Lux-sicle. OK?

[Rick Inman]

Are there any negative effects in leaving an al80 out in below freezing temperatures?
Also, what about filling a freezing tank? Should give me a nice fill, yes?

 

[Don Burke]

I don't know of any ill effects to the tank alloys due to reasonable environmental temperatures.

Keep in mind that the temperature of the gas, not the temperature of the tank, determines how many molecules are in a given volume at a given pressure.

 

[Rick Inman]

Don Burke once bubbled...
Keep in mind that the temperature of the gas, not the temperature of the tank, determines how many molecules are in a given volume at a given pressure.

Sure, but doesn't the temp of the tank effect the temp of the gas? As a tank is being filled, air that has already entered the tank would be cooled by the tanks lower temperature, therefore allowing more air molecules in a given volume at a given temp. Am I seeing something wrong here? Or are we talking an inconsequential amount (meaning less than 100psi)?

 

[Don Burke]

Rick Inman once bubbled... Sure, but doesn't the temp of the tank effect the temp of the gas? As a tank is being filled, air that has already entered the tank would be cooled by the tanks lower temperature, therefore allowing more air molecules in a given volume at a given temp. Am I seeing something wrong here? Or are we talking an inconsequential amount (meaning less than 100psi)?

Absolutely.

The fill rate needs to be slow enough so the conduction from the tank (a pretty slow process) can overcome the heating due to compression (a pretty fast process with most fill rates). You might want to fill, wait and top off, although few shops will want to do that.

An ideal gas at 3000psig at zero degrees Farenheit will be at something over 3600psig at 100 degrees Farenheit. That's a bit more than six psig per degree.

 

[Rick Inman]

Don Burke once bubbled...
Absolutely.

The fill rate needs to be slow enough so the conduction from the tank (a pretty slow process) can overcome the heating due to compression (a pretty fast process with most fill rates). You might want to fill, wait and top off, although few shops will want to do that.

An ideal gas at 3000psig at zero degrees Farenheit will be at something over 3600psig at 100 degrees Farenheit. That's a bit more than six psig per degree.

Great. Thanks Don!

 

[Genesis]

are rated at 70F.

If you fill at a colder temperature (after cooling), you need to fill to a lower pressure. If you fill at a higher temperature, then you should fill to the temperature-adjusted pressure.

Otherwise you run the risk that with a pressure shift you are exceeding the rating of the tank. This probably won't bite you with a steel tank, but it very well might with an AL one; they're rather intolerant of overfilling.