Why do we put oxygen in aluminum cylinders?

[Wookie]

40% is an arbitrary number the diving industry adopted years ago. I recall some justification for the number, but it was loose.

Well, back when we dove a PO2 of 1.6, 40% is right around 100 feet, which is an easy number to remember.

 

[cathal]

The millions of tanks that get filled with N32 should give you more than enough proof that 32% is waaaaaay lower than the danger zone.

Ok so do we know how low exactly is way lower? And under what conditions is it way lower? Finally what exactly is the "Danger Zone",?

 

[Patoux01]

40 has been the industry standard for a long time now.
I'm just being practical. If 32 were dangerous, we'd have known by now.

If you want probabilities, basically blowing up when opening a tank of 32 would most likely be around 0.000001 at most.

 

[100days-a-year]

Anorak; the word I was looking for to describe the discussion of potential explosions using 02 in Al tanks.Much more likely to die breathing the wrong mix at depth.

 

[KevinNM]

I think 40% is or was considered a theshold by NASA. Highly enriched O2 atmospheres have very different fire behaviors than less enriched O2 atmospheres. Fires in 40% are bad, for example, Nomex (what they make fire fighter bunker gear out of) will ignite in 40% (or 32%) but iirc most metals will not.

 

[boulderjohn]

I think 40% is or was considered a theshold by NASA. Highly enriched O2 atmospheres have very different fire behaviors than less enriched O2 atmospheres. Fires in 40% are bad, for example, Nomex (what they make fire fighter bunker gear out of) will ignite in 40% (or 32%) but iirc most metals will not.

What I read somewhere years ago and cannot find now was that in the aftermath of the Apollo I fire that killed three astronauts, including most famously Gus Grissom, NASA experiments indicated that atmospheres with 50% O2 or more behaved about the same in terms of danger, but that danger dropped quickly at lower concentrations.

 

[JohnnyC]

It's worthwhile to add safeties early and often. Wondering if you have enough gas isn't a good feeling to have.

Still trying to find a case where someone died by having too much gas.....

 

[RayfromTX]

Still trying to find a case where someone died by having too much gas.....

Such an easy straight line. I can't wait to see the come backs on that one.

 

[Doby45]

Still trying to find a case where someone died by having too much gas.....

This one time at band camp, this guy ate chili and was farting all night. In the morning they found him smothered with a pillow, too much gas.

 

[JohnnyC]

This one time at band camp, this guy ate chili and was farting all night. In the morning they found him smothered with a pillow, too much gas.

Da**it there's always one.....