I did not know this about oxygen...

[rjack321]

My point is that to create a destructive explosion the amount of fuel should be significant; not a milligram of hydrocarbons.

1 mg of oil is actually a significant amount of contamination. Especially in the tortured confines of a valve or on a valve seat. Once ignition takes place you have a huge problem because an aluminum cylinder itself is also fuel.

Your perception that you need "a bunch" of hydrocarbons for there to be a problem is incorrect.

 

[DiveClimbRide]

Like the aluminum walls of the pressure vessel.

Heed these words. Aluminum doesn't even take particularly much to ignite. I've seen the rememnants of an aluminum pony bottle after a car fire. The aluminum caught fire and weakened the wall of the cylinder enough that the cylinder ruptured before the burst disk went. That quick.

 

[tmassey]

Your perception that you need "a bunch" of hydrocarbons for there to be a problem is incorrect.

I missed this part in the original reply. At the risk of beating a dead horse, please note this: a person’s intuitive understanding of normal compressed gas management concepts are *not* valid for oxygen. Compressed O2 at 50% or greater change all the rules. Things that are 100% safe with nitrogen or air can be demonstrably dangerous with O2.

Even perfectly clean systems with *zero* hydrocarbon contamination but incompatible (or marginally compatible) materials can be ignited in the presence of high-pressure oxygen and improper technique. Even Viton o-rings, Teflon hoses, aluminum cylinders and carbon steel fittings. Another quote from Oxy Hacker’s Companion: “At the White Sands O2 seminar... they had yet to find a hose that they could not light up at will with HP O2!”

O2 is unique. (Well, O2 and F2.) It has special properties, and that changes all the rules. It’s not unmanageable, but it requires special handling. And maybe worse, it’s not predictable: you can do the same thing 100 times and be fine... until you’re not.

 

[lowviz]

...//... Number 4 is new for me. If someone can educate me, please do.

There are at least two mechanisms for creating havoc by quickly opening a gas valve that adds a high-pressure gas to a LOW-pressure oxygen environment.

Particle acceleration:
(self-explanatory)

Dieseling:
When breathing compressed gas (open circuit) you may notice that the gas is cold. The compressed gas in the cylinder starts out at dive temperature. When you expand a bit of that gas to a far greater volume (so that you can breathe it), the heat energy that it contains is "diluted" across the new volume. It is COLD. (Apologies to my old Thermo prof.)

All the same rules apply, now let's run it in reverse. Assume that there is 100% LOW-pressure O2 in the hose. It is at dive (or room) temperature. Now we jam all that energy down into a tiny space and INCREASE the temperature:
adiabatic compression - Gas compression engineering - Eng-Tips

The solution to either of the above problems, as supported by my O2 cleaning course, is simple. Open any enriched O2 gas valve ever so gently...

 

[rjack321]

There are at least two mechanisms for creating havoc by quickly opening a gas valve that adds a high-pressure gas to a LOW-pressure oxygen environment.

Particle acceleration:
(self-explanatory)

Dieseling:
When breathing compressed gas (open circuit) you may notice that the gas is cold. The compressed gas in the cylinder starts out at dive temperature. When you expand a bit of that gas to a far greater volume (so that you can breathe it), the heat energy that it contains is "diluted" across the new volume. It is COLD. (Apologies to my old Thermo prof.)

All the same rules apply, now let's run it in reverse. Assume that there is 100% LOW-pressure O2 in the hose. It is at dive (or room) temperature. Now we jam all that energy down into a tiny space and INCREASE the temperature:
adiabatic compression - Gas compression engineering - Eng-Tips

The solution to either of the above problems, as supported by my O2 cleaning course, is simple. Open any enriched O2 gas valve ever so gently...

That video was great.

A number of years ago there was a recall in O2 regs which were spontaneously combusting. They were plenty clean enough. The problem was their internal design and gas flow path caused the aluminum body to ignite. Most medical o2 regs have switched over to brass bodies for this reason although you can still buy el cheapo aluminum ones at your own risk.

 

[The Ruttmeister]

O2 is unique. (Well, O2 and F2.) ...

If you are screwing around with Flourine, you deserve everything you get. Which will probably be dead.

That stuff is scary.