Fire Extinguishers
A fire extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations. Typically, a fire extinguisher consists of a hand-held cylindrical pressure vessel containing an agent which can be discharged to extinguish a fire.
There are two main types of fire extinguishers: stored-pressure and cartridge-operated.
In stored pressure units, the expellant is stored in the same chamber as the firefighting agent itself. Depending on the agent used, different propellants are used. With dry chemical extinguishers, nitrogen is typically used; water and foam extinguishers typically use air. Stored pressure fire extinguishers are the most common type.
Cartridge-operated extinguishers contain the expellant gas in a separate cartridge that is punctured prior to discharge, exposing the propellant to the extinguishing agent. This type is not as common, used primarily in areas such as industrial facilities, where they receive higher-than-average use. They have the advantage of simple and prompt recharge, allowing an operator to discharge the extinguisher, recharge it, and return to the fire in a reasonable amount of time. Unlike stored pressure types, these extinguishers use compressed carbon dioxide instead of nitrogen.
Fire extinguishers are further divided into handheld and cart-mounted (also called trolley mounted extinguishers).
Handheld extinguishers weigh from 0.5 to 14 kilograms, and are hence, easily portable by hand. Trolley mounted units typically weigh more than 25 kilograms. These wheeled models are most commonly found at construction sites, airport runways, heliports, as well as docks and marinas, industries, shop floors.
There is no official standard for the colour of fire extinguishers, though they are typically painted signal red.
The types of fires and additional standards are described in IS 15683, NFPA 10: Standard for Portable Fire Extinguishers, 2013 edition.
