Chemical Extinguishing Systems

Dry chemical agents are effective on flammable liquids, greases and other class B fires. They are also effective on small fires in electrical equipment such as panel boards, switchboards, and other class C fires. 

Dry chemical agents do not work well on deep-seated fires in ordinary combustible materials such as wood, paper textiles, and other class A fires. This is especially true where the cooling effect of water is needed for complete extinguishing of the fire. 

Most dry chemical systems use sodium bicarbonate. This dry chemical agent works best to extinguish flammable liquids, but also works on electrical fires. One problem with this agent is that it is corrosive and can damage the finely polished metal surfaces found in electrical equipment. 

Monoammonium phosphate is an agent used in multipurpose extinguishers ( ABC type extinguishers). This is a especially desirable for the untrained person. These extinguishers are not to be used on fire involving combustible metals. 

On a monthly basis, inspection should be conducted in accordance with the manufacturer s maintenance manual. As a minimum, this visual inspection should include verification that the  

The inspection should be documented with any deficiencies or recommended included. 

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NFPA 17 Standard for Dry Chemical Extinguishing Systems, 1998 edition. National Fire Protection Association, Quincy, MA. 

Dry chemical extinguishing systems-This is used primarily for flammable liquid fires since they provide a rapid flame knockdown and e.xtinguishment. 

In addition to the sprinkler system adequacy, is additional fire protection, such as an automatic dry chemical extinguishing system or a other system, warranted Is an explosion suppression system warranted ... 

The fryers and cooking apparatus found in cafeterias will most likely be protected by kitchen hood systems. NFPA 17 Standard for Dry Chemical Extinguishing Systems and NFPA 17A Standard for Wet Chemical Extinguishing Systems will apply depending on the type of agent deployed by the system. Jones (2009) explains these systems and their requirements by comparing th with sprinkler systems, in that... 

Dry-chemical extinguishing systems are used to protect flammable-liquid storage rooms, dip tanks, kitchen range hoods, deep-fat fryers, and similar hazardous areas and appliances. Because dry chemical is nonconductive, these systems are useful in the protection of oil-filled transformers and circuit breakers. Dry-chemical systems are not recommended for tele-phone-switchboard or computer protection. Dry chemicals are also widely used in portable fire extinguishers. 

National Fire Protection Association (NFPA). NFPA 17, standard for dry chemical extinguishing systems. Quincy, MA NFPA 2013. 

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