In Reply to: Re: PV = T posted by Chuck Tribolet on February 23, 2007 at 15:32:28:

Chuck - good math using Gay-Lussac's formula, but you calculated the impact on the 4000 psi "bank" tank (actually 4014.7 psia) going to 3014.7 psia. Yes, it gets cold as pressure decreases (temperature decreases).

Redo this using the tank being filled (assuming its at 1000 psig or 1014.7 psia) and you'll see it gets warm - but such a quick fill may delay the conduction of heat through the cylinder walls for a minute or so and maybe the diver did not notice it afterward.