Gas fire extinguishing device. Gas fire extinguishing system - timely elimination of a fire. Extinguishing gases

Gas compositions dine with a combination of properties that make it possible to stop the ignition. They are divided into thinners (CO2, Inergen and other compressed gases), which reduce the level of oxygen, and inhibitors (freons), which chemically slow down the burning 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 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;
• harmlessness to the environment;
• high distribution rate.

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 at facilities with a massive stay of people (over 50 people) and in rooms that people cannot leave before the automatic gas fire extinguishing installation is launched.

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 highest prevalence among freons in the territory Russian Federation due to the low price. However, when using it, precautions must be taken to avoid its dangerous effects on service personnel.

Freon 23

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

• human impact - harmless;
• the smallest fire-extinguishing mass among freons;
• constant control of the mass of GOTV.

Like carbon dioxide, it is stored in gas fire extinguishing modules under its own vapor pressure. This explains the low filling factor of the module (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"

Fluoroketone FK-5-1-12 ("dry water") is the latest generation of gas fire extinguishing compositions (GOTV) for fire extinguishing systems. Main advantages:

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

It has been used in fire extinguishing systems for more than ten years at facilities with high safety requirements for maintenance personnel. It was developed by a well-known American company as an alternative to restricted freons. 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 constraining factors limiting the growth of further implementation are foreign production and the foreign political environment.

Freon 227ea (heptafluoropropane)

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

• human impact: safe for humans;
• filling factor in 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 that restrict the use of bromine and chromium containing agents. It is used in automatic gas fire extinguishing installations according to table 8.1 of SP 5.13130.2009. It can be used at facilities with a massive or constant presence of people, while the fire extinguishing concentration should not exceed the standard by more than 25%. Inferior to other GOTVs in terms of thermal stability (600°C).

Freon 318C

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

• safe for humans;
• filling factor in the gas fire extinguishing module - 1.2 kg/l;
• harmless to the environment.

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 a little to it in terms of safety for humans and environmental parameters. Almost all manufacturers of gas fire extinguishing systems can fill it into GPT modules. 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;
• harmless to the environment.

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 enters the source of fire, but copes with it due to a sharp decrease in the level of oxygen. It has become widespread in Western countries, but is now rarely used in Russia, due to the 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;
• harmless to the environment.

AQUAMARINE is used in modular fire extinguishing installations with water mist. An effective composition of combined action. When extinguishing them, oxygen is isolated from the combustion zone, smoldering is excluded due to surface cooling and a protective film preventing re-ignition. The composition was developed by the AFES company 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 action 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 (MGP) are designed to detect, localize and extinguish a fire of solid combustible materials, combustible liquids and electrical equipment in industrial, warehouse, amenity and other premises, as well as to issue a fire alarm signal to a room with a round-the-clock presence of 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 are easily eliminated by simple ventilation. At the same time, unlike other systems, AUGPT units do not freeze and are not afraid of heat. They work in the temperature range: from -40C to +50C.

In practice, there are two methods of gas fire extinguishing: volumetric and local-volumetric, however, the volumetric method is most widely used. Considering the economic point of view, the local-volume method is only beneficial in cases where the volume of the room is more than six times the volume occupied by the equipment, which is usually protected by 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 the main 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, outlet nozzles that ensure delivery and release of gas into the protected premises, 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 OTV

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

Compressed gas fire extinguishing compositions: 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 as FM200. Used to extinguish fires in the presence of people. Environmentally friendly product, has no restrictions for long-term use. It has more effective extinguishing performance and higher cost of industrial production.

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

Gas fire extinguishing Freon is effective tool to extinguish a fire in the premises, tk. gas penetrates immediately into the most hard-to-reach places and fills the entire volume of the room. The consequences of actuating the Freon gas fire extinguishing installation are easily eliminated after smoke removal and ventilation.

The safety of people during gas fire extinguishing Freon is determined in accordance with the requirements of regulatory documents NPB 88, GOST R 50969, GOST 12.3.046 and is ensured by preliminary evacuation of people before the fire extinguishing gas is supplied according to the signals of annunciators during the time delay intended for this. 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)

MIJU consists of a horizontal tank for storing CO2, a shut-off and starting device, devices for controlling the amount and pressure of CO2, refrigeration units and a control panel. Modules are designed to protect rooms up to 15 thousand m3. The maximum capacity of MIJU is 25 tons of CO2. The module stores, as a rule, the working and reserve supply of CO2.

An additional advantage of MIJU is the possibility of its installation outside the building (under a canopy), which allows significant savings in production space. In a heated room or a warm block-box, only control devices MIJU and switchgears UGP (if any).

MGP with a cylinder capacity of up to 100 l, depending on the type of combustible load and filled with GOTV, can protect a room with a volume of not more than 160 m3. To protect premises of a larger volume, the installation of 2 or more modules is required.
A feasibility study showed that in order to protect rooms with a volume of more than 1500 m3 in UGP, it is more expedient to use isothermal modules for liquid carbon dioxide (MIZHU).

MIJU is designed for fire protection of premises and process equipment as part of carbon dioxide gas fire extinguishing installations and provides:

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

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

control of pressure and weight of the liquid during refueling and operation;

the ability to check and configure safety valves without depressurizing the tank.

In protected premises, a gas fire extinguishing method is used, the principle of which is to release a special non-combustible substance in a gaseous state. Pressurized gas (freon, nitrogen, argon, etc.) displaces oxygen, which supports combustion, from the room where the fire broke out.

Classification of fires eliminated by extinguishing the gas method

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

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

Volumetric fire protection is used in the protection of specialized banking equipment, museum valuables, archival documents, data exchange centers, server rooms, communication nodes, devices, gas pumping facilities, diesel, generator rooms, dispatching and other expensive property objects, both industrial and commercial. economic.

The premises where the control of nuclear power plants is located, telecommunications equipment, drying and painting chambers must be equipped with automatic gas fire protection without fail.

Advantages of the method

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

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

• safety of active materials;
• high speed and efficiency of elimination of fires;
• covering the entire volume of the protected premises;
• high service life of gas-type equipment installations.

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

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

Device and principle of operation of installations

Automatic gas fire extinguishing installations (AUGP) include two or more modules containing a gas fire extinguishing agent, piping and nozzles. Fire is detected and the unit is switched on by means of a special fire alarm, which is integral part equipment.

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

During daily operation, atmospheric control of the occurrence of smoke (smoke detectors) and elevated temperatures ( heat detectors) indoors. Continuous monitoring of the integrity of the circuits for starting the fire extinguishing system, breaks in the circuits, and the formation of short circuits is also carried out using fire alarm systems.

The gas fire extinguishing method occurs in automatic mode:

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

The occurrence of a fire is a signal for the automatic start of 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 fire leads to the automatic shutdown of the ventilation system, the supply of non-combustible gas under high pressure through pipelines to the atomizers. Due to the high concentration of gas mixtures, the duration of the gas fire extinguishing process is no more than 60 seconds.

Varieties 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 combustible substances are stored. Here, fire detection is impossible without automatic alarm systems.

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

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

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 consoles.

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

The classification of AUGP is also carried out according to the methods of supply of fire extinguishing agents, according to volumetric methods (local - a fire extinguishing agent is supplied directly to the place of ignition, 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 norms established by the current legislation in full compliance with the requirements of customers of the designed facilities. Design, calculation and installation activities are carried out by professionals.

Creation project documentation begins with a survey 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, the characteristics of humidity, the ways of evacuation of people in the event of an urgent need to leave the building.

When determining the location of this fire fighting equipment Special attention it is necessary to give the amount of oxygen in areas of congestion of people at the time automatic start. The amount of oxygen in these places must comply with acceptable standards.
When mounted gas equipment it must be protected from mechanical influences.

Measures for the maintenance of fire fighting equipment

Automatic fire fighting systems gas type need 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 performance of smoke and fire sensors, as well as alarm means.

Each operation of fire extinguishing equipment must be accompanied by subsequent refueling of 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.

For the first time, gas was used to extinguish a fire at the end of the 19th century. And the first in gas fire extinguishing installations (UGP) was carbon dioxide. At the beginning of the last century, the production of carbon dioxide plants began in Europe. In the thirties of the twentieth century, fire extinguishers with freons were used, extinguishing agents methyl bromide type. In the Soviet Union, devices using gas to extinguish a fire are the first. In the 1940s, 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 using steam, water, powder or foam as an extinguishing agent. Despite this, they are widely used. The use of UGP in archives, storerooms of museums and other repositories with combustible values ​​is unrivaled, due to the practical absence of material harm from their use.

Besides . The use of powder and foam can ruin expensive equipment. Aviation also uses gas.

The rapid spread of gas, the ability to penetrate into all cracks, allows the use of installations based on it to ensure the safety of premises with a difficult layout, dropped ceilings, many partitions and other obstacles.

Application gas installations operating on the basis of dilution of the object's atmosphere requires joint work with integrated security systems. For guaranteed fire extinguishing, all doors and windows must be closed and forced or closed natural ventilation. To alert people inside the premises, light, sound or voice signals are given, a certain time is given to exit. After that, the fire extinguishing begins directly. Gas fills the premises, regardless of the complexity of its layout, 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 GOTVs are chemically neutral, do not pollute environment, and freon 227EA, 318C can also be used in the presence of people. Nitrogen plants are effective in the petrochemical industry, in extinguishing fires in wells, mines and other facilities where explosive situations are possible. Installations with carbon dioxide can be used with operating electrical installations with voltage up to 1 kV.

Disadvantages of gas fire extinguishing:

• the use of GOTV is inefficient in open areas;
• gas is not used to extinguish materials that can burn without oxygen;
• for large facilities, gas equipment requires a separate special annex to accommodate gas tanks and related equipment;
• nitrogen plants are not used to extinguish 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 the UGP are limited to nitrogen, argon, inergen, freons 23, 125, 218, 227ea, 318C, carbon dioxide, sulfur hexafluoride. The use of other gases is possible upon agreement of technical specifications.

Gas extinguishing agents (GOTV) are divided into two groups according to the method of extinguishing:

• The first is freons. They extinguish the flame by chemically slowing down the burning rate. In the ignition zone, freons disintegrate and begin to interact with combustion products, this reduces the combustion rate to complete attenuation.
• The second is gases that reduce the amount of oxygen. These include argon, nitrogen, inergen. Most materials require more than 12% of the 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 in gas fire extinguishing installations must be used depends on the object of protection.

Note!

According to the type of storage, DHWs are divided into compressed (nitrogen, argon, inergen) and liquefied (all the rest).

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

Types of gas fire extinguishing systems

Gas fire extinguishing installations (UGP) are of two types: station and modular. To ensure the security of several rooms, a modular UGP is used. For the whole object, a station setting is usually used.

UGP components: gas fire extinguishing modules (MGP), nozzles, switchgears, pipes and GFFS.

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

In work, 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.

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

The best five IHL modules

• OSK Group - Russian manufacturer extinguishing devices with 17 years of experience in this field. The company produces devices using Novec 1230. This fire extinguishing agent is used in gas fire extinguishing installations that can be used in power and similar rooms in the presence of people. ZPU with pressure gauge and safety bursting disc. Available in volumes from 8 liters to 368 liters.
• MINIMAX modules from a German manufacturer are especially reliable due to the use of seamless vessels. MGP range from 22 to 180 liters.

• Welded tanks are used in MGP developed by VFAspect low pressure, as GOTV - freons. Are issued in volume 40, 60, 80 and 100 l.
• MGP "Flame" are produced by NTO "Flame". Use tanks for low-pressure compressed gases and freons. A large range is produced from 4 to 140 liters.
• Modules from the company "Spetsavtomatika" are produced for compressed gases of high and low pressure and freons. The equipment is easy to maintain, efficient in operation. 10 standard sizes MGP are produced from 20 to 227 liters.

In modules of all manufacturers, in addition to electric and pneumatic start, manual start of devices is provided.

The use of new gaseous extinguishing agents such as Novec 1230 (fluoroketone group), as a result, the possibility of extinguishing a fire in the presence of people, increased the effectiveness of the fire extinguishing system due to early response. And the harmlessness of the use of fumes for material assets, despite the significant cost of equipment and its installation, become 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 Technos-M + LLC

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

Their advantage lies in fire-extinguishing compositions that are relatively safe for humans, the complete absence of damage to the protected object when the system is triggered, repeated use of equipment and extinguishing a fire 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 for extinguishing fires of class A, B, C, according to GOST 27331, and electrical equipment with a voltage not higher than that specified in the technical documentation for the applied fire extinguishing agents.

Gas fire extinguishers are mainly used for volumetric fire extinguishing in the initial stage of a fire in accordance with GOST 12.1.004-91. GOTVs are also used for phlegmatization of an explosive environment in the petrochemical, chemical and other industries.

fumes are non-conductive, easily evaporate, do not leave marks on the equipment of the protected object, in addition, an important advantage of fumes is their

suitability for extinguishing expensive electrical installations under voltage.

It is forbidden to use GOTV 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 flour, etc.);

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

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

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

e) metal hydrides;

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

g) oxidizers (nitrogen oxides, fluorine). It is forbidden to extinguish class C fires if it is possible to release or enter combustible gases into the protected volume, followed by the formation of an explosive atmosphere.

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

As a rule, the maximum voltage at which it is possible to carry out extinguishing without turning off electrical installations with all GFFS is no more than 1 kV. For extinguishing electrical installations with voltages up to 10 kV, only CO2 of the highest grade can be used - according to 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 slow down the combustion process (halocarbons and their mixtures with inert gases - freons).

Depending on the state of aggregation, gas 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.

■ Application restriction.

■ Environmental impact.

■ Possibility of removal of GOTV after application.

It is preferable to use gases that:

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

■ thermal racks (form minimal amount thermal decomposition products that are corrosive, mucosal irritant and poisonous if inhaled);

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

■ economical (provide minimum specific financial costs);

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

■ provide versatile methods for module filling, storage and transportation, and refilling. The most effective in extinguishing a fire are chemical gases-freons. The physico-chemical 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 normative 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 GOTV is ranked by toxicity in case of a massive leak, then compressed gases are the least dangerous, because carbon dioxide protects a person from hypoxia.

The freons used in the systems (according to NPB 88-2001 *) are of low toxicity and do not show a pronounced picture of intoxication. In terms of toxicokinetics, freons are similar to inert gases. Only with prolonged inhalation exposure to low concentrations, freons can 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 ​​of a person's safe stay in the environment of the most commonly used freon brands in our country at various concentrations (Table 1).

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

Freon-125 is ozone-safe. In addition, it has maximum thermal stability compared to other freons, the thermal decomposition temperature of its molecules is more than 900 ° C. The high thermal stability of freon-125 allows it to be used to extinguish fires of smoldering materials, because at the 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 the efficiency (protected volume from a similar module) differs slightly. It is inferior to freon-125 in terms of thermal stability.

The specific costs of CO2 and freon-227ea practically coincide. CO2 is thermally stable in firefighting. But the effectiveness of CO2 is low - a similar module with freon-125 protects the volume by 83% more than the CO2 module. The fire extinguishing concentration of compressed gases is higher than that of freons, therefore, 25-30% more gas is required, and, consequently, the number of containers for storing gaseous 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 over 5% (92 g/m3) 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 drops 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 absolute environmental friendliness and safety for humans of these gases 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 bulky and expensive. In addition, the use of inert gases and their mixtures in AUGPT is associated with 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 overseas and tend to be expensive. However, their low fire-extinguishing concentration, environmental friendliness and the ability to use low-pressure modules make their use attractive and promise good prospects for the use of such fumes 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 freons is offset by the cost of the installation itself, installation of the system and its Maintenance. A particularly important quality of freons used in fire extinguishing systems (in accordance with NPB 88-2001 *) is their minimally harmful effect on humans.

Tab. 2. Summary table of characteristics of the most commonly used GOTV in the territory of the Russian Federation

Gas fire extinguishing installations are specific, expensive and quite difficult 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, exaggerating the merits or hiding the shortcomings of certain gas fire extinguishing installations.