Pressure in tank

[DogDiver]

Self serve at Amigos in Fort White Florida. Fill to any pressure up to 4,000 PSI.

 

[tmassey]

My jaw absolutely hit the floor the first time I saw that place. I literally had to get out my cell phone and shoot a video to send to my wife. Self-service gas fills — even Trimix! without a single other person in sight. Only in Cave country. Amazing.

 

[tursiops]

That was my thought--and why I wonder about a shop that does this with my AL80s. I've seen 3300, even a bit more on occasion.
But would you call it an overfill to say 3200 if it cooled down to 3000?

Yes, of course it is an overfill; 3200 is greater than 3000. But, is it anything to worry about? Most think not. And, as it cools down, it is not an overfill for very long.
If the tank is filled slowly enough, you fill it to 3000 and ti will stay there. But that is REALLY slow.

 

[Charles2]

the tanks are certified for use at 5000 psi (which is how they are retested at hydro) for 100,000 fill cycles. So again, using them at "new tank overfill" pressure is still plenty conservative.

Not quite right, but I get your point. Here are the relevant specs:

49 CFR 178.46 - Specification 3AL seamless aluminum cylinders.

(5) Each new design and any significant change to any acceptable design must be qualified for production by testing prototype samples as follows:
(i) Three samples must be subjected to 100,000 pressure reversal cycles between zero and service pressure or 10,000 pressure reversal cycles between zero and test pressure at a rate not in excess of 10 cycles per minute without failure.
(ii) Three samples must be pressurized to destruction and failure may not occur at less than 2.5 times the marked cylinder service pressure. Each cylinder must remain in one piece. Failure must initiate in the cylinder sidewall in a longitudinal direction. Rate of pressurization may not exceed 200 psig per second.

 

[tursiops]

Not quite right, but I get your point. Here are the relevant specs:

49 CFR 178.46 - Specification 3AL seamless aluminum cylinders.

(5) Each new design and any significant change to any acceptable design must be qualified for production by testing prototype samples as follows:
(i) Three samples must be subjected to 100,000 pressure reversal cycles between zero and service pressure or 10,000 pressure reversal cycles between zero and test pressure at a rate not in excess of 10 cycles per minute without failure.
(ii) Three samples must be pressurized to destruction and failure may not occur at less than 2.5 times the marked cylinder service pressure. Each cylinder must remain in one piece. Failure must initiate in the cylinder sidewall in a longitudinal direction. Rate of pressurization may not exceed 200 psig per second.

That is the spec for a new design or a design change, not for a hydro test.