| Often, someone who needs a fire extinguisher will buy | | | | dioxide extinguishers are only ever used for B |
| an ABC fire extinguisher without giving much thought | | | | (flammable liquid) and C (electrical fires) extinguishers. |
| to the actual fire hazards they need to protect against. | | | | For computer, medical and scientific equipment, and |
| When buying fire extinguishers, you need to know | | | | aircraft electronics, carbon dioxide would be a better |
| several things about extinguishers in order to make an | | | | choice than dry chemical extinguishers because a |
| informed decision, specifically, the fire class you need | | | | carbon dioxide extinguisher leaves no residue. |
| to protect against and special conditions you need to | | | | - Metal/sand: Some class D fire extinguishers use |
| consider (computer electronics, for example). | | | | metal or sand, such as sodium chloride (NaCl) or |
| Classes of fire extinguishers | | | | powdered copper metal, to smother fires from metals |
| When it comes to fire extinguishers, there are five | | | | and metal alloys. |
| classes of fires: A, B, C, D, and K. | | | | Special applications |
| - Class A - Fire extinguishers rated for Class A fires | | | | Some fire hazards require specialized extinguishers. |
| have a green triangle with an "A" in the center as well | | | | Here are a few examples of those applications. |
| as a pictogram of a garbage can and wood burning. | | | | Metal or sand extinguishers are used to put out class |
| These extinguishers are used to put out fires for | | | | D (metal and metal alloy) fires: |
| common combustibles like paper, cloth, rubber, and | | | | - Salt (sodium chloride--NaCl) is the most commonly |
| some plastics (materials that leave ash when burnt, | | | | used material in metal/sand extinguishers. NaCl |
| hence, the "A"). | | | | extinguishers work well with fires involving magnesium, |
| - Class B - Fire extinguishers rated for Class B fires | | | | sodium, potassium, alloys of potassium and sodium, |
| have a red square with a "B" in the center as well as | | | | uranium, and powdered aluminum. |
| a pictogram of a gasoline can with a burning puddle. | | | | - Sodium carbonate extinguishers are also used on |
| These extinguishers are used to extinguish fires for | | | | fires involving sodium, potassium, and alloys of |
| flammable liquids like gasoline, lubricating oil, diesel fuel, | | | | potassium and sodium. Where stress corrosion of |
| and many organic solvents found in laboratories (things | | | | stainless steel is a consideration, this type of fire |
| found in barrels, hence "B"). | | | | extinguisher would be a better choice than an NaCl |
| - Class C - Fire extinguishers rated for Class C fires | | | | extinguisher. |
| have a blue circle with a "C" in the center as well as a | | | | - Powdered copper (Cu) metal is used for fires |
| pictogram of an electric plug with a burning outlet. | | | | involving lithium and lithium alloys. |
| These extinguishers are used to extinguish electrical | | | | - Graphite powder extinguishers are used on lithium |
| fires for energized electrical equipment, electric motors, | | | | fires as well as fires that involve high-melting-point |
| circuit panels, switches, and tools ("C" for | | | | metals like titanium and zirconium. |
| current-electrical). | | | | - Sodium-bicarbonate-based extinguishers are used on |
| - Class D - Fire extinguishers rated for Class D fires | | | | fires involving metal alkyls and pyrophoric liquids. |
| have a yellow pentagram (star) with a "D" in the | | | | Halotron I is a clean agent replacement for Halon 1211, |
| center as well as a pictogram of a burning gear and | | | | which was banned from use due to its ozone |
| bearing. These extinguishers are used to extinguish | | | | depleting properties. Halotron I extinguishers are used |
| fires from metals and metal alloys like titanium, sodium, | | | | for extinguishing fires in computer rooms, clean rooms, |
| and magnesium. | | | | and where telecommunications equipment or |
| - Class K - Class K fire extinguishers are used | | | | electronics are present. Halotron leaves no residue and |
| specifically for cooking fires from grease, fat, and | | | | is nonconducting but is more expensive than carbon |
| cooking oil ("K" for kitchen). You can get fire | | | | dioxide. It should be noted that Halotron I will no longer |
| extinguishers with a single class rating or multiple fire | | | | be produced after 2015. |
| class ratings (ABC or BC, for example). | | | | FE-36 (CleanGuard) extinguishers are another clean |
| Fire extinguishing materials | | | | agent replacement for Halon 1211. FE-36 extinguishers |
| Fire extinguishers use different materials for | | | | are less toxic than Halon 1211 and Halotron I and |
| extinguishing fires. When choosing your extinguisher, | | | | reportedly have no ozone-depleting potential. FE-36 is |
| you need to determine what type of fire you may be | | | | also used for fires in computer rooms, clean rooms, |
| fighting and then choose the best extinguishing material | | | | and where telecommunications equipment or |
| for your application. | | | | electronics are present. Unlike Halotron I, FE-36 is not |
| - Water: Water, or APW, extinguishers use | | | | planned for phase-out. |
| pressurized water to extinguish fires. APW | | | | Nonmagnetic fire extinguishers: Wherever strong |
| extinguishers can only be used for Class A fires | | | | magnets are in use, for example, near magnetic |
| (combustibles such as paper, cloth, etc.); they cannot | | | | resonance imaging (MRI) or nuclear magnetic |
| be used for putting out other classes of fires. | | | | resonance spectrometers (NMRSs), nonmagnetic fire |
| - Dry chemical: Dry chemicals are used to extinguish | | | | extinguishers should be chosen. The strong magnetic |
| A-, B-, C-, or D-type fires. They work by putting a fine | | | | fields generated by this type of equipment can cause |
| layer of chemical dust on the material that is burning. | | | | steel cylinder fire extinguishers to fly across a room |
| Dry chemical extinguishers are very effective at | | | | with deadly force. |
| putting out fires. However, dry chemical extinguishers | | | | It is important to ensure that you have the proper fire |
| can be abrasive and corrosive to electronics and | | | | extinguishers for your environment or potential fire |
| certain other materials. | | | | dangers. It can be the difference between whether |
| - Carbon dioxide: Carbon dioxide works by removing | | | | your fire is eliminated or causes a catastrophy. |
| oxygen from the immediate vicinity of the fire. Carbon | | | | |