Electrical firing

Portable fire extinguishers are classified according to appHcabiHty Class A for soHd combustibles Class B for flammable Hquids Class C for electrical fires that require a nonconducting agent and Class D for combustible metals. Water frequently is used for Class A extinguishers bicarbonates for Class B and Class BC carbon dioxide or Freon for Class C ammonium phosphate for Class ABC and powdered salt, sodium chloride, for Class D. 

By the early 1980s high-gloss DMCs using low-profile resins were finding use in kitchen appliances such as steam iron bases, toaster end-plates and casings for electric fires. 

Heating, direct Any heating system that does not have a heat-transfer medium, e.g., an electric fire or a gas fire. 

The use of supplementary heating (e.g. electric fires without permission). 

Carbon dioxide is useful where the minimum damage should be caused to the materials at risk, on fires in liquid, solids or electrical fires but not where there is a high risk of reignition. It is likely to be ineffective outdoors due to rapid dispersal. It is unsuitable for reactive metals, metal hydrides or materials with their own oxygen supply, e.g. cellulose nitrate. 

Dry powders are effective on flammable liquid or electrical fires. Special powders are available for use on metals. 

Vaporizing liquid halogen agents are electrically non-conductive and are effective on a wide range of combustibles, particularly flammable liquids and electrical fires. A lock-off system is required on fixed installations to protect personnel, the normal extinguishing concentration being 5% by volume. 

Do not use an aerosol spray when smoking, or near any other source of ignition, e.g. an electric fire, hot-plate etc. 

An additional class not currently included in British Standard EN2 is Class F fires including cooking oils or fats. Electrical fires are not classified since any fire involving, or initiated by, electrical equipment will fall within Class A, B or C. 

The penetration and cooling action of water is required with Class A fires, e.g. those involving paper, wood, textiles, refuse. Water is applied in the form of a jet or spray foam or multi-purpose powder extinguishers are alternatives. Extinguishment of a Class B fire can be achieved by the smothering action of dry chemical, carbon dioxide or foam. Most flammable liquids will float on water (refer to Table 6.1 under Specific gravity ), so that water as a jet is unsuitable a mist may, however, be effective. Water is also widely used to protect equipment exposed to heat. Dry powders are effective on flammable liquid or electrical fires. 

Dry powders are effective on flammable liquid or electrical fires. Special powders are available for use on metals. Dry powder extinguishers may be used on Class C fires, including gases and liquefied gases in the form of a liquid spillage or a liquid or gas leak. This must be accompanied by other actions, e.g. stopping the leak this is necessary to avoid accumulation of an unbumed flammable gas-air mixture which could subsequently result in an explosion. Activation may be automatic by a detection system, or manual. 

The workshop, too, looks much as it always did, though the presses have been shoved closer together on the brick floor at one end to make room at the other for a couple of armchairs that I remember, now standing before a two-bar electric fire. One is much more sat-in than the other, I can see, and on the bookcase next to it is a fleet of photograph frames. There s a small desk covered... 

The most frequent troubles in electric firing are insufficient battery power, or shorts or breaks in the circuit. 

Beach, R., Preventing static electricity fires, Chem. Eng., 71, 73,1964. 

Utilities such as steam, electricity, fire water should be separated protected by the effects of an incident so that they may be continuously maintained. Where large facilities or critical installations are present the supply of these services from two or more remote locations should be evaluated. 

Office Ordinary Combustibles Electrical Fire MPS Heat Smoke NFPA 101, Section 26-3.4.1. 

Kitchens and Cafeterias Cooking Electrical Fire MPS Heat NFPA 101, Section 8-3.4.1 NFPA 96, Section 7-3.1.4... 

Control Rooms Electrical Fire MPS Smoke NFPA 75, Section 6.2... 

Turbine Package Electrical Fire Hydrocarbon Fire Heat Optical NFPA 30, Section 5-5.5.1. 

The extinguishing agent in a class C fire extinguisher must be electrically non-conductive. Both carbon dioxide and dry chemicals can be used in electrical fires. An advantage of carbon dioxide is that it leaves no residue after the fire is extinguished. When electrical equipment is not energized, extinguishers for class A or B fires may be used. 

Switchgear Facility Electrical Fire NFPA 850 1. CO2 System 2. Preaction Sprinkler 1. NFPA 12 2. NFPA 13... 

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