Fighting fires in homes or on technological facilities for special purposes, requires compliance with certain measures and rules of fire safety. Violation of these rules can lead to a serious fire hazard situation.
The most common causes of fires are:
- Faulty wiring and electrical equipment;
- Improper use of electrical appliances.
Contents
Extinguisher selection criteria
In the event of a fire hazardous situation in the premises with electrical equipment, it is recommended to use primary fire extinguishing means: fire extinguishers, easily moved from place to place and used to extinguish fires with special substances that stop combustion. The main rule when selecting a fire extinguisher is the proper monitoring of a number of factors: the characteristics of the protected equipment, room category, the volume of the protected area, the properties and mass of the products exposed to fire. The effectiveness of the fire extinguisher to extinguish a fire of any class should also be considered.
The use of extinguishing agents, depending on the class of fire according to GOST 27331-87.
| fire class | fire class characteristic | fire class | Fire class characteristic subclass | Recommended extinguishing media |
|---|---|---|---|---|
| А | Solid combustion | А1 | Combustion of solids accompanied by smoldering (e.g. wood, paper, coal, textiles) | Water with wetting agents, foam, refrigerants, AVCE type powders |
| А2 | Burning solids not smouldering (rubber, plastics) | All types of extinguishing agents | ||
| B | Burning of liquids | В1 | Burning of liquids insoluble in water (petrol, petroleum products) and liquefied solids (paraffin) | Foam, sprayed water, water with addition of fluorinated surfactant, chladones, CO2, powders such as ABCE and ALL |
| В2 | Burning polar liquid substances soluble in water (alcohols, acetone, glycerin, etc.) | Foam on the basis of special blowing agents, thinly spread water, chladones, powders such as ÀÂCE and ALL | ||
| С | Combustion of gaseous substances | - | Household gas, propane, hydrogen, ammonia, etc. | Volumetric extinguishing and phlegmatization with gas compositions, powders type AVCE and ALL, water for cooling equipment |
| D | Combustion of metals and metal-containing substances | D1 | Combustion of light metals and their alloys (aluminum, magnesium, etc.), except alkali metals | Special powders |
| D2 | Combustion of alkali metals (sodium, potassium, etc.) | Special powders | ||
| D3 | Combustion of metal containing compounds (organometallic compounds, metal hydrides) | Special powders |
Which fire extinguisher to use for extinguishing electrical equipment
When a fire occurs, the following varieties of fire extinguishers are used:
Powder fire extinguishers
The main indicator of a powder fire extinguisher is the proper spraying of an extinguishing agent under pressure. The mixture includes ammonium salt, sodium salt and potassium salt with specialized additives. Typically, this type of fire extinguisher is used to stop all fires. The powder mixture, when sprayed, covers and envelopes the surface of the object. Air access is stopped and the fire is extinguished. Powder fire extinguishers are permitted for Class (A to D, see. table above).
In practice, this method of elimination of fire is not very much complained about. When extinguishing valuable items, rooms that hold documentation, devices, electronics, this method is not recommended because it is virtually impossible to conduct a thorough cleaning of the equipment.
Air-foam fire extinguishers
Air-foam fire extinguishers are filled with a composition consisting of water and foam-forming additives.
When the trigger is actuated, carbon dioxide gas squeezes the foaming solution under high pressure. The blowing agent is then mixed with air in a special nozzle to form a foam that cools the objects of fire. During extinguishing, a foam film is formed that insulates the surface with the open fire from oxygen.
Air-foam type fire extinguishers are used when solids, combustible and flammable liquids are burning (fire classes A and B, see table above.).
Carbon dioxide fire extinguishers
These fire extinguishers are cylinders filled with liquefied carbon dioxide (CO2). These devices are used to extinguish fires where a combustible substance interacts with an oxidizer. The oxidizer here is oxygen in the air. Carbon dioxide fire extinguishers are approved for Class B, C and E fires (Electrical installations with voltages of up to 10 kV). Carbon dioxide is ineffective for substances that can smolder or burn without an air mixture.
Aerosol fire extinguishers (GOA and AGS)
Extinguishing in aerosol fire extinguishers takes place either with a solid filler, where the extinguishing aerosol is released by the flame, or with a powdered fine dispersed composition. The use of GOA and AGS is very productive in fires of live electrical installations.
Chladon fire extinguishers (marking OH).
Devices of this type are filled with a mixture of hydrocarbon derivatives including fluorine, chlorine, bromine substances. This is a relatively new method of extinguishing, and very effective. A serious disadvantage is that a person can be in the room where this fluorine-containing gas is sprayed for no more than five minutes because of its toxicity. Cold water fire extinguishers are successfully used in cases of ignition of electrical equipment, server rooms, rooms with equipment, control rooms, electrical switchboards, generator rooms.
Some features of extinguishing
When electrical equipment fires, it is imperative that the fire is extinguished from the top down. The fire extinguisher must not be brought within 1 m of the flaming electrical installation. It is most effective to influence the fire with several devices at the same time.
To avoid freezing your hands which are not protected by special gloves, it is not recommended to take hold of the nozzle of the carbon dioxide fire extinguisher which is directed to the flames.
It is necessary to start extinguishing from the leeward side, directing the jet of substance at the edge of the fire.
In case of fire of live electrical installations it is necessary to use aerosol fire extinguishers.
When a fire occurs in technological rooms for electrical equipment - server rooms, equipment rooms, control rooms, it is necessary to use coolant fire extinguishers.
Extinguishing electrical wiring
When there is electrical contact between points in an electrical circuit with different potentials (short circuit), a fire may result.
Warning! Do not extinguish live electrical wiring with water! It is strictly forbidden, as it can cause an electric shock.
If flames appear, the first thing to do is to switch off the electricity at the switchboard immediately. If the mains is de-energized, you can use any available extinguishing tools - water, sand or a fire extinguisher. Extinguishing powder and aerosol extinguishing media can be used to extinguish flammable fires in electrical installations (see above). If there is an open fire, it is necessary to turn off the electricity at the switchboard. If this is not possible, call the fire brigade immediately.
Extinguishing domestic electrical appliances
According to the code of practice SP 9.13130.2009 it is necessary to use fire extinguishing means in case of ignition of domestic electrical appliances.
- Powder-filled fire extinguishers are allowed to extinguish electrical equipment up to 1000 volts.
- Carbon dioxide fire extinguishers are allowed to extinguish electrical equipment with voltages up to 10,000 volts (10 kV).
- It is strictly prohibited to use carbon dioxide extinguishers for extinguishing electrical equipment with voltages above 1 kV and the length of the fire extinguishing agent jet is less than 3 meters.
Extinguishing in an electric control room
An electrical control room is usually a separate room with a switchboard or cabinet in it. It is the starting point of the power supply in the building.
Designing fire extinguishing in electric board, guided by a set of rules SP 5.13130.2009 and choose the gas (AUGP), or automatic powder fire extinguishing installation (AUPT). Water fire extinguishing (sprinklers, drenchers) is not used in the server room.
Gas fire suppression installations (AGF) are used depending on:
- depending on the extinguishing method: volumetric extinguishing or local extinguishing;
- the method of storage of gas extinguishing agent: centralized, modular;
- the method of activation from the starting pulse: with electric, pneumatic, mechanical start.
The advantage of this method is that the compositions used in gas fire-extinguishing installations do not emit any poisonous fumes upon contact with burning surfaces.
Gas extinguishing modules (GEF) can be located both in the protected premises and outside on a special rack. The modular gas fire-extinguishing installation consists of cylinders with shut-off and starting devices (SSD), pipelines with atomizers (nozzles), shut-off valves, selected by calculation.
Extinguishing gas effectively extinguishes fires by volume and easily penetrates into various areas of the object, where the supply of other substances that stop the combustion is difficult. After fire suppression or unauthorized start-up, the gas extinguishing agent (GOTV) has almost no harmful effect on the protected values compared to other extinguishing agents - water, foam, powder and aerosol, is easily removed by ventilation.
Carbon dioxide (CO2) or chladone is traditionally used to protect industrial facilities (diesel, hydrocarbon storage, compressor rooms, etc.).
Nozzles, through which the gas is released, must be placed in the room, taking into account its location and to ensure uniform distribution of the gas mixture throughout the volume. Therefore, the necessary hydraulic calculation is carried out. The difference in flow rates of the gas substance between the two extreme nozzles on the same distribution pipe should not be more than 20%, otherwise the gas will come out unevenly and the extinguishing will not happen.
Automatic powder fire extinguishing installations (AUPP) are used to extinguish fires of classes A, B, C and electrical equipment (live electrical installations).
Depending on the construction of the powder fire extinguishing module, the systems can have a distribution pipeline or without it. According to the method of storing gas in the module, which displaces the powder when triggering the trigger mechanism, installations are divided into injection, with a gas-generating element, with a cylinder of compressed or liquefied gas.
The size of the protected area, increased by 10%, or the size of the protected volume, increased by 15% is taken as the calculation zone of local fire-extinguishing. When calculating the number of modules, the calculation is based on the condition of ensuring uniform filling of the volume with the powder mixture.
It was mentioned earlier that, for practical reasons, designers are not in a hurry to use the AUPP system. The equipment of a panel or server room can be hopelessly ruined.
Extinguishing electrical installations depending on power
When extinguishing fires of electrical installations, depending on the different voltages, different types of fire extinguishers are used.
400 volts (0.4 kV).
Powder, carbon dioxide, halide, water and foam fire extinguishers (the last two when disconnected from the power supply).
1000 volts (up to 1 kV).
Powder and carbon dioxide fire extinguishers.
10,000 volts (up to 10 kV)
Carbon dioxide fire extinguishers.
What is prohibited to extinguish electrical equipment
What fire extinguishers are not allowed to extinguish live electrical equipment and wiring? What rules must be observed when electrical equipment catches fire?
Do not use powder fire extinguishers to extinguish electrical equipment with voltages above 1000 V.
Air-foam fire extinguishers are not used to extinguish fires of live electrical equipment.
Carbon dioxide fire extinguishers are ineffective for extinguishing fires of electrical equipment energized above 10 kV.
It is strictly prohibited to extinguish live electrical wiring with foam and water compositions, including seawater.
A fairly common cause of fires in electrical installations is a violation of the requirements of current regulations on fire safety. First of all - it is careless handling of fire. The cause of the fire can be smoking in an unauthorized place, improper maintenance of electrical appliances. In order to control the operating personnel of technological plants the periodic testing of knowledge on fire safety issues is carried out, and explanatory work with the population is carried out.
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