A fire extinguisher is the primary equipment that is used in case of detection of a source of ignition and allows it to be completely or partially eliminated before the arrival of the fire service. That is why these devices, according to safety regulations, must be in every home, office, company and even in a car. What types of fire extinguishers can be found today?
General information
A fire extinguisher is a stationary or mobile device designed to extinguish small spontaneous fires. All these devices work by the principle of injecting their contents onto a hearth or object engulfed in flames.
Most often they have the appearance of a special red cylinder equipped with a special nozzle or tube. And the substance contained inside it is under pressure and, if necessary, is removed to the surface by pressing the appropriate lever.
Fire extinguishers: types and characteristics
Depending on their direct purpose and the expected class of fire, all fire extinguishers can be conditionally divided into five types:
- liquid;
- powder;
- gas or carbon dioxide;
- air foam;
- air-emulsion.
What fire extinguishers are called liquid?
Liquid or water types of fire extinguishers are fire fighting equipment designed to extinguish class A fires (ignition of solid substances) and B (combustion of liquid substances).
They are in the form of cylinders labeled "OV" and contain water or a water-based solution, which includes chemically active substances. It is noteworthy that such devices are not suitable for extinguishing other classes of fire. But on the other hand, it is precisely liquid devices that are considered the most safe for health due to the presence of natural components in their composition.
What are powder fire extinguishers?
Powder devices are universal types of fire extinguishers used that can be safely used to extinguish almost all classes of fires: A, B, C (ignition of gaseous substances) and E (combustion of electrical appliances and other objects under the influence of electricity). They have the established marking “OP” (general purpose or use equipment).
The composition of such fire extinguishers includes substances having a powder base, as well as mineral salts and other components that allow you to keep the device in its original state. In other words, they save the powder from moisture and do not prevent the formation of lumps in it.
What subspecies of fixtures are powder extinguishers?
Powder extinguishers (purpose, types, application of these devices are listed in this article) are conventionally divided into separate groups:
- injection;
- gas generating;
- self-working.
The composition of injection devices, as a rule, includes two components: a fire extinguishing powder and an inert gas (for example, nitrogen or carbon dioxide can play its role). Sometimes, instead of inert gas, air is placed in the cylinders under pressure of 15-16 atm. With the help of such a device it is possible to extinguish fires of classes A to E.
In addition, there is an internal pressure indicator on the head of the injection fire extinguishers, which clearly demonstrates their performance. If everything is in order with the equipment, the green light on the indicator scale lights up.
Gas-generating - fire extinguishers operating on the principle of using energy, the generation of which occurs during the extinguishing of the fire (at this moment gas escapes and the fire extinguishing agent is released).Such devices have a general start-up principle, with the exception of the required waiting period (6-10 seconds). Here are the types (fire extinguishers of this type can be seen in the photo below) that relate to gas appliances.
Self-extinguishing extinguishers also exist. As their name implies, such devices can work without the direct involvement of a person. Most often they are part of a fire extinguishing system and are able to operate exclusively at a certain temperature. It is these devices that are usually installed in offices, in warehouses, in garages and domestic premises.
What are gas fire extinguishers?
Gas or carbon dioxide devices are a large group of devices that have one common marking “OU”. It includes the following types of fire extinguishers:
- aerosol;
- carbon dioxide-bromoethyl.
Many years ago, the same group included dangerous tetrachloride fire extinguishers, known for their negative effect on the human body. The fact is that during a fire extinguishing with the help of such equipment, a chemical reaction occurred: gas was released that is dangerous for breathing. Therefore, it was possible to use the equipment only by putting on a gas mask, which caused extreme inconvenience.
Later, safer carbon dioxide types of fire extinguishers containing carbon dioxide began to be produced. Moreover, such devices have acquired both a mobile and a manual look. Such equipment, as practice shows, is used to extinguish class B and C fires. Most often they are used where it is impossible to get rid of the flame with water or powder.
The composition of aerosol and carbon-bromoethyl extinguishers includes the so-called halogenated hydrocarbons. When they are used, a lot of oxygen accumulates in the source of ignition (up to 18%), only at this concentration of gas the fire is extinguished.
Where can I not use gas fire extinguishers?
However, far from everywhere it is possible to use gas types of fire extinguishers, and their application directly depends on the combustion process. In particular, it is impossible to extinguish the flame on those objects that are made, for example, of aluminum, magnesium or sodium. The fact is that such substances can burn without oxygen, so gas devices will simply not work on them.
They also cannot be used to extinguish a pipeline or equipment with a high operating temperature. This is due to the cooling effect that is observed when reactive carbon dioxide is used. Otherwise, a sharp drop in temperature can lead to subsequent depressurization.
What are air-foam fire extinguishers used for?
Air-foam fire extinguishers are devices that are used to suppress sources of ignition of materials that are prone to prolonged decay, such as paper, coal, wood and plastic. In addition, with the help of such fire extinguishers it is possible to extinguish the flame that has arisen on liquids having an oil base, for example, oil, oils and paints.
However, air-foam equipment cannot be used to extinguish buildings and structures made of aluminum, sodium, magnesium, potassium and other alkaline earth metals. They are also not suitable for extinguishing a flame in electrical installations that are connected to electricity.
Thanks to water-foam fire extinguishers, it is possible to quickly localize the source of ignition due to the foam cover released from them, blocking the access of oxygen to a burning object.
What are air-emulsion fire extinguishers?
Air-emulsion fire extinguishers - devices designed to extinguish fires of classes A, B and E. Their operating principle is based on the energy of compressed air, used when applying a fire-extinguishing emulsion to a flame.
Using such fire extinguishers, fires associated with gaseous substances (propane, ammonia, household gas), alkaline earth metals and the combustion of cotton and pyroxylin cannot be extinguished.
We examined what types of fire extinguishers are and the purpose of each type.
