Gas fire extinguishing: device, principle of operation, types. Gas fire extinguishing: installations, system and modules

What is 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 fire safety standards for each specific facility.

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

Name	Characteristic
Name 125, R125	125, R125, Pentafluoroethane
Chemical formula	C2F5H
System Application	firefighting
Molecular weight	120.022 g/mol
Boiling point	-48.5 ºС
Critical temperature	67.7 ºС
critical pressure	3.39 MPa
Critical Density	529 kg/m3
Melting temperature	-103 °C HFC type
Ozone depletion potential	ODP 0
Potential global warming	HGWP 3200
Maximum allowable concentration in the working area	1000 m/m3
Hazard Class	4
Approved and recognized	EPA, NFPA

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.

At normal conditions 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 an effective tool to extinguish a fire in the premises, tk. gas penetrates instantly into the most inaccessible 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 CO2 storage tank, a lock-start device, CO2 quantity and pressure control devices, 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 MIJU control devices and UGP switchgears (if any) are installed.

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 premises and technological equipment as part of gas fire extinguishing installations with carbon dioxide 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.

A feasibility study showed that in order to protect premises with a volume of more than 2000 m3 in the UGP, it is more expedient to use isothermal modules for liquid carbon dioxide (MIZhU).

MIJU consists of an isothermal CO2 storage tank with a capacity of 3,000 liters to 25,000 liters, a shut-off device, CO2 quantity and pressure control devices, refrigeration units and a control cabinet.

Of the UGP available on our market, which use isothermal tanks for liquid carbon dioxide, Russian-made MIJU surpass foreign products in their technical characteristics. Isothermal tanks of foreign production must be installed in a heated room. MIZHU of domestic production can be operated at an ambient temperature of up to minus 40 degrees, which allows you to install isothermal tanks outside buildings. In addition, unlike foreign products, the design of the Russian MIJU allows supplying CO2 to the protected room, dosed by weight.

Freon nozzles

Nozzles are installed on the UGP distribution pipelines for uniform distribution of GFFS in the volume of the protected premises.

Nozzles are installed on the outlet openings of the pipeline. The design of the nozzles depends on the type of supplied gas. For example, to supply freon 114B2, which under normal conditions is a liquid, two-jet nozzles with jet collision were previously used. Currently, such nozzles are recognized as ineffective. Normative documents recommend replacing them with impact or centrifugal nozzles that provide a fine spray of freon type 114B2.

To supply freon type 125, 227ea and CO2, radial type nozzles are used. In such nozzles, the flows of the gas entering the nozzles and the outgoing gas jets are approximately perpendicular. Nozzles of the radial type are divided into ceiling and wall. Ceiling nozzles can supply gas jets to a sector with an angle of 360 °, wall nozzles - about 180 °.

An example of the use of radial type ceiling nozzles as part of AUGP is shown in rice. 2.

Arrangement of nozzles in the protected room is carried out in accordance with the technical documentation of the manufacturer. The number and area of ​​nozzle outlets is determined by hydraulic calculation, taking into account the flow rate and spray pattern specified in technical documentation on nozzles.

AUGP pipelines are made of seamless pipes, which ensures the preservation of their strength and tightness in dry rooms for a period of up to 25 years. Applied pipe connection methods are welded, threaded or flanged.

To maintain the consumption characteristics of piping for long term nozzles should be made of corrosion-resistant and durable materials. Therefore, leading domestic firms do not use nozzles made of aluminum alloys coated, and use only nozzles made of brass.

The right choice of UGP depends on many factors.

Let's look at the main of these factors.

Fire protection method.

UGP are designed to be created in a protected room (volume) gas environment non-combustible. Therefore, there are two methods of fire extinguishing: volumetric and local-volumetric. In the vast majority, the bulk method is used. The volume-local method is economically beneficial when the protected equipment is installed in a large area, which, according to regulatory requirements, does not need to be fully protected.

NPB 88-2001 provides regulatory requirements for local volumetric method extinguishing only for carbon dioxide. Based on these regulatory requirements, it follows that there are conditions under which a local fire extinguishing method in terms of volume is more economically feasible than a volumetric one. Namely, if the volume of the room is 6 times or more than the conventionally allocated volume occupied by the equipment subject to the protection of the APT, then in this case the local fire extinguishing method is economically more profitable than the volumetric one.

Gas extinguishing agent.

The choice of gas extinguishing agent should be made only on the basis of a feasibility study. All other parameters, including the efficiency and toxicity of GOTV, cannot be considered as decisive for a number of reasons.
Any of the fumes allowed for use is quite effective and the fire will be eliminated if the normative fire extinguishing concentration is created in the protected volume.
An exception to this rule is the extinguishing of materials prone to smoldering. Research conducted at the Federal State Institution VNIIPO EMERCOM of Russia under the supervision of A.L. Chibisov showed that the complete cessation of combustion (flaming and smoldering) is possible only with the supply of three times the standard amount of carbon dioxide. This amount of carbon dioxide makes it possible to reduce the oxygen concentration in the combustion zone below 2.5% vol.

According to the regulatory requirements in force in Russia (NPB 88-2001), it is forbidden to release a gas fire extinguishing agent into a room if there are people there. And this limitation is correct. The statistics of the causes of death in fires shows that in more than 70% of deaths, deaths occurred as a result of poisoning by combustion products.

The cost of each of the GOTV differs significantly from each other. At the same time, knowing only the price of 1 kg of gas extinguishing agent, it is impossible to estimate the cost of fire protection for 1 m 3 of volume. We can only say unequivocally that protection of 1 m 3 of volume with GOTV N 2 , Ar and Inergen is 1.5 times more expensive than other gas fire extinguishing agents. This is due to the fact that the listed GOVs are stored in gaseous fire extinguishing modules in a gaseous state, which requires a large number of modules.

UGP are of two types: centralized and modular. The choice of the type of gas fire extinguishing installation depends, firstly, on the number of protected premises at one facility, and secondly, on the availability of free premises in which a fire extinguishing station can be placed.

When protecting 3 or more premises at one facility, located at a distance of no more than 100 m from each other, from an economic point of view, centralized UGP is preferable. Moreover, the cost of the protected volume decreases with an increase in the number of premises protected from one fire extinguishing station.

At the same time, a centralized UGP, compared to a modular one, has a number of disadvantages, namely: the need to fulfill a large number of requirements of NPB 88-2001 for a fire extinguishing station; the need to lay pipelines through the building from the fire extinguishing station to the protected premises.

Gas extinguishing modules and batteries.

Gas fire extinguishing modules (MGP) and batteries are the main element of the gas fire extinguishing installation. They are intended for storage and release of GOTV into the protected area.
MGP consists of a cylinder and a shut-off and starting device (ZPU). Batteries, as a rule, consist of 2 or more gas fire extinguishing modules, united by a single factory-made collector. Therefore, all the requirements that apply to MHL are the same for batteries.
Depending on the gas fire extinguishing agent used in the gas fire extinguishing agent, gas fire extinguishers must meet the requirements listed below.
MGP filled with freons of all brands should ensure the release time of GOTV not exceeding 10 s.
The design of gas fire extinguishing modules filled with CO 2 , N 2 , Ar and "Inergen" must ensure the release time of GFEA not exceeding 60 s.
During the operation of the MGP, control of the mass of the filled GOTV should be ensured.

Freon 125, freon 318Ts, freon 227ea, N 2 , Ar and Inergen mass control is carried out using a manometer. With a decrease in the pressure of the propellant in cylinders with the above freons by 10%, and N 2, Ar and Inergen by 5% of the nominal MHL, it must be sent for repair. The difference in pressure loss is caused by the following factors:

With a decrease in the pressure of the propellant gas, the mass of freon in the vapor phase is partially lost. However, this loss is no more than 0.2% of the initially filled mass of freon. Therefore, the pressure limitation equal to 10% is caused by an increase in the time for the DHW release from the gas fired unit as a result of a decrease in the initial pressure, which is determined on the basis of the hydraulic calculation of the gas fire extinguishing installation.

N 2 , Ar and "Inergen" are stored in gas fire extinguishing modules in a compressed state. Therefore, reducing the pressure by 5% of the initial value is an indirect method for the loss of mass of GFEA by the same value.

Weight loss control of DHW displaced from the module under the pressure of its own saturated vapors (freon 23 and CO 2) must be carried out by a direct method. Those. the gas fire extinguishing module charged with freon 23 or CO 2 must be installed on the weighing device during operation. At the same time, the weighing device must provide control of the mass loss of the gaseous fire extinguishing agent, and not the total mass of the gas fired extinguishing agent and the module, with an accuracy of 5%.

The presence of such a weighing device provides that the module is installed or suspended on a strong elastic element, the movement of which changes the properties of the load cell. An electronic device reacts to these changes, which generates an alarm signal when the parameters of the load cell change above threshold. The main disadvantages of the tensometric device are the need to ensure the free movement of the cylinder on a solid metal-intensive structure, as well as negative impact external factors - connecting pipelines, periodic shocks and vibrations during operation, etc. The metal consumption and dimensions of the product increase, problems with installation increase.
In modules MPTU 150-50-12, MPTU 150-100-12, a high-tech method for monitoring the safety of GFFS is used. The electronic mass control device (UKM) is built directly into the locking and starting device (LPU) of the module.

All information (GOTV mass, calibration date, service date) is stored in the UKM storage device and, if necessary, can be displayed on a computer. For visual control, the LSD of the module is equipped with an LED that gives signals about normal operation, a decrease in the mass of the FA by 5% or more, or a failure of the UKM. At the same time, the cost of the proposed gas mass control device as part of the module is much less than the cost of a tensometric weighing device with a control device.

Isothermal module for liquid carbon dioxide (MIZHU).

MIJU consists of a horizontal CO 2 storage tank, a lock-start device, CO 2 quantity and pressure control devices, refrigeration units and a control panel. Modules are designed to protect rooms up to 15 thousand m 3 . The maximum capacity of MIJU is 25 tons of CO 2 . The module stores, as a rule, the working and reserve supply of CO 2 .

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 MIJU control devices and UGP switchgears (if any) are installed.

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 m 3. 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 m 3 in the UGP, it is more expedient to use isothermal modules for liquid carbon dioxide (MIZHU).

Nozzles are designed for uniform distribution of GOTV in the volume of the protected premises.
Arrangement of nozzles in the protected room is carried out in accordance with the manufacturer's specifications. The number and area of ​​nozzle outlets is determined by hydraulic calculation, taking into account the flow rate and spray pattern specified in the technical documentation for the nozzles.
The distance from the nozzles to the ceiling (ceiling, false ceiling) should not exceed 0.5 m when using all GFFS, except for N 2 .

Pipe wiring.

The distribution of pipelines in the protected room, as a rule, should be symmetrical with equal distance of nozzles from the main pipeline.
Piping installations are made of metal pipes. The pressure in the pipelines of the installation and the diameters are determined by hydraulic calculation according to the methods agreed in in due course. Pipelines must withstand pressure during tests for strength and tightness of at least 1.25 Rrab.
When freons are used as fumes, the total volume of pipelines, including the collector, should not exceed 80% of the liquid phase of the working freon supply in the installation.

Routing of distribution pipelines of installations using freon should be carried out only in a horizontal plane.

When designing centralized installations using refrigerants, the following points should be taken into account:

• connect the main pipeline of the room with the maximum volume should be closer to the battery with GOTV;
• when batteries with a main and a reserve reserve are connected in series to the station collector, the main reserve should be the most remote from the protected premises from the condition of the maximum release of freon from all cylinders.

The correct choice of gas fire extinguishing installation UGP depends on many factors. Therefore, the purpose of this work is to show the main criteria affecting optimal choice UGP and the principle of its hydraulic calculation.
The following are the main factors influencing the optimal choice of GPE. Firstly, the type of combustible load in the protected room (archives, storage facilities, electronic equipment, technological equipment, etc.). Secondly, the value of the protected volume and its leakage. Thirdly, the type of gas fire extinguishing agent GOTV. Fourthly, the type of equipment in which GOTV should be stored. Fifth, the type of UGP: centralized or modular. The last factor can take place only if it is necessary to provide fire protection for two or more rooms at one facility. Therefore, we consider the mutual influence of only the four factors listed above. Those. assuming that only one room needs fire protection at the facility.

Of course, the correct choice of the CPP should be based on optimal technical and economic indicators.
It should be especially noted that any of the approved fumes eliminates a fire regardless of the type of combustible material, but only when a standard fire extinguishing concentration is created in the protected volume.

We will evaluate the mutual influence of the factors listed above on the technical and economic parameters of the UGP based on the condition that the following fumes are allowed for use in Russia: freon 125, freon 318Ts, freon 227ea, freon 23, CO 2 , N 2 , Ar and mixture (N 2 , Ar and CO 2), which has the trademark "Inergen".

All gaseous fire extinguishing agents can be divided into three groups according to the method of storage and control methods for gas fire extinguishing agents in MGP gas fire extinguishing modules.

The 1st group includes freon 125, freon 318C and freon 227ea. These freons are stored in MGP in liquefied form under the pressure of a propellant gas, most often nitrogen. Modules with the listed refrigerants, as a rule, have an operating pressure not exceeding 6.4 MPa. Control of the amount of freon during the operation of the plant is carried out by the pressure gauge installed on the MGP.

Freon 23 and CO 2 make up the 2nd group. They are also stored in a liquefied form, but are forced out of the MGP under the pressure of their own saturated vapors. The working pressure of modules with the listed GOV must have a working pressure of at least 14.7 MPa. During operation, the modules must be installed on weighing devices that provide continuous control of the mass of freon 23 or CO 2 .

The 3rd group includes N 2 , Ar and Inergen. GOTV data is stored in MGP in a gaseous state. Further, when we evaluate the advantages and disadvantages of GFFS from this group, only nitrogen will be considered. This is due to the fact that N2 is the most effective fire extinguishing agent (it has the lowest fire extinguishing concentration and at the same time the lowest cost). The control of the mass of GOTV of the 3rd group is carried out by a pressure gauge. N 2 , Ar or Inergen are stored in modules at a pressure of 14.7 MPa or more.

Gas fire extinguishing modules, as a rule, have a cylinder capacity not exceeding 100 liters. Modules with a capacity of more than 100 liters according to PB 10-115 are subject to registration with the Gosgortekhnadzor of Russia, which entails a fairly large number of restrictions on their use in accordance with the specified rules.

An exception is the isothermal modules for liquid carbon dioxide MIJU with a capacity of 3.0 to 25.0 m3. These modules are designed and manufactured for storage in gas fire extinguishing installations of carbon dioxide in quantities exceeding 2500 kg or more. MIJU are equipped with refrigeration units and heating elements, which allows you to maintain pressure in the isothermal tank in the range of 2.0 - 2.1 MPa at an ambient temperature of minus 40 to plus 50 degrees. WITH.

Let's look at examples of how each of the 4 factors affects the technical economic indicators UGP. The mass of GOTV was calculated according to the method described in NPB 88-2001.

Example 1 It is required to protect electronic equipment in a room with a volume of 60 m 3. The room is conditionally sealed. Those. K2 = 0. The calculation results are summarized in Table. one.

Table 1

The economic substantiation of the table in specific figures has a certain difficulty. This is due to the fact that the cost of equipment and GOTV for firms - manufacturers and suppliers has a different cost. However, there is a general trend that with an increase in the capacity of the cylinder, the cost of the gas fire extinguishing module increases. The cost of 1 kg CO 2 and 1 m 3 N 2 are close in price and two orders of magnitude less than the cost of freons. Analysis of the table. 1 shows that the cost of UGP with freon 125 and CO 2 are comparable in value. Despite the significantly higher cost of freon 125 compared to carbon dioxide, the total price of freon 125 - MGP with a 40 l cylinder will be comparable or even slightly lower than the carbon dioxide - MGP set with an 80 l cylinder - weighing device. It can be unambiguously stated that the cost of HFP with nitrogen is significantly higher compared to the two previously considered options. Because 2 modules with maximum volume required. More space will be required to accommodate 2 modules in the room and, naturally, the cost of 2 modules with a volume of 100 l will always be more than an 80 l module with a weighing device, which, as a rule, is 4-5 times less expensive than the module itself.

Example 2 The parameters of the room are similar to example 1, but it is not the radio-electronic equipment that needs to be protected, but the archive. The results of the calculation, similarly to the 1st example, are presented in Table. 2 summarize in table. one.

table 2

Based on the analysis of Table. 2 can be unambiguously stated, and in this case, the gas fire extinguishing installations with nitrogen are much higher in cost than gas fire extinguishing installations with freon 125 and carbon dioxide. But in contrast to the 1st example, in this case it can be more clearly noted that the lowest cost is the UGP with carbon dioxide. Because with a relatively small difference in cost between MGP with a cylinder with a capacity of 80 l and 100 l, the price of 56 kg of freon 125 significantly exceeds the cost of a weighing device.

Similar dependencies will be traced if the volume of the protected room increases and/or its leakage increases. Because all this causes a general increase in the amount of any type of GOTV.

Thus, only on the basis of 2 examples it can be seen that it is possible to choose the optimal UGP for the fire protection of a room only after considering at least two options with different types of GFFS.

However, there are exceptions when a CFD with optimal technical and economic parameters cannot be applied due to certain restrictions imposed on gas fire extinguishing agents.

Such restrictions, first of all, include the protection of especially important objects in a seismically hazardous zone (for example, nuclear power facilities, etc.), where it is required to install modules in seismic-resistant frames. In this case, the use of freon 23 and carbon dioxide is excluded, since the modules with these fumes must be installed on weighing devices that exclude their rigid fastening.

In case of fire protection of premises with permanently present personnel (air traffic control rooms, halls with control panels of nuclear power plants, etc.), restrictions are imposed on the toxicity of fumes. In this case, the use of carbon dioxide is excluded, since the volumetric fire-extinguishing concentration of carbon dioxide in the air is fatal to humans.

When protecting volumes of more than 2000 m 3 from an economic point of view, the most acceptable is the use of carbon dioxide filled in MIJU, in comparison with all other GOTVs.

After the feasibility study, the amount of GFEA required to extinguish the fire and the preliminary amount of MGP become known.

Nozzles must be installed in accordance with the spray patterns specified in the technical documentation of the nozzle manufacturer. The distance from the nozzles to the ceiling (ceiling, suspended ceiling) should not exceed 0.5 m when using all GFFS, except for N 2.

Piping, as a rule, should be symmetrical. Those. nozzles must be equidistant from the main pipeline. In this case, the consumption of GOTV through all nozzles will be the same, which will ensure the creation of a uniform fire extinguishing concentration in the protected volume. Typical examples of symmetrical piping are shown in rice. 1 and 2.

When designing piping, one should also take into account the correct connection of the outlet pipelines (rows, bends) from the main pipeline.

Cross-connection is possible only if the flow rate of G1 and G2 is equal in value (Fig. 3).

If G1? G2 , then opposite connections of rows and bends with the main pipeline must be spaced in the direction of GFFS movement at a distance L exceeding 10 * D, as shown in Fig. 4. Where D is the internal diameter of the main pipeline.

No restrictions are imposed on the spatial connection of pipes when designing UGP piping when using GFFS belonging to the 2nd and 3rd groups. And for the piping of the UGP with GOTV of the 1st group, there are a number of restrictions. This is caused by the following:

When pressurizing freon 125, freon 318C or freon 227ea in MGP with nitrogen to the required pressure, nitrogen partially dissolves in the listed freons. Moreover, the amount of dissolved nitrogen in freons is proportional to the boost pressure.

After opening the locking and starting device of the LSD of the gas fire extinguishing module under the pressure of the propellant gas, the freon with partially dissolved nitrogen enters the nozzles through the piping and exits through them into the protected volume. At the same time, the pressure in the system (modules - piping) decreases as a result of the expansion of the volume occupied by nitrogen in the process of freon displacement, and the hydraulic resistance of the piping. There is a partial release of nitrogen from the liquid phase of the freon and a two-phase medium is formed (a mixture of the liquid phase of the freon - gaseous nitrogen). Therefore, a number of restrictions are imposed on the piping of the UGP, which uses the 1st group of GFFS. The main meaning of these restrictions is aimed at preventing the separation of a two-phase medium inside the piping.

During design and installation, all UGP piping connections must be made as shown in Fig. 5a, 5b and 5c

and it is forbidden to perform in the forms shown in Fig. 6a, 6b, 6c. The arrows in the figures show the direction of the GFEA flow through the pipes.

In the process of designing the UGP in an axonometric view, a piping layout, pipe length, number of nozzles and their elevations are performed. To determine the inner diameter of the pipes and the total area of ​​the outlets of each nozzle, it is necessary to perform a hydraulic calculation of the gas fire extinguishing installation.

Control of automatic gas fire extinguishing installations

When choosing the best option control of automatic gas fire extinguishing installations, it is necessary to be guided by the technical requirements, features and functionality of the protected objects.

The main schemes for constructing control systems for gas fire extinguishing installations:

• autonomous gas fire extinguishing control system;
• decentralized gas fire extinguishing control system;
• centralized gas fire extinguishing control system.

Other options are derived from these typical schemes.

To protect local (separate) premises in one, two and three directions of gas fire extinguishing, as a rule, it is justified to use offline installations gas fire extinguishing (Fig. 1). An autonomous gas fire extinguishing control station is located directly at the entrance to the protected premises and controls both threshold fire detectors, light or sound alert, and devices for remote and automatic start-up of a gas fire extinguishing installation (GFS). The number of possible directions of gas fire extinguishing according to this scheme can reach from one to seven. All signals from the autonomous gas fire extinguishing control station go directly to the central control station to the station's remote display panel.

Rice. one. Autonomous gas fire extinguishing control units

The second typical scheme - the scheme of decentralized control of gas fire extinguishing, is shown in fig. 2. In this case, an autonomous gas fire extinguishing control station is built into an already existing and operating integrated security system of the facility or a newly designed one. Signals from an autonomous gas fire extinguishing control station are sent to address units and control modules, which then transmit information to the central control station at the central fire alarm station. A feature of the decentralized control of gas fire extinguishing is that in the event of failure of individual elements of the complex security system of the facility, the autonomous gas fire extinguishing control station remains in operation. This system allows you to integrate any number of gas fire extinguishing areas into your system, which are limited only by the technical capabilities of the fire alarm station itself.

Rice. 2. Decentralized management of gas fire extinguishing in several directions

The third scheme is the scheme of centralized control of gas fire extinguishing systems (Fig. 3). This system is used when the requirements for fire safety are priority. The fire alarm system includes addressable analog sensors that allow you to control the protected space with minimal errors and prevent false alarms. False alarms of the fire protection system occur due to contamination of ventilation systems, supply and exhaust ventilation (smoke from the street), strong wind etc. Prevention of false alarms in addressable analog systems is carried out by monitoring the dust level of the sensors.

Rice. 3. Centralized control of gas fire extinguishing in several directions

The signal from the addressable analog fire detectors is sent to the central fire alarm station, after which the processed data through the addressable modules and blocks is sent to autonomous system gas fire extinguishing control. Each group of sensors is logically linked to its direction of gas fire extinguishing. The centralized gas fire extinguishing control system is designed only for the number of station addresses. Take, for example, a station with 126 addresses (single loop). Let's calculate the number of addresses needed to maximize the protection of the premises. Control modules - automatic/manual, gas supply and malfunction - these are 3 addresses plus the number of sensors in the room: 3 - on the ceiling, 3 - behind the ceiling, 3 - under the floor (9 pcs.). We get 12 addresses per direction. For a station with 126 addresses, this is 10 directions plus additional addresses for managing engineering systems.

The use of centralized control of gas fire extinguishing leads to a rise in the cost of the system, but significantly increases its reliability, makes it possible to analyze the situation (control of the dust content of sensors), and also reduces the cost of its maintenance and operation. The need to install a centralized (decentralized) system arises with additional management of engineering systems.

In some cases, in gas fire extinguishing systems of a centralized and decentralized type, fire extinguishing stations are used instead of a modular gas fire extinguishing installation. Their installation depends on the area and specifics of the protected premises. On fig. 4 shows a centralized control system for gas fire extinguishing with a fire extinguishing station (OGS).

Rice. 4. Centralized control of gas fire extinguishing in several directions with a fire extinguishing station

The choice of the optimal variant of the gas fire extinguishing installation depends on a large amount of initial data. An attempt to summarize the most significant parameters of gas fire extinguishing systems and installations is shown in fig. 5.

Rice. 5. Selection of the optimal option for gas fire extinguishing installation according to technical requirements

One of the features of AGPT systems in automatic mode is the use of addressable analog and threshold fire detectors as devices that register a fire, when triggered, the fire extinguishing system is launched, i.e. release of fire extinguishing agent. And here it should be noted that the reliability of the fire detector, one of the cheapest elements of the fire alarm and fire extinguishing system, determines the performance of the entire expensive fire automation complex and, consequently, the fate of the protected object! In this case, the fire detector must meet two basic requirements: early detection of fire and the absence of false positives. What determines the reliability of a fire detector as an electronic device? From the level of development, the quality of the element base, assembly technology and final testing. It can be very difficult for a consumer to understand all the variety of detectors on the market today. Therefore, many are guided by the price and the availability of a certificate, although, unfortunately, it is not a guarantee of quality today. Only a few manufacturers of fire detectors openly publish failure rates, for example, according to the Moscow manufacturer System Sensor Fair Detectors, returns of its products are less than 0.04% (4 products per 100 thousand). This is certainly a good indicator and the result of multi-stage testing of each product.

Of course, only an addressable analog system allows the customer to be absolutely confident in the performance of all its elements: smoke and heat sensors that control the protected premises are constantly interrogated by the fire extinguishing control station. The device monitors the state of the loop and its components, in case of a decrease in the sensitivity of the sensor, the station automatically compensates for it by setting the appropriate threshold. But when using addressless (threshold) systems, sensor failure is not detected, and the loss of its sensitivity is not monitored. It is believed that the system is in working order, but in reality, the fire control station in the event of a real fire will not work properly. Therefore, when installing automatic gas fire extinguishing systems, it is preferable to use addressable analog systems. Their relatively high cost is offset by unconditional reliability and a qualitative reduction in the risk of fire.

In the general case, the working draft of the RP of a gas fire extinguishing installation consists of an explanatory note, a technological part, an electrical part (not considered in this work), a specification of equipment and materials, and estimates (at the request of the customer).

Explanatory note

The explanatory note includes the following sections.

Technological part.

1. • 
     The subsection Technological part provides a brief description of the main components of the UGP. The type of the selected gas fire extinguishing agent GOTV and the propellant gas, if any, is indicated. For freon and a mixture of gaseous fire extinguishing agents, the number of the fire safety certificate is reported. The type of MGP gas fire extinguishing modules (batteries) selected for storing gas fire extinguishing agent, the number of the fire safety certificate are given. A brief description is given of the main elements of the module (batteries), the method for controlling the mass of GFEA. The parameters of the electric start of the MGP (batteries) are given.
1. General Provisions.

In the general provisions section, the name of the object for which the working draft of the UGP has been completed, and the rationale for its implementation, is given. Normative and technical documents are given, on the basis of which the design documentation was made.
The list of the main regulatory documents used in the design of the UGP is given below. NPB 110-99
NPB 88-2001 as amended. #1
Due to the fact that constant work is underway to improve regulatory documents, designers must constantly adjust this list.

2. Appointment.

This section indicates what the gas fire extinguishing installation is intended for and its functions.

3. Brief description of the protected object.

In this section, in general terms, a brief description of the premises subject to UGP protection, their geometric dimensions (volume) is given. It is reported about the presence of raised floors and ceilings with a volumetric method of fire extinguishing or the configuration of the object and its location with a local method in terms of volume. Provides information about the maximum and minimum temperature and humidity, the presence and characteristics of the ventilation and air conditioning system, the presence of permanently open openings and the maximum allowable pressure in the protected premises. Data on the main types of fire load, categories of protected premises and zones classes are given.

4. Main design decisions. This section has two subsections.

It is reported about the selected type of nozzles for uniform distribution of the gaseous fire extinguishing agent in the protected volume and the accepted standard time for the release of the estimated mass of GFEA.

For centralized installation, the type of switchgear and the number of the fire safety certificate are given.

Formulas are given that are used to calculate the mass of the gas fire extinguishing agent UGP, and used in the calculations numerical values basic values: the accepted normative fire extinguishing concentrations for each protected volume, the density of the gas phase and the residue of GFEA in modules (batteries), the coefficient taking into account the loss of gas fire extinguishing agent from the modules (batteries), the remainder of GFFS in the module (batteries), the height of the protected room above the level sea, the total area of ​​permanently open openings, the height of the premises and the time of supply of GOTV.

The calculation of the time of evacuation of people from premises protected by gas fire extinguishing installations is given and the time for stopping ventilation equipment, closing fire dampers, air dampers, etc. is indicated. (if available). At the time of evacuation of people from the premises or stop of ventilation equipment, closing of fire dampers, air dampers, etc. less than 10 s, it is recommended to take the delay time for the release of GOTV to be 10 s. If all or one of the limiting parameters, namely, the estimated time for the evacuation of people, the time for stopping ventilation equipment, closing fire dampers, air dampers, etc. exceeds 10 s, then the delay time for the release of GOTV must be taken according to greater value or close to it, but in a big way. It is not recommended to artificially increase the GOTV release delay time for the following reasons. Firstly, UGP are designed to eliminate the initial stage of a fire, when there is no destruction of enclosing structures and, above all, windows. The appearance of additional openings as a result of the destruction of enclosing structures during a developed fire, not taken into account when calculating the required amount of GFEA, will not allow creating a standard fire extinguishing concentration of a gaseous fire extinguishing agent in the room after the operation of the fire extinguishing agent. Secondly, an artificial increase in the time of free burning leads to unreasonably large material losses.

In the same subsection, based on the results of calculations of the maximum allowable pressures, carried out taking into account the requirements of paragraph 6 of GOST R 12.3.047-98, it is reported on the need to install additional openings in the protected premises to relieve pressure after the operation of the UGP or not.

1. • Electrical part.

     This subsection reports on the basis of which principles fire detectors are selected, their types and numbers of fire safety certificates are given. The type of the control and monitoring device and the number of its fire safety certificate are indicated. A brief description of the main functions that the device performs is given.

2. The principle of operation of the installation.

   This section has 4 subsections, which describe: "Automatic enabled" mode;

   • "Automatic disabled" mode;
   • remote start;
   • local start.
3. Power supply.

   This section indicates to which category of ensuring the reliability of power supply an automatic gas fire extinguishing installation belongs and according to what scheme the power supply of devices and equipment included in the installation should be carried out.

4. The composition and placement of elements.

   This section has two subsections.

   • Technological part.

     This subsection provides a list of the main elements that make up the technological part of an automatic gas fire extinguishing installation, places and requirements for their installation.

   • Electrical part.

     This subsection provides a list of the main elements of the electrical part of an automatic gas fire extinguishing installation. Instructions are given for their installation. Brands of cables, wires and conditions for their laying are reported.

5. The professional and qualification composition of persons working at the facility for the maintenance and operation of the automatic fire extinguishing installation.

The composition of this section includes the requirements for the qualifications of personnel and their number in the maintenance of the designed automatic gas fire extinguishing installation.

1. Measures for labor protection and safe operation.

   This section reports regulatory documents, on the basis of which installation and commissioning work should be carried out and maintenance of an automatic gas fire extinguishing installation should be carried out. The requirements for persons admitted to the service of an automatic gas fire extinguishing installation are given.

Describes the measures that must be taken after the operation of the UGP in the event of a fire.

REQUIREMENTS OF THE BRITISH STANDARDS.

It is known that there are significant differences between Russian and European requirements. They are determined by national characteristics, geographical location and climatic conditions, the level of economic development of countries. However, the main provisions that determine the effectiveness of the system should be the same. The following are comments on British Standard BS 7273-1:2006 Part 1 for Electrically Actuated Gas Volumetric Fire Suppression Systems.

British BS 7273-1:2006 replaced BS 7273-1:2000. The fundamental differences between the new standard and the previous version are noted in its preface.

• BS 7273-1:2006 is a separate document, but it (unlike the Russian NPB 88-2001*) contains references to regulatory documents with which it should be used. These are the following standards:
• BS 1635 "Recommendations for Icons and Abbreviations for Drawings of Fire Protection Systems";
• BS 5306-4 Equipment and installation of fire extinguishing systems - Part 4: Specification for carbon dioxide systems;
• BS 5839-1:2002 concerning fire detection and alarm systems for buildings. Part 1: "Norms and rules for the design, installation and maintenance of systems";
• BS 6266 Code of Practice for Fire Protection of Installations of Electronic Equipment;
• BS ISO 14520 (all parts), "Gas fire extinguishing systems";
• BS EN 12094-1, "Fixed Fire Protection Systems - Components gas systems fire extinguishing" - Part 1: "Requirements and test methods for automatic control devices".

Terminology

Definitions of all key terms are taken from BS 5839-1, BS EN 12094-1, BS 7273 defines only a few of the terms listed below.

• Automatic/manual and manual only mode switch - a means of switching the system from automatic or manual activation mode to manual activation only mode (moreover, the switch, as explained in the standard, can be made in the form of a manual switch in the control device or in other devices, or in the form separate door interlock, but in any case it must be possible to switch the activation mode of the system from automatic / manual to manual only or vice versa):
  • automatic mode (in relation to a fire extinguishing system) is a mode of operation in which the system is initiated without manual intervention;
  • manual mode - one in which the system can only be initiated through manual control.
• Protected area - the area under the protection of the fire extinguishing system.
• Coincidence - the logic of the system, according to which the output signal is given in the presence of at least two independent input signals that are simultaneously present in the system. For example, the output signal for extinguishing activation is generated only after the detection of a fire by one detector and at least when another independent detector of the same protected zone has confirmed the presence of a fire.
• Control device - a device that performs all the functions necessary to control the fire extinguishing system (the standard indicates that this device can be made as a separate module or as an integral part of an automatic fire alarm and fire extinguishing system).

System design

The standard also notes that the requirements for the protected area should be established by the designer in consultation with the client and, as a rule, the architect, specialists from contractors involved in the installation of fire alarm systems and automatic fire extinguishing systems, fire safety specialists, experts from insurance companies, responsible person from the health department, as well as representatives of any other interested departments. In addition, it is necessary to plan in advance the actions that should be taken in the event of a fire in order to ensure the safety of persons in the area and the effective functioning of the fire extinguishing system. Such actions should be discussed at the design stage and implemented in the proposed system.

The design of the system must also comply with the standards BS 5839-1, BS 5306-1 and BS ISO 14520. Based on the data received during the consultation, the designer is obliged to prepare documents containing not only a detailed description of the design solution, but, for example, a simple graphic representation of the sequence of actions leading to the launch of a fire extinguishing agent.

System operation

In accordance with the specified standard, an algorithm for the operation of the fire extinguishing system should be formed, which is given in graphical form. An example of such an algorithm is given in the annex to this standard. As a rule, in order to avoid unwanted release of gas in case of automatic operation of the system, the sequence of events should involve the detection of a fire simultaneously by two separate detectors.

Activation of the first detector must at least result in the indication of the "Fire" mode in the fire alarm system and the activation of an alert within the protected area.

The release of gas from the extinguishing system must be monitored and indicated by a control device. To control the release of gas, a pressure or gas flow sensor must be used, located so as to control its release from any cylinder in the system. For example, in the presence of coupled cylinders, the release of gas from any container into the central pipeline must be controlled.

Interruption of communication between the fire alarm system and any part of the fire extinguishing control device must not affect the operation of fire detectors or the operation of the fire alarm system.

Requirement to improve performance

The fire alarm and warning system should be designed in such a way that in the event of a single loop failure (break or short circuit), it detects a fire in the protected area and, at least, leaves the possibility of manually turning on the fire extinguishing. That is, if the system is designed in such a way that the maximum area controlled by one detector is X m 2, then in the event of a single loop failure, each operable fire detector must provide control of the area for a maximum of 2X m 2, the sensors must be evenly distributed over the protected area.

This condition can be met, for example, by using two radial plumes or one loop with short-circuit protection devices.

Rice. one. System with two parallel stubs

Indeed, at a break or even at short circuit one of the two radial loops, the second loop remains in working condition. At the same time, the arrangement of the detectors should ensure the control of the entire protected area by each loop separately. (Fig. 2)

Rice. 2. Arrangement of detectors in “pairs”

More high level operability is achieved by using ring loops in addressable and addressable analog systems with short circuit isolators. In this case, in the event of a break, the ring loop is automatically converted into two radial loops, the break location is localized, and all sensors remain operational, which keeps the system functioning in automatic mode. When the loop is short-circuited, only the devices between two adjacent short-circuit isolators are switched off, and therefore most of the sensors and other devices remain operational as well.

Rice. 3. Ring loop break

Rice. 4. Short circuit loop

A short circuit isolator usually consists of two symmetrically connected electronic keys, between which a fire detector is located. Structurally, the short-circuit isolator can be built into the base, which has two additional contacts (input and output positive), or built directly into the sensor, into manual and linear fire detectors and into functional modules. If necessary, a short-circuit isolator made as a separate module can be used.

Rice. 5. Short circuit isolator in sensor base

Obviously, systems with one "two-threshold" loop, which are often used in Russia, do not meet this requirement. When such a loop breaks, a certain part of the protected area remains uncontrolled, and in the event of a short circuit, control is completely absent. The "Fault" signal is generated, but until the malfunction is eliminated, the "Fire" signal is not generated for any sensor, which makes it impossible to turn on the fire extinguishing manually.

False alarm protection

Electromagnetic fields from radio transmitters can cause false signals in fire alarm systems and lead to the activation of the processes of electrical initiation of gas release from fire extinguishing systems. Practically all buildings use equipment such as portable radios and cell phones; base transceiver stations of several cellular operators can be located near or on the building itself. In such cases, measures must be taken to eliminate the risk of accidental release of gas due to exposure to electromagnetic radiation. Similar problems can arise if the system is installed in locations with high field strengths, such as near airports or radio transmitting stations.

It should be noted that a significant increase in last years the level of electromagnetic interference caused by the use of mobile communications has led to an increase in European requirements for fire detectors in this part. According to European standards, a fire detector must withstand electromagnetic interference with a strength of 10 V / m in the ranges of 0.03-1000 MHz and 1-2 GHz, and with a strength of 30 V / m in the cellular communication ranges of 415-466 MHz and 890-960 MHz, and with sinusoidal and pulse modulation (Table 1).

Table 1. LPCB and VdS requirements for the immunity of sensors to electromagnetic interference.

*) Pulse modulation: frequency 1 Hz, duty cycle 2 (0.5 s - on, 0.5 s - pause).

European requirements comply modern conditions operation and several times exceed the requirements even for the highest (4th degree) rigidity according to NPB 57-97 "Instruments and equipment of automatic fire extinguishing and fire alarm installations. Noise immunity and noise emission. General technical requirements. Test methods" (Table 2) . In addition, according to NPB 57-97, tests are carried out at maximum frequencies up to 500 MHz, i.e. 4 times less compared to the European tests, although the "effectiveness" of the effect of interference on a fire detector usually increases with increasing frequency.

Moreover, according to the requirements of NPB 88-2001 * clause 12.11, in order to control automatic fire extinguishing installations, fire detectors must be resistant to electromagnetic fields with a degree of rigidity not lower than the second.

Table 2. Requirements for the immunity of detectors to electromagnetic interference according to NPB 57-97

Frequency bands and intensity levels electromagnetic field when tested according to NPB 57-97, neither the presence of several cellular communication systems with a huge number of base stations and mobile phones, nor the increase in power and the number of radio and television stations, nor other similar interferences are taken into account. Transceiver antennas of base stations, which are located on various buildings, have become an integral part of the urban landscape (Fig. 6). In areas where there are no buildings of the required height, antennas are installed on different masts. Usually, a large number of antennas of several mobile operators are located on one object, which increases the level of electromagnetic interference several times.

In addition, according to the European standard EN 54-7 for smoke detectors, the following tests are mandatory for these devices:
- for moisture - first at a constant temperature of +40 °C and a relative humidity of 93% for 4 days, then with a cyclic change in temperature for 12 hours at +25 °C and for 12 hours - at +55 °C, and with relative humidity at least 93% for another 4 days;
- corrosion tests in SO 2 gas atmosphere for 21 days, etc.
It becomes clear why, according to European requirements, the signal from two PIs is used only to turn on fire extinguishing in automatic mode, and even then not always, as will be indicated below.

If the detector loops cover several protected areas, then the signal to initiate the release of fire extinguishing agent into the protected area where a fire was detected should not lead to the release of fire extinguishing agent into another protected area, the detection system of which uses the same loop.

Activation of manual fire call points should also not affect the release of gas in any way.

Establishing the fact of a fire

A fire alarm system must meet the recommendations given in BS 5839-1:2002 for the appropriate system category, unless other standards are more applicable, such as BS 6266 for the protection of electronic equipment installations. The detectors used to control the release of gas from an automatic fire extinguishing system must operate in coincidence mode (see above).

However, if the hazard is of such a nature that the slow reaction of the system associated with the coincidence mode can be fraught with serious consequences, then in this case the gas is released automatically when the first detector is activated. Provided that the probability of false detection and alarms is low, or people cannot be present in the protected area (for example, spaces behind false ceilings or under raised floors, control cabinets).

In general, measures should be taken to avoid unexpected gas release due to false alarms. Coincidence of the operation of two automatic detectors is a method of minimizing the probability of a false start, which is essential in the case of the possibility of a false operation of one detector.

Non-addressable fire alarm systems, which cannot identify each detector individually, must have at least two independent loops in each protected area. In addressable systems using the match mode, one loop is allowed (provided that the signal for each detector can be identified independently).

Note: In zones protected by traditional unaddressed systems, after the activation of the first detector, up to 50% of the detectors (all other detectors of this loop) are excluded from the coincidence mode, that is, the second detector activated in the same loop is not perceived by the system and cannot confirm the presence of a fire. Addressable systems provide monitoring of the situation by a signal from each detector and after the activation of the first fire detector, which ensures maximum system efficiency by using all other detectors in coincidence mode to confirm a fire.

For coincidence mode, signals from two independent detectors should be used; different signals from the same detector cannot be used, for example, generated by one aspirating smoke detector for high and low sensitivity thresholds.

Type of detector used

The choice of detectors shall be made in accordance with BS 5839-1. In some circumstances, earlier detection of a fire may require two different detection principles - for example, optical smoke detectors and ionization smoke detectors. In this case, it must be provided uniform distribution detectors of each type throughout the protected area. Where a match mode is used, it should normally be possible to match signals from two detectors operating on the same principle. For example, in some cases two independent loops are used to achieve a match; the number of detectors included in each loop, operating according to different principles, should be approximately the same. For example: where four detectors are required for room protection, and these are two optical smoke detectors and two ionization smoke detectors, each loop should have one optical detector and one ionization detector.

However, it is not always necessary to use different physical principles for fire detection. For example, given the type of fire expected and the required rate of fire detection, it is acceptable to use detectors of the same type.

The detectors must be placed in accordance with the recommendations of BS 5839-1, according to the required system category. However, when using the match mode, the minimum density of the detectors must be 2 times the recommended density in this standard. To protect electronic equipment, the fire detection level must meet the requirements of BS 6266.

It is necessary to have means of quickly identifying the location of hidden detectors (behind false ceilings, etc.) in the "Fire" mode - for example, by using remote indicators.

Control and indication

Mode switch

The mode switching device - automatic / manual and only manual - must provide a change in the mode of operation of the fire extinguishing system, that is, when personnel access an unattended area. The switch must be put into manual control mode and be provided with a key that can be removed in any position and must be placed near the main entrance to the protected area.

Note 1: The key is for the responsible person only.

The key application mode shall comply with BS 5306-4 and BS ISO 14520-1 respectively.

Note 2: Door interlock switches operating when the door is locked may be preferred for this purpose, in particular where it is necessary to ensure that the system is in manual control when personnel are present in the protected area.

Manual start device

The operation of the fire extinguishing manual release device must initiate the release of gas and requires two separate actions to be taken to prevent accidental operation. The manual release shall be predominantly yellow in color and shall be labeled to indicate its function. Usually, the manual start button is covered with a cover and two actions are required to activate the system: open the cover and press the button (Fig. 8).

Rice. eight. The manual start button on the control panel is located under the yellow cover

Devices that require the glass cover to be broken to access are not desirable due to the potential hazard to the operator. Manual release devices must be easily accessible and safe for personnel, and their malicious use must be avoided. In addition, they must be visually different from manual call points of the fire alarm system.

Start delay time

A start delay device may be built into the system to allow personnel to evacuate personnel from the protected area before the release of gas occurs. Since the period of delay in time depends on the potential speed of the spread of fire and the means of evacuation from the protected area, given time should be as short as possible and not exceed 30 seconds, unless a longer time is specified by the relevant agency. Activation of the time delay device shall be indicated by a warning audible signal in the protected area ("pre-start warning signal").

Note: A long delay in start-up contributes to the further spread of the fire and the risk of thermal decomposition products from some extinguishing gases.

If a start delay device is present, the system can also be equipped with an emergency blocking device, which must be located near the exit from the protected area. As long as the button on the device is pressed, the countdown of the prestart time should stop. When you stop pressing, the system remains in the alarm state, and the timer must be restarted from the beginning.

Emergency blocking and reset devices

Emergency interlock devices should be present in the system if it is operating in automatic mode when people are present in the protected area, unless otherwise agreed in consultation with interested parties. The type of "pre-start warning horn" must be changed to control the activation of the emergency blocking device, and there must also be a visual indication of the activation of this mode on the control unit.
In some conditions, extinguishing mode reset devices may also be installed. On fig. 9 shows an example of the structure of a fire extinguishing system.

Rice. 9. The structure of the fire extinguishing system

Sound and light indication

Visual indication of the system status should be provided outside the protected area and located at all entrances to the premises so that the state of the fire extinguishing system is clear to personnel entering the protected area:
* red indicator - “gas start”;
* yellow indicator - “automatic / manual mode”;
* yellow indicator - “manual mode only”.

A clear visual indication of the operation of the fire alarm system within the protected area should also be provided when the first detector is activated: in addition to the audible warning recommended in BS 5839-1, the warning lights should flash to alert building occupants of the possibility of a gas release. Light warning must comply with the requirements of BS 5839-1.

Easily distinguishable audible warning signals should be given at the following stages:

• during the gas start delay period;
• at the start of the gas.

These signals may be identical, or two distinct signals may be given. The signal turned on in stage "a" must be turned off when the emergency blocking device is in operation. However, if necessary, it can be replaced during its broadcast by a signal that is easily distinguished from all other signals. The signal turned on in stage "b" must continue to operate until it is manually turned off.

Power supply, plumbing

The power supply of the fire suppression system must comply with the recommendations given in BS 5839-1:2002, clause 25. The exception is that the words "FIRE SUPPRESSION SYSTEM" must be used instead of the words "FIRE ALARM" on labels described in BS 5839-1 :2002, 25.2f.
The fire suppression system must be powered in accordance with the recommendations given in BS 5839-1:2002 clause 26 for cables with standard flame retardant properties.
Note: There is no need to separate the cables of the fire extinguishing system from the cables of the fire alarm system.

Acceptance and commissioning

Once the installation of the fire extinguishing system is completed, clear instructions describing how to use it should be prepared for the person responsible for the use of the protected spaces.
Everyone and responsibility for the use of the system must be assigned in accordance with BS 5839-1, and management and personnel must be familiar with the safe handling of the system.
The user must be provided with an event log, a certificate of installation and commissioning of the system, as well as all tests for the operation of the fire extinguishing system.
The user must be provided with documentation relating to various parts equipment ( junction boxes, piping), and wiring diagrams - that is, all documents relating to the composition of the system, according to the points recommended in the standards BS 5306-4, BS 14520-1, BS 5839-1 and BS 6266.
These diagrams and drawings should be prepared in accordance with BS 1635 and updated as the system changes to include any modifications or additions made to it.

In conclusion, it can be noted that in the British standard BS 7273-1:2006 there is not even a mention of duplicating fire detectors to increase the reliability of the system. Strict European certification requirements, the work of insurance companies, the high technological level of production of fire detectors, etc. - all this provides such high reliability that the use of backup fire detectors becomes meaningless.

Materials used in the preparation of the article:

Gas fire extinguishing. British standards requirements.

Igor Neplokhov, Ph.D.
Technical Director of the POZHTEHNIKA Group of Companies for Substation.

- Magazine “ , 2007

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, fire extinguishing agents such as methyl bromide, were used. 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.

The use of gas installations operating on the basis of dilution of the object’s atmosphere requires joint work with complex systems security. For guaranteed fire extinguishing, all doors and windows must be closed and forced or natural ventilation must be turned off. To alert people inside the premises, light, sound or voice signals are given, given certain time 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 the 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, more than a dozen domestic and foreign companies use IHL in the Russian market.

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 low-pressure tanks are used in MGP developed by VFAspekt, freons are used as GFFS. 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 of the Novec 1230 type (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

Recently, in fire safety systems of small objects to be protected by automatic fire extinguishing systems, automatic gas fire extinguishing installations are becoming more common.

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, the most frequently asked questions are about the choice fire extinguishing gases and hydraulic calculation of 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) chemicals and their mixtures, polymer 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: the 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);

■ thermally stable (form a minimum amount of thermal decomposition products that are corrosive, irritating to the mucous membrane and poisonous when 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 generic methods filling modules, 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).

Concentration, % (vol.)			10,0 | 10,5 | 11,0				12,0 12,5 13,0
Safe exposure time, min.
Freon 125HP
Freon 227ea

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, the ambient air temperature of the working area should not exceed +60 ° С.

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 higher pressure in the modules, which makes them less safe during transportation and operation.

In recent years, modern fire-extinguishing agents of a new generation have begun to appear on the domestic market.

These special formulations are predominantly produced overseas 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 agents in the future.

Based on all of the above, we can say that the most effective and currently available fire extinguishing agents are freons. The relatively high cost of freons is compensated 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

CHARACTERISTIC	GAS EXTINGUISHING AGENT
Name GOTV	carbon dioxide		Freon 125	Freon 218	Freon 227ea	Freon 318C	Sulfur hexafluoride
Name variations	Carbon dioxide	TFM18, FE-13			FM200, IGMER-2
Chemical formula										N2 - 52%, Ag - 40% CO2 - 8%
		TU 2412-312 05808008	TU 2412-043 00480689	TU 6-021259-89	TU 2412-0012318479399	TU 6-021220-81
Fire classes	AND ALL UP TO 10000 V
Fire extinguishing efficiency (fire class A2 n-heptane)
Minimum volumetric fire extinguishing concentration (NPB 51-96*)
Relative permittivity (N2 = 1.0)
Module fill factor
Aggregate state in AUPT modules	Liquefied gas	Liquefied gas	Liquefied gas	Liquefied gas	Liquefied gas	Liquefied gas	Liquefied gas	compressed gas	compressed gas	compressed gas
Mass control of GOTV	Weighing device	Weighing device	pressure gauge	pressure gauge	pressure gauge	pressure gauge	pressure gauge	pressure gauge	pressure gauge	pressure gauge
Pipe wiring	No limits	No limits	Taking into account the stratification	No limits	Taking into account the stratification	Taking into account the stratification	No restrictions	No limits	No limits	No limits
The need for boost
Toxicity (NOAEL, LOAEL)					9,0%, > 10,5%
Interaction with fire load	Strong cooling		>500-550 °С	> 600 °C highly toxic				Missing	Missing	Missing
Calculation methods	MO, LPG NFPA12		MO, ZALP, NFPA 2001		MO, ZALP, NFPA 2001
Availability of certificates					FM, UL, LPS, SNPP
Warranty period of storage
Production in Russia

Gas fire extinguishing installations are specific, expensive and quite difficult to design and install. To date, there are many companies that offer various gas fire extinguishing installations. 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.

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Non-state educational institution of secondary vocational education Law College of the International Police Association

Course work

Fire extinguishing agents used in automatic fire extinguishing installations

Completed by: Gorbushin Ilya Nikolaevich

Course 3 group 4411

Specialty: 280703 Fire safety

Head: Peskichev S.V.

Introduction

1. Classification of fire extinguishing agents

1.1 Water installations

1.2 Powder plants

1.3 Gas installations

1.4 Foam plants

1.5 Aerosol plants

1.6 Combined installation

2. Cases in which the installation of automatic fire extinguishing systems is mandatory

2.1 Advantages and disadvantages of automatic fire extinguishing

Conclusion

Bibliographic list

Introduction

Automatic fire extinguishing systems are used to quickly respond to signs of fire and prevent fire. They can be compared to a fire brigade permanently on site.

Automatic fire extinguishing systems can be installed in almost any room. The most relevant locations for such systems are large closed-type parking lots, server rooms, industrial premises where there is a possibility of fire during the production process, document archives, etc.

1. Classificationautomaticsystemsfirefighting

Fire extinguishing installations - a set of stationary technical means of extinguishing a fire by releasing a fire extinguishing agent. Fire extinguishing installations must ensure the localization or elimination of a fire.

Fire extinguishing installations are divided into aggregate and modular according to the design.

According to the degree of automation - automatic, automated and manual.

By type of fire extinguishing agent - water, foam, gas, powder, aerosol and combined.

According to the method of extinguishing - into volumetric, surface, locally-volumetric and locally-surface.

1. 1 Waterinstallations

Water installations are sprinkler and deluge. Sprinkler installations are designed for local extinguishing of fires in rapidly flammable premises, for example, wooden ones, and deluge installations are designed to extinguish a fire immediately throughout the facility.

In sprinkler extinguishing systems, the sprinkler (sprinkler) is mounted in a pipeline filled with water, special foam (if the room temperature is above 5°C) or air (if the room temperature is below 5°C). In this case, the extinguishing agent is constantly under pressure. There are combined sprinkler systems in which the supply pipeline is filled with water, and the supply and distribution pipes can be filled with air or water, depending on the season. The sprinkler is closed with a thermal lock, which is a special flask designed for depressurization when a certain ambient temperature is reached.

After the sprinkler is depressurized, the pressure in the pipeline becomes less, due to which the special valve in the control node. After that, the water rushes to the detector, which detects the operation and gives a command signal to turn on the pump.

Sprinkler fire extinguishing systems are used for local detection and elimination of fires with triggering fire alarm, special warning systems, smoke protection, evacuation management and provision of information about fire locations. The service life of sprinklers that have not worked is ten years, and sprinklers that have worked or are damaged must be completely replaced. During the design of the pipeline network, it is divided into sections. Each of these sections can serve one or several rooms at once, and can also have a separate fire control system control unit. An automatic pump is responsible for the working pressure in the pipeline.

Drencher automatic fire extinguishing systems (drencher curtains) differ from sprinkler ones in that they do not have thermal locks. They also have a high water consumption and the possibility of simultaneous operation of all sprinklers. Sprinkler nozzles are various kinds: jet with high pressure, two-phase gas-dynamic, with liquid atomization by impact with deflectors or by interaction of jets. When designing deluge curtains, the following are taken into account: the type of deluge, the estimated pressure, the distance between the sprinklers and their number, the power of the pumps, the diameter of the pipeline, the volume of the liquid tanks, the installation height of the deluge.

Drencher curtains solve the following tasks:

localization of the fire;

dividing areas into controlled sectors and preventing the spread of fires, as well as harmful products burning outside the sector;

Cooling of technological equipment to acceptable temperatures.

Recently, automatic fire extinguishing systems using water mist have been widely used. The droplet size after spraying can reach 150 microns. The advantage of this technology is the more efficient use of water. In the case of extinguishing fires using conventional installations, only a third of the total volume of water is used to extinguish the fire. Fine water extinguishing technology creates a water mist that eliminates fire. This technology allows you to eliminate fires with a high degree of efficiency with rational water consumption.

1.2 Powderinstallations

The principle of operation of such devices is based on extinguishing a fire by supplying a fine powder composition to the fires. According to current fire safety regulations, all public and administrative buildings, technological premises and electrical installations, as well as storage and production premises must be equipped with automatic powder installations.

Installations do not provide a complete cessation of combustion and should not be used to extinguish fires:

Combustible materials prone to spontaneous combustion and smoldering inside the volume of the substance (sawdust, cotton, grass flour, paper, etc.);

· chemicals and their mixtures, pyrophoric and polymeric materials prone to smoldering and burning without air access.

1.3 Gasinstallations

The purpose of gas fire extinguishing installations is to detect fires and supply a special fire extinguishing gas. They use active compositions in the form of liquefied or compressed gases.

Compressed fire extinguishing mixtures include, for example, Argonite and Inergen. All compositions are based on natural gases that are already present in the air, such as nitrogen, carbon dioxide, helium, argon, so their use does not harm the atmosphere. The method of extinguishing with such gas mixtures is based on the substitution of oxygen. It is known that the combustion process is supported only when the oxygen content in the air is not less than 12-15%. When liquefied or compressed gases are released, the amount of oxygen falls below the above figures, which leads to the extinction of the flame. It must be taken into account that a sharp decrease in the level of oxygen inside a room in which people are present can lead to dizziness or even fainting, therefore, when using such fire extinguishing mixtures, evacuation is usually necessary. Liquefied gases used for fire fighting purposes include: carbon dioxide, mixtures and synthesized gases based on fluorine, for example, freons, FM-200, sulfur hexafluoride, Novec 1230. Freons are divided into ozone-friendly and ozone-depleting. Some of them can be used without evacuation, while others can only be used indoors in the absence of people. Gas installations are most suitable for ensuring the safe operation of electrical equipment that is energized. Liquefied and compressed gases are used as fire extinguishing agents.

Liquefied:

freon23;

freon125;

freon218;

freon227ea;

Freon318C;

hexaphosphoric sulfur;

Inergen.

1.4 Foaminstallations

Foam fire extinguishing installations are mainly used to extinguish flammable liquids and combustible liquids in tanks, combustible substances and oil products located both inside and outside buildings. Foam APT deluge installations are used to protect local areas of buildings, electrical appliances, transformers. Sprinkler and deluge installations for water and foam fire extinguishing have a fairly close purpose and device. A feature of APT foam installations is the presence of a tank with a foaming agent and dosing devices, with separate storage of the components of the fire extinguishing agent.

The following dosing devices are used:

· dosing pumps, providing the supply of the foaming agent to the pipeline;

· automatic dispensers with a Venturi pipe and a diaphragm-plunger regulator (with an increase in water flow, the pressure drop in the Venturi pipe increases, the regulator provides an additional amount of foam concentrate);

ejector-type foam mixers;

· Dosing tanks using the differential pressure created by the Venturi pipe.

Other distinguishing feature foam fire extinguishing installations - the use of foam sprinklers or generators. There are a number of disadvantages inherent in all water and foam fire extinguishing systems: dependence on water supply sources; the difficulty of extinguishing premises with electrical installations; complexity of maintenance; large, and often irreparable, damage to the protected building.

1.5 Aerosolinstallations

For the first time, the use of aerosol means for extinguishing fires was described in 1819 by Shumlyansky, who used black powder, clay and water for these purposes. In 1846, Kuhn proposed boxes filled with a mixture of saltpeter, sulfur and coal (smoky powder), which he recommended to throw into a burning room and tightly close the door. Soon the use of aerosols was discontinued due to their low efficiency, especially in leaky rooms.

Volumetric aerosol fire extinguishing installations do not provide a complete cessation of combustion (fire suppression) and should not be used to extinguish:

fibrous, loose, porous and other combustible materials prone to spontaneous combustion and (or) smoldering inside the layer (volume) of the substance (sawdust, cotton, grass flour, etc.);

chemicals and their mixtures, polymeric materials prone to smoldering and burning without air access;

metal hydrides and pyrophoric substances;

metal powders (magnesium, titanium, zirconium, etc.).

It is forbidden to use the settings:

in rooms that cannot be left by people before the generators start working;

premises with a large number of people (50 people or more);

Indoors of buildings and structures III and below the degree of fire resistance according to SNiP 21-01-97 installations using fire-extinguishing aerosol generators having a temperature of more than 400 ° C outside the zone 150 mm away from outer surface generator.

1.6 Combinedinstallation

Automatic combined fire extinguishing installation (AUKP) - an installation that provides fire extinguishing with the help of several fire extinguishing agents.

Typically, AUCS is a combination of two individual fire extinguishing installations that have a common object of protection and an operation algorithm (for example, combinations of fire extinguishing agents: medium expansion powder-foam; low expansion powder-foam; powder-atomized water; gas-medium expansion foam; gas-foam low expansion; gas-atomized water; gas-gas; powder-gas). The choice of a combination of fire extinguishing agents should take into account the features of fire extinguishing: the rate of fire development, the presence of heated protected surfaces, etc.

2. casesvwhichinstallationautomaticsystemsfirefightingobligatory

fire extinguishing sprinkler deluge automatic

In accordance with current fire safety regulations, the above systems in without fail must be equipped with:

· data centers, server rooms, data centers - data processing centers, as well as other premises intended for storage and processing of information and museum valuables;

· underground car parks of the closed type; elevated parking lots with more than one floor;

· one-storey buildings built of light metal structures with the use of combustible heaters: for public purposes - with an area of ​​more than 800 m2, for administrative purposes - with an area of ​​more than 1200 m2;

Buildings selling flammable and combustible liquids and materials, except for those selling packages up to 20 liters;

buildings with a height of more than 30 meters (except for industrial buildings included in the fire hazard categories "G" and "D", as well as residential buildings);

buildings of trade enterprises (except for those engaged in trade and storage of products made from non-combustible materials): over 200 m2 - in the basement or basement floors, more than 3500 m2 - in the ground part of the building;

· all one-story exhibition halls with an area of ​​more than 1000 m2, as well as more than two floors;

· cinema and concert halls with a capacity of more than 800 seats;

other buildings and structures in accordance with fire safety standards.

2.1 Advantagesandlimitationsautomaticfirefighting

Not all substances used for firefighting are safe for human body: some contain chlorine and bromine in their composition, which negatively affect internal organs; others dramatically lower the degree of oxygen in the air, which can cause suffocation and lead to loss of consciousness; others irritate the respiratory and visual systems of the body.

Firefighting with water is one of the most effective and safest methods for most all cases. However, this method of fighting fires requires a large amount of water needed to extinguish the fire. It is necessary to build capital engineering structures for uninterrupted water supply. In addition, water during extinguishing can cause serious material damage.

Among the advantages of gas installations, it is worth noting the following:

Extinguishing fires with their help does not lead to corrosion of equipment;

the consequences of their use are easily eliminated with the help of standard ventilation of the room;

They are not afraid of rising temperatures and do not freeze.

Along with the above advantages, the disadvantage of some gases is their rather high danger to humans. However, recently scientists have developed completely safe gaseous substances, for example, Novec 1230. In addition to safety for human health, the indisputable advantage of this substance is its harmlessness to the atmosphere. Novec 1230 is completely safe for the ozone layer, does not contain chlorine and bromine, its molecules completely break down under the influence of ultraviolet radiation in about five days. In addition, it is not dangerous for any property. This substance is certified, including compliance with fire safety rules and regulations, sanitary and epidemiological standards, and can be used throughout Russia. An automatic fire extinguishing system using Novec 1230 is able to quickly eliminate fires of various complexity classes.

The use of powder systems for extinguishing fires is absolutely harmless to the human body. The powder is very easy to use and costs very little. It does not harm the premises and property, but has a short shelf life.

Conclusion

The purpose of using automatic fire extinguishing installations is to localize and extinguish fires, save the lives of people and animals, as well as real and movable property. The use of such means is the most effective method of fighting fires. Unlike manual fire extinguishers and alarm systems, they create all the necessary conditions for effective and prompt localization of fires with minimal risk to health and life.

Bibliographiclist

1. Federal Law No. 123 of July 22, 2008 "Technical regulation on fire safety requirements"

2. Smirnov N.V., Tsarichenko S.G., Zdor V.L. and others. “Regulatory and technical documentation on the design, installation and operation of fire extinguishing installations, fire alarms and smoke removal systems” M., 2004;

3. Baratae A.N. "Fire and explosion hazard of substances and materials and means of extinguishing them" M., 2003.

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