation for the effects of raised WOB and gas viscosity at depth and their relationship to C02.

Lets not forget he'd done a successful dive to that depth prior to this fatal accident. As for his diving history? It depends what the dives were.

I know some good trimix divers who haven't done 200 mix dives. Most of the lads i dive with in Delta are lucky if they do 20 dives a year total. 350 dives is 17 years experience to them. However 95% of the 20 dives they do do in a year are 60-90m.

No one had the proper level of experience at that depth. With 20/20 hind sight you wouldn't do that dive on anything but Heleox and he should have aborted as soon as it was obvious the body was intact. However the mental attitude of having a go is something sadly I can well understand. I'd probably have pushed my luck as well. Stupid decisions under water is something I accept happens.

Had the same man done the same dive with the common knowledge we have today (thanks in no small part Dr Simon Mitchells reserch into his death). I reckon he'd have succeeded.


ATB

Mark

matthewoutram
16-11-11, 08:39 PM
And?

I don't think its relevant to what happened.

...




The dive on which David Shaw died was the 333rd of his career. At the time of his world record setting dive, he had been diving for just over 5 years.


I disagree, I think experience comes with both time and number of dives. Silly dive, period.

Regards
Matt.

NotDeadYet
16-11-11, 08:52 PM
Had the same man done the same dive with the common knowledge we have today (thanks in no small part Dr Simon Mitchells reserch into his death). I reckon he'd have succeeded.

What knowledge? Not to put your unit together in the wrong sequence using the wrong materials cut to the wrong shape?

ashsg79
16-11-11, 09:56 PM
theres a lot of slating going on about the classic, handsets failing/turning off etc/etc. If you are tuned in like i like to be you can hear the solenoid fire, now if i don't hear that thing fire within five minutes then i doubly check my handsets. Now i may get slated here but you are pretty fu**ing unlucky to have both handsets go down on you not hear the buzzer and not hear the solenoid fire? Its all about awareness and please correct me if im wrong i only have about 20 hours on my classic but treat it with respect (but do not over complicate things!)

Keep up with maintenance/dont abuse the scrubber (is £6 really worth your life) do all your checks, pre breathe and calibrate before EVERY dive (it takes 20 seconds/about 5 bar O2)

and if you do the above then imho you will be fine. Oh and the most important thing get trained off someone who knows what they are doing, and knows the classic/vision whatever breather inside and out and has vast experience on the given unit.

slate away :)
my 2p's worth

IF IN DOUBT BAILOUT PEEP'S

divetheworld
17-11-11, 08:04 AM
True for Classic not for Vision.

Matt.

Both units use LP regulator hoses as cable protectors and have the handsets exposed to loop gas. If you cut off either the Vision or Classic, you flood the unit.


How much is a HUD - about a grand?

Cheers
Matt.

Half that.


Copying skips understanding.
WWW.NARKEDAT90.COM

NotDeadYet
17-11-11, 09:22 AM
Both units use LP regulator hoses as cable protectors and have the handsets exposed to loop gas. If you cut off either the Vision or Classic, you flood the unit.



Half that.


Copying skips understanding.
WWW.NARKEDAT90.COM

I never knew that. Does that also mean the opposite, if you flood the unit then (potentially) you can flood the handsets?

Sent from my GT-I9100 using Tapatalk

Rob Dobson
17-11-11, 09:32 AM
now if i don't hear that thing fire within five minutes then i doubly check my handsets.

Out of interest how often do you check your handsets when you can hear the solenoid firing?

ashsg79
17-11-11, 09:45 AM
Out of interest how often do you check your handsets when you can hear the solenoid firing?

i aim for every 2 mins and cross check master to slave

NotDeadYet
17-11-11, 09:45 AM
Out of interest how often do you check your handsets when you can hear the solenoid firing?

My unit had a very noticeable solenoid click. More a punch in the kidneys than a click really (handset light dimmed when it fired because it drew so much power). Anyway, I found I got into the rhythm of it quite quickly. You noticed when it wasn't there and equally you noticed if it was there more than you expected. So much so that when the electronics died I ran it on the pushbutton for six months and it was almost bang on target every time because I was injecting in the same rhythm I was used to with the solenoid.

The HH solenoid is much quieter. It's great being able to use one AA battery over a few dives as opposed to 16 of them for one dive but I really miss being as aware of it firing. I think sound of the unit running is a great secondary health cue, I wish I could turn the volume up on mine.

Sent from my GT-I9100 using Tapatalk

matthewoutram
17-11-11, 10:26 AM
Half that.

This is the one I looked at:

http://narkedat90.com/shop/images/product/HUD_APDCLASSIC_FULLKIT_MOLEX.JPG

£941.15 delivered, maybe there are other options. ADP Classic HUD Kit (EXPORT ONLY) (http://narkedat90.com/shop/product/hud_kit_apd_classic/)

I understood that the Vision handset is potted.

Matt.

ashsg79
17-11-11, 10:28 AM
This is the one I looked at:

http://narkedat90.com/shop/images/product/HUD_APDCLASSIC_FULLKIT_MOLEX.JPG

£941.15 delivered, maybe there are other options. ADP Classic HUD Kit (EXPORT ONLY) (http://narkedat90.com/shop/product/hud_kit_apd_classic/)

I understood that the Vision handset is potted.

Matt.

thats what i looked at as well, if it can be done for half that i would be interested definately

erikradstrom
17-11-11, 10:48 AM
theres a lot of slating going on about the classic, handsets failing/turning off etc/etc. If you are tuned in like i like to be you can hear the solenoid fire, now if i don't hear that thing fire within five minutes then i doubly check my handsets. Now i may get slated here but you are pretty fu**ing unlucky to have both handsets go down on you not hear the buzzer and not hear the solenoid fire? Its all about awareness and please correct me if im wrong i only have about 20 hours on my classic but treat it with respect (but do not over complicate things!)

Keep up with maintenance/dont abuse the scrubber (is £6 really worth your life) do all your checks, pre breathe and calibrate before EVERY dive (it takes 20 seconds/about 5 bar O2)

and if you do the above then imho you will be fine. Oh and the most important thing get trained off someone who knows what they are doing, and knows the classic/vision whatever breather inside and out and has vast experience on the given unit.

slate away :)
my 2p's worth

IF IN DOUBT BAILOUT PEEP'S

If the slave turns off before the master there is no alarm, no buzzer nothing. I dive a classic and I have kept the old solenoid just because I can hear it. I would react if it stopped firing, but that not true to all people so I don´t use it as an argument that it is a safe unit.

The Classic is an ok unit, it doesn´t kill you but you need to be observant. Maybe more than on other units, but it doesn´t make it a dangerous unit because of this. It’s a great unit to start with because you need to learn the basics, I dive mine without a HUD and someone earlier called that dumb but I would say that a person that can’t manage a Rebreather without a HUD is dumb and should rethink if Rebreather diving is something you should do. HUD´s are great but you should be able to dive a Rebreather without one without its getting dangerous.

I dive 3 stages, lights and a camera and I still check the PO2 on the handset, sometimes it´s a PITA but it works. If you pass out from the handset turning off than it´s not the unit that killed you, it´s your bad judgment and skills. You don’t breathe the loop to dangerous levels within a couple of breaths. It takes time and if you didn´t check you PO2 within that time you failed at the first rule you learned on you MOD 1 course. Always know you Po2.

humpbackdiving
17-11-11, 10:53 AM
Out of interest how often do you check your handsets when you can hear the solenoid firing?

do you want an honest answer? on vision - not that often, well as i should
book answer - often.

Hence I am not looking forward to the quite solenoid if/when I have to change mine.

the little audible squirt of o2 is very balming.

matthewoutram
17-11-11, 11:30 AM
do you want an honest answer? on vision - not that often, well as i should
book answer - often.

Hence I am not looking forward to the quite solenoid if/when I have to change mine.

the little audible squirt of o2 is very balming.

What quiet solenoid?

jturner
17-11-11, 11:38 AM
Both units use LP regulator hoses as cable protectors and have the handsets exposed to loop gas. If you cut off either the Vision or Classic, you flood the unit.

Are you sure? I was under the impression the Vision handset hose was sealed and so wasn't exposed to the loop? Dunno about the classic.

humpbackdiving
17-11-11, 11:39 AM
Isn't 2nd gen quieter than 1st? It may be that the difference is not that noticeable.

matthewoutram
17-11-11, 11:43 AM
Isn't 2nd gen quiter than 1st? It may be that the diifeence is not that noticeable.

Second Generation is obsolete, they are quieter but can be heard. The current solenoid is based on the same design as the first but with a low-power coil like the second. They are noisy and easy to hear.

Matt.

matthewoutram
17-11-11, 11:43 AM
If the slave turns off before the master there is no alarm, no buzzer nothing. I dive a classic and I have kept the old solenoid just because I can hear it. I would react if it stopped firing, but that not true to all people so I don´t use it as an argument that it is a safe unit.

The Classic is an ok unit, it doesn´t kill you but you need to be observant. Maybe more than on other units, but it doesn´t make it a dangerous unit because of this. It’s a great unit to start with because you need to learn the basics, I dive mine without a HUD and someone earlier called that dumb but I would say that a person that can’t manage a Rebreather without a HUD is dumb and should rethink if Rebreather diving is something you should do. HUD´s are great but you should be able to dive a Rebreather without one without its getting dangerous.

I dive 3 stages, lights and a camera and I still check the PO2 on the handset, sometimes it´s a PITA but it works. If you pass out from the handset turning off than it´s not the unit that killed you, it´s your bad judgment and skills. You don’t breathe the loop to dangerous levels within a couple of breaths. It takes time and if you didn´t check you PO2 within that time you failed at the first rule you learned on you MOD 1 course. Always know you Po2.

Good post, pretty much sums it up for me.

Matt.

whelk
17-11-11, 01:02 PM
A bit of a digression, but huge thanks to the participants in this thread. I'd love a rebreather but as a newbie it's hugely overwhelming; you hear so many people say so many different things (most of them dire warnings that contradict other dire warnings), but this is really helpful. So, uh, thanks. :)

Mark Chase
17-11-11, 10:20 PM
What knowledge? Not to put your unit together in the wrong sequence using the wrong materials cut to the wrong shape?

Not quite

A: not to use a trimix with a 50m+ END due to depth related viscosity issues.

B: To minimise WOB and work load due to retained C02 issues at great depth


Had he been aware of the importance of thease issues possably hed have looked more closley at the design and function of his unit and realised the material and asembly were in error. Up untill then i have no doubt he was confident hed been doing it corectly. It does beg the question of who taught him to dive the MK15 or what reserch hed done.

I understood the standard componenet he should have used was hard to obtain and that the felt pad was a common replacement? The asembly however was aparently wrong so why was he doing it this way?

ATB

Mark

Mark Chase
17-11-11, 10:42 PM
theres a lot of slating going on about the classic, handsets failing/turning off etc/etc. If you are tuned in like i like to be you can hear the solenoid fire, now if i don't hear that thing fire within five minutes then i doubly check my handsets. Now i may get slated here but you are pretty fu**ing unlucky to have both handsets go down on you not hear the buzzer and not hear the solenoid fire? Its all about awareness and please correct me if im wrong i only have about 20 hours on my classic but treat it with respect (but do not over complicate things!)

Keep up with maintenance/dont abuse the scrubber (is £6 really worth your life) do all your checks, pre breathe and calibrate before EVERY dive (it takes 20 seconds/about 5 bar O2)

and if you do the above then imho you will be fine. Oh and the most important thing get trained off someone who knows what they are doing, and knows the classic/vision whatever breather inside and out and has vast experience on the given unit.

slate away :)
my 2p's worth

IF IN DOUBT BAILOUT PEEP'S

Don't believe the hype.

Never trust the unit to do what its supposed to do. Confirm everything with hard checks against known gases.

I did 160 something fault free hours underwater on my Inspo Classic before it failed by both handsets switching off.

There was no buzzer warning.

Personally on sea dives with my 8mm hood on I couldn't hear my solenoid fire at all unless i made a conscious effort to listen out for it.

And calibrating before every dive??

Why

If your cells have dropped out of calibration overnight there's something wrong with them or the loom and you would be calibrating over a possible bad electrical connection.

I used the old AP cells for the last six years and they were pretty good (unlike the new ones). On average id say i calibrate my unit once every two or three months.

I check the cells in air then i check them in pure 02. If they are correct why calibrate?

If your unit calibrated yesterday and today its significantly out then you must ask the question as to why its out. Cells erode over time and failure is progressive . Usually your warned by an increase in performance. IE faster reaction time on the cell and higher millivolt output. QED if cell 2 was suddenly reading high? Id suspect it was about to fail. If its suddenly reading low? id swap it over with cell one and see if the error follows the cell. If so its a cell issue if not its a wiring issue.

What I wouldn't do is calibrate over the issue.


I had a Hammer Head controller for my inspo. I put thee new cells in it and went to calibrate. It rejected the cells.

I phoned Martin Parker to say the cells had failed and he blamed the Hammer Head.

So i put the cells in my old Inspo Classic head and calibrated them no problem

Drove to the dive site and jumped in the water. And flushing 02 at 8m found two of the cells were current limited so i had to abort the dive.

ATB

Mark

ashsg79
17-11-11, 10:55 PM
any info on the half price (than a grand) HUD? not really been able to follow this thread today

ashsg79
17-11-11, 11:14 PM
Don't believe the hype.

Never trust the unit to do what its supposed to do. Confirm everything with hard checks against known gases.

I did 160 something fault free hours underwater on my Inspo Classic before it failed by both handsets switching off.

There was no buzzer warning.

Personally on sea dives with my 8mm hood on I couldn't hear my solenoid fire at all unless i made a conscious effort to listen out for it.

And calibrating before every dive??

Why

If your cells have dropped out of calibration overnight there's something wrong with them or the loom and you would be calibrating over a possible bad electrical connection.

I used the old AP cells for the last six years and they were pretty good (unlike the new ones). On average id say i calibrate my unit once every two or three months.

I check the cells in air then i check them in pure 02. If they are correct why calibrate?

If your unit calibrated yesterday and today its significantly out then you must ask the question as to why its out. Cells erode over time and failure is progressive . Usually your warned by an increase in performance. IE faster reaction time on the cell and higher millivolt output. QED if cell 2 was suddenly reading high? Id suspect it was about to fail. If its suddenly reading low? id swap it over with cell one and see if the error follows the cell. If so its a cell issue if not its a wiring issue.

What I wouldn't do is calibrate over the issue.


I had a Hammer Head controller for my inspo. I put thee new cells in it and went to calibrate. It rejected the cells.

I phoned Martin Parker to say the cells had failed and he blamed the Hammer Head.

So i put the cells in my old Inspo Classic head and calibrated them no problem

Drove to the dive site and jumped in the water. And flushing 02 at 8m found two of the cells were current limited so i had to abort the dive.

ATB

Mark

Why not calibrate before every dive?? You are obviously more experienced than me so please explain where the harm in doing so is?

Suzuki416
18-11-11, 07:39 AM
I only calibrate if I've taken the head off (put new sorb in). I don't calibrate every dive. (13yr old Fibreglass Classic)

NotDeadYet
18-11-11, 07:42 AM
Not quite

A: not to use a trimix with a 50m+ END due to depth related viscosity issues.

B: To minimise WOB and work load due to retained C02 issues at great depth


Had he been aware of the importance of thease issues possably hed have looked more closley at the design and function of his unit and realised the material and asembly were in error. Up untill then i have no doubt he was confident hed been doing it corectly. It does beg the question of who taught him to dive the MK15 or what reserch hed done.

I understood the standard componenet he should have used was hard to obtain and that the felt pad was a common replacement? The asembly however was aparently wrong so why was he doing it this way?

ATB

Mark

Do we really need 5 years of learning to know a 50m END wasn't a good idea? If nothing else his unit was designed for heliox, you really need to question if it is wise to second guess what in today's money was a $25m design programme. A read through the specs in the manual should have been enough. They have been used to around 500m in the 70's.

Felt pads are common on Mk15's because they are held away from the scrubber in a cage inside the lid. It is a lot harder for them to fall against the scrubber. On the 15.5 the absorbent pads are loose fit on top of it. Felt is totally the wrong material, as soon as it gets wet it is directly going to affect the WOB.

The standard part is foam sheet. The spacer was the wrong way round so he had in effect a wet towel sat right on top of the scrubber. That would have done it at any depth.

He was a clever guy but in my entirely subjective view the whole project had no other outcome right from the start. A total and pointless waste.

Sent from my GT-I9100 using Tapatalk

Mark Chase
18-11-11, 07:50 AM
Why not calibrate before every dive?? You are obviously more experienced than me so please explain where the harm in doing so is?

I wrote it all in the thread you just cut and paste.

Cells work on a chemical reaction. They are perminantly on from the day they were manufactured. They take months to deterioate, not hours. If a cell has fallen out of calibration overnight then theres a fault which should not be calibrated over.

What i call "blind" cal;ibration (IE who cares what the cells read just calibrate imediatly before the dive), is dangerous because the most likley time for a cell to fail is the day after you preped the unit. What can hapens is you calibrae the cells during prep the day before and then switch off the unit and store it overnight waiting for the dive. The cells are now soaking in pure 02 and working flat out. Next day they are dead or near dead after something like 18-20 hours soaking in 02 and working hard.

So your on the boat an kitting up and cell two which you calibrated yesterday is reading high ( A good sign its about to fail) so you calibrate it over the problem and go diving. From the second you jump in the cell is in failure mode as it burns through the last of the reactive layer on the cell face in 1.3PP02

Did you cange out all three cells at the same time?

Now you in a situation where more than one cell could be failing on the same dive.

After the overnight burn out hapened to me I changed my equipmnet set up routeen so id check the head in air (PITA on a Classic) then asemble the rig and triple flush with 02 to check cells reading 0.95 -1.0. Then inject diluient for positive presure test, then id do a neg test and my last test was to flush diluient accross the cells to get the PP02 of my dill (Usualy below 0.21)

After that id close the loop and leave the cells soaking overnight in trimix not 02

On the boat id turn on the unit and let it find 0.7 low set ponit. After which id manualy inject 02 to bring the unit back up to 0.95-1.0. If all the cells were in that range i'm good to dive.

Finaly at 7-8m id inject 02 and spike the cells to 1.7-1.8 to insure they were capable of well above set point 1.3 and shalow deco of 1.6


HTH


ATB

Mark

Dangerous Dave
18-11-11, 07:53 AM
any info on the half price (than a grand) HUD? not really been able to follow this thread today

Stick a rEvo NGDream on it Ash, can be had for less than €500 new from the factory.

Mark Chase
18-11-11, 08:12 AM
Do we really need 5 years of learning to know a 50m END wasn't a good idea? If nothing else his unit was designed for heliox, you really need to question if it is wise to second guess what in today's money was a $25m design programme. A read through the specs in the manual should have been enough. They have been used to around 500m in the 70's.

Felt pads are common on Mk15's because they are held away from the scrubber in a cage inside the lid. It is a lot harder for them to fall against the scrubber. On the 15.5 the absorbent pads are loose fit on top of it. Felt is totally the wrong material, as soon as it gets wet it is directly going to affect the WOB.

The standard part is foam sheet. The spacer was the wrong way round so he had in effect a wet towel sat right on top of the scrubber. That would have done it at any depth.

He was a clever guy but in my entirely subjective view the whole project had no other outcome right from the start. A total and pointless waste.

Sent from my GT-I9100 using Tapatalk


I agree with all that you are saying but again my point is had the issues of retained C02 due to WOB been common knowladge at they time as they are today, do you not think more focus would have been put on that issue?

From day one I have said his END was insain. I am guessing he was more focused on reducing deco than anything else but the critical point here is he must have felt he could manage the END but i am confident the issue of gas viscosity never entered his mind.

ATB

Mark

NotDeadYet
18-11-11, 08:21 AM
I agree with all that you are saying but again my point is had the issues of retained C02 due to WOB been common knowladge at they time as they are today, do you not think more focus would have been put on that issue?

From day one I have said his END was insain. I am guessing he was more focused on reducing deco than anything else but the critical point here is he must have felt he could manage the END but i am confident the issue of gas viscosity never entered his mind.

ATB

Mark

No, I dont think anything would have been different. I think it was a dive that would have gone ahead whatever.

Sent from my GT-I9100 using Tapatalk

1693
18-11-11, 08:37 AM
I check the cells in air then i check them in pure 02. If they are correct why calibrate? Personally, I'd call that calibrating.

I understand what you're saying Mark - just calibrating without understanding or paying attention to what's going on is worse than useless. But, if you do pay attention to what's going on and, more importantly, understand it then what's the harm in doing it every time the head goes back in?

I do the same as Suzuki and calibrate whenever I replace the head. I like to see the raw numbers and see how they respond as the PO2 rises. If I calibrated yesterday and today I'm getting something way different to .21 on any cell when I switch the unit on I'll investigate.

Also, on the JJ the solenoid battery voltage doesn't get checked until the solenoid fires as it needs to be checked under load. Getting that checked as soon as the head goes back in, rather that during a pre-breathe when I'm all kitted-up has already saved me having to probably miss a dive.

philsiswick
18-11-11, 08:56 AM
Personally, I'd call that calibrating.

I understand what you're saying Mark - just calibrating without understanding or paying attention to what's going on is worse than useless. But, if you do pay attention to what's going on and, more importantly, understand it then what's the harm in doing it every time the head goes back in?

I do the same as Suzuki and calibrate whenever I replace the head. I like to see the raw numbers and see how they respond as the PO2 rises. If I calibrated yesterday and today I'm getting something way different to .21 on any cell when I switch the unit on I'll investigate.

Also, on the JJ the solenoid battery voltage doesn't get checked until the solenoid fires as it needs to be checked under load. Getting that checked as soon as the head goes back in, rather that during a pre-breathe when I'm all kitted-up has already saved me having to probably miss a dive.

+1

Mark Chase
18-11-11, 09:10 AM
Personally, I'd call that calibrating.

I understand what you're saying Mark - just calibrating without understanding or paying attention to what's going on is worse than useless. But, if you do pay attention to what's going on and, more importantly, understand it then what's the harm in doing it every time the head goes back in?

I do the same as Suzuki and calibrate whenever I replace the head. I like to see the raw numbers and see how they respond as the PO2 rises. If I calibrated yesterday and today I'm getting something way different to .21 on any cell when I switch the unit on I'll investigate.

Also, on the JJ the solenoid battery voltage doesn't get checked until the solenoid fires as it needs to be checked under load. Getting that checked as soon as the head goes back in, rather that during a pre-breathe when I'm all kitted-up has already saved me having to probably miss a dive.

I dissagree. Confirming cells is not calibrating.

If a cell is reading 0.8 when it was calibrated yesterday at 1.0 its likely theres a fult. Calibrating the unit to make the cell showing 0.8 show 1.0 is just compounding the problem.

Seeing a cell reading 0.8 and thinking thats odd id better calibrate the unit, is NOT a good responce to the issue.

My unit litraly goes months wiothout being calibrated simply because it doesn't need calibrating. It still reads in range when I switch it on so why calibrate?

Dive a KISS for a few years and you will soon get used to this method.


When i owned a Hammer Head i complained to Kevin Jurgonson that it needed pure 02 to calibrate and i couldent get this on red sea livaboards.

His responce was f#ck how long are you away for? your unit shouldent need recalibrating within a fortnight unless you have a cell failure


The simple fact is this: You should be checking your cells for linnier responce. To do this you need a two point check in air and in 02. You can not test the high P02 range by calibrating, you can only test it by 02 flush.

If they pass the linier test why do you need to calibrate?

If they fail the linnier test why are you calibrating over the problem?


Personaly on asembley my unit fires the solinoid like mad without calibrating if i have the 02 switched off. I have to switch the low set point to 0.19 to stop it fireing like mad.

Just switch on the hand sets without switching on the 02 on a 0.7 set point and your test load issue is solved.


ATB

Mark

1693
18-11-11, 09:17 AM
My unit litraly goes months wiothout being calibrated simply because it doesn't need calibrating. It still reads in range when I switch it on so why calibrate?So when do you calibrate - when new cells go in, then never? Better hope those cells were linear the one and only time you ever bothered.

Me, I've got a [email protected] cell checker that I run the cells through every few months. Sounds like I know a lot more about going on with my cells than you ;)

Mark Chase
18-11-11, 09:55 AM
So when do you calibrate - when new cells go in, then never? Better hope those cells were linear the one and only time you ever bothered.

Me, I've got a [email protected] cell checker that I run the cells through every few months. Sounds like I know a lot more about going on with my cells than you ;)



I usually calibrate when the pure 02 reading drops below 0.95.

If it drops below 0.9 ill strip out the cells clean the contacts check the wiring swap the low cell onto another terminal and re test before calibration.

When i adopted this system on my Inspo classic my cell errors disappeared. Main problem on the classic was black crud forming on the cell pins. Next common problem was wire breakage at the mo lex connector in the loom.

Digger turned up at my house once with his KISS complaining about constant cell errors.

We striped out his head and found very heavy corrosion on the cell pins and mo lex connections. He'd basically been calibration over bad connections. When a good or worse connection was made due to vibration the cell readings dropped out and produced a cell error.

This problem was made worse for me on my KISS with the Shearwater display on a Fischer connector. I had corrosion issues inside the Fischer connector that caused fluctuations in the displayed cell readings. I noticed the problem because my HUD was remaining constant when my handset was showing cell errors.

I had to extend my cleaning protocol to include the Fischer connector which was regularly cleaned in Biox and then assembled dry in baby oil. I kept the amount of time it was disconnected from the unit to an absolute minimum to avoid internal corrosion.

The JJ, rEvo and Inspo were great because you have easy access to the cells to enable checking for broken wires and dirty cell contacts. On the KISS it was much more of a pain.

ATB

Mark

Suzuki416
18-11-11, 10:23 AM
Mark,

The reason I 'calibrate' once I've assembled the head (before I put the back on) is to pick up any faults that may or may not have happened.

I also bounce the po2 up at 6 - 8m to check for current limiting but:

I'd rather be above water fixing a problem than below water dealing with it.

Suzuki416
18-11-11, 10:34 AM
The Inspro manual says:

Calibrate every day of use.

&

It is essential though to recalibrate at least every 3 hours of diving.

matthewoutram
18-11-11, 05:10 PM
Why not calibrate before every dive?? You are obviously more experienced than me so please explain where the harm in doing so is?

I can't think of a single reason why I wouldn't follow the manufacturers recommendation and calibrate before every dive. Recommending anything else is foolish.

Matt.

matthewoutram
18-11-11, 05:11 PM
I agree with all that you are saying but again my point is had the issues of retained C02 due to WOB been common knowladge at they time as they are today, do you not think more focus would have been put on that issue?

From day one I have said his END was insain. I am guessing he was more focused on reducing deco than anything else but the critical point here is he must have felt he could manage the END but i am confident the issue of gas viscosity never entered his mind.

ATB

Mark

Had he simply not built the experience needed to make such a dive?

Suzuki416
18-11-11, 06:04 PM
I can't think of a single reason why I wouldn't follow the manufacturers recommendation and calibrate before every dive. Recommending anything else is foolish.

Matt.

What they do say is what I posted:

It is essential though to recalibrate at least every 3 hours of diving
& Calibrate every day of use.

Nowhere in the manual does it say Calibrate every DIVE.

Two Hats
18-11-11, 06:26 PM
What they do say is what I posted:

It is essential though to recalibrate at least every 3 hours of diving
& Calibrate every day of use.

Nowhere in the manual does it say Calibrate every DIVE.

To be fair to Matt, a lot of his dives would be around or over 3 hours:)

mala
18-11-11, 06:36 PM
I can't think of a single reason why I wouldn't follow the manufacturers recommendation and calibrate before every dive. Recommending anything else is foolish.

Matt.

i think i would be more inclined to know why the manufacturer was recommending calibration before every dive.

seems a bit ott.

i was taught on a meg but it would be nice to know what the inspro instructers teach.

Mark Chase
18-11-11, 07:02 PM
Mark,

The reason I 'calibrate' once I've assembled the head (before I put the back on) is to pick up any faults that may or may not have happened.

I also bounce the po2 up at 6 - 8m to check for current limiting but:

I'd rather be above water fixing a problem than below water dealing with it.


How does calibrating "pick up any fauilts"?

Can you explain how this would hapen?

ATB

Mark

Mark Chase
18-11-11, 07:16 PM
The Inspro manual says:

Calibrate every day of use.

&

It is essential though to recalibrate at least every 3 hours of diving.


I can't think of a single reason why I wouldn't follow the manufacturers recommendation and calibrate before every dive. Recommending anything else is foolish.

Matt.



Forget the brain washing and explain in practical terms why you think this is the corect way to manage cells.

Give me one single practical reasion why calibrating helps anything except normal cell variations?


If a cell is working corectly IE displaying 0.21 in air and 0.98 in pure 02, explain the benifit of calibrating that cell?

If a cell is displaying 0.8 when yesterday it was displaying 0.98 then explain how calibrating over this helps with the corrosion o the conection that caused the error? Do you beleive the faulty contact is now a constent that can be managed by claibration?

ATB

Mark

Mark Chase
18-11-11, 07:27 PM
The Inspro manual says:

Calibrate every day of use.

&

It is essential though to recalibrate at least every 3 hours of diving.


i think i would be more inclined to know why the manufacturer was recommending calibration before every dive.

seems a bit ott.

i was taught on a meg but it would be nice to know what the inspro instructers teach.


The only reasion for the Inspo to request calibration before every dive would be if the unit was incapable of retaining the previous calibration information.

Under such circumstances the Inspo displays "Must Calibrate"

In normal usage it displayes "do you wish to calibrate"

To which my answer is usualy NO unless the cells are 0.9 -0.95 or if i have ruled out any other factors that could be influancing my cell readings.

The simple truth is 90% of Inspo divers just calibrate without any primary or secondary checks. I was taught that way by one of the longest standing Inspo Instructors. There was no mention of poor contact issues heat sink faults or cell failure in my trainig and not in that of many other Inspo students i have talked too.

When i explain two point cell checking and in water cell confirmation i usualy am told theri instructor didnt cover this on the course. Something in this day and age with cell failure an accepted situation, I find staggering.

ATB


Mark

Neil McLeod
18-11-11, 07:33 PM
Regarding rate of calibration. If you think the barometric pressure has changed then surely a cal is necessary?

Neil

ashsg79
18-11-11, 07:33 PM
The only reasion for the Inspo to request calibration before every dive would be if the unit was incapable of retaining the previous calibration information.

Under such circumstances the Inspo displays "Must Calibrate"

In normal usage it displayes "do you wish to calibrate"

To which my answer is usualy NO unless the cells are 0.9 -0.95 or if i have ruled out any other factors that could be influancing my cell readings.

The simple truth is 90% of Inspo divers just calibrate without any primary or secondary checks. I was taught that way by one of the longest standing Inspo Instructors. There was no mention of poor contact issues heat sink faults or cell failure in my trainig and not in that of many other Inspo students i have talked too.

When i explain two point cell checking and in water cell confirmation i usualy am told theri instructor didnt cover this on the course. Something in this day and age with cell failure an accepted situation, I find staggering.

ATB


Mark


i was taught to do a linearity check on my course

mala
18-11-11, 07:44 PM
Regarding rate of calibration. If you think the barometric pressure has changed then surely a cal is necessary?

Neil

probably....... if you are up a mountain.

Mark Chase
18-11-11, 08:03 PM
Regarding rate of calibration. If you think the barometric pressure has changed then surely a cal is necessary?

Neil


Barametrc presure is only an issue for calibration its self. Once calibrated it becomes a non issue.

ATB

Mark

Mark Chase
18-11-11, 08:04 PM
i was taught to do a linearity check on my course

Could you please explain the process you were taught?

ATB

Mark

Suzuki416
18-11-11, 08:23 PM
How does calibrating "pick up any fauilts"?

Can you explain how this would hapen?

ATB

Mark

it also verifys to me that I have connected the right cells to the Inspro controller & they are working !
I have 4 connected.
How this would happen is:
Head is apart for sorb change, battery change, cell change = calibrate before getting in water...

Why would I get in & ck @ 6M to find I have a fault?

Head off = calibrate.

& don't forget I also do the cell ck @ 6 - 8m

along with a bubble ck
or should I skip that as I've done my pos & neg before the dive?

ashsg79
18-11-11, 08:30 PM
Could you please explain the process you were taught?

ATB

Mark

not quite sure what you are looking for here, but i was taught to do my FLAGS (and all other usual prep, analyze gases etc even on air dil, you never know when the fill station may f*ck up), calibrate for the day, go to 5m do a bubble check, flush with O2 upto 1.5 check the readings on the handsets, the dil flush back down to 0.7. is this what you are looking for??

Suzuki416
18-11-11, 08:40 PM
Forget the brain washing and explain in practical terms why you think this is the corect way to manage cells.

Thats a fair point however I was trained that way &
other than its in the manual & I don't want to give Martin Parker's Laywers the satisfaction of saying:
The diver was not following the recommended practices as laid out in the manual (pages 42,47 & 48) so the unit was not at fault :tongue:


Give me one single practical reasion why calibrating helps anything except normal cell variations?

how about it doesn't calibrate - would you still dive it ?

What happens if you haven't dived the unit for a couple of weeks?
at what point do you say yes I need to calibrate this unit ?

AP have said that:
Calibrate every day of use.
&
It is essential though to recalibrate at least every 3 hours of diving.

Now I understand you don't agree with this but thats your issue & at least AP have put a line in the sand.

mala
18-11-11, 08:46 PM
Thats a fair point however I was trained that way &
other than its in the manual & I don't want to give Martin Parker's Laywers the satisfaction of saying:
The diver was not following the recommended practices as laid out in the manual (pages 42,47 & 48) so the unit was not at fault :tongue:



how about it doesn't calibrate - would you still dive it ?

What happens if you haven't dived the unit for a couple of weeks?
at what point do you say yes I need to calibrate this unit ?

AP have said that:
Calibrate every day of use.
&
It is essential though to recalibrate at least every 3 hours of diving.

Now I understand you don't agree with this but thats your issue & at least AP have put a line in the sand.

i think ap know how long the cells last.
maybe they think that the units dont go for more than 3 hours without a fault?

Mark Chase
18-11-11, 08:46 PM
it also verifys to me that I have connected the right cells to the Inspro controller & they are working !
I have 4 connected.
How this would happen is:
Head is apart for sorb change, battery change, cell change = calibrate before getting in water...

Why would I get in & ck @ 6M to find I have a fault?

Head off = calibrate.

& don't forget I also do the cell ck @ 6 - 8m

along with a bubble ck
or should I skip that as I've done my pos & neg before the dive?


I cant make any sense of this?

Why would checking the cells in air then in puer 02 and getting 0.21 then 0.98 result in a fault at 6m?

You do the checks at 6-8m you can't do at ambient. IE check the cells go over 1.6

How does calibrating deturminn you have fitted the right cells?

How do you fit the wrong cells????

Why would a pos neg check avoid the need for a bubble check? you cant check first stages and SPGs with a pos neg test?

By your logic having just calibrated the unit and found you have a low battery warning you take the head off and swap out a battery and now you need to do a claibration again????

Why? Will the cells have deterioated in the last 10mins? If so how would they possably last for a three hour dive?


I am not being funny here i am just atempting to get my head around your logic.


ATB

Mark

Mark Chase
18-11-11, 09:07 PM
not quite sure what you are looking for here, but i was taught to do my FLAGS (and all other usual prep, analyze gases etc even on air dil, you never know when the fill station may f*ck up), calibrate for the day, go to 5m do a bubble check, flush with O2 upto 1.5 check the readings on the handsets, the dil flush back down to 0.7. is this what you are looking for??

No

A linnier check on the cells would involve a two point analisis against a fixed PP02 of a known gas.

IE you hve to expose the cells to a low PP02 gas (AIR for example) and you would get a reading of 0.21 ish

Then you expose the cells to pure 02 and you get a reading of 0.98 ish

If you dont get thse two readings the dells are described as non linier. IE they are calibrated at 1.0pp02 but read in error at 0.21pp02 The extent of this error can identifie a serious problem.

IE you calibrate the cells at 1.0 but an exposure to air reveals that two of them read 0.35 at ambient air. This would indicate that the cells are current limited and the calibration at 1.0 ca not be trusted or that the cells are non linier and may not be accurate at 1.3


Flushing to 1.5 only shows that the cells can go to 1.5? thats fine if your not going past 1.3 but if like me you go to 1.6 on deco you need to flush above 1.6.

Flushing with diluient down to 0.7 tells you nothing as the unit will attempt to maintain 0.7 automaticly so you dont actualy know if your on 0.7

You have to go to a depth where the dill is above 0.7 then do a dill flush.

So at 40m on 21/35 diluient you flush will dill on low set point and our cells should read 1.05 and because your above 0.7 the solinoid wont fire and screw up the readings

Thease are hard data checks. They do not rely on the computer in the unit as they are hard data against a known PP02 for a fixed gas.

Set ponts are bullshit. They just display what ever the computer feels it should display. It may be corect but the only way to confirm that is to check against a known and fixed PP02 which is provided by the analised diluient and 02 gas on your back


When Nigles unit was displaying 1.3 1.3 1.3 he was very happy .

Until he got back on the boat and his unit was still displaying 1.3 1.3 1.3

Personaly I have had cell 1 showing 1.3 Cell 2 showing 1.3 and cell 3 showing 1.5

Cell 3 was the only one working

When cells die I have also had this in reverse. Two cells showing 1.5 and one showing 1.3 ans the 1.3 cell was the only corect cell.

Recalibrating wasn't the answer to these problems.

ATB

Mark

mala
18-11-11, 09:31 PM
ive been looking at both and was wondering if anyone could give me any opinions of each unit. i live near Ap so servicing and repairs would be easy but have heard the meg is alot simpler, im ideally looking for an eccr and i will be using it for pretty much all dives from 10-55m at the moment and hopefully deeper.

thanks in advance
James



if you cant afford the meg then get an inspro.
2p

Mark Chase
18-11-11, 09:43 PM
Thats a fair point however I was trained that way &
other than its in the manual & I don't want to give Martin Parker's Laywers the satisfaction of saying:
The diver was not following the recommended practices as laid out in the manual (pages 42,47 & 48) so the unit was not at fault :tongue:

When i voiced a few concerns over Mod1 and the teachings of APD I am told Martin Parker placed a bet id be dead soon. That was several years ago now. I have mentioned it on forums before but hes never denied this.

I'd rather confound the bugger by staying alive



how about it doesn't calibrate - would you still dive it ?

So your saying i check it in air and its wrong and i check it in pure 02 and its wrong and then I try and calibrate it but it fails calibration??? Do I dive it?


Errrrr NO

In fact i don't even bother trying to calibrate it. I find the source of the problem first, then fix it, then calibrate it but only if its required (IE new cell inserted).





What happens if you haven't dived the unit for a couple of weeks?
at what point do you say yes I need to calibrate this unit ?

If I haven't dived the unit for a few months and i switch it on in air and it displays 0.21 and I flush it with o2 and it shows 0.98, then Id still not calibrate it

What good would it do me?

This happened several times on n the KISS after enforced winter lay offs. On the Inspo Classic of course it would say MUST CALIBRATE so id calibrate it then take the head off and test it in air and flush it with 02 and test it in 02 to confirm the calibration.

Then id dive it but id do all the normal pre dive and in water checks as well


Which are:


Switch on unit to low set point (0.19 on my JJ unit but 0.7 on my Inspo) and ensure it holds low set point

Whilst sitting on the boat, Manually inject 02 to ensure unit can hit at least 0.95

Prior to jumping in ensure 0.95 minimum PP02

jump in and immediately check PP02

Swim to shot and check PP02 before descending

Descend to 6m for bubble check

Descend to 8m and inject 02 to 1.7 PP02

Vent full lung of gas through nose suck in diluent and descend to max depth on low set point

At bottom of the shot ensure PP02 of diluent matches that displayed on the screen. If necessary dill flush to confirm

Switch to high set point and ensure cells reach chosen set point

Periodically throughout the dive spike the 02 manually to insure cells read above 1.3 (or set point)

On deco before leaving 6m stop triple flush with 02 to 1.6pp02 (or as close as you can get) then descend to ensure cells not current limited to 1.6.

Ascend and complete deco at 3 or do 5min ascent.





AP have said that:
Calibrate every day of use.
&
It is essential though to recalibrate at least every 3 hours of diving.

Now I understand you don't agree with this but thats your issue & at least AP have put a line in the sand.

AP are not god. Its just a few divers who made up their own rules.

The diluent check I do is nicked from Leon Scamerhorn from Meg. Its called the Scammerhorn slide.

So Martins right and Leon is wrong?

Not really, just two different divers with two different ideas.

Leon reckons you should run the Meg on low set point and manually maintain high set point. I don't agree with this idea either. Do you? If you were taught on a Meg and read the Meg manual would you consider this the correct way to dive a CCR? Or just Leon's way?

In Mod 1 what were you taught as a first response for a suspected C02 hit?

I was taught to do a dill flush. Which to any one who knows anything about C02 hits is about as much use as reciting three Hail Marie's. If you of a religious persuasion id say reciting the Hail Marie's has more chance of helping your situation.

My point being don't believe the manual or Mod1 / 3 is a definitive guide to how to dive a CCR.

Nor are my ideas definitive. I have a fair amount of CCR time (1000- 1500 hours underwater over 7 years) on five different units but I am still learning new ideas.

Last year i changed from a low helium bailout gas (less deco) to a high helium bailout gas on advice from Dr Mitchell concerning gas viscosity and C02 hits. I also reduced my bailout max PP02 from 1.6 down to 1.3 due to being told about the relationship between 02 tox depth and C02.


If someone can come up with a convincing argument ill follow their idea.

I haven't found a convincing argument for blindly calibrating a CCR immediately before a dive. I have however found and experienced reason why you shouldn't.

ATB

Mark

Mark Chase
18-11-11, 09:45 PM
if you cant afford the meg then get an inspro.
2p

Get a Vision anyway because its a better unit for a UK diver then the Meg. If you realy like the Meg get a JJ

1693
18-11-11, 09:49 PM
A linnier check on the cells would involve a two point analisis against a fixed PP02 of a known gas.You cannot infer linearity from two points. You can fit ANY curve between two points.

Mark Chase
18-11-11, 09:51 PM
You cannot infer linearity from two points. You can fit ANY curve between two points.

Its a damed site better than one.

ATB

Mark

SimonK
18-11-11, 10:19 PM
You cannot infer linearity from two points. You can fit ANY curve between two points.

He is doing a three point check, there is an implicit assumption that the cell will read zero at zero PPO2. If it doesn't then the test doesn't prove or disprove linearity, on the other hand the cell most likely has problems if the numbers don't line up.

Nothing wrong with a curve through two points, once talked my way out of a problem with MoD by drawing a beautiful parabola through two points!

S

Mark Chase
18-11-11, 10:29 PM
He is doing a three point check, there is an implicit assumption that the cell will read zero at zero PPO2. If it doesn't then the test doesn't prove or disprove linearity, on the other hand the cell most likely has problems if the numbers don't line up.

Nothing wrong with a curve through two points, once talked my way out of a problem with MoD by drawing a beautiful parabola through two points!


S


Be honest..... you fired a misile and THAT sorted out the problem :D

matthewoutram
19-11-11, 07:36 AM
What they do say is what I posted:

It is essential though to recalibrate at least every 3 hours of diving
& Calibrate every day of use.

Nowhere in the manual does it say Calibrate every DIVE.



It is normal to calibrate before every dive.


It is so important it is in bold.

Matt.

matthewoutram
19-11-11, 07:40 AM
i think i would be more inclined to know why the manufacturer was recommending calibration before every dive.

seems a bit ott.

i was taught on a meg but it would be nice to know what the inspro instructers teach.

Rich Stevenson taught me to calibrate every dive.

Martin Parker recommends calibration every dive.

It is in the manual.

You can skip calibration and you can supress "Must Calibrate", on your head be it. (Not your head, mala ;-)

Matt.

matthewoutram
19-11-11, 07:52 AM
Forget the brain washing and explain in practical terms why you think this is the corect way to manage cells.

Give me one single practical reasion why calibrating helps anything except normal cell variations?


If a cell is working corectly IE displaying 0.21 in air and 0.98 in pure 02, explain the benifit of calibrating that cell?

If a cell is displaying 0.8 when yesterday it was displaying 0.98 then explain how calibrating over this helps with the corrosion o the conection that caused the error? Do you beleive the faulty contact is now a constent that can be managed by claibration?

ATB

Mark

The Inspiration includes a range of automated cell-health check that are only performed during calibration. I also watch the final-calibration values, which tells me a lot about cell health. I don't od any of the convoluted procedures required on other units - the Inspiration includes such routines which I make use of as per my training.

Calibration removes the small variations caused by temperature, atmospheric pressure and humidity and I'd rather dive with recently calibrated cells rather than ones that were done a few weeks ago.

Regards
Matt.

matthewoutram
19-11-11, 07:58 AM
I cant make any sense of this?

Why would checking the cells in air then in puer 02 and getting 0.21 then 0.98 result in a fault at 6m?

You do the checks at 6-8m you can't do at ambient. IE check the cells go over 1.6

How does calibrating deturminn you have fitted the right cells?

How do you fit the wrong cells????

Why would a pos neg check avoid the need for a bubble check? you cant check first stages and SPGs with a pos neg test?

By your logic having just calibrated the unit and found you have a low battery warning you take the head off and swap out a battery and now you need to do a claibration again????

Why? Will the cells have deterioated in the last 10mins? If so how would they possably last for a three hour dive?


I am not being funny here i am just atempting to get my head around your logic.


ATB

Mark

For all your questions I simply ask "why not?". Calibrating does not do any harm, so if a diver wants to do it then that is OK. I'd say it's a lot more OK to do it twice in 10 minutes than it is to advise folks don't do it for several weeks at a time.

Hell, people cannot even remember to turn units on never mind recommending skipping major steps.

Matt.

matthewoutram
19-11-11, 08:01 AM
AP are not god.

Unless you're talking about Inspirations?

NotDeadYet
19-11-11, 08:22 AM
For all your questions I simply ask "why not?". Calibrating does not do any harm, so if a diver wants to do it then that is OK. I'd say it's a lot more OK to do it twice in 10 minutes than it is to advise folks don't do it for several weeks at a time.

Hell, people cannot even remember to turn units on never mind recommending skipping major steps.

Matt.

I calibrate every time I assemble the unit because it is part of the standard checklist I use. I really don't want to start getting into different steps for different conditions or worse, into the mindset of "I'll leave it and do it next time, it'll be OK just this once". If you are looking at the numbers you are getting and why you are calibrating then what is the problem? I check and record the mV of each cell in air and O2 as part of that process.

I know nothing about Inspirations but on my unit working through the checklist takes 40-60min and it gives me a lot of reassurance that I've checked what needs to be checked.

Mark Chase
19-11-11, 08:44 AM
For all your questions I simply ask "why not?". Calibrating does not do any harm, so if a diver wants to do it then that is OK. I'd say it's a lot more OK to do it twice in 10 minutes than it is to advise folks don't do it for several weeks at a time.

Hell, people cannot even remember to turn units on never mind recommending skipping major steps.

Matt.

I have explained why not several times but your not reading it.

You have provided no logical reasion as to why calibrating over a cell thats dropped 0.2 over night is a good plan

You have provided no logical reasioning why calibrating a cell that reading corectly is a good plan

My M8 Martin said so is not a logical reasion (see comment on training for what to do in the event of a suspected C02 hit)

Total reliance on the macheen is a very very bad idea.

ATB

Mark

Mark Chase
19-11-11, 08:47 AM
I calibrate every time I assemble the unit because it is part of the standard checklist I use. I really don't want to start getting into different steps for different conditions or worse, into the mindset of "I'll leave it and do it next time, it'll be OK just this once". If you are looking at the numbers you are getting and why you are calibrating then what is the problem? I check and record the mV of each cell in air and O2 as part of that process.

I know nothing about Inspirations but on my unit working through the checklist takes 40-60min and it gives me a lot of reassurance that I've checked what needs to be checked.



The inspo is not like that. Its automated check list is more like

Is 02 on confirm
Is diluient on Confirm
Do you wish to calibrate? Confirm
Automatic calibration.
Job done.

ATB

Mark

matthewoutram
19-11-11, 09:48 AM
I have explained why not several times but your not reading it.

I am reading it, but I am not correcting the English, spelling or grammar, Mark. Please understand that I am also comprehending it. What you are observing is not my lack of reading but my lack of agreement.


You have provided no logical reasion as to why calibrating over a cell thats dropped 0.2 over night is a good plan

You have provided no logical reasioning why calibrating a cell that reading corectly is a good plan

My M8 Martin said so is not a logical reasion (see comment on training for what to do in the event of a suspected C02 hit)

Total reliance on the macheen is a very very bad idea.

ATB

Mark

I'm not replying, Mark, to condescending comments. You should know better.

Thanks
Matt.

http://i1214.photobucket.com/albums/cc497/MatthewOutram/cal.png

1018052
19-11-11, 10:09 AM
Two paras above your quote on page 56 it states



....the oxygen cells need to be calibrated prior to each dive or at least prior to each day of use...


So the recommended minimum is daily. Which is what I think Suzuki said.






It is normal to calibrate before every dive.


It is so important it is in bold.

Matt.

1693
19-11-11, 10:11 AM
I have explained why not several times but your not reading it.Mark, you don't seem to be reading what others are writing either. I posted that I like to calibrate to watch the raw voltage figures rise, yet you responded with some crap about calibrating over an O2 reading of 0.8 when I never mentioned any such thing.

I've just switched my unit on and all 3 cells are reading 0.20 with almost identical voltages around 10mV. So, I'm out by 1% since the last calibration - I think I can live with that. I'm guessing the O2 will be pretty much there or thereabouts but I really can't be arsed to find out. I do know that the cells read around 50mV when I last calibrated and my arithmetic is good enough to know that that's what I'd expect.

I will still calibrate next time and I'll watch the voltage rise. expecting to see all 3 cells rise in unison. If they don't do that or the final reading is not 5 times the starting voltage, I'll suspect that something is wrong. This will be well before I'm kitted-up and doing a pre-breathe, at which time I'd really have little or no time to do anything about it and be forced to bail or wing-it.

You appear to be a lone voice on this issue yet you continue to ignore the valid reasons people are offering, making out that we're just pushing buttons and hoping for the best.

matthewoutram
19-11-11, 10:34 AM
Two paras above your quote on page 56 it states



So the recommended minimum is daily. Which is what I think Suzuki said.

Yes, it says: "Consequently the oxygen cells need to be calibrated before each dive".

A debate on independent cell checking could be interesting, and in this case I think Mark has some valid points. However, conflating these points with calibration isn't useful.

I also have a cell checker which I use occasionally, but not before every dive. I recently checked some cells in it - first check in April, good results. Next check in September - result, all failed. None linear, one with no output. Cells are fickle, let's not take anything to chance and use all the tools we have to verify them before every dive.

Regards
Matt.

http://i1214.photobucket.com/albums/cc497/MatthewOutram/sect6.png

Mark Chase
19-11-11, 03:23 PM
Mark, you don't seem to be reading what others are writing either. I posted that I like to calibrate to watch the raw voltage figures rise, yet you responded with some crap about calibrating over an O2 reading of 0.8 when I never mentioned any such thing.

I've just switched my unit on and all 3 cells are reading 0.20 with almost identical voltages around 10mV. So, I'm out by 1% since the last calibration - I think I can live with that. I'm guessing the O2 will be pretty much there or thereabouts but I really can't be arsed to find out. I do know that the cells read around 50mV when I last calibrated and my arithmetic is good enough to know that that's what I'd expect.

I will still calibrate next time and I'll watch the voltage rise. expecting to see all 3 cells rise in unison. If they don't do that or the final reading is not 5 times the starting voltage, I'll suspect that something is wrong. This will be well before I'm kitted-up and doing a pre-breathe, at which time I'd really have little or no time to do anything about it and be forced to bail or wing-it.

You appear to be a lone voice on this issue yet you continue to ignore the valid reasons people are offering, making out that we're just pushing buttons and hoping for the best.



Nick I have no problem being the kid who tells the emperor hes naked.

Not one of you has provided a single logical argument to support the concept that the units must be calibrated every day / dive except "thats what the book said to do"

If i have missed a point of argument in reading all these posts could you please highlight it for me.


At the moment I have:

1: Because the book/my instructor who's following the guidelines of the course written by the same person who wrote the book said so

2: ?

Ill do the same for you.


1: Calibrating over a cell thats reading 0.21 - 0.98 in Air / 02 has absolutely no benefit as the cell is already in range.

2: A cell thats drooped significantly out of calibration in a 24 hour period has a fault and should not be calibrated over.

3: 90% of the cell errors on the Inspiraion Classic are down to wiring loom issues and corrosion on the Molex connection issues. (This obviously dosent count for the new APD cells which fail al the time)

4: Cells work by a chemical reaction similar to rust eating through steel. The act of oxidation causes a tiny voltage which is measured to provide a MV output figure which is converted to PP02. The cells do not vary significantly in their output during the main working phase of their life. QED calibration is rarely required when the cells are healthy. So if a cell Requiems regular calibration its an indication that its either faulty or about to die. So calibrating for the hell of it isn't helpfully as you do not build up a feeling for the performance of the cell.


I am impressed by you diligence during calibration as most of the Inspo divers I see on the boat just hit calibrate and get on with something else.



ATB

Mark

NotDeadYet
19-11-11, 04:05 PM
So why would hitting "no" and getting on with something else be any better?

Sent from my GT-I9100 using Tapatalk

matthewoutram
19-11-11, 04:25 PM
Nick I have no problem being the kid who tells the emperor hes naked.

Not one of you has provided a single logical argument to support the concept that the units must be calibrated every day / dive except "thats what the book said to do"

You're getting all hot under the collar, Mark. And for no reason. Your advocation is not related to calibration, but to some orthogonal cell health check. I don't think anyone here is saying that your tips are not useful, but they are not instead-of but as-well-as calibration.

Perhaps if you've a different unit where the advice is different then fair enough, I can only speak about the Inspiration. My knowledge of the Meg is that the situation on Calibration is different - in this case maybe your opinion is more valid.


If i have missed a point of argument in reading all these posts could you please highlight it for me.


At the moment I have:

1: Because the book/my instructor who's following the guidelines of the course written by the same person who wrote the book said so

You seem to be stating that you know better than the manufacturer. I think that's a big claim. It is not a claim I shall accept, no matter how many different (or actually the same) ways you put it.



2: ?

Ill do the same for you.


1: Calibrating over a cell thats reading 0.21 - 0.98 in Air / 02 has absolutely no benefit as the cell is already in range.

So what's the disadvantage? Why deviate from SOP?


2: A cell thats drooped significantly out of calibration in a 24 hour period has a fault and should not be calibrated over.

So what will you do, grab a soldering iron and start hacking at your loom? Or will you recalibrate and accept that the amount of moisture/ambient pressure/temperature/oxygen in your tank/yadda is now different to that that it was yesterday?


3: 90% of the cell errors on the Inspiraion Classic are down to wiring loom issues and corrosion on the Molex connection issues. (This obviously dosent count for the new APD cells which fail al the time)

Not all Classics have Molex, in fact most units now do not.


4: Cells work by a chemical reaction similar to rust eating through steel. The act of oxidation causes a tiny voltage which is measured to provide a MV output figure which is converted to PP02. The cells do not vary significantly in their output during the main working phase of their life. QED calibration is rarely required when the cells are healthy. So if a cell Requiems regular calibration its an indication that its either faulty or about to die. So calibrating for the hell of it isn't helpfully as you do not build up a feeling for the performance of the cell.

I don't know for sure that cell fail linearly. Can you point me to the literature, please?


I am impressed by you diligence during calibration as most of the Inspo divers I see on the boat just hit calibrate and get on with something else.

Thanks.


Regards
Matt.

matthewoutram
19-11-11, 04:27 PM
So why would hitting "no" and getting on with something else be any better?

Sent from my GT-I9100 using Tapatalk

Oh, I typed a lot and you said the same in 14 words!

Two Hats
19-11-11, 04:49 PM
Oh, I typed a lot and you said the same in 14 words!

He's a jock, they're tight with everything;)

PeterVICEG
19-11-11, 05:25 PM
For me, quoting SOP is not a reasoned arguement.

The debate is now about how best to be shure you have healthy cells. As I understand it, all that callibration does is "tell" the controller that what ever voltage it recieves is representative of 100% O2. If the cells also read properly at .21 % the cells are fine, up to a PO2 of 1. This does nothing to assure you that it will work to a higher PO2.

If your cell's output changes, and you recallibrate, all you have done is avoid dealing with an issue. You have "told" the controller that it is fine when it may well not be.

Prior to today's dive I flooded my head with O2 and watched the volltage readings rise and fall to see if the cell tracked properly. When I hit the drink I will do as Mark does and only then will i believe that all is well. I track cell out put and get concerned when a cell is high or low or fast or slow. I take little comfort in callibaration as it says very little of the health of my cells and is really only a setting of the controller.

Peter

matthewoutram
19-11-11, 05:30 PM
For me, quoting SOP is not a reasoned arguement.

The debate is now about how best to be shure you have healthy cells. As I understand it, all that callibration does is "tell" the controller that what ever voltage it recieves is representative of 100% O2. If the cells also read properly at .21 % the cells are fine, up to a PO2 of 1. This does nothing to assure you that it will work to a higher PO2.

If your cell's output changes, and you recallibrate, all you have done is avoid dealing with an issue. You have "told" the controller that it is fine when it may well not be.

Prior to today's dive I flooded my head with O2 and watched the volltage readings rise and fall to see if the cell tracked properly. When I hit the drink I will do as Mark does and only then will i believe that all is well. I track cell out put and get concerned when a cell is high or low or fast or slow. I take little comfort in callibaration as it says very little of the health of my cells and is really only a setting of the controller.

Peter

That's fine, but it is not about calibration, it is about cell health check, which is a different topic.

PeterVICEG
19-11-11, 06:06 PM
That's fine, but it is not about calibration, it is about cell health check, which is a different topic.

Which was my point.

Major Clanger
19-11-11, 08:12 PM
Erm, clear as...so how often should the meg be calibrated???

dynarob
19-11-11, 08:46 PM
Well I can completely see what Mark is saying and even though the necessity of this requirement to recalibrate has been questioned by myself before, this thread has certainly given me more food for thought.

Is there a way of getting the 'raw' mV readings with an Inspiration? I am 99.99% sure there isn't, I have certainly never seen it and I wasn't taught it.

I am guessing that most of the other units give this info and therefore cell condition is a bit more obvious to those guys.

matthewoutram
19-11-11, 08:52 PM
Well I can completely see what Mark is saying and even though the necessity of this requirement to recalibrate has been questioned by myself before, this thread has certainly given me more food for thought.

Is there a way of getting the 'raw' mV readings with an Inspiration? I am 99.99% sure there isn't, I have certainly never seen it and I wasn't taught it.

I am guessing that most of the other units give this info and therefore cell condition is a bit more obvious to those guys.

The end calibration values are the mv values in air. This is why calibration of the Inspiration is so useful.

Matt.

dynarob
19-11-11, 09:09 PM
The end calibration values are the mv values in air. This is why calibration of the Inspiration is so useful.

Matt.

Sorry, I'm probably being thick here but could you expand on that a bit.

As far as I can tell mV is hidden from the user, we only get to see PPO2 (which is the mV reading with a different correction factor for each cell based on the calibration in O2). At the end of calibration I see something like 0.98 0.98 0.98 (IIRC - I haven't really dived mine for over a year).

For all I know some cells could be reading 7mV in air and the others 13mV in air - it is hidden from me (OK I can check them with a multimeter).

If you could see the actual mV readings as calibration took place then it would be painfully obvious to most people how their cells were performing or more importantly how their performance is changing over time.

matthewoutram
19-11-11, 09:15 PM
Sorry, I'm probably being thick here but could you expand on that a bit.

As far as I can tell mV is hidden from the user, we only get to see PPO2 (which is the mV reading with a different correction factor for each cell based on the calibration in O2). At the end of calibration I see something like 0.98 0.98 0.98 (IIRC - I haven't really dived mine for over a year).

For all I know some cells could be reading 7mV in air and the others 13mV in air - it is hidden from me (OK I can check them with a multimeter).

If you could see the actual mV readings as calibration took place then it would be painfully obvious to most people how their cells were performing or more importantly how their performance is changing over time.

If you are seeing 0.98 on the handset in 100% O2 (i.e. on calibration) then you have 9.8mv in air with the multimeter. This is how the Inspiration works.

Matt.

SCILLY DIVER
19-11-11, 09:23 PM
Every time I check gas mixes I have to reset the analysers cells for an accurate reading. So it make's sense to me to calibrate just before I dive for an accurate readout .

dynarob
19-11-11, 09:23 PM
If you are seeing 0.98 on the handset in 100% O2 (i.e. on calibration) then you have 9.8mv in air with the multimeter. This is how the Inspiration works.

Matt.

That's not my understanding of it.

The Inspiration accepts cells which give readings of between 7mV and 13.5mV in air, you should never see for example 1.35 on the handsets after calibration. Immediately after calibration they should read the PPO2 of the gas you set in the unit to calibrate to, usually EAN98 or PPO2 of 0.98, this is regardless of the mV reading in air.

SimonK
19-11-11, 09:33 PM
The end calibration values are the mv values in air. This is why calibration of the Inspiration is so useful.

Matt.

Not on my classic. Not sure quite what it is, probably PP02 with a nominal scale factor, 50mV for 1 Bar perhaps? However it gives the same information as the raw mV since with a fixed scale factor it is directly proportional.

Going back to Marks point.
If I send a piece of kit to our calibration lab at work they will test it against a standard, if its well within tolerance that's it. If its out of tolerance or marginal it gets adjusted or 'calibrated'.
What Mark is proposing is that the cell calibration is checked before diving but not adjusted unless necessary. This makes it less likely that an unstable cell is hidden by continuously being calibrated back to the correct value at 1Bar PPO2.

Cells should be stable over a period of weeks if not months. If they need calibrating every day or even twice a day then there is something wrong. This does NOT mean that you shouldn't check they are reading correctly before every dive.

Personally I calibrate the unit at home in slow time a day or two before a trip then leave it alone. If the cells start wandering and I feel the need to recalibrate on the boat its a deliberate act and a cause for concern.

Now I think I will go off to that other thread an discuss tank mesh!

S

matthewoutram
19-11-11, 09:37 PM
That's not my understanding of it.

The Inspiration accepts cells which give readings of between 7mV and 13.5mV in air, you should never see for example 1.35 on the handsets after calibration. Immediately after calibration they should read the PPO2 of the gas you set in the unit to calibrate to, usually EAN98 or PPO2 of 0.98, this is regardless of the mV reading in air.

You're right, the range is 7-13.5mv. Get your unit out of the shed and measure the mv in air and then calibrate it. The values will be the same but the decimal is in a different place. The calibrated value is gas x pressure, not mv.

The display shows the mv output in air, fact.

Regards
Matt.

matthewoutram
19-11-11, 09:44 PM
Not on my classic. Not sure quite what it is, probably PP02 with a nominal scale factor, 50mV for 1 Bar perhaps? However it gives the same information as the raw mV since with a fixed scale factor it is directly proportional.

...

Now I think I will go off to that other thread an discuss tank mesh!

S

As below from MP in reply to AM.

Matt.




With regards to measuring the voltage of the cell. Rather than use a
multimeter and strip the cells out I simply use the Inspiration to measure
the output. It is easy to see what value the cells get to during
calibration. During "flushing" we use a constant cal factor so the display
(at the end of flushing) reflects what the cell's output is in air - 0.81 is
an 8.1mV cell in air, 0.96 is a 9.6mV cell in air, 1.07 is a 10.7 mV cell in
air.
So by keeping an eye on these values you can get a more complete idea of the
condition of the cell and how it reacts to oxygen, which is more important
than the output in air.

SimonK
19-11-11, 09:51 PM
As below from MP in reply to AM.

Matt.

I sit corrected!

Diving Dude
19-11-11, 09:52 PM
l can't add to the discussion, but keep it up guys, this is very interesting.

matthewoutram
19-11-11, 09:54 PM
I sit corrected!

Good. Get a GnT, I've got one :-)

matthewoutram
19-11-11, 09:58 PM
Erm, clear as...so how often should the meg be calibrated???

I don't have a meg but I understand it does not do it's own calibration like the Inspiration. You have to do it manually (flush) or with a "head-only" kit. It is therefore more fiddly to do than the Inspiration (which I calibrate when kitted as I turn on before every dive). I suspect that the advice for these is more in line with Mark's comments (i.e. calibrate infrequently). Totally different to an Inspiration, and a differentiator when selecting (which was, I believe, the OT).

Regards
Matt.

dynarob
19-11-11, 10:01 PM
As below from MP in reply to AM.

Matt.

Thanks.

Light bulb moment :)

I always assumed it was showing PPO2 based on the previous times calibration values - which did always worry me a little as they were always nearly 0.1PPO2 different either way to what I ended up with :omg: I always put that down to cells being what they are.

WTF I wasn't taught this or it doesn't seem to be spelt out very clearly (if at all) in the manual (para 6.6 in the manual talks about PPO2 values during calibration) I don't know. I wonder how many other Inspo users know (or understand) this.

matthewoutram
19-11-11, 10:05 PM
Since I had the file open I thought someone might like this - it's also from the Deas/Anne-Marie era:



Cell failure can occur at any time – what makes you think you’ll pick it up with a pressure test? It’s quite a good test once a cell has failed, but what’s the point in confirming that when it’s obvious in other ways?

Cell reaching old age will die – what makes you think you’ll pick it up prior to a dive? Cell outputs die extremely quickly when they reach the end of their life, you can watch it drop. ( see my water tank explanation – the one with a 100ft microbore pipe on it) – the easiest way to tell whether it’s old is to look at the label.

Reminds me of a joke: Two old dears in the old peoples home – granny says to the old chap next to her – I bet I can tell how hold you are. No you can’t says the old man, yes I can she says,”undo your flys”. He undoes his zip and she pushes her hand inside and she has a feel around for a couple of mins. You’re 92 she says. Good god how did you know that ? says the old man …. You told me yesterday.

matthewoutram
19-11-11, 10:07 PM
Thanks.

Light bulb moment :)

I always assumed it was showing PPO2 based on the previous times calibration values - which did always worry me a little as they were always nearly 0.1PPO2 different either way to what I ended up with :omg: I always put that down to cells being what they are.

WTF I wasn't taught this or it doesn't seem to be spelt out very clearly (if at all) in the manual (para 6.6 in the manual talks about PPO2 values during calibration) I don't know. I wonder how many other Inspo users know (or understand) this.

Right - most good info comes to users from the "list". Since AM/Deas closed the archives due to litigation most gems are now hidden. Luckily we have YD et al.

Cheers
Matt.

Major Clanger
19-11-11, 10:08 PM
I don't have a meg but I understand it does not do it's own calibration like the Inspiration. You have to do it manually (flush) or with a "head-only" kit. It is therefore more fiddly to do than the Inspiration (which I calibrate when kitted as I turn on before every dive). I suspect that the advice for these is more in line with Mark's comments (i.e. calibrate infrequently). Totally different to an Inspiration, and a differentiator when selecting (which was, I believe, the OT).

Regards
Matt.

New aspect for me, mod 1 in January. Have the head-only kit and seems reasonably straight forward to calibrate, just not sure at this stage if the pre-dive check is literally that for the cal' before every dive.

The Duck
19-11-11, 10:10 PM
l can't add to the discussion, but keep it up guys, this is very interesting.

+1

Having just bought a Classic I'm finding this a very interesting discussion.

SimonK
19-11-11, 10:18 PM
Good. Get a GnT, I've got one :-)

Talisker

So the scale factor they use is very close to 1/50. For the sake of simple Maths assume air is 0.20 PPO2 then a cell that gives 10mV in air will give 50mV at 1Bar. Divide that 50mV by 50 and you get the 1.00 shown on the handset.

PeterVICEG
20-11-11, 03:59 AM
New aspect for me, mod 1 in January. Have the head-only kit and seems reasonably straight forward to calibrate, just not sure at this stage if the pre-dive check is literally that for the cal' before every dive.

Sorry to be slow to get back, had to go diving. I should have qualified my remarks that my experience is confined to the Meg. It is very easy and quick to check with the head only kit to see if the cells are responding. Takes very little O2 and I do that before every dive. Usualy the night before. On the dive I do the "Scamahorn slide". Bubble check at 20 feet and then flush with O2 to confirm cells are not current limited.

Calibration happens for new cells, and once and a while. It seems that cells can drift a little, and not be done, so then calibrate. Mostly to feel better.

The meg handset and my Shearwater both can read out in millavolts. Some Meg divers write the Mv at 1.2 or 1.3 PO2 on tape on the side of the handset. Peace of mind at depth as there is some certainty to read the raw data and know you are in range.

I too have learned much from this thread. I have an idea as to how the basic eccr works, but had no notion that the latest crop do so many things when calibrated. I am still not convinced that all of this is nessesary, but each to his own.

Peter

NotDeadYet
20-11-11, 08:16 AM
Right - most good info comes to users from the "list". Since AM/Deas closed the archives due to litigation most gems are now hidden. Luckily we have YD et al.

Cheers
Matt.

Gordon closed the archives because of them? That's yet another thing I didn't know.

What a great contribution to safety that pair have made.

Sent from my GT-I9100 using Tapatalk

matthewoutram
20-11-11, 08:43 AM
Talisker

So the scale factor they use is very close to 1/50. For the sake of simple Maths assume air is 0.20 PPO2 then a cell that gives 10mV in air will give 50mV at 1Bar. Divide that 50mV by 50 and you get the 1.00 shown on the handset.

Yes, this seems quite likely. If you have mv output at the end of calibration and atmospheric pressure and calibration gas are known then mv output in air is a straight calculation - (end-cal-mv * ppO2-in-air) / (barometric-presure-in-bar * cal-gas-fraction).

e.g. for 1020mb and 98% and end-cal-mv as 50mv we would have (50 * 0.21) / (1.02 * 0.98) = 10.5mv in air.

For this example the handset should show 0.99 at the end of the calibration as this would be the maximum 98% and 1020 mbar could achieve (you would only get 1.0 if you put 100% and 1000mb).


The meg handset and my Shearwater both can read out in millavolts. Some Meg divers write the Mv at 1.2 or 1.3 PO2 on tape on the side of the handset. Peace of mind at depth as there is some certainty to read the raw data and know you are in range.

I too have learned much from this thread. I have an idea as to how the basic eccr works, but had no notion that the latest crop do so many things when calibrated. I am still not convinced that all of this is nessesary, but each to his own.

Peter

Yes, I do the same with the end-cal-values (which are mv output in air) - this shows me cell health (i.e. any decay) every dive.

Regards
Matt.

Major Clanger
20-11-11, 08:59 AM
and I do that before every dive. Usualy the night before. ...

Thanks for this, so to clarify, on a two dive day you will do the cal' check the night before.

matthewoutram
20-11-11, 09:34 AM
Gordon closed the archives because of them? That's yet another thing I didn't know.

What a great contribution to safety that pair have made.

Sent from my GT-I9100 using Tapatalk

Yes. The archives were being used by AM in the litigation against APD, so Gordon took them off line. I have a copy of most things since 2002 in my "Inspiration" box as I am an untidy person :-)

Matt.

SimonK
20-11-11, 09:47 AM
I suspect that the mV in air thing is a happy accident rather than design intent which is why it's not in the manual.
If you set your default scale factor for the nominal cell output of 10mV in air, in order to show a reasonable PPO2 during cal, then the mV in air reading falls out of the maths during calibration.

matthewoutram
20-11-11, 09:52 AM
I suspect that the mV in air thing is a happy accident rather than design intent which is why it's not in the manual.
If you set your default scale factor for the nominal cell output of 10mV in air, in order to show a reasonable PPO2 during cal, then the mV in air reading falls out of the maths during calibration.

Martin says it is by design, but you're right, it is not in the manual. It is mentioned on the list many many times, though. An easier accident would be to show mv output, but the display on a classic is 8-bit (0..255, with a decimal), so it would be more difficult to fit (but not too hard) but probably less useful to the diver in practice. I guess this is why it's designed this way, but i do not know. It is also why the max display is 2.55 even when 100% O2 at 20m would be 3.00, for example.

Here's another MP quote from those AM days.



The cell's mV output in air is a very poor indicator of the health of the
cell. In fact, the decay (of the mV output in air) is so negligible through
the cell's life that I would say - if it is your practice to remove cells
and measure their outputs in air then you are wasting your time.

If a cell's output is outside the range of 7.5 to 13mV in air then the
rebreather will reject it BUT very often the real problem is not the cell
but the oxygen % or ambient pressure entered by the diver. All too often
divers assume it is 100% when in some far flung destinations it could be
much less.

As AM says - Garbage In , garbage out.


Cheers
Matt.

NotDeadYet
20-11-11, 10:39 AM
I suspect that the mV in air thing is a happy accident rather than design intent which is why it's not in the manual.
If you set your default scale factor for the nominal cell output of 10mV in air, in order to show a reasonable PPO2 during cal, then the mV in air reading falls out of the maths during calibration.

On my old KISS I'd knackered a display and the off the shelf meter needs modding to read ppO2 rather than mV. I was in a hurry and couldn't be arsed (I'm also a technical incompetent with a soldering iron) so I just dropped it straight in. I ended up diving for a couple of years with one display reading straight voltage, I'd got into the habit of running my unit at 50mV rather than 1.0.

It's an even simpler relationship on my Mk15, I've got high output cells so ~21mv in air and 100mv in oxygen.

SimonK
20-11-11, 10:59 AM
It's an even simpler relationship on my Mk15, I've got high output cells so ~21mv in air and 100mv in oxygen.

Can't beat that 1980's (or was it 1880's) US military technology

Mark Chase
20-11-11, 11:01 AM
So why would hitting "no" and getting on with something else be any better?

Sent from my GT-I9100 using Tapatalk



Because i do a manual check against a known gas and dont rely on the unit to interprit what it thinks it sees for me.

Computers are ultimatly dumb. i dont beleive they can teel the diference between a 0.2 drop in cell out put or a bad conection. They will just calibrate anthing in the accepted range. FOr an inspo that a big range. On the Hammer Head they are a lot more fussy.

I had to special order my cells from APD for the HH with a minimum 9v output from new. The Inspo ones will pass at 7.5 volts.

As I said I had two spanking new cells that wouldent calibrate on a Hammer Head but did on a Inspo and they both were current limited.

I have also had cells calibrate on the inspo then go out of range but stay constent during a dive. Which sugested they hadent calibrated properly.

Cell errors were a pain on the Inspo classic untill i adopted the diciplin of looking at contact issues and cell performance during set up. I cant take any credit fo this as it was Ann Marrie who braught it to our attention in about 2004-5 whith her reports on cell performance on cells less than 12months old. Prior to this and dispite doing Mod1 and Mod3 i had never herd of current limited cells.

ATB

Mark

Mark Chase
20-11-11, 11:37 AM
You're getting all hot under the collar, Mark. And for no reason. Your advocation is not related to calibration, but to some orthogonal cell health check. I don't think anyone here is saying that your tips are not useful, but they are not instead-of but as-well-as calibration.


Seriously M8 i am not in the least bit angry I am enjoying a healthy discussion on a diving relevant issue.


Perhaps if you've a different unit where the advice is different then fair enough, I can only speak about the Inspiration. My knowledge of the Meg is that the situation on Calibration is different - in this case maybe your opinion is more valid.


IMHO All CCR should be dived the same way



You seem to be stating that you know better than the manufacturer. I think that's a big claim. It is not a claim I shall accept, no matter how many different (or actually the same) ways you put it.


Back in 2004 I had a similar multi page debate where i was repeatedly told i was going to die and that the Manufacturer was right and i was wrong.

Back then the issue i was fighting for was saying all CCR should have a HUD

Again in 2004 i argued strongly that the Manufacturer was wrong and qualified divers shouldn't have to dive Air to 40m on their new CCR

I argued that the Auto Air on the Inspo plumbed in to inboard 3ltr tins was a joke for bailout

In 2005 i was similarly told i was talking out of my arse and going to die when i suggested the Inspo should have a BOV

In 2007 I argued strongly against the loose pack video Martin Parker put out about how to fill a scrubber

About the same time maybe 2008 I started arguing that the design an materials of the Inspo Classic hand sets were faulty and should have been modified

Around that time i argued also that the MOd1 training program was seriously at fault for teaching "sanity breaths" by dill flush to manage possible C02 hits

I have also argued that the Inspo Classic and Inspo Visions supposedly separate controllers are not separate and can fail simultaneously.

So frankly M8 i have no problem taking issue with the Manufacturers stance on their and or their training.




So what's the disadvantage? Why deviate from SOP?


If the cell is calibrated over the top of an intermittent fault like a bad contact then during the die that fault can disappear causing the cell calibration to go out of range. For the most part this just pisses people off with a cell error warning but if its two cells? then the issue can be more serious.

Once i adopted my system of checking cells and avoiding unnecessary calibration id say my cell failure issues all but vanished.




So what will you do, grab a soldering iron and start hacking at your loom? Or will you recalibrate and accept that the amount of moisture/ambient pressure/temperature/oxygen in your tank/yadda is now different to that that it was yesterday?

If all three cells are showing low or high its likely to be a barometric pressure issue. If its one or two cells its not.

Usually id solve the problem using Biox. Id dip the Molex connectors in an egg cup full of warm Biox and clean the cell pins using a cotton bud soaked in biox (this must be done with the cell vertical so as not to drip biox into the cell) On more than one occasion i have had to remove the cable from the Molex connector trim it back and reconnect it. The cable turns black inside the Molex but it can also fray and leave only a couple of strands in contact.

I have never re soldered the contacts but i know some people do.




Not all Classics have Molex, in fact most units now do not.

I have only had my Molex connection unit for 2 years so its too early to comment. On the JJ when you replace a cell you replace the entire loom. It comes fixed to the cell.



I don't know for sure that cell fail linearly. Can you point me to the literature, please?

They don't fail lininer as the failure may be in the construction rather than in the chemical reaction front. But when the cell is not broken they do perform in a lininer way. If the chemical reaction that produces the MV output wasn't near constant you couldn't use them for monitoring o2 as they would go out of range mid dive.

The usual path to failure is an increase in sped of reaction and MV output. I ran my old AP cells for two years due to the problems with sourcing Coax cells. Before they failed they were chucking out high mv and you could tell during the final two or three uses that they were running hot and about to fail. The cells in Air were OK but in 02 at ambient I was getting 1.04 a week or two after previous reading / calibration so a steady upward creep in MV output and a fast reaction time.

Far more of a concern is a cell more than 0.1 low within a week of the last calibration. This usually indicates a bad contact or damage to the loom wire. Either that or the cell is accurate and the other two are reading high and on their way out.





ATB

Mark

Mark Chase
20-11-11, 12:06 PM
Originally Posted by Martin Parker, 24/11/05
With regards to measuring the voltage of the cell. Rather than use a
multimeter and strip the cells out I simply use the Inspiration to measure
the output. It is easy to see what value the cells get to during
calibration. During "flushing" we use a constant cal factor so the display
(at the end of flushing) reflects what the cell's output is in air - 0.81 is
an 8.1mV cell in air, 0.96 is a 9.6mV cell in air, 1.07 is a 10.7 mV cell in
air

So by keeping an eye on these values you can get a more complete idea of the
condition of the cell and how it reacts to oxygen, which is more important
than the output in air


Matt you need to re read the above very carefulley.

The end figure does not give you the MV output in air with any relation to testing. Its just an aproximation.

The end calibration reading on a Inspo Classic is always 0.98 0.98 0.98 cells do not always output 9.8mv

There is a reading just befor that which is on screen for a second or two at best and that might be 0.96 1.04 0.98 that may or may not relate to the air MV output

Using a constant calibration factor its only showing the end output devided by 50. If the cells are non linnier than its not showing the actual read out in air.

To clarifie. If the cell is showing 50mv output in 100% 02 and this is displayed as 1.00 you may be forgiven for thinking the MV output in air was 10mv. But if the cell is non linier it may be reading 7mv at 21% 02 and displaying 0.14


Testing the cells in pure 02 and extrapolating ofr output in Air is not any sort of two point calibration.


As i say you need to read between the lines with what the manufactror tell you. Its not Gospel.

ATB

Mark

Mark Chase
20-11-11, 12:26 PM
Originally Posted by Martin Parker 10/0/06
Cell failure can occur at any time – what makes you think you’ll pick it up with a pressure test? It’s quite a good test once a cell has failed, but what’s the point in confirming that when it’s obvious in other ways?

Cell reaching old age will die – what makes you think you’ll pick it up prior to a dive? Cell outputs die extremely quickly when they reach the end of their life, you can watch it drop. ( see my water tank explanation – the one with a 100ft microbore pipe on it) – the easiest way to tell whether it’s old is to look at the label.


Again great care needed when reading the above.

The age printed on the cell isn't particularly relevant. AP used to test the cells than put them in a bag and vacuum pack them. As the chemical reaction inside the cell needs 02 to function the cell doesn't age much inside the bag. So APD would sell you a cell that was 6months old the day it arrives and it may rattle in your dive box as a spare for another six months and then be fitted. So the date stamp can be a year old when the cells been in use 1 month.

I started marking my cells with date installed so if i coped it i wouldn't be accused of diving old cells.

Now as for pressure testing? As i said before I have had cells pass calibration and fail on the dive. Once two brand new cells and first dive they failed at 6m.

thats because the cell was current limited. Which means they are incapable of outputting a MV above say 50mv

On land with Ambient 02 I have no way of checking the cell above 1.00pp02 so I cant test for current limiting between 1.0 and 1.7. If you have a cell checker you can test before you dive and this will avoid the issue of having to abort at 6m.

BUT i don't know haw a cell checker copes with the issues of thermal compensation.

This is the problem with the new AP cells i am told. Its an air gap issue between the thermal compensator and the control board.

It is possible to roughly asses cell health on land. A cell outputting less than 9mv in air is suspect. It would be rejected out of hand by a Hammer Head calibration but for some reason AP still use them. To check a cells air output i would take the cell out of the vacuum wrap and put it in a sealed bag of pure 02 overnight.

Now its chemical reaction has stabilized id let it rest in air and check it for MV output either in the CCR or with the Inspo (because air checks were a PITA with flashing numbers low PP02 warnings and buzzers going off) id check the MV output using an Avo meter.

A MV output below 9 would lead me to suspect a current limited cell.

A MV output over 13 would lead me to suspect the cell was about to burn out.

I dived two APD cells to death last year during the cell drought and they were both showing over 14mv in air before they died with a historic air MV output of 10 and 10.5

So if i were planning a big dive with cells outputting 15mv on pre dive checks, i'd bin the cells and try some new ones.


ATB

Mark

NotDeadYet
20-11-11, 01:13 PM
Because i do a manual check against a known gas and dont rely on the unit to interprit what it thinks it sees for me.

That's what you do. But earlier you said you see loads of divers who just hit "calibrate" and get on with something else. Why do you think the opposite of that is what you have written above? If they are calibrating without thinking then the other choice is to say no to calibration without thought either.

Cal'ing or not is irrelevant, it is a procedure fault. Either works only as long as the diver is thinking about what they are doing. Everything else is just a circular argument with no end.

Mark Chase
20-11-11, 01:22 PM
That's what you do. But earlier you said you see loads of divers who just hit "calibrate" and get on with something else. Why do you think the opposite of that is what you have written above? If they are calibrating without thinking then the other choice is to say no to calibration without thought either.

Cal'ing or not is irrelevant, it is a procedure fault. Either works only as long as the diver is thinking about what they are doing. Everything else is just a circular argument with no end.


I don't see it as a circular argument

Not manually checking the unit in air and 02 prior to a dive is bad and calibrating blind over potential faults is not great either but i suppose the unit will pick up on the worst issues.

It all goes back to a "the unit will save me attitude"

I have the attitude of I will survive despite the unit trying to kill me.

My training didn't include analysis of the calibration process, two point checks, millivolt output checks or current limiting checks.

If you do all that AND calibrate then fine but its not what i see happening on boats.


ATB

Mark

matthewoutram
20-11-11, 01:58 PM
The end calibration reading on a Inspo Classic is always 0.98 0.98 0.98 cells do not always output 9.8mv

They are the calibrated values, not the end-of-cal (stable Flushing Bag) values to which I refer. Sorry if I was not clear.


There is a reading just befor that which is on screen for a second or two at best and that might be 0.96 1.04 0.98 that may or may not relate to the air MV output

Yes, they are the ones that show the mv output in air - in your example 9.6mv, 10.4mv and 9.8mv.


Using a constant calibration factor its only showing the end output devided by 50. If the cells are non linnier than its not showing the actual read out in air.

Exactly, as the cells decay the values drift, and you can see this easily at the end of every calibration. It is why I calibrate every dive, not ever now-and-then. If I expect to see 0.96, 1.04 and 0.98 and I don't then something is wrong and I must investigate.

Matt.

matthewoutram
20-11-11, 02:07 PM
The age printed on the cell isn't particularly relevant. AP used to test the cells than put them in a bag and vacuum pack them. As the chemical reaction inside the cell needs 02 to function the cell doesn't age much inside the bag. So APD would sell you a cell that was 6months old the day it arrives and it may rattle in your dive box as a spare for another six months and then be fitted. So the date stamp can be a year old when the cells been in use 1 month.

I started marking my cells with date installed so if i coped it i wouldn't be accused of diving old cells.

I believe the recommendation is 18 months from manufacture, not from install. 12 month warranty from purchase date. This is what I follow anyhow.


A MV output below 9 would lead me to suspect a current limited cell.

A MV output over 13 would lead me to suspect the cell was about to burn out.

The allowed range is 7.0-13.5mv. Below 9.0 is OK, below 7.0 is not.

I agree that a change in values means the cell is having a problem, hence why I am "banging on" about those end-cal values, watching them and making a frequent mental note.

Matt.

NotDeadYet
20-11-11, 02:08 PM
If you do all that AND calibrate then fine but its not what i see happening on boats.

I'm not surprised. All you'd see me do on a boat is a few cursory checks and get in the water. That's all I see anyone do.

My unit is rigged and checked before it goes near a boat. Not seeing it and it not happening aren't the same thing.

Calibrating or not calibrating is irrelevant and like I said I think it is a pointless argument. If it hits 0.21 and 1.0 in the right places then why cal but equally cal'ing and checking it at 0.21 and 1.0 is valid too.

I know myself from diving a KISS that I found myself getting in the water with the displays hitting near enough the right numbers because it was such a pain in the arse to calibrate. And I also know that I found myself accepting an increasingly big gap on that "near enough" before I would recalibrate. I don't think that is a particularly good situation. I like push button calibration, I think if something is easy to do then it is more likely tobe done properly and I like calibrating every time the unit gets put together. I can't comment on what other divers do because I only see what they do on the boat itself and to be honest I don't really pay any attention to how they rig their units so all my comments are confined to just me.

matthewoutram
20-11-11, 02:22 PM
I'm not surprised. All you'd see me do on a boat is a few cursory checks and get in the water. That's all I see anyone do.

My unit is rigged and checked before it goes near a boat. Not seeing it and it not happening aren't the same thing.

Calibrating or not calibrating is irrelevant and like I said I think it is a pointless argument. If it hits 0.21 and 1.0 in the right places then why cal but equally cal'ing and checking it at 0.21 and 1.0 is valid too.

I know myself from diving a KISS that I found myself getting in the water with the displays hitting near enough the right numbers because it was such a pain in the arse to calibrate. And I also know that I found myself accepting an increasingly big gap on that "near enough" before I would recalibrate. I don't think that is a particularly good situation. I like push button calibration, I think if something is easy to do then it is more likely tobe done properly and I like calibrating every time the unit gets put together. I can't comment on what other divers do because I only see what they do on the boat itself and to be honest I don't really pay any attention to how they rig their units so all my comments are confined to just me.

Couldn't agree more. And my comments only relate to me and by usual buddy. What other people do it up to them.

As this thread is about Meg/Inspo choices, how you'd like to approach calibration is something to consider. Neither approach is wrong, but these 2 units in this regard are quite different.

Matt.

PeterVICEG
20-11-11, 06:03 PM
Thanks for this, so to clarify, on a two dive day you will do the cal' check the night before.

If I am on a boat or am doing multi day dives, I do not do the head check between dives or even between days. I do not consider this a "cal check".

This is a good thread for me, (was it good for you :-)) but for me I still think that calibaration when nessesary but not nessesarily calibration.

As I understand it callibration by route will paper over problems and tell you little about cell health. I track Mv output instead.

When I got my unit it came with a check sheet that was IMHO more about covering the manufacturers ass than being helpful. I modified the check list a couple of times making shorter and more relavant. I am going to shorten it more. Maybe down to tracking Mv output and a check to make sure I have confimed the check valves on the DSV or BOV.

Peter

matthewoutram
20-11-11, 08:32 PM
As I understand it callibration by route will paper over problems and tell you little about cell health. I track Mv output instead.

I think we're saying the same thing (sort of) and doing the same check (sort of), but using a different method on 2 different machines. I agree that we should be monitoring our cell health, and I also agree it probably isn't essential to calibrate every dive. I calibrate (much to some peoples annoyance ;-) as this is how I was taught, the feature is built-in to my switch-on routine (hence it is easy and accessible with zero extra steps), it is the recommended procedure and it is my way of tracking those end-cal values.

The other reason I like to calibrate before the dive is that I can then be sure that ppO2 values are as close to right as I can get. Cells drift (even dying cell) slowly, and my dive is less than 4 hours, so I just need them to work for that length of time and I am safe for that dive. Not everyone's cup-of-tea, but I can live with that.

I've enjoyed the banter, and we've all found out some strong opinions, have a nice evening guys and girls, work tomorrow :-)

Cheers
Matt.

Mark Chase
20-11-11, 09:05 PM
I believe the recommendation is 18 months from manufacture, not from install. 12 month warranty from purchase date. This is what I follow anyhow.

So what do you do with your spare cells? Throw them away unopened and un used after 12 months?

The old AP cells were expected to work for three years from date of manufacture. Personally i rejected cells more than six months old when AP sold them to me as they could be in my box for 12 months before use if i haven't had a cell fail in that time. So months old the day i put them in my unit.

That pretty much worked for me. The only cell failures i ever had were brand new cells not ones that id been running a year.



The allowed range is 7.0-13.5mv. Below 9.0 is OK, below 7.0 is not.

Below 9 is not good below 8 is seriously bad. As I said before the Hammer Head rejects cells below 9mv output. Kevin Jurganson told me this is because in tests cells outputting less than 9mv had a 65% failure rate.

I have not had a cell below 8mv that wasn't current limited.

Ill have a look tomorrow and see if any of my old cells are showing 7mv in air and try and demo this for you.


ATB

Mark


I agree that a change in values means the cell is having a problem, hence why I am "banging on" about those end-cal values, watching them and making a frequent mental note.

Matt.[/QUOTE]

Mark Chase
20-11-11, 09:23 PM
I think we're saying the same thing (sort of) and doing the same check (sort of), but using a different method on 2 different machines. I agree that we should be monitoring our cell health, and I also agree it probably isn't essential to calibrate every dive. I calibrate (much to some peoples annoyance ;-) as this is how I was taught, the feature is built-in to my switch-on routine (hence it is easy and accessible with zero extra steps), it is the recommended procedure and it is my way of tracking those end-cal values.

The other reason I like to calibrate before the dive is that I can then be sure that ppO2 values are as close to right as I can get. Cells drift (even dying cell) slowly, and my dive is less than 4 hours, so I just need them to work for that length of time and I am safe for that dive. Not everyone's cup-of-tea, but I can live with that.

I've enjoyed the banter, and we've all found out some strong opinions, have a nice evening guys and girls, work tomorrow :-)

Cheers
Matt.



So what we have here is one of two things that will hapen.


1: the cells are still in calibration from the last calibration and the new calibration was pointless.


2: The cells have significantly altered since the last calibraion (lets say yesterday prepping the unit) but rather than notice this error (that occured in air over night when the cells were not under stress and should raise concerns) You calibrate the unit to bring it back into line despite the fault and then jump in to go diving carrying the fault?


The justification appearers to be that despite the fact humidity and temperature change will make the cells inaccurate during the space of a three -four hour dive you feel it important to get the start point showing 0.98 instead of 0.97.

The cells have an accuracy of +/- 0.05 in use and the only two possibility's for a calibration just before a dive are that it was either totaly unnecessary, or it covering up a problem because lets face it it shouldent have been necessary, but this doesn't change your feeling you need to calibrate

In closing it would apear that on a rocking and roling boat you check the MV end output in the second before it switches to calibration PP02 and mentaly extrapolate the MV in air and compare it with the figures you memorised from the previous calibration.

Correct me if i have got any of the sequance of events wrong.



ATB

Mark

matthewoutram
20-11-11, 10:44 PM
So what do you do with your spare cells? Throw them away unopened and un used after 12 months?

No, I don't manage my cells like that. As always there is more than one way, Mark. I put them in new and prove them in a confined environment for a few hours. Bad cells normally fail early, good cells normally work for the full 12 month cycle. At 12 months I replace them. The old cells become my spares and the new cells go in. I've never had the need to put one of the old ones back in.

I did when I first started CCR have a spare in a bag and yes I did chuck it away.


Below 9 is not good below 8 is seriously bad. As I said before the Hammer Head rejects cells below 9mv output. Kevin Jurganson told me this is because in tests cells outputting less than 9mv had a 65% failure rate.

So you believe KJ but not MP. Interesting.


I have not had a cell below 8mv that wasn't current limited.

Ill have a look tomorrow and see if any of my old cells are showing 7mv in air and try and demo this for you.


Feel free, but it's a duff test because I'm not talking about cells that have decayed to 8mv, but I am talking about one that starts its life at 8mv (never seen one lower out of the bag myself).



1: the cells are still in calibration from the last calibration and the new calibration was pointless.

What harm did the "pointless" calibration do? It was not done blind, it was done for a reason.


2: The cells have significantly altered since the last calibraion (lets say yesterday prepping the unit) but rather than notice this error (that occured in air over night when the cells were not under stress and should raise concerns) You calibrate the unit to bring it back into line despite the fault and then jump in to go diving carrying the fault?

Personally in 9 years I've never seen that. A small drift of 0.0x where x is normally 1 or 2, but not "significant". If I saw 0.16 or 0.08 on the display in air then of course this means a problem (especially if we are talking about just overnight) - the same as if I see 1.12 as the end cal-value yesterday and now I see 0.78. Same problem, needs investigation. Never seen it, though. What I do see (especially with these new APD cells) is that the end-cal value is moving faster than is normal (normal is that the values don't change quickly at all, maybe just by 0.05 in 12 months). Just a few weekends ago I had one that said 0.98 (last dived in August) and on this day in October it now showed 0.82. That's a big difference. That cell in the pot was still linear (so could be calibrated) but this indicates that cell is dying prematurely. It has now been replaced, before the error become problematic.


The justification appearers to be that despite the fact humidity and temperature change will make the cells inaccurate during the space of a three -four hour dive you feel it important to get the start point showing 0.98 instead of 0.97.

Not sure what your point is, but I'd go with yes.


The cells have an accuracy of +/- 0.05 in use and the only two possibility's for a calibration just before a dive are that it was either totaly unnecessary, or it covering up a problem because lets face it it shouldent have been necessary, but this doesn't change your feeling you need to calibrate

That's right. I think your confusing small daily changes with some big cell fluctuation/decay, though. As I said before cell health check and calibration are different things.


In closing it would apear that on a rocking and roling boat you check the MV end output in the second before it switches to calibration PP02 and mentaly extrapolate the MV in air and compare it with the figures you memorised from the previous calibration.

Yes, the boat normally rocks. This is the UK. And no, I'm not extrapolting anything, those numbers are the mv in air - I'm just confirming they are the same (which in 9 years they always have been). If one showed up as 0.8 when before it was 1.1 I would not go in the water.

It you're trying to say I'm advocating only calibrating when kitted for the dive then that's not what I'm saying - I calibrate at home before I pack the car, and the day before the dive and just before the dive. All "pointless" in your eyes, but not in mine. I "memorise" (as you put it) those values and they always come out the same - unless the cell is naff, in which case it can be addressed. After it is address I still go on to do the same number of pointless calibrations - they take 2 minutes and are cost-free, I don't see any need to avoid them.


Correct me if i have got any of the sequance of events wrong.

Other than the dramatisation, yes.

Cheers
Matt.

gobfish1
20-11-11, 11:45 PM
i enjoyed the thread ,, good points from both matt and mark ,,

mark ,,
we dont all walk away ,, and maybe now after this thread even less will be walking away ,,

Garspeed
22-11-11, 09:07 AM
Guys

Have to say that this is the most interesting and informative thread I have read on YD for years so well done guys for sharing your thoughts with all. Both of you have excellent points which should be considered by all but I would also like to add a few things that I have picked up regarding Visions in particular over the last few months when I have suffered 4 new AP cell failures, as follows...

- new cells from AP should read min 0.95 ppO2 prior to calibrating. As detailed above somewhere this equates to 9.5mV in air so if they are lower than this call AP and get them changed out
- for me calibration is an excellent method of checking the heath of my cells but it doesn't give the full picture. If you start with air in the loop (as you should), carefully monitor the process and know what to expect you can easily pick up faults which as Mark rightly says you should be wary of calibrating over
- to get the full picture of your cells health you need to drive the ppO2 higher than normal, hence O2 flush at 6m to get 1.6ppO2 or use narked @ 90 cell checker or similar (my buddy has just bought one so I am looking forward to trying this out)
- AP strongly recommend calibrating before every single dive, even thought the manual says daily is okay
- on the Vision start up menu, there are actually 2 calibration messages that can come up. "Calibrate Y/N" means that the 3 cells are all in line with current ppO2 output so the computer thinks that the previous calibration is therefore okay to use. You can therefore re-calibrate if you want to but you don't need to. "Must Calibrate Y/N" is shown when the 3 cells are not giving similar outputs and the computer wants you to re-calibrate but you can still choose not to (I am surprised that it doesn't force you to calibrate here)
- I am still building experience on my unit so am no expert but my old cells seem to be dropping off with values of around 0.85 ppO2 generally shown before calibration. My most recent new cells are all around 1.00 which is very re-assuring. When cells fail to reach above 0.75 during calibration you will get a cell error and can no longer dive your unit (7.5mV in air) due to failed calibration. This is what has happened to me each time my new cells have failed. My old cells however tend to drift apart, especially towards the end of a 2nd dive when I have not managed to dry out the head between dives and this gives you lots of beeps, flashing red lights etc due to cell errors. This in my opinion is why you need to calibrate between dives ie to take into account how the dampness in your head is affecting the output of each cell (which can be different) and therefore calibrate accordingly to correct it.

I hope the above helps the many Vision users out there. As mentioned, I am no expert but as always, you seem to learn much more when things go wrong and I have had more than my fair share of cell issues these last few months.

Cheers
Gar

Mark Chase
22-11-11, 10:18 AM
So you believe KJ but not MP. Interesting.


I only beleive experiance. KJ and MP have vested interests so its big pinch of salt stuff when i talk to them.

From personal experiance cells from new with less than 8mv in air have been current limited imediatly or within a few dives.

That said when i had the cells that were below 8mv in air i phoned Martin parker who told me they would be fine and blamed the problem on the Hammer Head

I Emailed Kevin Jurgonson and asked why his unit wouldent calibrate and he said it was because cells outpuing that low were likley to fail.

Both cells failed using an Inspo head (because i couldent get the HH to accept the cells)

So on the basis of that little event KJ was right and MP was wrong.

Martin kindley sent me out two replacement cells. I thaught this was good service and was happy dispite the lost dive.

Right up till I got my CC statement and found hed charged me for the two replacement cells. He must have held my CC information to do this as i obviously wouldn't have paid again knowingly.



What harm did the "pointless" calibration do? It was not done blind, it was done for a reason.


None if it wasn't blind.

My personal isue with this is people who rely on the unit to inspect and check the cells. If you realy are checking MV 0utput against previous readings when you calibrate, than theres no issue. The only question id ask is why not just flush the unit with 02 and check the PP02 readout? That would give you a lot more time to think rather than catching those number that apear just beofre it switches to calibrated PP02



Its been a good thread. I can see that your pretty vigilant in your pre dive routine. As is often the case with these discussions the target is not the person on the other side of the debate it is those who follow neither discipline


Thanks for keeping it all on topic and civil


ATB

Mark

matthewoutram
22-11-11, 10:42 AM
I only beleive experiance. KJ and MP have vested interests so its big pinch of salt stuff when i talk to them.

Good plan. I'm thinking the same way. I also found Paul R's paper pretty good on this topic: http://www.revo-rebreathers.com/uploads/downloadsitems/Understanding_oxygen_sensors.pdf


From personal experiance cells from new with less than 8mv in air have been current limited imediatly or within a few dives.

I agree with that, actually. Normal output seems to be over 9mv, but less than 11mv. Outside this is not a great place to be - especially out of the bag. Given that your cells are in this range from new then it is the deviation that needs to be monitored.


The only question id ask is why not just flush the unit with 02 and check the PP02 readout? That would give you a lot more time to think rather than catching those number that apear just beofre it switches to calibrated PP02

That's an alternative, and a valid one. The unit actually gives a lot of time to see those values during Calibration as getting those last couple of 0.0x's takes a good few seconds. No reason why you're test cannot be done and used successfully. Personally I use the solenoid, with the unit stood-up, to create the pool of O2 right in the lid where the cells are.


Its been a good thread. I can see that your pretty vigilant in your pre dive routine. As is often the case with these discussions the target is not the person on the other side of the debate it is those who follow neither discipline

I think a good few folks reading this will think a little more about what they are doing - and that is a good thing. Cell health is very important to monitor - the checks Garspeed mentions above being the main ones, and the ones you advocate Mark being the others.

Calibration isn't always needed, but I do it anyway - not like a sheep, but because if you pay attention you can really start to see how these "little buggers" work.


Thanks for keeping it all on topic and civil

Cheers Mark.
Matt.

Diving Dude
22-11-11, 12:13 PM
Get a room you two. :D

But when you do, please keep the cell discussions for here.

matthewoutram
22-11-11, 12:29 PM
LOL


Get a room you two. :D

But when you do, please keep the cell discussions for here.

Dive Africa
22-11-11, 12:29 PM
Hey there

I go diving for a couple of days and it took me a couple of hours to read the banter.

Me (diving a meg - seeing that we do not have to calibrate every dive/day:rolleyes:) will use the following methods:
- I will calibrate every time I change altitude.before a trip (at the dive sites altitude) - this happens quite a lot - not technically a requirement but i find that some discrepancies come in when I do not - albeit a small change.
- I will not calibrate again at a specific site (even if I dive there for a week) - unless I see an anomaly. I.e cells measure this today but slightly different the next or three cells start drifting apart in readings (sligtly) at any point.
- largish anomalies will lead me to check cell linearity - this I do by checking mV (per cell) at air and at O2 and comparing it with table - also you will start seeing problems in the cell's behavior - one changes faster than the other - funny enough a cell quite often reads higher and tracks faster just before it falls over
- I will every once and a while also do a pressure pot test (3 to 6 months) - when there is one around. - I dump my cells every 12 months whether they good or not and yes I change all my cells at once (which propably will create more banter :embarassed:.

Major Clanger
22-11-11, 12:45 PM
If I have to calibrate my meg every time I change attitude I'd never stop. Oh sorry you said altitude :) Good thread. I go Meg in Jan 12.

Dive Africa
22-11-11, 12:54 PM
You'll enjoy the Meg - it really is a good machine

If I can convince the government - I am hoping to get a Pathfinder early next year, in addition to my Meg - to use as a side-mount/traveling and for the shallow stuff and as 40th birthday present - I need a big one not handling the 40 thing very well:angel:

Major Clanger
22-11-11, 01:07 PM
Lucky you, next year I have to handle the 50 thing.

Dive Africa
22-11-11, 01:10 PM
LOL - don't worry the Meg will make it better:)

PeterVICEG
22-11-11, 02:50 PM
Lucky you, next year I have to handle the 50 thing.

It worked for my 60 thing!

Brad_Horn
22-11-11, 10:28 PM
Interesting discussion on the calibration aspects and cell failure issues.

Something the doesn't appear to have been discussed on the meg vs inspo debate is the recent disclosure by Leon on 2 separate occasions that the Meg can now be dived on just one cell. See Leon destroyed Meg at 215 Feet on Vimeo (http://vimeo.com/31557013) and NACD Rebreather Summit 2011 - Part 3 - ISC on Vimeo (http://vimeo.com/32257064) Unknown by me if it is a true sensor fusion aka what DL have published that lets the unit run on 1 good cell with 2+ faulty cells or just Leon diving it on a single cell with the other 2 slots empty.

If the Meg can now run off cell fusion which needs to be clarified as opposed to voting logic as per the Inspo that appears to be a massive improvement in diver safety as you would then have true cell redundancy with 3 oxygen cells in a recreational eCCR. Can the Meg even test cells during a dive to poll those that still work within the required limits and if so how have ISC modified the cells to achieve this is something else thats linked to the issue to question.

On the other side of the coin is Leon purely running the risk of recommending diving on a single cell on his rebreather to try and sell units whilst not disclosing that the Meg still uses a 3 cell voting logic? If so that may just point to the financial climate rather then any real difference in the two CCRs....

Regards
Brad

Dive Africa
23-11-11, 06:28 AM
Hey Brad

This point was debated in depth (to death) on Rebreatherworld.

My understanding is that Leon never recommended that the Meg be dived on one cell only, merely showed as a redundancy feature that it will get you out of the water, even if 2 of the 3 cells fail.

Recommendation is always to dive all 3 cells.

Dries

Mark Chase
23-11-11, 07:53 AM
Hey Brad

This point was debated in depth (to death) on Rebreatherworld.

My understanding is that Leon never recommended that the Meg be dived on one cell only, merely showed as a redundancy feature that it will get you out of the water, even if 2 of the 3 cells fail.

Recommendation is always to dive all 3 cells.

Dries


But it was just sales gimmic. Personaly I found the whole thin a bit of an insult to my intelegance

You cant run a meg on one cell unless the other two cells are totaly disconected. (as he did in his vid) If they are still attached and giving some sort of reading then they make it virtualy impossable if thers voting logic. If the Meg dosent have voting logic what cells does it use to decide an a set point?


If there was a system on the Meg which allowed you to cancle out one or two of the cells id be impressed. IE you could pull up a menue and instruct the unit to use cell 3 only for PP02. Apart from that I cant see an advantage.

ATB

Mark

Mark Chase
23-11-11, 07:55 AM
double post

Dive Africa
23-11-11, 07:58 AM
Off course it was a sales gimmic

Meg does have voting logic - but because it also shows actual milivolts and you have been trained in this regard - (even if two cells fail) you would be able to find good cell quite easily and then finish dive (manually on correct cell)

This is not a meg unique feature.

Mark Chase
23-11-11, 07:59 AM
No Brad if you want to test your cells during a dive and decide which one is acurate and use this for your PP02 you need a processor with a billion + nerurons (your brain) and a KISS


Dill flush? Use Shearwater computer to tell you what the PP02 should be at your present depth with a known diluient. (or god forbid work it out in your head) Check which cell is closeset to that PP02. Folow that cell. Job done.

No need for 1000s in RD and CE mark. Just a bit of comon sense required.


Lets see.

18/45 diluient at 50m thats .18 X 6 so 6X1 is errrrrrr 6 and 8 X 6 is errrrrr 48 add them together remembering the decimal place and we have a PP02 of 1.08

Flush Flush now which cell is showing 1.08?


ATB

Mark

Dive Africa
23-11-11, 08:00 AM
correct, as simple as this

taylojonyd
23-11-11, 08:04 AM
If there was a system on the Meg which allowed you to cancel out one or two of the cells id be impressed. IE you could pull up a menu and instruct the unit to use cell 3 only for PP02. Apart from that I cant see an advantage.


You mean like you can on the Sentinel ;)

(user can disable 2 of 3 cells & electronics will work using remaining cell)

Mark Chase
23-11-11, 08:06 AM
You mean like you can on the Sentinel ;)

(user can disable 2 of 3 cells & electronics will work using remaining cell)


Excelent design

tel me why you sold it again :D

ATB

Mark

matthewoutram
23-11-11, 08:21 AM
It would indeed be nice on all units if you could turn-off cells underwater and allow the big brain to take over. You get a similar effect if you put the SP down to 0.7 (or less) (i.e. turn off the Voting Logic) and use the button, though.

You can do the same stunt with a inspiration vision, just disconnect the cells and jump in switched off - turn on, clear the start error, suppress the warning, away you go. I've not come across the term "sensor fusion" but is sounds like some built-in cell health check (which I thought the Discovery had?) - I didn't see that mentioned in the "promotional stupidity" video. As Mark says a dil flush does the same job anyhow.

Cheers
Matt.

NotDeadYet
23-11-11, 08:33 AM
What I'd like to have seen is what happens if you lose that single cell. I know on the Hammerhead it would make the dive exciting and you'd have to react very quick.

On the old Mk15 controller if you had a cell go out of range then it froze it out and replaced it with a number that was 70% of the cells in range then averaged the whole thing out. Standard setpoint is 0.9, lose a cell and it ends up being held at 1.0, lose two and it ends up running at around 1.2.

Sent from my GT-I9100 using Tapatalk

taylojonyd
23-11-11, 08:54 AM
What I'd like to have seen is what happens if you lose that single cell. I know on the Hammerhead it would make the dive exciting and you'd have to react very quick

On the Sentinel (which I sold, liked the electronics!) disabling the remaining cell (i.e. disable all 3) simply turns off the CCR functionality. primary handset became a VR3/VRx computer doing deco against a fixed set-point that you specified & you ran unit manually using secondary (I had the dumb one).

Mark Chase
23-11-11, 09:08 AM
My whole problem with new tec like this "Cell Fusion" (what ever that is) is the way it enables people to dive CCR who perhaps shouldn't be diving one.

Its an issue that relates back to automated calibration as well in terms of blind faith in the machine over personal accountability


I can understand automation when the human equivalent is too complex. In this way i understand why we have conversion and compensation from Millivolts into PP02. Doing it manually is too much to ask. But for critical safety checks i always prefer manual

Id explain it like this:

IF you want to add 2 + 2 you could make a fist and stick out two fingers then stick out two more fingers and count the result.

You end up with solid indisputable proof that its 4. If you use a pocket calculator and punch in 2 + 2 and it responds with 4, how do you know thats correct?

Simple with 2+2 but what about the cubed rout of 832?

Now on a CCR you have the choice with a modern unit to lit it do all the checks and calibration and in the end it spits out a figure we just accept and dive with. Unlike the math question of the cubed rout of 832 we know there are variables that could mess up the calculation. The problem is now one of Physics. At school we did all the math for Physics "in a vacuum" because in the real world the math would be influenced by many possible outside forces that could make the results total garbage.

The activity of a CCR is dynamic. The readings influenced not only by cell performance but by temperature, humidity and quality of signal contacts.

All this aside in general they work reliably and give consistent performance

On a totally manual CCR you develop a feel for the performance of the unit. It becomes intuitive. Some argue that by listeing to the solenoid fire on a ECCR they have developed the same level of intuitive feel. (not me i couldn't hear it)

When it feels wrong you can carry out simple checks on cell health. Inject 02 to see if all cells go above set point? Flush with diluent to see if cells are accurate.

The accuracy of he cells against a dill flush is hard data against a fixed datum (the gas in your diluent) You don't have to second guess it. Its a fact just like the four fingers sticking up on the 2+2 problem.

If you rely on the machine to do it your back to the cubed rout of 832. You just have to accept the computer is right even though you are aware the computer cant handle the variables.

Despite the automation some divers Will still carry out hard checks. Fr them the electronics are a diving aid, not a crutch.

For those that don't? then its all down to luck if you survive the day.

People like AD Ward will try and convince me they have got it all covered. And it is possible. Now when i break in my car i break with total confidence because i know even in the snow my ABS and Dynamic Stability Control will catch my lack of skill. If one day they should fail no doubt ill end up in a ditch but they have had millions if not billions of pounds of RD spent on them so its a pretty safe bet.

Mind you?

Did you see the results of Mercedes automated anti rear end breaking system?

I believe Mercedes have a few more pounds to spend on RD than Alex.

Mercedes Auto Brake Fail - YouTube (http://www.youtube.com/watch?v=BYY7OfQ4-5A)

NotDeadYet
23-11-11, 09:17 AM
On the Sentinel (which I sold, liked the electronics!) disabling the remaining cell (i.e. disable all 3) simply turns off the CCR functionality. primary handset became a VR3/VRx computer doing deco against a fixed set-point that you specified & you ran unit manually using secondary (I had the dumb one).

On the Hammerhead if you lose all three cells then bizarrely because all three cells are in agreement (zero) it assumes they are right. Cue massive solenoid firing. I've raised it that it can't be hard to have a sanity check in the code but they would rather have flashing lights and a fooking GPS in the next revision rather than actually fix one of the big weaknesses.

It might sound unlikely to lose all three cells but with many units running either a common negative or a common positive across the cells then to me it doesn't sound that remote.

Sent from my GT-I9100 using Tapatalk

matthewoutram
23-11-11, 09:40 AM
My whole problem with new tec like this "Cell Fusion" (what ever that is) is the way it enables people to dive CCR who perhaps shouldn't be diving one.

I guess that's the point, especially for the manufacturers. Here's the link to the APOC Sensor Fusion, which appears as always as PDF: http://www.deeplife.co.uk/or_files/DV_O2_sensor_fusion_100212.pdf At least I didn't know what this was:



The Sensor Fusion Algorithm is designed to reject as invalid any readings from the
Rebreather’s oxygen sensors which diverge by more than 10% from those of the other sensors
and then to ‘fuse’ or combine the valid readings to form a single result for PPO2 monitoring
purposes. The algorithm will prefer a high reading to a low reading, as the primary failure mode
of the sensors has been engineered to be failure low. An additional layer seeks to safeguard
the diver from risks of hypoxia or hypercapnia.
The operations are applied to the data flow from the oxygen sensors, regardless of their status,
each time a PPO2 value is required to be read form any sensor.



But for critical safety checks i always prefer manual

I prefer both. A system of manual checks for cell health (check previous calibrated values in air and in o2, linearity check at 6m (or deeper with care), dil flush check, physical inspection of the cells and loom, pressure pot check, end-cal-value check etc). I also think there is a lot to be gained from automation as it provides a regular and repeatable way to go about things.


Id explain it like this:

IF you want to add 2 + 2 you could make a fist and stick out two fingers then stick out two more fingers and count the result.

You end up with solid indisputable proof that its 4. If you use a pocket calculator and punch in 2 + 2 and it responds with 4, how do you know thats correct?

Simple with 2+2 but what about the cubed rout of 832?

832/10 is 83, which is quite close to 9 and 9x9 is 81, so I'll have a stab at 9.2?


On a totally manual CCR you develop a feel for the performance of the unit. It becomes intuitive. Some argue that by listeing to the solenoid fire on a ECCR they have developed the same level of intuitive feel. (not me i couldn't hear it)

You do develop the feel for the same on eCCR, but you have to work at it. With manual you either work at it right away or you don't get that second chance. Perhaps here we are talking more about training, rather than the units themselves. Certainly with fully-automated units there could be a tenancy to dumb-down the training so that divers don't even know about this stuff.

I would think you can fly both the Meg and the Inspo manually if you want - but frankly, why would you want to?

I like the idea of the electronics being an aid not a crutch.

No one is diving the APOC iCCR, Cell Fusion or not - that's a totally theoretical machine. (Please, lets not contaminate this thead with APOC discussion...go here for that and grab post 6138...https://www.yorkshire-divers.com/forums/osel-apocalypse/79728-apocalypse-mccr-154.html

Cheers
Matt.

Mark Chase
23-11-11, 09:49 AM
On the Hammerhead if you lose all three cells then bizarrely because all three cells are in agreement (zero) it assumes they are right. Cue massive solenoid firing. I've raised it that it can't be hard to have a sanity check in the code but they would rather have flashing lights and a fooking GPS in the next revision rather than actually fix one of the big weaknesses.

It might sound unlikely to lose all three cells but with many units running either a common negative or a common positive across the cells then to me it doesn't sound that remote.

Sent from my GT-I9100 using Tapatalk



Thats one of those OMG failure modes that leaves you scratching your head in amazement.

On my Hammer Head if you had a low batery the fireing of the solinoid would put the voltage so low the unit would shut down.

Then the batery would recover enough for the wet switch to switch the unit back on where upon it would fire a shit load of 02 in to test the cells

The load of the solinoid would kill the battery and the whole cycle repeted its self

It was impossable to override the wet switches so at 80m it would just keep fireing in 02.

All good fun

I am told this is now fixed. However i wasent too impressed with "strap it on a divers back" RD in the field.

ATB

Mark

matthewoutram
23-11-11, 09:52 AM
Thats one of those OMG failure modes that leaves you scratching your head in amazement.

On my Hammer Head if you had a low batery the fireing of the solinoid would put the voltage so low the unit would shut down.

Then the batery would recover enough for the wet switch to switch the unit back on where upon it would fire a shit load of 02 in to test the cells

The load of the solinoid would kill the battery and the whole cycle repeted its self

It was impossable to override the wet switches so at 80m it would just keep fireing in 02.



Turn the O2 off ;-)

Mark Chase
23-11-11, 09:59 AM
Turn the O2 off ;-)


Three problems

1: The residual 02 in the hose still alowes for enough injection to spike the PP02
2: You lose manual 02 inject so have to go OC or SCR

3: At 80m the now empty hose will crush flater than a witches tit puting enormous presure on the crimped joints and possably resulting in a failure which looses you access to the 02 shalow so no 100% CCR at 6m to finish deco

I was going to put an inline isolator on the 02 side (like the detachable 02 feed on the solinoid of the Meg) but in the end i just sold it and baught a KISS

ATB

Mark

NotDeadYet
23-11-11, 10:10 AM
It is fixed but it is still sensitive to voltage. Well, cold really. Low temps kill cheap AA batteries, high drain batteries are fine. I switch at this time of year until about April and I've never had a problem.

On a Mk15 it's less of an issue as it has an attenuator on the oxygen line so it can never fire more than that each cycle. If you turn the O2 off then it is all HP hosing and pipework so no crushing or strained seals.

Sent from my GT-I9100 using Tapatalk

taylojonyd
23-11-11, 10:13 AM
It is fixed but it is still sensitive to voltage. Well, cold really. Low temps kill cheap AA batteries, high drain batteries are fine. I switch at this time of year until about April and I've never had a problem.

So I guess there's some advantage to having the batteries inside the loop where it's relatively warm!!!

matthewoutram
23-11-11, 10:23 AM
Three problems

1: The residual 02 in the hose still alowes for enough injection to spike the PP02

Blow it out of the exhale dump.


2: You lose manual 02 inject so have to go OC or SCR

I take a redundancy bottle of O2 with a separate whip.


3: At 80m the now empty hose will crush flater than a witches tit puting enormous presure on the crimped joints and possably resulting in a failure which looses you access to the 02 shalow so no 100% CCR at 6m to finish deco

Why would the pressure in the hose drop to 0 and not equalise to 9 bar? Even LP hose can take several tens of bar internal pressure - why it is different in this case?

Cheers
Matt.

1693
23-11-11, 11:50 AM
Blow it out of the exhale dump.It enters the loop on the inhale side of the scrubber on the JJ-CCR


Why would the pressure in the hose drop to 0 and not equalise to 9 bar? Even LP hose can take several tens of bar internal pressure - why it is different in this case?+1, the solenoid isn't a pump

Mark Chase
23-11-11, 12:05 PM
Blow it out of the exhale dump.


I take a redundancy bottle of O2 with a separate whip.



Why would the pressure in the hose drop to 0 and not equalise to 9 bar? Even LP hose can take several tens of bar internal pressure - why it is different in this case?


Cheers
Matt.


Where is the exhale dump in the hose feeding the solinoid?

Seporate redundent o2 is defo an option.


The solinoid sucks the gas out of the solinoid feed hose and the hose goes flat as a ribbon.

ATB

Mark

Dive Africa
23-11-11, 12:09 PM
Why not just consider adding a manual slide shut-off on the solenoid O2 feed?

Mark Chase
23-11-11, 12:09 PM
It enters the loop on the inhale side of the scrubber on the JJ-CCR

+1, the solenoid isn't a pump

Wouldent the 9bar crushing efect on the hose push the 02 through the solinoid as you vent gas from the loop?

The ADV works on a negitive presure in the loop to fire and i am sure the solinoid would work the same way so as you hit neg t would vent gas out of the 02 line into the unit alowing the hose to crush.

Maybe i am wrong but that what id expect to hapen.

ATB

Mark

Mark Chase
23-11-11, 12:10 PM
Why not just consider adding a manual slide shut-off on the solenoid O2 feed?


Thats exactly what i considered but on the Inspo the hose routing for the solinoid feed didnt offer an easy location for it.

ATB

Mark

Dive Africa
23-11-11, 12:13 PM
Buy a meg - then you would not need it in the 1st place (me playing devil's advocate :wink:0)

Dive Africa
23-11-11, 12:19 PM
Sorry - I though we where talking about a Hammerhead - I know you assume we are talking about an Inspo with a Hammerhead head?

I preferred the travel frame on the Inpso in any event - not the CD one but the one made by the Yanks - so would have been able to add shut-off

1693
23-11-11, 12:21 PM
Wouldent the 9bar crushing efect on the hose push the 02 through the solinoid as you vent gas from the loop?

The ADV works on a negitive presure in the loop to fire and i am sure the solinoid would work the same way so as you hit neg t would vent gas out of the 02 line into the unit alowing the hose to crush.The solenoid doesn't 'suck' it merely opens. The inside of the loop is at ambient, otherwise the lungs and corrugated hoses would also 'go as flat as a ribbon' - think about it. This is why a fixed IP reg will fail to deliver gas below a given depth.

The ADV fires as you create a slightly negative pressure by bottoming out the lungs. Even Linda Lovelace couldn't generate 9 Bar of suction.

matthewoutram
23-11-11, 12:45 PM
It enters the loop on the inhale side of the scrubber on the JJ-CCR

I know the loop on the Meg is the opposite way around - so the O2 is on the inhale side.


Where is the exhale dump in the hose feeding the solinoid?

On the Inspiration the exhale dump is in the middle of the exhale counterlung, right above the o2 button. So assuming conventional set-up you push the button and simultaneously pull the dump and the gas goes out of the pipework and into the water.


Seporate redundent o2 is defo an option.

IMHO it is the most valuable "bail-out" gas that can be taken, but is generally overlooked in favour of monster OC gear. Most divers still dive with OC mentality - cell health checking is actually way down the list of problems CCR divers have diving CCR.


The solinoid sucks the gas out of the solinoid feed hose and the hose goes flat as a ribbon.

Actually the solenoid opens and the gas flows due to pressure difference. So when the solenoid is stuck open you get flow until interstage pressure equal ambient then the flow stops. The hose does not collapse because as Nick says:


+1, the solenoid isn't a pump

Cheers
Matt.