[ChancellorErik]

Bear with me, for I have very little knowledge of chemistry, hopefully this is the right place to ask this question.

I'm interested in finding a non-toxic substance that when at standard temperature and pressure (or reasonable earth conditions) is a gas, but under a slight amount of pressure could be contained as a liquid. Ideally, it would change state rapidly when the pressure change occurs as to dissipate if the container it is in is broken.

Anybody have any thoughts? I'm sure that under extreme pressure this could happen with any gas, but I'm mostly interested in if it's possible for this to occur very close to STP. Thanks!

[fledarmus]

How close to STP? And how non-toxic? Most refrigerants match that description - ammonia, freons, propane, and butane have all been used.