The Life of Fire Extinguishers Pressure Contained & Dry Chemicals all over the world... In structure of Fire Extinguishers there is a top pin to press under by the grips of fire extinguishers which can let the pressurized dry chemicals with Nitrogen gas(normally 7-9kgf/cm2) erupt through the hole inside the valves of fire extinguishers...Originally the Nitrogen gas contains at least 0.3 percent of moisture in its original production and the dry chemicals are covered by silicone in order to prevent moisture penetrating into the dry chemicals. If the dry chemicals touch moisture then the dry chemicals start to cement making ball like clinkers in the cement industries or sand in the beaches.the balls or stiffened dry chemicals are gathering at the outlet of the valves of fire extinguishers and then these ball hinder the sufficient eruption of dry chemicals, even though the dry chemicals are pressurized with Nitrogen gases... Therefore the life of fire extinguishers all over the world can not exceed two or three years, because of this kind of structural problems of Pressure-contained Fire Extinguishers(Dry Chemical Powder filled)..