When most people picture a fire extinguisher, the image that is called to mind is that of a CO2 extinguisher. With their large, metals cylinders of bright red and hard horns, these fire extinguishers have been installed as an emergency measure in homes and businesses for generations. Carbon dioxide extinguishers can be differentiated from similar extinguishers by the lack of any sort of pressure gauge at the top of the tank.
While there are other red fire extinguishers that use dry chemicals instead of compressed carbon dioxide gas, you can easily spot a CO2 extinguisher by the fact that there will be no gauge at the top of the devices tank. CO2 fire extinguishers have a limited range of only a few feet and are typically only used to put out small fires or clear the way for safe evacuation of the area. Each CO2 extinguisher must be recharged every five years.
The Walter Kindle Company first invented the carbon dioxide extinguisher in 1924 at the request of the Bell Telephone Company. Bell had been having difficulty finding a dry chemical extinguisher that could effectively extinguish the electrical fires that sometimes broke out on early telephone switchboards. The CO2 proved particularly effective at controlling electrical fires, and their popularity quickly grew throughout the industrial sector.
Another factor influence the widespread adoption of the carbon dioxide extinguisher was the fact that it was considerably safer to use than the earlier chemical models. The dry chemicals that were used in the other fire extinguishers were known to cause toxic reactions in people in the immediate vicinity of their use that ranged from mild to deadly. In fact, the relatively harmless effects of the CO2 extinguisher are a big factor in the continued popularity of the device in the modern world.
CO2 extinguishers operate by releasing highly pressurized carbon dioxide onto that comes out a velocity that is high enough to remove all of the oxygen out of the area of a fire and extinguish the source of combustion. The gas that is released from CO2 extinguishers is also very cold and rapidly lowers the temperature of a fire. While CO2 extinguishers are very common in many buildings, they are not effective at extinguishing all fires. However, there are effective at controlling many fires long enough for residents to evacuate a building or for the fire department to arrive on the scene.
CO2 extinguishers are actually not the preferred fire extinguishers of choice for many types of fires. CO2 extinguishers are particularly ineffective in battling Class A fires. Class A fires constitute all fires that are fuelled by ordinary, combustible material. Because CO2 fires do not push enough oxygen away from the fire for the necessary amount of time to extinguish a Class A fire, these fires can easily continue to smoulder and reignite. Instead, CO2 extinguishers are designed to put out exclusively electrical and liquid fuelled fires. In case of an emergency, these extinguishers can also be used to save a human being who has caught on fire.
CO2 extinguishers are regularly seen on television and film as a set prop. Because CO2 extinguishers are fairly safe to use, production companies often use them for extinguishing a stunt man when he is set on fire for the scene. However, actual fire rescue workers rarely use CO2 extinguishers for real life rescues in less absolutely necessary.