HYDROSTATIC PRESSURE TESTING is a pressure test that is required every 12 years on dry chemical, wet chemical systems, halon, halotron, FE-36, and other clean agent fire extinguishers. This pressure test is also required every five years on CO2 compressed gas, and all liquid type fire extinguishers, including pressurized water, liquid chemical and Class K wet chemical extinguishers. The hydrostatic pressure test is performed to confirmed the integrity and insure the safety limits of the pressure vessel (cylinder) so it is safe to pressurize and use as a fire extinguisher in the event it is needed to fight a fire. This procedure is required under National Fire Protection Association (NFPA) pamphlet #10, 17,17A, 11, #2001 Standards and Department of Transportation (DOT) Regulations.