Extinguishers sprinklers

Fire-detection devices such as flame-sensing or ioni2ation-interference types operate much more rapidly than sprinkler heads and are used extensively both as alarms and to activate fixed fire-extinguishing systems. 

If an ethyl ether fire occurs, carbon dioxide, carbon tetrachloride, and dry chemical fire extinguishers meeting National Eire Prevention Association Code 1 and 2 requirements may be used successhiUy (23). Water may also be effectively appHed (see Plant safety). Hose streams played into open tanks of burning ethyl ether serve only to scatter the Hquid and spread the fire. However, ether fires may be extinguished by a high pressure water spray that cools the burning surface and smothers the fire. Automatic sprinklers and deluge systems are also effective. 

Fine water spray systems may be potentially superior to CO9 apphcations and may replace halon environments such as telephone central offices and computer rooms. In the fine spray dehveiy system, water is delivered at relatively high pressure (above 100 psi [0.689 MPa]) or by air atomization to generate droplets significantly smaUer than those generated by sprinklers. Water flow from a fine spray nozzle potentially extinguishes the fire faster than a sprinkler because the droplets are smaUer and vaporize more quickly. Preliminaiy information indicates that the smaller the droplet size, the lower the water flow requirements and the less chance of water damage. 

Regarding fires, water is the primary extinguishing agent, and it should be available in adequate supply and pressure at all of the locations in the plant. The layout for various types of installations and the appropriate recommendations are found in the standards of the National Fire Protection Association. Fire hydrants, hose lines, automatic sprinkler and water spray systems should all be a part of the permanent equipment facilities of the plant. 

Define areas and buildings to use wet and dry sprinkler systems, foam systems, location of hand and hose fire extinguishers, fire carts, fire engines. 

Some alloys are softer than the component metals. The presence of big bismuth atoms helps to soften a metal and lower its melting point, much as melons would destabilize a stack of oranges because they just do not fit together well. A low-melting-point alloy of lead, tin, and bismuth is employed to control water sprinklers used in certain fire-extinguishing systems. The heat of the fire melts the alloy, which activates the sprinklers before the fire can spread. 

If sprinklers are required, or if the sprinkler system is to be modified, such work should only be performed by a company certified to do it. Fire extinguishers are almost always required. The number of them, their placement, and the types needed are matters to be discussed with fiire officials. Extinguishers should be regularly serviced by qualified specialists. 

Many office buildings rely on ceiling sprinkler systems as effective means of extinguishing a fire. How are these systems activated The heat generated by a fire is the key to the operation of such water sprinklers. 

Sprinklers and fire protection systems are required by NFPA Codes, but are often dependent on the overall size of the facility and quantity of stored flammable/combustible material. The wisest course of action is to provide heat and smoke detectors in each laboratory and provide a sprinkler system at least in the hallways. Each laboratory should have at least one ABC portable fire extinguisher. Computers have become more important to laboratories than ever. Halon fire extinguishing systems are available which are nondestructive to both electronic equipment and human life. These should be employed for fire protection. 

Containment systems are also used in conjunction with an automatic foam-water sprinkler/deluge system where rapid fire extinguishment is expected. 

Fixed installations, such as water spray systems, halon systems, sprinkler systems, carbon dioxide extinguishing systems, explosion suppression systems, and other fire protection installations are often provided with flow and trouble detection switches connected to transmitters. A signal indicating the condition of the system should be sent to the attended location(s). 

In the majority of applications in processing facilities handling flammable gases or liquids, or liquefied flammable gases, fixed water-based fire protection systems will control, but not extinguish, the fire. Foam-water sprinkler systems are an alternative to water sprinkler systems. Both water and foam-water sprinkler systems are discussed in Chapter 7. 

In-rack sprinklers can result in smaller more easily controlled, suppressed, or extinguished fires, with fewer operation sprinklers. This can have the added benefits of reduced quantity of contaminated water runoff and reduced product damage. 

The convective updraft from severe fires, frequently involving flammable and combustible liquids may prevent water droplets from standard V2-in (1.3-cm) orifice sprinklers from reaching the seat of the fire and product may continue burning until it has been consumed or manually extinguished. Therefore, the variety of new high performance, large orifice, large droplet, or early suppression fast response (ESFR) sprinkler systems should be considered. 

Fire extinguishment can be attained with certain products by using a sprinkler system that discharges a low expansion foam or AFFF agent, typically at concentrations of 1%, 3%, or 6% with water. Foam-water sprinkler systems have been successfully tested with ordinary products and containerized storage of flammable and combustible liquids. The cooling capabilities of foam-water... 

NFPA 11—Standard for Low-Fxpansion Foam NFPA 11A—Standard for Medium- and High-Expansion Foam Systems NFPA 12—Standard on Carbon Dioxide Extinguishing Systems NFPA 12A—Standard on Halon 1301 Eire Extinguishing Systems NFPA 13—Standard for the Installation of Sprinkler Systems NFPA 15—Standard for Water Spray fixed Systems for Fire Protection NFPA 25—Standard for the Inspection, Testingand Maintenance of Water-Based Fire Protection Systems... 

The dry pipe system was probably too slow in operation and did not provide a density sufficient to extinguish the fire. The new system was designed for a sprinkler density of 0.6 gpm/ ft (24 Ipm/m ) which was more than three times the original design density. 

The local fire department arrivedjust after the explosion at 11 22 A.M. With the limited water supply on two of the fire trucks and the utilization of another fire truck to pump water directly from a nearby cooling water tower basin, the firemen were able to slow the fire spread. By 11 30 A.M., the Maintenance Department was able to transfer the set of batteries from the impaired diesel fire pump to the other diesel fire pump. On completion of this task, this diesel fire pump was started. The automatic deluge sprinkler protection was severely damaged by the fire/explosions and had to be valved into the off position. Three fixed monitors were turned onto lull flow and directed at the fire. Also, the firemen and fire brigade used two hose streams olF nearby fire hydrants for fire fighting purposes. At 11 58 A.M., the fire was under control. Final fire extinguishment was accomplished by 12 10 p.m. 

The correct answer is choice d. The firefighters would check all of the other choices when they do an inspection, keeping in mind that people s safety can depend on the proper functioning of sprinkler systems, electrical wires and outlets, and fire extinguishers. 

There are two types of thermal sensors the rate-of-rise sensor and the absolute temperature sensor. Fixed temperature sensors are usually either bimetallic or low-melting-point fusible link devices that activate sprinklers or other extinguishing devices. 

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