Fleming hasserved as a member of more than a dozen NFPA technical commit-tees, including the Committee on Automatic Sprinklers. Fleming, P.E., is vice president of engineering, NationalFire Sprinkler Association, Patterson, New York. How-ever, because automatic sprinklers are used, the wateris usually stopped from flowing unless heat from thefire has also activated one or more sprinklers. As with a delugesystem, a separate detection system is used to activatea deluge valve, admitting water to the piping. A preaction system is similar to a deluge system exceptthat automatic sprinklers are used, and a small airpressure is usually maintained in the piping networkto ensure that the system is air tight. Deluge systems are used for pro-tection against rapidly spreading, high hazard fires.Ĥ. When acti-vated, the deluge valve admits water to the pipingnetwork, and water flows simultaneously from all ofthe open sprinklers. A special delugevalve holds back the water from the piping, and is ac-tivated by a separate fire detection system. A deluge system is one that does not use automaticsprinklers, but rather open sprinklers. Dry systems are used where the wa-ter in the piping would be subject to freezing.ģ. The oper-ation of one or more sprinklers will allow the air pres-sure to escape, causing operation of the dry valve,which then permits water to flow into the piping tosuppress the fire. The valve is kept closed by air ornitrogen pressure maintained in the piping. A dry pipe system is similar to a wet system, except thatwater is held back from the piping network by a spe-cial dry pipe valve. The application ofheat to any sprinkler will cause that single sprinkler tooperate, permitting water to discharge over its area ofprotection.Ģ. Automatic sprinklersare connected to the piping such that each sprinklerprotects an assigned building area.
It consists of a network of pipingcontaining water under pressure. A wet pipe system is by far the most common type ofsprinkler system. There are four basic types of sprinklersystems:ġ. However, even when water from sprinklers will notsuppress the fire, its cooling ability can protect structuralelements of a building by containing the fire until it can beextinguished by other means.Īutomatic sprinkler systems are considered to bethe most effective and economical way to apply water tosuppress a fire. Applying water in afine mist has also been successful. To combat such fires, foam so-lutions can be introduced into the water to provide an ef-fective cover and smother the fire. Instead, the hy-drocarbons will float on top of the water, continuing toburn and possibly spread. The quantities of such products must be con-sidered, however, because application of sufficient watercan overcome the reaction of minor amounts of thesematerials.Īnother drawback of water is that it is more densethan most hydrocarbon fuels, and immiscible as well.Therefore, water will not provide an effective cover forburning hydrocarbons, or mix with them and dilute themto the point of not sustaining combustion. In some cases, the use ofwater can produce heat, flammable or toxic gases, or ex-plosions. Water is not the perfect extinguishing agent, how-ever, and is considered inappropriate for the protection ofcertain water reactive materials. A single gallon of watercan absorb 9280 Btus (2586.5 kJ) of heat as it increasesfrom a 70F (21C) room temperature to become steam at212F (100C). It also has very desirable fire extin-guishing characteristics such as a high specific heat andhigh latent heat of vaporization. Water is the most commonly used fire extinguishingagent, mainly due to the fact that it is widely availableand inexpensive.