Oxygen Clean Tank

[Dive-aholic]

Let's be clear: it's a tank full of AIR and some tiny amounts of oil, corroded metal, etc. It's not a cylinder full of acetylene or something. It isn't full of mineral oil or kerosene or coated in cosmoline. I just believe that there simply isn't enough stuff to burn in that tank to cause a "major conflagration."

I want to see a documented instance of a SCUBA cylinder (which was always filled with a BREATHING GAS, not some filthy pressure vessel that used to have oil in it or something) being filled via PPB with O2 that catastrophically exploded due to conflagration. Surely if it is so dangerous someone can provide this information.

Show me REAL evidence and I will shut my mouth about the O2 issue forever.

Oxyhacker

 

[The Chairman]

CO poisoning is an even better reason to only do partial pressure blends on an Oxy clean tank.

The DOT requires a hydro every 5 years.

I am not sure WHO requires cylinders to be marked, I thought it was OSHA but could not find it on their site or on DOT.

As for certifying that a cylinder is Oxygen clean or that it has passed a vis, that is up to the individual dive shops. There are no laws to that effect.

I do know that you are not supposed to transport over 120 cf of gas in a private, non marked vehicle. Yeah, that's gonna happen!

 

[Dive-aholic]

Let's see...this weekend I transported about...

Never mind...

 

[Leadking]

The best way to describe the problem with oil and oxygen is to look at a diesel engine. At a compression ration of 18: 1 (265 lbs) the oil will ignite. Scuba cylinders are 200:1

Use your imagination.

 

[Gil57usa]

The way a scuba cylinder will combust is if you have hydrocarbons, O2, and then adiabatic heating due to a sharp rise in pressure, the last thing can be tricky, I bet it could be slamming O2 into a tank too fast, or maybe even O2 turning a corner quickly in a valve . . . get the three points of the triangle fire together, and boom goes the dynamite.

Well said. Oxygen is an oxidizer that increases the burn rate of an existing fuel ie. oil. It is not a fuel itself. Pure oxygen will not burn by itself. You have to have fuel (hydrocarbons), Oxygen and heat to for combustion to occur. Obviously the reason some people get away with partial pressure blending in a non-O2 clean tank is because the temperature never rises to the point of combustion. GIVE IT TIME! You are literally playing with fire.

 

[PhilEllis]

Let's be clear: it's a tank full of AIR and some tiny amounts of oil, corroded metal, etc. It's not a cylinder full of acetylene or something. It isn't full of mineral oil or kerosene or coated in cosmoline. I just believe that there simply isn't enough stuff to burn in that tank to cause a "major conflagration."

I want to see a documented instance of a SCUBA cylinder (which was always filled with a BREATHING GAS, not some filthy pressure vessel that used to have oil in it or something) being filled via PPB with O2 that catastrophically exploded due to conflagration. Surely if it is so dangerous someone can provide this information.

Show me REAL evidence and I will shut my mouth about the O2 issue forever.

Your argument that cylinder cleaning is not necessary is a difficult one to make. It is comparable to going over to NASA in Huntsville, Alabama and standing in front of the guys that made the moon landing work, aruging that the pictures we all saw on television were staged in a desert location in Arizona. When you argue with Lee and Vance, and Dick at Global, you are arugeing with guys that actually know what they are talking about.

An aluminum cylinder that is constantly refilled with clean air gets progressively less clean. While our ultra clean scuba air has greatly reduced hydrocarbons, it doesn't have zero. Therefore, the more you fill and use a scuba cylinder, the more it progressively gets contaminated.....no matter WHO makes the air and no matter HOW CAREFUL they are. Those are the facts. So, frequent recleaning is required.

If the only issue at stake here is the "small amount of hydrocarbon" present in the cylinder, we would have no problem. However, what actually happens is much more catastrophic. Those "small amount of hydrocarbons" only begin the fire. The pressure and temperature elevate so fast at the beginning of the fire that the metal in the cyinder starts to become the fuel. In a matter of nano-seconds, the whole process gets out of control.

On the issue of your friends empirical experience filling cyinders: Good luck is an amazing thing. My store is located on a pretty busy 4 lane street. I bet you I could put on a blindfold and ear plugs and walk across that street hundreds of times without getting hit by a car. Does that mean it is safe? Of course not. Being the only one with a blindfold and ear plugs, I may be lead to believe it is safe, but the onlookers, who have their eyes open, know different. Do they need to see a car hit me to know it is unsafe? I don't think so.

Thanks,

Phil Ellis

 

[H2Andy]

It is comparable to going over to NASA in Huntsville, Alabama and standing in front of the guys that made the moon landing work, aruging that the pictures we all saw on television were staged in a desert location in Arizona.

oh, come on!

everybody knows the fake landing was staged in Area 51

 

[Crazy Fingers]

The best way to describe the problem with oil and oxygen is to look at a diesel engine. At a compression ration of 18: 1 (265 lbs) the oil will ignite. Scuba cylinders are 200:1

Use your imagination.

This is not a fair comparison because there is a (roughly) stoichiometric ratio between air and fuel present. There is nowhere close to a stoich ratio in a scuba tank. If there was you would be dead.

 

[Crazy Fingers]

Oxyhacker

Looks like an interesting book... I will see if the Library has it or can get it. Thanks.

 

[Crazy Fingers]

http://www.scubaboard.com/showthread.php?t=143346 The link to the pictures doesn't work anymore, but just imagine a burnt out garage with charred scuba stuff strewn about the lawn.

I also recall some anecdote about an AL40 that fell over while being filled that killed the operator. I believe this happened in Florida. Maybe some one closer has better details.

Well it appears that:
1) The link is down.

2) No one on that thread really knew what happened anyways since there is no explanation.

3) He is suspected of boosting O2 which is a completely different animal. Yes I will agree that compressing O2 in your garage is dangerous and a patently bad idea. It is not the same as transfilling.