YD Scuba Diving Forums banner

1 - 20 of 23 Posts

·
The Artist formerly known as 'Kirky'
Joined
·
2,228 Posts
Discussion Starter #1
Imported post

Hiya - while waiting for my 12l twins for Xmas, I was considering the following. Whilst they will be O2 clean I wont always be diving nitrox. A colleague of mine suggested getting my pony O2 cleaned and using a 40% mix (I`ve only got the basic nitrox card) for deco. Now I wont be doing major deco dives but would this be any use when doing my 5m safety stop on dives > 18m ?? Will I feel any less knackered or is this just a waste of time & money
 

·
Killed in the line of Duty. RIP.
Joined
·
173 Posts
Imported post

Kirky
I presume that you'll get a load of replies to this as it seems there's only me and thee who hasn't done the advanced nitrox course
And I've got mine booked for the new year, if you want to have a look at it get hold of Andy H (Dalesdiver).
 

·
Registered
Joined
·
3,914 Posts
Imported post

It certainly can't do anything but good for you post-dive condition, but how much good is open to debate.

If you're getting O2 clean tanks but will be using regular air fills (which may not be sufficiently 'clean' ) you may want to think about a personal filter so you can double filter to maintain your tanks O2 clean status (Beaver have one for about £80 but I'm sure I've seen then for about £70 elsewhere)
HTH
Steve
 

·
Registered
Joined
·
162 Posts
Imported post

Steve, have a good point. You can also make sure that the air fills are properly filtered. I'm assuming that you get your air where you get the nitrox, right? I would insist on clean air.

The Pony question is a valid one. I'm sure that the richer the mix the less N content in your stream. This would be handier for multiple dives. I'm not sure about the knakeredness, though. I do the same with my 4L (45% O2 <>). Even on my holiday this summer I did that. Some people gave me a dirty look and it is expensive, but I feel better doing a safety stop on 45 and higher, than using air.

Take care

Lawrence
 

·
Registered
Joined
·
12,240 Posts
Imported post

Hayhurst's your man for questions like this. As an aside, NEVER - even if you're not yet Nitrox cert'd and never intend to be - have you cylinders filled with anything other than DOUBLE-FILTERED 21%. Insist on it when you get your fills - and if the place can't/won't offer it, go elsewhere for your fills.
 

·
Premium Member
Joined
·
5,739 Posts
Imported post

Point to bear in mind - if you have EAN40 in your pony, plan and limit your dive depth as if ALL your gas was EAN40 - if you are diving deeper than 25m with air as your main gas and EAN40 in your pony, you CANNOT use your pony in an emergency (unless you are willing to risk an O2 toxicity seizure that is!)
 

·
Killed in the line of Duty. RIP.
Joined
·
173 Posts
Imported post

As soon as he sends the lesson notes and I get chance to read them, I'll arrange a date to suit him, perferably mid week.
But at a time and date to suit Andy H, I understand he's aready booked up for January and well into Feb, again unless its mid week when he says he can do almost one to one.
 

·
Killed in the line of Duty. RIP.
Joined
·
173 Posts
Imported post

I'll send you an email as soon as I get the papers and we'll sort a date out if you want
Sooner rather than later.
 

·
Resident Sprog Plod
Joined
·
835 Posts
Imported post

Defo, I did my Basic Nitrox a few weeks ago with Andy and everyone else. It was a great course and the diving / training was very good. I was doing basic nitrox to make up a segment of the SDI Advanced program. I cant wait to do advanced nitrox and the deco course.
 

·
Registered
Joined
·
947 Posts
Imported post

Kirky,

post dive fatigue can more than likely be attributed to sub-clinical DCS. You can go a long way to reduce this by slowing down your ascents. Stick to 10m/min and do you safety stop @ 6m (not 5). From 6m to the surface go at 1m/min (so take 5mins to reach the surface after your 6m stop). You should notice a marked improvement (even on air :reaper: ) if you do this. One thing you should also (always) do is stay horizontal during your ascents and deco.

Obviously using nitrox as backgas will help you a lot. If you were using 36% as backgas for your 18m dive, there would be no real point switching to 40% for your 6m stop. If you switched to pure O2 it would make a difference but would be over the top.

Have a look at this - http://www.fullcave.com/oxygenwindow.htm

40% is not a great deco gas - 50% is much better.

Dunno if that will help or not  - It's all pretty standard stuff so maybe :eek:uttahere:

Mark

look at all those edits lol





(Edited by Mark at 1:50 pm on Dec. 4, 2002)


(Edited by Mark at 1:55 pm on Dec. 4, 2002)


(Edited by Mark at 1:59 pm on Dec. 4, 2002)
 

·
The Artist formerly known as 'Kirky'
Joined
·
2,228 Posts
Discussion Starter #13
Imported post

Mark - some good points - I try to stick to the basics in terms of ascents but will slow it down a bit further. As far as the 50% is cincerned - this was what I was advised but can only currently go for 40% due to certification - something for the list next year I think !!

Thanks to all for the feedback
 

·
A short fat well off crap cave diver. Likes wrecks
Joined
·
15,343 Posts
Imported post

Just to step right in with a controversial statement for my first post:

40 02% will give a P02 of 1.6 at 30m which is more than acceptable risk for bail out as long as the diver is calm and in practice. The P02 at 40M is apx 2 which qualifies under the NOAA exceptional exposure tables as a 30mn max exposure limit??. So I would happyly bail out to 40% at 40m and start to ascend immediatly.

CNS limites are time dependent and of course condition dependant so I feel that a bail out and immediat ascent at 10m/min to 30m is an acceptable risk. I use 1.6pp for deco all the time and switch to 50% at 21m and 80% at 9m.  

Mind you you shouldent be at 40 with anything less than a twin set IMO

Mark Chase  
 

·
Killed in the line of Duty. RIP.
Joined
·
173 Posts
Imported post

Kirky
If you send me an email I'll send a spread sheet with the O2 depths V CNS shown, then you can quickly decide the mix you want to use

[email protected]
 

·
The Artist formerly known as 'Kirky'
Joined
·
2,228 Posts
Discussion Starter #16
Imported post

Hiya folks - thanks to all for the info - its amazing how views differ !!

I`ll still put a high mix in the pony for shallow deco only - not for bailout at depth - thats what (hopefully) the twins will cover.


(Edited by kirky at 6:51 pm on Dec. 8, 2002)
 

·
Registered
Joined
·
12,240 Posts
Imported post

Hey Kirky,

I was at Dales's house yesterday with Davey and saw your brand-new Twin-set sitting there.....all sparkly and new.....and saying to me...."Please take me somewhere wet and dive with me....."

Seriously mate, they look the Nads. Enjoy em and hope to dive with you soon.
 

·
Registered
Joined
·
1,786 Posts
Imported post

They were there but wot with me being a thieving git I've had em away..

Psst!! mister, wanna buy a twinset?

Bren's right kirky me ol'mate.. they look luverly, all shiney and nice like...
 

·
The Artist formerly known as 'Kirky'
Joined
·
2,228 Posts
Discussion Starter #19
Imported post

All I can say is WOOOOOOOOHOOOOOOOOOOOO!!!!!

Off to Cape next Sat to try them out - picking them up Tues pm. Cant wait.

I`ll be dusting them for prints so be warned !! - Oh how I`ll cry when the first scratch appears. I`ll be at the Dotty gig in January and hope to meet up with some of you guys - Only met John H & Ben to date and they are good folk - especially John when he`s effin and blindin !!

If anyone fancies another Cape bimble next Saturday give me a shout. Was in the Dock today assisting a rescue course - 10m of vis - luxury - but gettin bloody cold at 7 degrees.

Cheers all
 

·
Registered
Joined
·
1,786 Posts
Imported post

I'm up for a meet on Saturday..  :biggrin:

kirky, I'm afraid the tanks will be scratched straight away, but hey mate, you don't really wanna look like Mr Burton shops window man now do ya..

Ok so anyone else up for a day of rig trimming and skill sets?
 
1 - 20 of 23 Posts
Top