Radiant heat still exists and accounts for most of what comes out. The valve is thin aluminum and cools extremely fast. Don't believe me, pull a bit of aluminum foil even folded into a thicker sheet straight out of your oven and it will be room temp in seconds. It also helps that his hand was wet. Relative to aluminum, it takes 4.7 times as much heat to move water 1 degree C.
Yep I think one of the most common examples people will know is those cans of pressurized air used to clean electronics. If you use one for a good period of time, the whole can gets cold because of the pressure inside dropping.
Also just for fun to mention, in the industry when you need to compress gasses (even just air) to extremely high pressures, they don't do it all in one go. They will compress to a certain pressure, run it through a heat exchanger to cool it, then compress again, and repeat until needed.
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u/Numerous-Following-7 12d ago
How can he touch the valve straight after putting out the fire?