How does temperature affect the pressure reading of a stored pressure fire extinguisher?
As the extreme temperature months of summer and winter come upon us, Buckeye receives a number of questions about “leakers” or over-pressurized extinguishers. Users will see that the pressure gauge indicator is not pointing straight up, that it is positioned in the low or high side of the green pie-shaped “charged” zone. In most cases it turns out that the extinguisher has been subjected to extremes in cold or heat during transit, storage, or mounting location. In the manufacturing process extinguishers are filled with extinguishing agent and pressurized with expellant gas at an ambient temperature of 68-70°F. The pressure gauge on the extinguisher is calibrated to show the normal charged pressure at this temperature and the pressure indicator on the gauge will be pointing straight up. As the extinguisher is exposed to extremes in temperature (hot or cold) the expellant gas will expand or contract accordingly. This will cause the pressure indicator to move left or right of center. As a
