High Risk CCR Practices - A good list of things that are not worth trying...

diverklondike

Over the last couple of months I have been seeing a recurring theme of people asking questions about things that I consider to be somewhat high risk or at least unreasonable risks when diving a CCR when there are other obvious alternatives. This includes things like the use of welding O2, ½ spacers in scrubbers and rechargeable batteries in units that are not designed to use them etc..

Please don’t take offense if I have mentioned something that you think is a good way to save a buck. It’s simply high risk behavior and not something that should be suggested to new divers as a way to safely cut corners.

In a Mark Chase like approach to getting some collaboration going here, I would like to see us come up with a list of those things that we can simply agree are “high risk behaviors” when it comes to diving CCRs. We will them place it as a “sticky” in the appropriate forum and use it as a point of reference for new and or uninformed divers. In the long run it might safe a life or avoid a near miss.

I welcome everyone’s input and suggestions on this. Here are the three items that come to mind for me as needless high risk practices:

• Use of welding O2
• ½ spacers in scrubbers that are not designed by the MFG
• Use of rechargeable batteries or non-MFG approved batteries in your rig

Dive Safe...

Mark

caveseeker7

Excellent idea, Mark!

- "putting all eggs in one basket" as Gordon Smith used to call it when it comes to
pO2 monitoring (only one display, no separate and independent redundancy) and
gas supply (hooking up OC bailout, BCD and drysuit to a single, small CCR tank)

- refilling used absorbent

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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.!"

osiris

• Not using a BOV
  
• Not using redundent PO2 monitoring devices

lizardland

Well... I'm guilty of two of the first three. I'm quite happy using welding gas, certainly there aren't many welders going kaboom in the UK, non-return valves are pretty much standard. I don't think I've ever used the manufacturer approved battery in anything and I've got a set of NiMH's ready to drop in the box this weekend.

Ok, I've done the half-fill once as well but that doesn't count.

One man's needless risk is someone else's standard procedure.

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nigelh

This is probably a problem. What is a risk one place is not a problem in another.

I see the paper on the welding O2 we used here (to weld with) and it's good stuff with 'worst case' impuities being a fraction of a percent of nitrogen and everything else tivial but in the Red Sea they wanted us to analyse the 'pure' O2 on the boat and offset for it so grief knows what I was breathing.

There are lots of things I wouldn't do to a rebreather but people seem to survive doing them.

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Abbo

I don't have access to welding O2, so it's not an issue for me, but I'm intrigued: Vance Harlow's Oxygen Hacker's Companion starts chapter 6 by explaining that welding oxygen comes out of the same tank as the medical O2. I can't see any good reason why I should not use it. Although it is only required to be 99.5% pure (higher than medical grade, at 95%) it is actually a lot higher than that. Sounds good to me.

I am guilty of not using the manufacturer-approved batteries. Frankly, I think it's high time ISC came up with a fix to their pain-in-the-butt batteries, which are expensive and time-consuming to get here on the other side of the world. I stick in off-the-shelf batteries. I try to avoid those with rapid decay curves at the end of their lives, but they are so much cheaper that you can afford to use once and throw away in extremis. I had a power outage during a dive once. It was a stupid mistake, and not one that I intend to make again, but it was not the end of the world: flying the unit manually is hardly an advanced skill. What am I missing?

Mdemon

I don't think I've ever dived non-welding aka Industrial O2 in the UK.

I use whichever batteries I can find which are cheapest and do the job.

I think your list needs refinement. The only 100% cast iron entry so far is the one about "picking bits out of slime and re-using it".

There are very few "black and white" entries you can make I'm afraid. Everything else is on a sliding scale. I won't dive without a BOV and independant PO2 monitoring if I can help it. Other people do so quite happily.

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Marvintpa

Using medical grade sorb?

Abbo

Ah, there's another thing I do: my bailout is connected to my onboard, which drives my wing and drysuit. I can isolate it if need be. This is exactly what I did on OC, with the isolation manifold. Was I wrong?

jiseson

stretching a cannister of sorbs' duration

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