Chemical Extinguishers

This type of extinguisher puts out fires by coating the fuel with a thin layer of fire retardant powder, separating the fuel from the oxygen. The powder also works to interrupt the chemical reaction. 

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C depending on the reference consulted). Fires may be controlled with carbon dioxide or dry chemical extinguishers. Recommended methods of handlings loadings unloadings and storage can be obtained from Material Safety Data Sheets and inquiries directed to suppHers of acetone. 

Because of thek flash pokits, nitroparaftins are classified as flammable Hquids under DOT regulations (ha2ard class 3, PG III). Nitromethane and nitroethane tires can be extinguished with water, CO2, foam, or class ABC dry chemical extinguishers. Nitroparaftins should not be exposed to dry caustic soda, lye, or similar alkaline materials. 

Some dry-chemical fire extinguishers contain sodium or potassium bicarbonate these should not be used on nitromethane or nitroethane fires. Dry chemical extinguishers can be used on nitropropane fires. 

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. 

The process area has combustible gas detectors, fireproofing, and a water deluge system. Cable trays are protected with deluge, and portable dry chemical extinguishers are in the process area. Diesel-powered fire water pumps can provide a maximum fire water demand for 4 hr. 

There are several types of dry chemical extinguishing agents. The three most popular are sodium bicarbonate, potassium bicarbonate (Purple K), and monoammonium phosphate. 

Dry chemical extinguishers subject to extremely low temperatures, -20°F (-29°C) or below, should use nitrogen rather than CO2 as the expellant gas (CO2 will liquefy at these temperatures). Special low-temperature hose, nozzle, and seals are also required. For more information on dry chemical extinguishers, refer to UL 299. 

Multipurpose dry chemical extinguishers (2-A 10B-C) should be provided for office buildings, auditoriums, field offices, change rooms and other low hazard occupancies. Travel distance from any hazard to an extinguisher should not... 

Multipurpose dry chemical extinguishers (20-A 80B-C) should be provided in warehouses and shop buildings where wood, paper, plastics, and other flammable solids, as well as flammable liquids, may be stored. In grease manufacturing and compounding or similar operations where little or no wood, paper, and similar combustibles are stored, but where flammable liquids may be prevalent, potassium bicarbonate dry chemical extinguishers should be used. Extinguishers should be located not more than 75 ft (23 m) away from any potential Class A fire hazard and not more than 50 ft (15 m) from Class B fire hazards. 

Within process unit battery limits of processing facilities, potassium bicarbonate dry chemical extinguishers should be provided along main access ways. On elevated structures, the extinguisher locations should be near stairway landings. 

Dry chemical extinguishers should be located on elevated main platforms with stairway access and on air cooler platforms. When determining the proper location for extinguishers, consideration should be given to hydrocarbon pump and compressor areas, hot-oil areas, or similar potential hazards, as well as access to the extinguisher from control rooms or battery limits. Extinguishers should be located so that one can be reached without traveling more than 50 ft (15 m) to any hazard. 

At least one potassium bicarbonate dry chemical extinguisher (120-B C) should be provided at each fired process heater handling liquid fuel or a liquid process stream. They should be installed on opposite sides, or ends, and adjacent to fire aisles. 

At least one potassium bicarbonate dry chemical extinguisher (120-B C) should be located in pump and compressor areas. 

Cooling towers should be provided with one multipurpose dry chemical extinguisher (20-A 80-B C) at the top of each stairway landing. 

Steam-generating plants, air compressor plants, and similar plants should be provided with potassium bicarbonate dry chemical extinguishers (120-B C) for Class B or Class C fires in the areas containing hydrocarbons or other flammable liquids. For fires in electrical equipment, at least one extinguisher (10-B C) should be provided. If Class Afire hazards exist, multipurpose dry chemical extinguishers (20-A 80-B C) or water extinguishers should be provided. 

One dry chemical extinguisher (3-A 10-B-C) should be provided on a combustion engine driven vehicle, compressor, or welding machine. 

An appropriate number, type, and size of hand-held fire extinguishers should be provided throughout the building to handle ordinary combustibles and electrical fires in the control room and related areas. Typically, clean agent or carbon dioxide fire extinguishers should be provided for electrical and electronic equipment. Dry chemical extinguishers should be avoided because of equipment contamination with powder. For use on ordinary combustible fires in the associated areas water or multipurpose dry chemical fire extinguishers should be provided. 

Where no fire water main is provided, at least two 150 lb (68 kg) wheeled dry chemical extinguishers should be provided and located within 50 ft (15 m) of pump or manifold areas and easily reached along emergency access paths. 

Class A fires involve combustible materials such as paper, wood, and cloth. A water-filled extinguisher is the most effective in putting out these fires. Residents should direct the nozzle toward the base of the fire and spray until all involved material is wet. A dry chemical extinguisher can also be used on some Class A fires. 

Energized electrical fires are in the Class C category. If it can be done quickly and safely, residents should attempt to shut off power before confronting this type of fire. Dry chemical extinguishers work well on these types of fires. Carbon dioxide extinguishers should be used for delicate electronic equipment such as computers as they will not damage the circuits. Water-filled extinguishers should only be used once the power has been turned off... 

Note a = alcohol foam b = carbon dioxide c = dry chemical extinguisher d = water. 

If in contaet, or mixed, with organic or other oxidizable substances, ignition or explosion may take place. Use flooding quantities of water or dry chemical extinguisher to fight fire.2... 

A fairly new major use for bromine is in clear completion fluids used in crude oil production. These are concentrated solutions of CaBr2 or CaBr2-ZnBr2, which have a high density. Several hundred pharmaceuticals contain bromine atoms. Other moderate-sized markets for bromine compounds are in photography, water treatment chemicals, extinguisher fluids, and dyes. 

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