expands when heated. That increases the pressure in
the tank. Above a certain pressure, the relief valve
opens to release a small amount of vapor. That release
keeps the pressure from building up too much inside
the tank. Once excess pressure has been released,
the relief valve closes automatically.
Its important to keep your tank painted with
a white, aluminum or other reflective color. A rusty,
unpainted or dark-colored tank may cause pressure
build-up resulting in a safety relief valve discharge.
your propane marketer whenever your relief valve pops
off, so they can determine the cause.