OC/DSV - essential or toy? Multiple choice too!

Mdemon

Rather than hi-jack yet another OC/DSV thread I'd like to ask people whether they think OC/DSVs should be standard kit supplied with the Rebreather?

Buying them as 3rd party seems sooooo expensive, £400GBP plus, which is a lot for a mouthpiece...

So, two questions in one really - are they essential or just a toy, and should manufacturers be fitting them as standard?

I can't help thinking of them in the same way as I do about ABS on cars - I wouldn't be without now.


Multiple choice, btw!

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caveseeker7

I choose 'Would love to have one' because I believe they increase safety by making fresh gas available with a simple twist. Doesn't get easier or quicker than that. Even more so when the diver needs another's assistance.

I think an OC integrated DSV shouldn't replace a completely separate gas supply, but for the first quick draw of gas to sort things out they're the way to go.

Preferably the manufacturer should supply it as that would obviously be the easiest and least expensive solution, but I can settle for a good aftermarket unit.

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Stefan



"Political Correctness is a doctrine, fostered by a delusional, illogical minority,
and rabidly promoted by an unscrupulous mainstream media,
which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.!"

ROB DAVIE

Obviously, there are widely varying schools of thought about when or IF one should bail out (other than for say, a loop flood).

I prefer to call a DSV a "bail-out valve" for the following reasons.

All three of the major malfunctions, (1) hypoxia, (2) hyperoxia, and (3) hypercapnea can cause subtle and creeping incapacitation.

Now I know that there are those who will say: "I know well my personal symptoms of these conditions, and will detect them in time to do something about them."

The literature, accident reports, anecdotal reports, and my training as a DMT all combine to negate this proposition, because it is simply not viable in all circumstances, but each diver must make his or her own choices.

I hail from the school of thought that believes that if you have a problem, you need to (1) stop, (2) breathe, (3) think, (4) and then act.

What better way to stop and get some "sanity breaths" than to reach up, twist the switch, and take a couple of breaths on a known, safe gas (which, preferably would be from a separate supply)? If you are suffering from creeping incapacitation, especially in your thinking processes, this will clear your head and allow you to analyze the problem in the light of clear and efficient (or at least more so) thinking processes! It helps to take some of the confusion out of the process.

Nothing in this process precludes you from going back on the loop right away, if your analysis shows that this would be safe and appropriate. There are a lot of times where you should do so. it simply gives you a chance to clear your thinking processes, and make the best decision.

The "bail-out valve" is a piece of safety equipment, much like the oxygen masks in our aircraft. With lowering cabin pressure, or smoke in the cockpit, we don these masks to provide the capability to provide fresh, cold gas (O2 in our case) so that we can think and react to the situation.

As we note in the recent Hellenic Airways crash, this procedure was not followed for some reason, with disastrous results!

I submit to you that the "Bail-out Valve" is a major piece of safety equipment, and should be on all re-breathers from the factory.

Cheers, lads and ladies!

Rob

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deepseacowboy

Now I'm a relative newbie to RBs, but I think this is essential. I think I should be able to flick a switch if I feel something's wrong, and I know I can flick a switch on my buddy's unit if he's lying unconscious. To think that I will have the presence of mind to close the loop, take it out of my mouth, deploy my bail out and then put it in my mouth is a little much. To think I can help my buddy do that is even more unrealistic.


Also - if I feel just slightly uncomfortable, with the OC/DSV I can take a few quick breaths on OC and see if that sorts it out or if it's the curry I ate for lunch. If I don't have the DSV, it's much harder (and much more obvious to your buddies) to take those test breaths, and so I think you may be hesitant to do it. I now have my DSV hooked up to my bailout tank. I still have a primary second stage on the reg on the tank, but I'm not feeling nervous about depleting my diluent if I switch.

My $0.02.

Alden

Philippe GERIN

I'm with you Stefan,
1) basic principle: a Rebreather should only be used to re-breath. "On board bail-out" tank, as one can read sometimes, has no meaning to me. on board dil tank is the only term that I comprehend (except for large back mounted tanks on RMV keyed SCR with off board plug-ins). Therefore, OC integrated DSV is for sanity breath only. I like mine & wouldn't do without.
2) I chose: option proposed by the manufacturer. Keeping the entry cost down for new Rebreather divers is important if we want to see our passion spread. You can always stagger your expenses.
Best
Philippe

nigelh

I have a Bob. I got it after a run-in with CO2 where I has a stage reg in my hand but could not stop breathing long enough to change onto it.

I remember looking at that reg and thinking I would pay a lot of money to be able to turn a switch and breath from it so I did.

My solution at the time was to start exhaling through my nose and let the ADV cut in. My mask flooded but I got to the point where I could pull the loop out and stuff the reg in and then close off the loop. I think my son was about to CBL me at that point.

My fault BTW. I followed bad internet advice and loose packed the scrubber and I assume it channeled early. I was about 2.5 hours into the stack and, thankfully, on a shallow 'second' dive.

nigelH
(appologies to those that have heard the story before)

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nigelh

Scuba_Vixen

My thoughts exactly.

If they came standard from the manufacturers, they'd be a much smaller increase in cost than as aftermarket upgrades. (production in numbers) Retrofitting should be kept in the mfgs. plan as well. If it's a drop in swap for the original dsv, they'll sell a lot more of them and reduce costs even more. Not to mention that a lot of folks will then upgrade to them and be safer.

As mentioned, it's a lot like seatbelts, air bags and antilock brakes. Lotsa whining about increased cost and "I don't need all that shit" at first, but as the merits began to come clear, most every one feels we're better off for them. There's probably very few of us that don't know some one that's alive, or better off, today as the result of "all that shit".



Darlene

decoweenie

One of the worse modern sins that caught everyone from time to time.

Personally, I make a point of only listening to only people who I actually met or known for years since anyone could sound soooo knowledgeable and capable on the Internet.

Glad you are OK though...

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pchanning

Well, I agree with all of you


Personally, I would not trade the mouthpiece now I have it. My rebreather has gone 'wrong' several times and the mouthpiece reduced the sphincter factor to zero. It was that simple.

Combine it with a GCS to an offboard supply, using first, via the ADV, the inboard if desired/ required, protect my airway, and dare I say it, I very nearly feel invincible.

This is not fancy equipment that permits a diver without enough confidence/ skills to 'advance' quicker than they should, as the DIR mob would purvey (diver skill), far from it. It is one of those things that one hopes to never use, but experiences recited on this forum have shown them to be invaluable, along with the 'open loop technique'.

To use Johns example (ABS) I dont intentionally drive into icy corners on brisk English winter mornings, but I'd be lying if I said that I haven't found myself in a hedge before. I also have done the same thing with ABS and it achieved the desired effect with minimal effort from me. Result..!!

Interestingly, the DIR fridges have a BOV (Bail Out Valve) fitted as standard, and their whole philosophy puts the emphasis on diver skill..!!

Co2 is elusive, unpredictable (generally, hits have happened within 'the established rules') debilitating and, as we have seen in the best of divers, often unrecoverable. BOV's take the drama out of a crisis.

Therefore I think a BOV should be fitted as standard. The Cis, KISS and DIR fridges all are.

It would be nice if AP cracked on and finished theirs, but hey, how long did it take them to do the ADV... , let alone make more Evo's. I dont think we'll be seeing one from them for quite some time.

just my Co2

paul

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Paul

The key to enlightenment... is survival.

pchanning

*cringes* that could sour the sauce.

Phi, no offence but the nice part about this whole 'Internet thing' is the fact that it causes thought, which, if I may say, is preferable to listening to someone proclaim that it's all bollocks. (thank you, and 'none taken' btw )

This forum is a valuable resource. Especially compared to some of the so called rebreather 'lists' available. The fact that I can talk to others that I have never met or dived with is quite nice and it flexes the cerebrum a bit more outside of my normal sphere of diving, causing me to think more. I would have learn't a lot less without it. Variety and exposure is key. You'll never totally sort the good information from the bad, but with the collective experience here, this forum does a pretty good job.

Keep it positive Phi and be gentle with us 'young-uns' we're quite fragile you know.

Anyway err... ... Bail-Out Valves... brilliant

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Cheers
Paul

The key to enlightenment... is survival.