Selecting the Right Fire Extinguishers
Frequently, somebody who requires a fire extinguisher will buy an ABC fire extinguisher without giving much thought to the actual fire hazards they will need to protect against. While purchasing fire extinguishers, you have to know a few things about extinguishers so as to make an educated choice, specifically, the fire course you need to safeguard against and special conditions you want to consider (computer electronic equipment, for instance).
Classes of fire extinguishers
If it comes to fire extinguishers, there are five classes of fires: A, B, C, D, and K.
Class A - Fire extinguishers rated for Class A fires have a green triangle with an "A" at the center as well as a pictogram of a garbage can and wood burning. These extinguishers are used to put out fires for common combustibles like paper, cloth, rubber, and some plastics (substances that render ashes when burnt, hence, the "A").
Class B - Fire extinguishers rated for Class B fires have a red square with a "B" in the centre as well as a pictogram of a gas can using a burning puddle. These extinguishers are used to extinguish fires for flammable liquids like gasoline, lubricating oil, diesel fuel, and lots of organic solvents found in laboratories (things found in barrels, therefore "B").
Class C - Fire extinguishers rated for Class C fires have a blue circle with a "C" in the centre as well as a pictogram of an electric plug in with a burning outlet. These extinguishers are used to extinguish electrical fires for energized electric equipment, electric motors, circuit panels, switches, and gear ("C" to get current-electrical).
Class D - Fire extinguishers rated for Class D fires have a yellow pentagram (star) using a "D" in the centre as well as a pictogram of a burning gear and bearing. These extinguishers are used to extinguish fires from metals and metal alloys like titanium, sodium, and magnesium.
Class K - Class K fire extinguishers are used specifically for cooking fires from grease, fat, and cooking oil ("K" for kitchen).
You can get fire extinguishers using a single class rating or multiple fire class ratings (ABC or BC, for instance).
Fire extinguishing materials
Fire extinguishers utilize various substances for extinguishing fires. When picking your extinguisher, you need to ascertain which type of fire you may be fighting and choose the best extinguishing material to the application.
Water: Water, or APW, extinguishers use pressurized water to extinguish fires. APW extinguishers can only be utilized for Class A fires (combustibles like paper, cloth, etc.); they cannot be used for putting out other classes of fires.
Dry compound: Dry chemicals are utilized to extinguish A-, B-, C, or D-type fires. They work by placing a fine layer of compound dust on the material that's burning. Dry chemical extinguishers are extremely capable of putting out fires. But, dry chemical extinguishers may be abrasive and corrosive to electronics and certain other substances.
Carbon dioxide: Carbon dioxide works by removing oxygen in the immediate vicinity of the fire. Carbon dioxide extinguishers are only ever used for B (flammable liquid) and C (electrical fires) extinguishers. For medical, computer and electronics, and aircraft electronics, carbon dioxide would be a much better option compared to dry chemical extinguishers because a carbon dioxide extinguisher leaves no residue.
Metal/sand: Some type D fire extinguishers use metal or sand, such as sodium chloride (NaCl) or powdered copper metal, to smother flames from metals and metallic alloys.
Special applications
Some fire hazards require specialized extinguishers. Listed below are a few examples of those programs.
Steel or sand extinguishers are used to put out class D (metal and metal alloy) fires:
Salt (sodium chloride--NaCl) is the most commonly used material in metal/sand extinguishers. NaCl extinguishers work nicely with fires between magnesium, magnesium, potassium, metals of sodium and potassium, uranium, and powdered aluminum.
Sodium carbonate extinguishers are also used on fires involving sodium, potassium, and alloys of sodium and potassium. Where stress corrosion of stainless steel is a consideration, this kind of fire extinguisher would be a better choice than an NaCl extinguisher.
Powdered copper (Cu) metal is used for fires between lithium ion and lithium alloys.
Graphite powder extinguishers are used on lithium fires in addition to fires that involve high-melting-point metals like titanium and zirconium.
Sodium-bicarbonate-based extinguishers are used on fires involving metal alkyls and pyrophoric liquids.
Halotron I is a clean agent replacement for Halon 1211, that was banned from use due to its ozone depleting properties. Halotron I extinguishers are used for extinguishing fires in computer rooms, clean rooms, and in which telecommunications equipment or electronic equipment are present. Halotron leaves no residue and is nonconducting but is significantly more expensive than carbon dioxide. It must be mentioned that Halotron I will no longer be produced after 2015.
FE-36 (CleanGuard) extinguishers are just another clean agent replacement for Halon 1211. FE-36 extinguishers are somewhat less toxic than Halon 1211 and Halotron I and reportedly don't have any ozone-depleting potential. FE-36 is also used for fires in computer rooms, clean rooms, and where telecommunications equipment or electronic equipment are present. Contrary to Halotron I, FE-36 isn't intended for phase-out.
Nonmagnetic fire extinguishers: Wherever strong magnets are in use, by way of example, close magnetic resonance imaging (MRI) or nuclear magnetic resonance spectrometers (NMRSs), nonmagnetic fire extinguishers must be chosen. The powerful magnetic fields created by this kind of equipment can cause steel pipe fire extinguishers to fly across an area with deadly force.
It's important to ensure that you have the proper fire extinguishers to your surroundings or potential fire risks. It can be the difference between if your fire is removed or causes a catastrophy.