Fire extinguishers are a first line of defense and required even if a building has a sprinkler system. According to NFPA #10 standards a fire extinguishers is required every 75 feet in a low hazard area and every 30 to 50 feet in a high hazard area. Fire extinguishers must be inspected annually by a licensed company. The owners of the equipment should be inspecting them monthly.
Every six years from the date of manufacture ABC, Halon and Halotron must be emptied, tested and refilled. The first 6 years is known as a six year maintenance and the second is know as a DC pressure test or hydrotest. Water and CO2 extinguishers require testing every 5 years.