[steve-k]

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its just a baby compared to the inspiration, but its what i hav got at the moment

within my diving circle i am the only one with a re-breather, and i have only had it a couple of months, just done 8 dives on it

there are obviously some rebreather gurus here, so could you please give me your opinion

am i being thaughtfull or foolhardy??

the drager ray is rated by drager as a semiclosed rb, to only use 50%o2 and a maximun depth of 22m, there is no give and take, these are the limits of the unit designed by drager,
now imo these limits hav been set by the 2 extreams of breathing rate and o2 consumption/absorbtion,
with an 8lpm nossle anything less than 50%o2 could be matabalised to below 17%02 in the loop with a breathing rete/absorbtion of 3/3.5 lpm, and with a breathing rate/absorbtion of 0.3lpm 50%o2 (about 44% in the loop) will hit 1,4ppo2 at 22m

now if you know your metabolic rate/o2 consumption and you do the maths you can see that these figures can be taylored to you,

i did a dive to 35m
i increased the size of the cylinder, took a bailout cylinder, decreased the mix to (aprox, cant rember) 35%, and had no problems, i hit 1.35ppo2 at 37m, i tried to simulate laboured breathing, but this had no effect on the ppo2
i took the unit 50% below its maximum depth, and i would plan dives to a maximum of 40n on the unit (but not till i have done more dives)
i allso intend to put a little 1.5litre cylinder on the unit for any deco (only small amounts up to 10 mins) i may occour

 

[angleseydiver]

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<font color='#000080'>just wanted to post to get rid of " inquest" post.
Don't know much about the semi's- went straight to Inspiration.

Love it!!

Unsolved inquests put a bit of a downer on things but you just treat it like a life-support machine- listen and monitor what it's doing, treat it with respect and it will do it's best to look after you.
I'm far from the best diver in the world, maybe one day it will catch me unaware, I'll do my best to see that it doesn't.
Electronics and sea-water aren't the best of mixes but the trade opposed to open-cicuit is worth the risk (maybe).
From what I gather the semi-closed offers much for shallower dives, and in-water time is what it's about, so go for it and enjoy! - but take it steady- learn the nature of the beast before you toy with it, 8 dives IMHO is a bit soon!
ATB and dive safe,
                             Terry
Get used to carrying an extra bottle! - you need it to fill your lift-bags!

 

[Rob Evans]

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I can't say I'm any sort of an expert on Rays (used to dive an Atlantis) but it's fair to say you've been doing your homework re:flow rates and PO2s.  I can only reiterate Anglesey's advice.  Don't go pushing too hard. I'd personally want a good few more hours on the unit before I started pushing the percentages.  I and most of the CCR/SCR guys I know spent most of the first year after getting the card mucking about at 20-30m, just cos the bouyancy characteristics of an RB can catch you out if you're not totally on top of it
Also if you're pushing 40m, think about your bailout.  Get water into the loop on the Ray and you're bollocksed unless you've got enough OC on board to handle all your ascent/deco.  
Drager kit always struck me as lovely for the mid-range stuff cos it's SO light and there's a lot less setting up req'd than on CCR.  However, there are paradoxically less get-outs if it all goes wrong than on CCR so treat the thing with respect and let us know how you get on mate.
Have you tried the Drager lists?

PS 1.5l for deco is WAAAYYY too little.  3l absolute minimum

 

[IDA71]

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Hi Steve,

You are correct in your assumptions & use of the Ray. With the standard 50% jet, you can go as low as 32% feed gas if you have a 1lpm O2 consumption rate. This will give approx 22% in the bag & thus is good for 50m @ 1.4 max PPO2.

I have a couple of neat programmes that allow you to mess with the variables & one of them has an OC bailout planner, if you fancy some deco. Mail me if you want copies.

Drager do sell a 32% jet for the Ray, but it wastes loads of gas & playing with the cylinder mix is far simpler.

I'm busy turning mine into a CCR at the mo.

Safe Diving

Chris W.

 

[steve-k]

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hi IDA71
i have some tables, but if you have the progs that would be appreciated

have looked at the sites on converting into a ccr, it looks reasonabley streight forward, and am interested myself

what would you use for o2 addition?  read somewhere that kiss will sell you there gizmo, but i have lost the link where i read this

sonofolime/scrubber life
i am assuming a maximum time of 100 mins from my canister, what do you use yours to?

 

[IDA71]

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<font color='#728FCE'>Hi Steve,

As you did not send e-mail, I have attached a zip file to this post with the 2 files in it.

I'm a self taught RB diver & have been using my IDA71 for the last 4 years. I use a neat little needle valve that I found after months of searching. It goes down to around .5lpm & up to a max of approx 5lpm. Costs about a tenner which is pretty good in comparison to the real KISS valve.

The problem with the hard shell RB's is they are a pain to transport out of the UK, hence the reason for moving to the Ray & making it CCR. Its just a big stab really. it's also good for remote shore dives away from established dive centres, just need a couple of cylinders to decant from. This is going to be one of the smallest lightest CCR RB's around. The one thing I don't like about the Ray in SCR mode is a very light unit that has 8-10kg  of lead strapped to it to sink it !

I have added a Dolphin ADV core to the Ray ADV, which does not have an SCR drilling, so you can use the Ray ADV purely for dilutant addition on demand. I have added another P-connector below the ADV in the right rear inhale counterlung, the O2 sensors fit in there. I have built a PPO2.com 3 sensor O2 monitor. I have modified a P-connector plug to carry the O2 feed from my KISS valve to the bottom of the scrubber, where an Oxygauge would normally go. Thus I get O2 diffusion through the scrubber bed.

The Ray scrubber holds 1.25kg sofnolime & I have run this for 2hrs+ in SCR mode & estimate that it should be good for 2hrs in CCR mode for shallower dives & 1hr for deeper dives. I haven't finished the O2 addition parts yet, but should have them done this weekend. I'll take some pics then & throw up a website.

Later

Chris W.

 

[steve-k]

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thx for the info
i am very pised at the moment
will reply fully when i sobre up lol  but good to here from you