text: If kept in a clean and dry place and the original seal is in tact, it should last a long time.\n\nThat being said, it's still a good idea to have it inspected anually by a extinguisher service company.  CO2 units DO NOT typically have a pressure guage and can leak.  Halongenated Agents, Pressurized Water, and Dry Chemical types do have a pressure guage or indicator button so at least you know the unit is up to pressure. \n\nIn the United States, CO2 and Pressurized water units must be hydrotested every 5 years.  Dry Chemical and Halogenated Agent units must be instpected internally every 6 years and recharged and come due for a hydrotest every 12 years.  If a unit fails this test, then it must be replaced.  Sometimes, depending on the size of the unit, it may just be less expensive to consider replacing the unit instead of paying for the test and possibly having it fail.  \n\nSomething of note: NFPA 10 (the national standard on portable fire extinguishers) is coming out with a new edition that will mandate the replacement of any stored-pressure dry chemical older than 1984.