Propane is a colorless, odorless gas sometimes used for heating homes, but more frequently used in gas grills and camping stoves. Because of the properties of propane, under some conditions propane tanks can freeze.
When a propane tank is being used, the propane inside is boiling. Propane boils--or turns to gas--at minus-44 degrees Fahrenheit, which makes the exterior of the propane tank cold. If there is a great deal of humidity in the air, condensation forms on the exterior of the tank. Because of the low temperature of the tank, this condensation often freezes.
Cold Exterior Temperatures
Extremely cold weather may also cause propane tanks to freeze. When exterior temperatures are very cold, the pressure in a propane tank lowers. Lower pressure causes the temperature of the propane to fall, slowing the flow of propane. This can also cause freezing in the propane tank.
The first two causes of propane freezing are part of the normal operation of a propane tank. However, there are conditions in which a propane tank freezes that present significant hazards. Both are caused by liquid propane entering the regulator valve. This can happen through overfilling of the propane tank or through incorrect storage. Neither condition happens often, but both are dangerous when they do occur.