I don't I put on my test call an inspector to witness it then call the local utility to accept the inspectors approval then they unlock the meter and put their own test on then when it passes I'm...
you get locked up its that simple
Some gasses turn into liquids when compressed (propane, butane), some turn into liquids when chilled to very cold temperatures (oxygen, nitrogen).
Given sufficient heat anything can turn to a gas.
Well nothing