Gas fire extinguishing device. Gas fire extinguishing system – timely extinguishing of fire. Gases used in extinguishing

Gas compositions have a combination of properties that make it possible to stop a fire. They are divided into diluents (CO2, Inergen and other compressed gases), which reduce the level of oxygen, and inhibitors (freons), which chemically slow down the combustion rate.

When choosing a gas extinguishing agent for a fire extinguishing system, it is necessary to be guided by economic feasibility, safety for humans and the environment, and the consequences of contact with the protected property.

Brief characteristics of popular GOTV

CO2

CO2 (liquid carbon dioxide) is one of the first and still popular gas fire extinguishing agents. Peculiarities:

• low price;
• environmentally friendly;
• high percentage of distribution.

Liquefied carbon dioxide, the ancestor of gas agents, has been used for more than a hundred years around the world. With the introduction of amendments to SP 5.13130.2009, it is necessary to exclude its use in facilities with large numbers of people (over 50 people) and in premises that cannot be left by people before starting the automatic gas fire extinguishing installation.

Freon 125

Freon 125 (pentafluoroethane) is the most common fire extinguishing agent. Main advantages:

• the cheapest gas;
• high percentage of application;
• good thermal stability (900 C).

For several decades, it has been traditionally used in gas fire extinguishing systems. It has the greatest prevalence among freons in the territory Russian Federation, due to the low price. However, when using it, precautions must be taken to prevent any hazardous exposure to operating personnel.

Freon 23

Freon 23 (trifluoromethane) is one of the safe gaseous fire extinguishing agents (GOF). Advantages:

• impact on humans - harmless;
• the smallest fire extinguishing mass among freons;
• constant control of the mass of GFFS.

Like carbon dioxide, it is stored in gas fire extinguishing modules under the pressure of its own vapors. This explains the low module filling factor (0.7 kg/l) and the high metal consumption and complexity (due to the presence of weighing devices) of gas fire extinguishing installations based on it. Despite all the shortcomings and limitations, this agent is quite widespread in Russia.

Fluoroketone FK-5-1-12 or “dry water”

Fluoroketon FK-5-1-12 (“dry water”) is the latest generation of gaseous fire extinguishing compounds (GOTV) for fire extinguishing systems. Main advantages:

• harmless to humans and the environment;
• On-site refueling is possible.

It has been used in fire extinguishing systems for more than ten years at facilities with high safety requirements for operating personnel. It was developed by a well-known American company as an alternative to refrigerants that are limited in use. It is best known under the name “dry water” and fluoroketone FK-5-1-12. Gas has become widespread throughout the world, including in Russia. The main limiting factors limiting the growth of further implementation are foreign production and the foreign policy situation.

Freon 227ea (heptafluoropropane)

Freon 227EA (heptafluoropropane) is one of the safe fire extinguishing agents (FFA). Main characteristics:

• effect on humans: safe for humans;
• coefficient of filling into the gas fire extinguishing module: 1.1 kg/l;
• high dielectric conductivity.

The gas extinguishing agent is ozone-safe and is not subject to the Montreal and Kyoto protocols limiting the use of bromine and chromium-containing agents. It is used in automatic gas fire extinguishing installations in accordance with table 8.1 SP 5.13130.2009. Can be used in facilities with a large or constant presence of people, while the fire extinguishing concentration should not exceed the standard by more than 25%. Inferior to other GFFEs in thermal stability (600° C).

Freon 318C

Freon 318C is a fairly rare gas fire extinguishing agent (perfluorocyclobutane, C4F8). Distinctive features:

• safe for humans;
• coefficient of filling into the gas fire extinguishing module - 1.2 kg/l;
• environmentally friendly.

Igmer, as it is sometimes called, is relatively rarely used in gas fire extinguishing installations. In terms of its properties, it is closest to its analogue Freon 227ea, losing slightly to it in terms of safety for humans and environmental parameters. Almost all manufacturers of gas fire extinguishing systems can fill gas fire suppression modules with it. But it is used extremely rarely, since there are alternative refrigerants that are more affordable and have better technical characteristics.

Inergen

Inergen is a mixture of inert fire extinguishing agents. Pros:

• safe for humans;
• produced in Russia;
• environmentally friendly.

It is obtained by mixing inert gases: carbon dioxide (8%), nitrogen (40%) and argon (52%). Unlike freons, it does not enter into any chemical reactions when it gets into a fire, and copes with it due to a sharp decrease in oxygen levels. It has become widespread in Western countries, but is now rarely used in Russia due to its high price and the availability of cheaper analogues.

AQUAMARINE

AQUAMARINE is newest generation liquid fire extinguishing agents developed in Russia. Advantages:

• safe for humans;
• low price;
• environmentally friendly.

AQUAMARINE is used in modular fire extinguishing installations with finely sprayed water. Effective composition of combined action. When extinguishing, it isolates oxygen from the combustion zone, eliminates smoldering due to cooling of the surface and forms protective film preventing re-ignition. The composition was developed by AFES as an economical liquid fire extinguishing agent, harmless to personnel, property and the environment. Stored and released from modular installations fire extinguishing with finely sprayed water (MUPTV). When released, it forms a highly dispersed foam, which decomposes under the influence of microorganisms in the environment, leaving no traces.

What's happened gas fire extinguishing? Automatic gas fire extinguishing installations (AUGPT) or gas fire extinguishing modules (GFP) are designed to detect, localize and extinguish fires of solid flammable materials, flammable liquids and electrical equipment in production, warehouse, household and other premises, as well as to issue a fire alarm signal to a room with round-the-clock presence of on-duty personnel. Gas fire extinguishing installations are capable of extinguishing a fire at any point in the volume of the protected premises. Gas fire extinguishing, unlike water, aerosol, foam and powder, does not cause corrosion of the protected equipment, and the consequences of its use can be easily eliminated by simple ventilation. At the same time, unlike other systems, AUGPT installations do not freeze and are not afraid of heat. They operate in the temperature range: from -40C to +50C.

In practice, there are two methods of gas fire extinguishing: volumetric and local volumetric, but the volumetric method is most widespread. Taking into account the economic point of view, the local volumetric method is beneficial only in cases where the volume of the room is more than six times the volume occupied by the equipment, which is usually protected using fire extinguishing installations.

System composition

Fire extinguishing gas compositions for fire extinguishing systems are used as part of an automatic gas fire extinguishing installation ( AUGPT), which consists of basic elements, such as: modules (cylinders) or containers for storing gas fire extinguishing agent, fire extinguishing gas filled into modules (cylinders) under pressure in a compressed or liquefied state, control units, pipeline, exhaust nozzles that ensure delivery and release of gas into the protected room, control panel, fire detectors.

Design gas fire extinguishing systems produced in accordance with the requirements of the standards fire safety for each specific object.

Types of used fire extinguishing agents

Liquefied gas fire extinguishing compounds: Carbon dioxide, Freon 23, Freon 125, Freon 218, Freon 227ea, Freon 318C

Compressed gas fire extinguishing compounds: Nitrogen, argon, inergen.

Freon 125 (HFC-125) - physical and chemical properties

OTV Freon 227ea

Freon-227ea is one of the most used agents in the global gas fire extinguishing industry, also known under the brand name FM200. Used to extinguish fires in the presence of people. An environmentally friendly product with no restrictions on long-term use. It has more effective extinguishing performance and higher industrial production costs.

Under normal conditions, it has a lower (compared to Freon 125) boiling point and saturated vapor pressure, which increases safety in use and transportation costs.

Gas fire extinguishing Freon is effective means for extinguishing fires in premises, because gas penetrates instantly into the most hard to reach places and fills the entire volume of the room. The consequences of activating the Freon gas fire extinguishing installation are easily eliminated after smoke removal and ventilation.

The safety of people during gas fire extinguishing Refrigerant is determined in accordance with the requirements of regulatory documents NPB 88, GOST R 50969, GOST 12.3.046 and is ensured by the preliminary evacuation of people before the supply of fire extinguishing gas according to siren signals during the designated time delay. The minimum duration of the time delay for evacuation is determined by NPB 88 and is 10 s.

Isothermal module for liquid carbon dioxide (MIZHU)

MIZHU consists of a horizontal tank for storing CO2, a shut-off and starting device, devices for monitoring the amount and pressure of CO2, refrigeration units and a control panel. The modules are designed to protect premises with a volume of up to 15 thousand m3. The maximum capacity of MIZHU is 25t CO2. As a rule, the module stores working and reserve CO2 reserves.

An additional advantage of the MIZHU is the ability to install it outside the building (under a canopy), which can significantly save production space. Only MIZHU control devices and distribution devices UGP (if available).

MGP with a cylinder capacity of up to 100 liters, depending on the type of combustible load and the filled flammable fuel, allows you to protect a room with a volume of no more than 160 m3. To protect larger premises, the installation of 2 or more modules is required.
A technical and economic comparison showed that to protect premises with a volume of more than 1500 m3 in the UGP, it is more expedient to use isothermal modules for liquid carbon dioxide (ILC).

MIZHU is designed for fire protection of premises and technological equipment as part of gas fire extinguishing installations with carbon dioxide and provides:

supply of liquid carbon dioxide (LC) from the MID reservoir through the shut-off and starting device (ZPU), refueling, refueling and draining (LC);

long-term non-drainage storage (DS) in a tank with periodically operating refrigeration units (RA) or electric heaters;

control of pressure and mass of liquid fuel during refueling and operation;

ability to check and configure safety valves without releasing pressure from the tank.

In protected areas, a gas fire extinguishing method is used, the principle of which is to release a special non-flammable substance in a gaseous state. Gas supplied under pressure (freon, nitrogen, argon, etc.) displaces oxygen, which supports combustion, from the room where the fire occurred.

Classification of fires extinguished by gas extinguishing

Automatic gas fire extinguishing is widely used in localizing fires belonging to the following classes:

1. combustion hard materials– class A;
2. combustion of liquids – class B;
3. burning of electrical wiring and live equipment – ​​class E.

Fire protection by volumetric method is used to protect specialized banking equipment, museum valuables, archival documents, data exchange centers, server rooms, communication nodes, instruments, gas pumping facilities, diesel, generator rooms, control rooms and other expensive property, both industrial and economic.

Premises where control of nuclear power plants, telecommunication equipment, drying and painting booths are located must be equipped with automatic gas fire protection without fail.

Advantages of the method

Unlike other fire extinguishing methods, automatic gas fire extinguishing covers the entire volume of the protected premises. The gas fire extinguishing mixture spreads throughout the entire room, including objects of spontaneous combustion, within a short time of 10 - 60 seconds, stopping the fire, leaving the protected valuables in their original form.

The main advantages of this fire extinguishing method include the following factors:

• safety of operating materials;
• high speed and efficiency of fire elimination;
• covering the entire volume of the protected premises;
• long service life of gas equipment installations.

The fire extinguishing gas mixture eliminates flames with great efficiency due to the ability of the gas to quickly penetrate into hard-to-reach sealed and screened areas of the protected facility, where access to conventional fire extinguishing means is difficult.

In the process of extinguishing a fire due to the activation of the AUGP, the gas formed does not cause harm to valuables in comparison with other extinguishing means - water, foam, powder, aerosols. The consequences of extinguishing a fire are quickly removed by ventilation or using ventilation means.

Design and principle of operation of installations

Automatic gas fire extinguishing installations (AUGP) consist of two or more modules containing a gas fire extinguishing agent, pipe lines and nozzles. Detection of fire and switching on of the installation occurs using a special fire alarm system, which is integral part equipment.

Gas fire-fighting modules consist of gas cylinders and starting devices. Gas cylinders are subject to repeated refilling after they are emptied during use. A complex automatic gas fire extinguishing system, consisting of several modules, is combined using special devices– collectors.

During daily operation, atmospheric monitoring of smoke occurrence (smoke detectors) and elevated temperature values ​​( heat detectors) indoors. Constant monitoring of the integrity of the fire extinguishing system startup circuits, breaks in the circuits, and the formation of short circuits is also carried out using fire alarm systems.

The gas fire extinguishing method occurs automatically:

• triggering of sensors;
• release of fire extinguishing gases under high pressure;
• displacing oxygen from the atmosphere of the protected room.

The occurrence of a fire is a signal to automatically start the gas fire extinguishing installation in accordance with a special algorithm, which also provides for the evacuation of personnel from the danger zone.

The received signal about the occurrence of a fire leads to automatic shutdown of the ventilation system, supplying non-flammable gas under high pressure through pipelines to the sprayers. Due to the high concentration of gas mixtures, the duration of the gas fire extinguishing process is no more than 60 seconds.

Types of automatic systems

The use of AUGP is recommended in rooms where there is no constant presence of people, as well as where explosive and flammable substances are stored. Here, fire detection is impossible without alarm systems that trigger automatically.

Depending on mobility automatic systems are divided into the following categories:

1. mobile installations;
2. portable AUGP;
3. stationary types of systems.

A mobile automatic gas fire extinguishing installation is located on special platforms, both self-propelled and towed. Installation of stationary equipment is carried out directly in the premises, control is carried out using remote controls.

Portable installations - fire extinguishers are the most common means of fire extinguishing. Their presence is mandatory in every room.

Classification of AUGP is also carried out according to the methods of supply of fire extinguishing agents, according to volumetric methods (local - fire extinguishing agent is supplied directly to the place of fire, complete extinguishing - throughout the entire volume of the room).

Requirements for design, calculation and installation work

When installing automatic fire extinguishing systems gas method it is necessary to comply with the standards established by current legislation in full compliance with the requirements of customers of the designed objects. Design, calculation and installation activities are carried out by professionals.

Creation project documentation begins with an inspection of the premises, determining the number and area of ​​rooms, features finishing materials, used in the design of ceilings, walls, floors. It is also necessary to take into account the purpose of the rooms, humidity characteristics, and evacuation routes for people in the event of an urgent need to leave the building.

When determining the locations of this fire fighting equipment Special attention it is necessary to pay attention to the amount of oxygen in crowded areas at the moment automatic switching on. The amount of oxygen in these places must meet acceptable standards.
When mounting gas equipment it is necessary to ensure its protection from mechanical influences.

Activities for maintenance of fire fighting equipment

Automatic fire protection systems gas type require regular preventive maintenance.

The operating condition and tightness must be checked monthly individual elements and the system as a whole.

It is necessary to diagnose the functionality of smoke and fire sensors, as well as alarm systems.

Each activation of fire extinguishing means must be accompanied by subsequent refilling of the containers with gas mixtures and reconfiguration of the warning system. Dismantling of the entire system is not required due to the fact that preventive operations are carried out at its location.

Gas was first used to extinguish fire at the end of the 19th century. And the first thing in gas fire extinguishing installations (GFP) was carbon dioxide. At the beginning of the last century, Europe began producing carbon dioxide plants. In the thirties of the twentieth century, fire extinguishers with freons were used, fire extinguishing agents type methyl bromide. For the first time in the Soviet Union, devices using gas to extinguish fire were used. In the 40s, isothermal tanks began to be used for carbon dioxide. Later, new extinguishing agents based on natural and synthetic gases were developed. They can be classified as freons, inert gases, carbon dioxide.

Advantages and disadvantages of fire extinguishing agents

Gas installations are much more expensive than systems that use steam, water, powder or foam as an extinguishing agent. Despite this, they are widely used. The use of UGP in archives, museum storerooms and other storage facilities with flammable valuables is beyond competition, due to the virtual absence of material harm from their use.

Besides . Using powder and foam can ruin expensive equipment. Gas is also used in aviation.

The rapidity of gas distribution and the ability to penetrate into all cracks allows the use of installations based on it to ensure the safety of premises with complex layouts, dropped ceilings, many partitions and other obstacles.

Application gas installations, operating on the basis of diluting the atmosphere of the object, requires collaboration with complex security systems. To guarantee fire extinguishing, all doors and windows must be closed and forced fire must be turned off or closed. natural ventilation. To alert people inside the premises, light, sound or voice signals are given, and a certain time is given to exit. After this, the actual fire extinguishing begins. Gas fills the premises, regardless of the complexity of its layout, within 10-30 seconds after the evacuation of people.

Installations using compressed gas can be used in unheated buildings, as they have a wide temperature range, -40 - +50 ºС. Some GFFS are chemically neutral and do not pollute environment, and freon 227EA, 318C can be used in the presence of people. Nitrogen installations are effective in the petrochemical industry, when extinguishing fires in wells, mines and other facilities where explosive situations are possible. Installations with carbon dioxide can be used when operating electrical installations with voltages up to 1 kV.

Disadvantages of gas fire extinguishing:

• the use of GFFS is ineffective in open areas;
• gas is not used to extinguish materials that can burn without oxygen;
• for large objects, gas equipment requires a separate special extension to accommodate gas tanks and related equipment;
• nitrogen installations are not used when extinguishing aluminum and other substances that form nitrides, which are explosive;
• It is impossible to use carbon dioxide to extinguish alkaline earth metals.

Gases used to extinguish fires

In Russia, the types of gas fire extinguishing agents permitted for use in fire extinguishing agents are limited to nitrogen, argon, inergen, freons 23, 125, 218, 227ea, 318C, carbon dioxide, and sulfur hexafluoride. The use of other gases is possible upon agreement of technical conditions.

Gas fire extinguishing agents (GFA) are divided into two groups according to the extinguishing method:

• The first is refrigerants. They extinguish the flame by chemically slowing down the burning rate. In the combustion zone, freons disintegrate and begin to interact with combustion products, this reduces the combustion rate until complete extinction.
• The second is gases that reduce the amount of oxygen. These include argon, nitrogen, and inergen. Most materials require more than 12% oxygen in the fire atmosphere to sustain combustion. By introducing an inert gas into the room and reducing the amount of oxygen, the desired result is obtained. Which fire extinguishing agent must be used in gas fire extinguishing installations depends on the object of protection.

Note!

Based on the type of storage, GFFS are divided into compressed (nitrogen, argon, inergen) and liquefied (all others).

Fluoroketones are a new class of fire extinguishing agents, developed by 3M. These are synthetic substances that are similar in effectiveness to freons and are inert due to their molecular structure. The extinguishing effect is obtained at concentrations of 4-6 percent. This makes it possible to use it in the presence of people. In addition, unlike freons, fluoroketones quickly decompose after use.

Types of gas fire extinguishing systems

There are two types of gas fire extinguishing installations (GFP): stationary and modular. To ensure the security of several rooms, a modular UGP is used. For the entire facility, a station installation is usually used.

UGP components: gas fire extinguishing modules (GFP), nozzles, switchgear, pipes and fire extinguishing agents.

The main device on which the operation of the installation depends is the MGP module. It is a tank with a shut-off and start-up device (ZPU).

It is better to use cylinders with a capacity of up to 100 liters, since they are easy to transport and do not require registration with Rostekhnadzor.

Currently on Russian market IHL is applied by more than a dozen domestic and foreign companies.

Top five IHL modules

• OSK Group – Russian manufacturer fire extinguishing devices with 17 years of development experience in this field. The company produces devices using Novec 1230. This fire extinguishing agent is used in gas fire extinguishing installations, which can be used in energy and similar premises in the presence of people. ZPU with pressure gauge and safety burst disc. Available in volumes from 8 liters to 368 liters.
• MINIMAX modules from a German manufacturer are particularly reliable due to the use of seamless vessels. MGP line from 22 to 180 liters.

• The MGP developed by the VFAspekt company uses welded tanks low pressure, as flue gases - freons. Available in 40, 60, 80 and 100l volumes.
• MGP "Plamya" are produced by NTO "Plamya". Reservoirs are used for compressed low-pressure gases and freons. A large range is available from 4 to 140 liters.
• Modules from the Spetsavtomatika company are produced for high- and low-pressure compressed gases and freons. The equipment is easy to maintain and efficient in operation. 10 standard sizes of MGP are produced from 20 to 227 liters.

In addition to electric and pneumatic start, modules from all manufacturers provide manual start of devices.

The use of new gas fire extinguishing agents such as Novec 1230 (fluoroketone group), as a result, the ability to extinguish a fire in the presence of people, has increased the efficiency of the fire extinguishing agent due to early response. And the harmlessness of the use of fire extinguishing agents for material assets, despite the significant cost of equipment and its installation, becomes a serious argument in favor of the use of gas fire extinguishing systems.

24.12.2014, 09:59

S. Sinelnikov
Head of the design department of Tekhnos-M+ LLC

IN Lately in systems fire safety small objects to be protected by systems automatic fire extinguishing, are becoming increasingly widespread automatic installations gas fire extinguishing.

Their advantage lies in fire extinguishing compositions that are relatively safe for humans, complete absence of damage to the protected object when the system is activated, repeated use of equipment and extinguishing fires in hard-to-reach places.

When designing installations, questions most often arise regarding the choice of fire extinguishing gases and hydraulic calculation installations.

In this article we will try to reveal some aspects of the problem of choosing a fire extinguishing gas.

All gas fire extinguishing compositions most commonly used in modern gas fire extinguishing installations can be divided into three main groups. These are substances of the freon series, carbon dioxide - commonly known as carbon dioxide (CO2) - and inert gases and mixtures thereof.

In accordance with NPB 88-2001*, all these gaseous fire extinguishing agents are used in fire extinguishing installations to extinguish fires of class A, B, C, in accordance with GOST 27331, and electrical equipment with a voltage not higher than that specified in the technical documentation for the used fire extinguishing agents.

Gas fire extinguishing agents are used primarily for volumetric fire extinguishing in the initial stage of a fire in accordance with GOST 12.1.004-91. Fluid gases are also used to phlegmatize explosive environments in the petrochemical, chemical and other industries.

GFFS are non-electrically conductive, evaporate easily, do not leave traces on the equipment of the protected object, in addition, an important advantage of GFFE is its

Suitable for extinguishing expensive live electrical installations.

It is prohibited to use fire extinguishing agent for extinguishing:

a) fibrous, loose and porous materials, capable of spontaneous combustion with subsequent smoldering of the layer inside the volume of the substance ( sawdust, rags in bales, cotton, grass meal, etc.);

b) chemical substances and their mixtures, polymer materials prone to smoldering and burning without air access (nitrocellulose, gunpowder, etc.);

c) chemically active metals (sodium, potassium, magnesium, titanium, zirconium, uranium, plutonium, etc.);

d) chemicals capable of undergoing authermal decomposition (organic peroxides and hydrazine);

e) metal hydrides;

f) pyrophoric materials (white phosphorus, organometallic compounds);

g) oxidizing agents (nitrogen oxides, fluorine). It is prohibited to extinguish class C fires if this may release or enter the protected volume of flammable gases with the subsequent formation of an explosive atmosphere.

In the case of using GFFE for fire protection of electrical installations, the dielectric properties of gases should be taken into account: dielectric constant, electrical conductivity, dielectric strength.

As a rule, the maximum voltage at which extinguishing can be carried out without shutting down electrical installations with all fire extinguishing agents is no more than 1 kV. To extinguish electrical installations with voltages up to 10 kV, you can use only the highest grade CO2 - in accordance with GOST 8050.

Depending on the extinguishing mechanism, gas fire extinguishing compositions are divided into two qualification groups:

1) inert diluents that reduce the oxygen content in the combustion zone and form an inert environment in it (inert gases - carbon dioxide, nitrogen, helium and argon (types 211451, 211412, 027141, 211481);

2) inhibitors that inhibit the combustion process (halocarbons and their mixtures with inert gases - freons).

Depending on the state of aggregation, gaseous fire extinguishing compositions under storage conditions are divided into two classification groups: gaseous and liquid (liquids and/or liquefied gases and solutions of gases in liquids).

The main criteria for choosing a gas extinguishing agent are:

■ Safety of people.

■ Technical and economic indicators.

■ Preservation of equipment and materials.

■ Restriction on use.

■ Environmental impact.

■ Possibility of removing GFZ after use.

It is preferable to use gases that:

■ have acceptable toxicity in the used fire extinguishing concentrations (suitable for breathing and allow personnel to be evacuated even when gas is supplied);

■ thermally resistant (form minimal amount thermal decomposition products that are corrosive, irritating to the mucous membrane and toxic if inhaled);

■ most effective in fire extinguishing (they protect the maximum volume when supplied from a module that is filled with gas to the maximum value);

■ economical (provide minimal specific financial costs);

■ environmentally friendly (do not have a destructive effect on the Earth’s ozone layer and do not contribute to the creation of the greenhouse effect);

■ provide universal methods for filling modules, storing and transporting and refilling. The most effective in extinguishing fires are chemical refrigerant gases. The physicochemical process of their action is based on two factors: chemical inhibition of the oxidation reaction process and a decrease in the concentration of the oxidizing agent (oxygen) in the oxidation zone.

Freon-125 has undoubted advantages. According to NPB 882001*, the standard fire extinguishing concentration of freon-125 for class A2 fires is 9.8% vol. This concentration of freon-125 can be increased to 11.5% vol., while the atmosphere is breathable for 5 minutes.

If we rank GFFS by toxicity in the event of a massive leak, then compressed gases are the least dangerous, because Carbon dioxide provides human protection from hypoxia.

The refrigerants used in the systems (according to NPB 88-2001*) are low-toxic and do not exhibit a pronounced pattern of intoxication. In terms of toxicokinetics, freons are similar to inert gases. Only with prolonged inhalation exposure to low concentrations can freons have an adverse effect on the cardiovascular, central nervous system, lungs. With inhalation exposure to high concentrations of freons, oxygen starvation develops.

Below is a table with temporary values ​​for the safe stay of a person in the environment of the most frequently used brands of refrigerants in our country at various concentrations (Table 1).

The use of freons when extinguishing fires is practically safe, because Fire extinguishing concentrations for freons are an order of magnitude lower than lethal concentrations for exposure durations of up to 4 hours. Approximately 5% of the mass of freon supplied to extinguish a fire is subject to thermal decomposition, therefore the toxicity of the environment formed when extinguishing a fire with freons will be much lower than the toxicity of the products of pyrolysis and decomposition.

Freon-125 is ozone-safe. In addition, it has maximum thermal stability compared to other freons; the temperature of thermal decomposition of its molecules is more than 900 ° C. The high thermal stability of freon-125 allows it to be used for extinguishing fires of smoldering materials, because at smoldering temperature (usually about 450°C) thermal decomposition practically does not occur.

Freon-227ea is no less safe than freon-125. But their economic indicators as part of a fire extinguishing installation are inferior to freon-125, and their efficiency (protected volume from a similar module) differs slightly. It is inferior to freon-125 in thermal stability.

The specific costs of CO2 and freon-227ea are almost the same. CO2 is thermally stable for fire extinguishing. But the effectiveness of CO2 is low - a similar module with freon-125 protects 83% more volume than a CO2 module. The fire extinguishing concentration of compressed gases is higher than that of freons, so 25-30% more gas is required, and, consequently, the number of containers for storing gas fire extinguishing agents increases by a third.

Effective fire extinguishing is achieved at a CO2 concentration of more than 30% vol., but such an atmosphere is unsuitable for breathing.

Carbon dioxide at concentrations greater than 5% (92 g/m3) has bad influence on human health, the volume fraction of oxygen in the air decreases, which can cause the phenomenon of oxygen deficiency and suffocation. Liquid carbon dioxide, when the pressure decreases to atmospheric pressure, turns into gas and snow at a temperature of -78.5 ° C, which cause frostbite of the skin and damage to the mucous membrane of the eyes.

In addition, when using coal acid automatic fire extinguishing installations ambient air temperature working area should not exceed +60° C.

In addition to freons and CO2, inert gases (nitrogen, argon) and their mixtures are used in gas fire extinguishing installations. The unconditional environmental friendliness and safety of these gases for humans are the undoubted advantages of their use in AUGPT. However, the high fire extinguishing concentration and the associated larger (compared to freons) amount of required gas and, accordingly, a larger number of modules for its storage, make such installations more cumbersome and expensive. In addition, the use of inert gases and their mixtures in AUGPT involves the use of more high pressure in modules, which makes them less safe during transportation and operation.

IN last years on domestic market Modern fire extinguishing agents of a new generation began to appear.

These special formulations are predominantly produced abroad and tend to be expensive. However, their low fire extinguishing concentration, environmental friendliness and the possibility of using low-pressure modules make their use attractive and promise good prospects for the use of such fire extinguishing substances in the future.

Based on all of the above, we can say that the most effective and affordable given time Fire extinguishing agents are freons. The relatively high cost of refrigerants is compensated by the cost of the installation itself, installation of the system and its Maintenance. A particularly important quality of refrigerants used in fire extinguishing systems (in accordance with NPB 88-2001*) is their minimally harmful effect on humans.

Table 2. Summary table of characteristics of the most commonly used state standards in the Russian Federation

Gas fire extinguishing installations are specific, expensive and quite complex to design and install. Today there are many companies that offer various settings gas fire extinguishing. Since there is little information in open sources on gas fire extinguishing, many companies mislead the customer by exaggerating the advantages or hiding the disadvantages of certain gas fire extinguishing installations.