Propane pressure relief valves

From LE:

But how does a tank overheat? Wouldn’t it have to be exposed to a very hot fire for some period of time?

The most common way for a tank to overheat is by normal atmospheric exposure, but certainly, exposure to fire will increase the temperature of a propane tank.

Propane facts:

Propane boils (converts from liquid to vapor) at – 44 F (-42.2 C)

A gallon of propane converts to 270 gallons of vapor.

The ignition temperature of propane is between 920 F and 1120 F.

Propane requires an air mixture of between 2.15 and 9.60 percent propane for ignition.

Standard DOT 20# propane tanks have a pressure relief valve rated at 250 PSI. The actual pressure at which the valve will release is dependant on many factors including age of the tank/valve, how much propane is in the tank and conditions outside the tank itself.

The following are vapor pressures of propane at various temperatures:

70 F = 96 PSI
100 F = 127 PSI
110 F = 230 PSI


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