Originally Posted by vabuckeye
Air, freon, water, propane, oil, and so on and so on will react to changes in temp. My point is that nitrogen will not and makes a better gas to check for leaks.
All matter reacts to changes in temp.
Like SD said (PVT), If the temp increases, and the gas is stored in a sealed container, the pressure will
change. The ideal gas law works for all gases, nitrogen included.
Nitrogen is mostly
inert (not fully inert), and is used so frequently because it is so widely available (78% of the atmosphere by volume).