redundant O2

Depth-junkie

Or better still on deep gas dives that staying on the loop is a priority and coming off the loop the last chance saloon just carry a small 02 bottle.

I carry a 2ltr evo bottle straped to my inspo case as redundant 02. So if inboard loss of 02 no drama, soloniod stuck open just close inboard down and run manualy via manual add buttons with the of board 02 . Much easyer than feathering opening and closing the valve on inboard 02 for hours.

A 2ltr strapped to the case is not noticable at all. And it saves you carrying a stage that is of no use untill you are shallow i,e 9m in the 80% case. If you carry stages and OC is you bailout plan, surely a bottom mix and a int mix will be of more use to you, and if need be fit a reg to the 2ltr an push up to 3m as your last stop and i could get 20min easy out of a 2ltr @ 3m. Plenty of time to enable a drop bottle to arrive or get out walking rather than in a wheel chair.

carrying a 80% and expecting a BT mix to last from say 90m, 80m, 70m or even 50m all the way up to 9m is asking a lot IMHO in a incident that would require a full OC bailout.


ATB
Gareth

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Alpine low rider of the P.D.D.T

dave t

True Gareth but I think that if you have to carry oc gas for your plan, carefully chosen mixes can replace an offboard o2, you can still run the Rebreather on say 60%nitrox and you can get on that OC at 15m or so. Offboard o2 is good (I carry it myself sometimes) but it wont be any good if the unit is flooded, and you cant breathe the loop.

I guess its about risk assesment and where our personal limits are. But I do try and make my system as flexible as possible. I hate carrying more kit that I need

Depth-junkie

I agree, hence why a BT mix of OC followed by a OC stage of say 21/30 or even 32/20 would be a better choice than 60% or 80% as it would enable you to get gas from depths in the 65m or 40m region after your 1st switch from a bottom mix baliout at what ever depth that may have been in 100m+ or 80m etc etc.

Or shallower mix dives in the 50-70m region a BT mix of say 18/40 followed by 50% or 32% and redundant 02 with a reg attached if need be. I personley think redundant 02 on all dives involving deco is a very important addition IMHO.

The redundant 02 can be used if needed OC, or it can be used to maintain the CCR manualy in the event of inboard loss of 02 via leak/HP seat failure or solaniod stuck open. Whilst still enabling a full ascent and deco on the unit whilst maintaing SP at the true desired level and not having to go semi closed and with PO2 levels that are ball park figures at best and not ideal.

Semi is an option to extend the gas volumes, with redundant 02 if the loop is good and you have a PO2 monitor working your laughing.




ATB
Gareth

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Alpine low rider of the P.D.D.T

apitkin

If you think 100% is not safe, why do you think 80% is?

Just interested...

Andy

tibby

Thanks to all for the interesting ideas and discussion. So far, in just a few posts, we covered four different ways of plumbing redundant O2:

1. 6cf bottle for O2 only
2. Team share of O2 via 7ft Rebreather long hose with QDs (carried in pocket) to fit CL manual add valves and LP hoses.
3. Steel 12cf bottle w/80% used for drysuit, wing and Rebreather spare O2.
4. Use rich BO gas to run the Rebreather deep and/or semiclosed.

I would call that a productive discussion. I will consider them all and see what works best for me.
Thanks again and keep'em coming.
Tibby

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Does the voice of reason change when you add helium to the mix?...hmm