I have to ask: How many had a fire in their dry suit using 50%

[dreamdive]

This is in response to the post about using 50% for dry suit inflation. I like to get a better perspective on this.
I personally had none nor do I know of anybody who had a drysuit fire using their 50%.

Do you and if so, please provide as much info as possible.

 

[Diver0001]

Fire in the drysuit from 50%? LOL

What possible source of ignition could there be?

R..

 

[Buliwyf]

Only that time when I lubed up completely with mineral oil so I could be shiny like a pro wrestler.

Where would the fuel and source of ignition be? Tanks need to be O2 cleaned so that there isn't any grease or oil fuel in them when hot air is shoved into them. Seeing a tank rapidly increase in pressure due to an oil fire inside is scary as heck.

Even the oxygen nightmare fire on the Apollo had fuel and a source of ignition, The high oxygen amount just made things insanely worse.

 

[CuzzA]

What possible source of ignition could there be?

Electronically heated garments???

 

[tbone1004]

Electronically heated garments???

a short in the carbon fiber vests could certainly be a source of ignition. Has it happened? Not to my knowledge, but it is a potential source of spark as the carbon fibers are very brittle

 

[BoltSnap]

If you pass gas???


LOL

 

[Scott]

I have never had an issue with 50% and none of my buddies have heard of any issues either.

Other than a heated vest shorting out what other ignition source would you have? I know there has been discussions in the past about using hand warmer packs with higher O2 percentages.

We need a manikin, bad heated vest, 50% and an old drysuit. Would be interesting, in a morbid way, to see what the reaction would be. A big boom or a slow burn.

 

[Akimbo]

I heard a "story" that there was a fire during an experimental open sea dive in Europe in the 1930s using Deep Sea Gear (copper helmet with small windows, surface supplied only, helmet open to huge baggy drysuit, freeflow supply w/o a demand regulator). As the story goes, the diver was on pure oxygen during in-water decompression (a normal procedure) and a spark was produced by the hard-wire communications system.

I always had my doubts about that story but we heard it during USN First Class Diving School in the early 1970s. This was not that long after the Apollo and EDU (USN Experimental Diving Unit) fires and a lot was being discovered and developed about proper oxygen handling. Obviously chamber fires were and are still the MAJOR concern.

I suppose there is a technical possibility that a fire in a modern drysuit could be produced on 50/50 AND with malfunctioning electric underwear, but it is remote. I definitely would NOT do it on pure O2 though. I don't understand why a diver would use decompression gas for drysuit inflation in the first place. Wouldn't they have to switch suit inflation hoses from their bottom mix to the decompression gas???

 

[kr2y5]

I don't understand why a diver would use decompression gas for drysuit inflation in the first place. Wouldn't they have to switch suit inflation hoses from their bottom mix to the decompression gas???

The question came up in the context of cold water sidemount diving. There are not as many convenient places to carry tanks as in backmount. I heard of divers using deco gas to avoid the need to carry a separate inflation bottle to keep their configuration more streamlined. I have not heard (not until now) of anyone doing the same with heating equipment, though, hence the OP in the other thread.

 

[boulderjohn]

I would guess that it is theoretically possible with electrically heated undergarments, and 50% acts surprisingly close to 100% in terms of supporting ignition.

It is unlikely that it has ever happened, though, for reasons that should not provide a lot of comfort for those considering it. Let's say it were possible to determine the likelihood that a spark will occur because of some electrical component. For the sake of argument, let's say that possibility is 0.5%--one in two hundred dives.

Now let's look at the rest of the numbers. What percentage of the world's divers use dry suits? What percentage of those divers use 50% for anything? What percentage of those divers use 50% for dry suit inflation? (I don't know anyone who does that myself.) What percentage of those divers use 50% while wearing anything with electricity inside the suit? Put that together, and you have a very, very tiny number of divers who are in a position to care about this.

That means the likelihood that it has happened will be very remote, especially considering the fact that the combination being discussed has not been around all that long. However, that does not change the original probability of a spark occurring on an individual dive.

Here is an analogy. Defective Takata airbags were installed in millions of cars around the world over more than a decade, causing many deaths and a massive recall. People are understandably afraid to drive in a car that has a defective Takata airbag. Considering the total number of miles driven by cars with those airbags over that time, the percentage of times that a fatality occurred is incredibly minuscule. Let's say that those defective Takata airbags had only been installed in one low-selling brand of car a couple of years ago. The odds are there wold not have been a single fatality by now. That would not make them any less dangerous on an individual basis.

There are simply not enough people diving under these conditions to make the number of times it has happened a meaningful statistic.