If you retail pool supplies or store large supplies of pool chemicals for a public swimming pool you have no doubt been informed by your fire marshal, insurance company representative, company safety manager, or fire equipment distributor that the NFPA standard (usually adopted as fire code) demands that only water type extinguishers be installed in areas containing pool chemicals. This article identifies and discusses the specific NFPA standard that applies here; it also explains why such a requirement is necessary.
NFPA 10 requires water type extinguishers shall be installed for the protection of pool chemicals. In fact, it demands that only water type extinguishers are installed in areas containing such chemicals and that absolutely no ordinary ABC dry chemical extinguisher be located there. The wording here in NFPA 10 18.104.22.168 and 22.214.171.124 is much stricter than the wording for protecting other special hazards. For instance, superheated cooking oils and delicate electronic equipment each require a special kind of extinguisher, but the NFPA 10 standard does not forbid a dry chemical extinguisher nearby to protect other furnishings and the building structure. So why do the fire codes demand the water type and prohibit the popular ABC dry chemical type extinguisher near a pool chemical hazard?
Simply put, when the agent in the dry chemical extinguisher comes in contact with the pool chemicals an explosive compound can result. Not so simply put, when the ammonium compounds (ammonium salts) discharged from the extinguisher reach the chlorine (oxidizers) nitrogen trichloride is formed. Nitrogen trichloride, NCI3 is explosive. If a dry chemical fire extinguisher were installed near pool chemicals the person responding to the fire might use it instead of the water type. It would be an easily made mistake but could have destructive or even deadly results.
While the water type is considered the safest extinguisher on pool chemicals, it can also be dangerous. Remember not to discharge a stream of water on an electric outlet or electrically energized equipment. It is also important to make sure you are able to operate your water extinguisher; they are heavy to lift and behave a little differently from dry chemical extinguishers. If you have already received fire extinguisher training it was probably in the use of dry chemical type extinguishers. So, ask your fire department or fire extinguisher service company for training in the use of water type extinguishers.
More helpful fire extinguisher information can be found at Bill’s Notes.