Do you use a rich mix for your suit only when your deep bailout has a lot of helium in it and you don't want to use a suit bottle?
Your Questions about Closed Circuit Rebreather (CCR) diving answered.
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Jack Hammer
Contributor
Yes I do when my bailout contains any helium, but I have never used a suit warmer of any kind either. I once mistakenly went diving with a 20/20 bailout without a deco gas. Since it was such a lean mix I figured it would be OK. I was wrong. I suppose if you add an ignition source it could be an issue.
Dave, THANK YOU for this (no snark intended). We so often get attached to our own posts and positions that we resist the need to self edit and learn. It means a lot coming from you, since you are such an experienced diver. These last few posts are an excellent learning exercise about the process in this forum. This is far more important and widely applicable than just the question of using a rich mix in a dry suit (which is an issue for very few people).
We just had Gareth Lock speak to our club last week. One of the things that he stressed was "just culture" - the idea that even the most senior and expert participants in any activity should be open to questioning, even by less experienced people. Not having a just culture is well known failure mode in aviation - the Tenerife disaster and others.
It is very difficult to get accurate information about fatalities, given the limits of these databases and the legal issue involved, but at least they do exist. There is absolutely no standard for reporting or archiving information about equipment failures that don't result in a death. So saying that there is no data or statistics or confirmed report of failure X just means that in our online conversations and/or personal experience, we have never encountered such a situation. That may mean that failure X isn't extremely common, but it doesn't mean that it doesn't happen.
In this case, a claim was made that a rich mix for suit gas wasn't a problem, because in the personal experience of the poster, it hadn't been a problem in 20 years (although he never uses heat). That's the very definition of normalization of deviance. Three other posters then offered examples of horrible accidents caused by this practice (which wouldn't have made it into a fatality database).
Dave, I DEFINITELY don't mean to give you a hard time about this - you did exactly the right thing, the just culture thing. A lesser diver would have doubled down on their original point, but you conceded the error and modified your viewpoint.
Please, everybody. When you are commenting here, resist the urge to make categorical statements based only on your own experience, or demanding non-existent statistics to refute a position.
I also know of a few divers who were burnt with just a bent nichrome wire but it was a small hotspot, not a "fire" which was mostly likely the consequence of the 50% suit gas. Since I use heat on most deco or trimix diver nowadays, I make a point to only use air for my suit. I would have no problem using 50% if I didn't have active heat
broncobowsher
Contributor
I grew up and had an oxy acetylene torch. Played with the oxygen. Learned what that gas can do. I have more respect for the oxygen side of the torch than the acetylene side of the torch. Acetylene may be flammable, Oxygen makes everything flammable. Stuff you don't think would be flammable, like a chunk of steal. The stupid stuff you do when you are young. If someone is good with a torch (I can't do it today) you can start cutting and turn off the fuel. The burning steal is the fuel to keep the cut going. Oxygen does not want to be oxygen by itself.
Static electricity in synthetic materials in a high oxygen environment, no thank you.
Static electricity in synthetic materials in a high oxygen environment, no thank you.
Fire needs 3 components (well technically four) fuel, oxygen, and an ignition source. If you take away the ignition source as in static electricity what is the risk? I don't believe the moist air inside a drysuit poses a risk of static buildup.
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