Outside temperature effecting tanks?

[swimmer_spe]

I know that when air gets pressurized, it heats up.

Am I right that if I have a tank filled in the summer, at say 30 C that if I use it in the winter, with the air at -30 C, would I have lost pressure?

What about the reverse. Would filling a tank in the deep freeze and then using it at hot summer temperatures cause it to increase in pressure?

Would that be enough to blow the burst disc?

 

[Slamfire]

I know that when air gets pressurized, it heats up.

Am I right that if I have a tank filled in the summer, at say 30 C that if I use it in the winter, with the air at -30 C, would I have lost pressure?

What about the reverse. Would filling a tank in the deep freeze and then using it at hot summer temperatures cause it to increase in pressure?

Would that be enough to blow the burst disc?

Yes.

Yes.

Not usually.

If you want to theoretically try some scenarios use Gay Lussac's formula:

P1/T1 = P2/T2

 

[Tbar]

But remember the T (temperature) is in degrees Kelvin.

Absolute zero (0 degrees Kelvin) is equivalent to −273.15 °C or −459.67 °F.

 

[Freewillow]

This is why, you loose some 10 to 20 bars when, on a hot sunny day, you jump into colder water

 

[Storker]

You may even lose more than 10-20bar, particularly with 300bar steels.

Just the other day I filled a couple of tanks. As usual, I took them up to 10% over working pressure to account for the heating up of the tank during filling. When full, they were nice and warm to the touch, I'd guess some 30-odd degrees C. Dropped by the club to top them off today, and after they'd cooled to somewhere in the single digits (C), the pressure had gone down to 280. Which is pretty much what my SPG usually shows before submerging unless I make sure to top off the tank after it has cooled off.

I've had the opposite experience as well: a 200bar tank with the standard 10% cold season overfill showed over 240bar on a warm summer day after being left in the trunk of my car for a while.


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[tstormdiver]

I have seen a "poor man's Haskel" used for O2 cylinders before. Fill to the 2200 psi capacity of the supply cylinder, cool the cylinders (small rebreather cylinders) in a refrigerator,... then before the cylinders warm up, fill back up to the highest pressure of the supply cylinders. Do this several times & you may be able to get an additional 300 psi or so. A pain to some, but for those who want that extra pressure.... it works.