Comment by jandrese
7 years ago
I had to do this once myself. I was surprised by how hot the bike pump was by the end. It was on the threshold between warm and hot. It wouldn't burn you on contact, but you wouldn't want to grip it hard for more than a couple of seconds either.
Was that more due to gas thermodynamics or mechanical friction?
I use bike pumps a lot, but only on bikes, so I've never experienced this.
I assume it was mostly due to ideal gas law reasons. Pumping up a highish pressure truck tire (~65 psi IIRC) did take quite a long time and I was pretty exhausted by the end.
Compress a gas, it warms up. I imagine that's the large part of it. Go grab the cooling fins on a large electrically-driven compressor after it's been running a while. No, wait, don't do that if you like your fingerprints. The cooling fins aren't to cool the motor, they're to cool the compressor housing where the piston goes up and down to compress air.