Quick question for CCR users CCR on surface

[Dr Stevil]

<font color='#0000FF'>Can one of you bubble-less divers confirm/deny that it is possible to set a CCR to give 100% O2 such that it could be used for DCI treatment at the surface? &nbsp;That is, without removing the 3l O2 bottle from your box and hooking it up to a normal reg. I'm prettty sure I remember that it is but just wanted to be 100% sure
Chee-az
steve

[angleseydiver]

<font color='#000080'>Hi Steve,
In theory on setpoint 1.0 it would work ( you could also use it manually as 100% o2 CCR). However, in practice there would be many pitfalls to the procedure when dealing with a stressed casualty- unfamiliarity with the equipment, you need to wear it to avoid hose-kinks etc, how much life left in scrubber? etc. Most CCR users carry an o2 bail-out DV so would generally be easier to use that to the sacrifice of efficiency,
even post-dive the 3l o2 cyl should be almost full 90% of the time.
ATB,
        Terry

[Dr Stevil]

<font color='#0000FF'>Thanks Terry, it was in respect of a practice exam question on what could be used in emergency situations, I guess if the emergency services hadn't yet arrived and you've exhausted the O2 and everyone's nitrox you'd be prepared to deal with the awkwardness of getting your casualty onto the RB.
Chee-az
steve

[steve-k]

<font color='#000080'>hmm not to sure about this one

true any o2 in the golden hour is better for you but

your patient could vomit down the hose and you may not notice untill its to late,
sat upright and out of the water is the least efficent breathing resisrance position, your pacent could find this stressfull

i think you would be better taking the o2 cylinder of the rig and putting a normal reg on it, it wont last as long but probably better for the pacient

[Rob Evans]

Altogether far too much messing about 'plumbing' a casualty into the unit - it would actually be quite a bit quicker whipping the O2 bottle off and sticking a reg on it. Granted that's assuming you have one lying around.
Assuming (yes I know, how impossible is that) a breathing rate of 25l per min, the casualty would still get 24 min off a 200 bar fill. &nbsp;If you were in a situation where the rescue services were hours away, then you might have to think about using the CCR but you'd have to really need to.

[Duncan Price]

O2 rebreathers for surface use have been around for a long time. &nbsp;They are widely used in mine's rescues and other hazardous environments. &nbsp;Such units like the Biopak have been converted for in water use. &nbsp;DAN have been investigating O2 CCR's for theraputic use but the product has not reached the market. &nbsp;There was a discussion amongst the cave resuce people in the UK last year about the use of CC O2 rebreathers for foul air rescue in caves and mines. &nbsp;I am building another CC O2 unit for dry therapic use in the event of DCI is remote places (when abroad) for just this purpose.

Duncan

[Rob Evans]

Fair enough, makes a whole lot of sense when you think about it, though they're probably a bit more wieldy than the &nbsp;yellow lump though
Just out of interest, are you planning to have a fill of lime permanently sat in the scrubber for any eventuality - weeks and weeks at a time, or just fill it at the beginning of the trip and empty it at the end (maybe get a sneaky sub-6m dip off the thing before you do).

[Duncan Price]

My current O2 pendulum RB (article) has been left full for several weeks after being prepared for a dive which did not happen and then used. &nbsp;The scrubber has end caps for the scrubber which seal it up so it is no different than storing the sodalime in a box.

BTW you can go a lot deeper than 6m on an O2 rebreather if you don't purge the loop of air before you dive. &nbsp;I've been to 11 m with no problems.

There are a number of advantages for using CC O2 for decompressing rather than OC O2: cost, duration and warmth. &nbsp;The sort of stuff I'm doing is done open circuit with a switch to the rebreather for deco.

[Rob Evans]

Nice article! Seems like everyone &amp; his dog's making O2 RBs at the mo, what with the number of websites there are on the subject. &nbsp;Presumably you got some symptoms when you were overbreathing the scrubber?

[Duncan Price]

Originally Posted by [b

Quote[/b] (Rob Evans @ July 09 2003,10:17)]Presumably you got some symptoms when you were overbreathing the scrubber?

Yes - though not the sort of response that you'd get if, for example, you breathed in and out of a plastic bag.  The best way that I can describe it is a feeling of unease, fear or whatever.  The best advice is to get off the loop asap.  Secondly, avoid getting into the situation in the first place - i.e. fresh scrubber, don't over work.

CO2 is highly narcotic and also exacerbates O2 toxicity.