Portable and Wheeled Fire Extinguishers
In the United States, fire extinguishers in all business and commercial buildings are generally required to be serviced and inspected by a Fire Protection service company at least annually. Some jurisdictions require more frequent service for fire extinguishers. At the time of service, a fire extinguisher tag is placed on the extinguisher to indicate the
type of service perform (annual inspection, recharge, new fire extinguisher) and date of service.
Fire extinguishers are divided into handheld and cart-mounted, also called wheeled extinguishers. Handheld extinguishers can weigh 1 to 30 pounds or more, and are easily
portable by hand. Cart-mounted units typically weigh 50+ pounds. These wheeled models are most commonly found at construction sites, airport runways heliports, as well as docks and marinas.
Types of Extinguishers
Dry Chemical extinguishers are usually rated for multiple purpose use. These units contain special extinguishing agents which smother and break the chain reaction on Class B fires, fuses and insulate Class A fires, and as a non-conductor of electricity, is effective on Class C fires.
Halotron I extinguishers, like carbon dioxide units, are "clean agents" that leave no residue after discharge. Halotron I is less damaging to the Earth's ozone layer than Halon 1211 (which was banned by international agreements starting in 1994). This "clean agent" discharges as a liquid, has high visibility during discharge, does not cause thermal or static shock, leaves no residue and is non-conducting. These properties make it ideal for computer rooms, clean rooms, telecommunications equipment, and electronics. These superior properties of Halotron I come at a higher cost relative to carbon dioxide.
Wet Chemical units are designed specifically for kitchen grease fire hazards and meet the new K Class listing now required for all extinguishers installed in restaurant kitchens. They contain a special agent which leaves no chemical residue to clean up.
Carbon Dioxide (CO2) extinguishers are most effective on Class B and C (liquids and electrical) fires. Since the gas disperses quickly, these extinguishers are only effective from 3 to 8 feet. The carbon dioxide is stored as a compressed liquid in the extinguisher; as it expands, it cools the surrounding air. The cooling will often cause ice to form around the "horn" where the gas is expelled from the extinguisher. Since the fire could re-ignite, continue to apply the agent even after the fire appears to be out.
Water Mist units are designed for use whenever there is a Class A hazard near electrical equipment and the environment is of paramount concern. The extinguishing agent is de-ionized water, and the wand provides greatest operator safety. There is no risk of electrical conductivity or thermal or static shock. Ideal for use in health care, data processing, telecommunication, and clean room facilities.
Water and Foam extinguishers contain water and compressed gas and should only be used on Class A (ordinary combustibles) fires. These extinguishers are ideally suited for all industrial and commercial applications, where easy to use, positive on-off operation is important. Water is used as an extinguishing agent, making it highly effective on deep seated Class A fires.
Fire Extinguisher Classification
Class A Extinguishers will put out fires in ordinary combustibles, such as wood and paper. The numerical rating for this class of fire extinguisher refers to the amount of water the fire extinguisher holds and the amount of fire it will extinguish.
Class B Extinguishers should be used on fires involving flammable liquids, such as grease, gasoline, oil, etc. The numerical rating for this class of fire extinguisher states the approximate number of square feet of a flammable liquid fire that a non-expert person can expect to extinguish.
Class C Extinguishers are suitable for use on electrically energized fires. This class of fire extinguishers does not have a numerical rating. The presence of the letter "C" indicates that the extinguishing agent is non-conductive.
Class D Extinguishers are designed for use on flammable metals and are often specific for the type of metal in question. Class D hazards are very dangerous. They burn hot (2500 F for magnesium, even higher for other metals). Most react violently with water, Halons, Halon substitutes and CO2. They emit toxic vapors (lithium fires produce huge amounts of dense smoke; the best extinguisher to use on lithium fires is the extinguisher with a copper agent). Proper extinguishing technique may require 8-15 lbs. or more of extinguishing agent per pound of burning material.
Class K fires are kitchen fires. This class was added to the NFPA portable extinguishers Standard 10 in 1998. Since July 1, 1998, all new extinguishers installed in restaurant kitchens must be K class rated.
Many extinguishers available today can be used on different types of fires and will be labeled with more than one designator, e.g. A-B, B-C, or A-B-C. If you have a multi-purpose extinguisher make sure that it is properly labeled.