Automatic gas fire extinguishing system. Gas fire extinguishing: installations, systems and modules

A technical and economic comparison showed that 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 (ILC).

MIZHU consists of an isothermal CO2 storage tank with a capacity from 3000 l to 25000 l, a shut-off and starting device, instruments for monitoring the amount and pressure of CO2, refrigeration units and a control cabinet.

Of the UGPs available on our market that use isothermal tanks for liquid carbon dioxide, MIZHU Russian made in their own way technical specifications superior to foreign products. Foreign-made isothermal tanks must be installed in a heated room. Domestic-made MIZHU can be operated at ambient temperatures down to minus 40 degrees, which makes it possible to install isothermal tanks outside buildings. In addition, unlike foreign products, the design of the Russian MIZHU allows the supply of CO2, dosed by mass, into the protected room.

Freon nozzles

To ensure uniform distribution of GFFS throughout the volume of the protected premises, nozzles are installed on the distribution pipelines of the UGP.

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

To supply refrigerants of type 125, 227ea and C02, radial type nozzles are used. In such nozzles, the flows of gas entering the nozzle and the gas jets exiting are approximately perpendicular. Radial type nozzles 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.

The placement of nozzles in the protected area is carried out in accordance with the technical documentation of the manufacturer. The number and area of ​​the outlet openings of the nozzles is determined by hydraulic calculation, taking into account the flow coefficient and spray map specified in technical documentation on the nozzles.

AUGP pipelines are made of seamless pipes, which ensures their strength and tightness in dry rooms for up to 25 years. The methods used to connect pipes are welded, threaded or flanged.

To maintain the flow characteristics of piping systems over a long service life, nozzles should be made of corrosion-resistant and durable materials. Therefore, leading domestic companies do not use nozzles made of aluminum alloys coated, and only brass nozzles are used.

The right choice of UGP depends on many factors.

Let's consider the main of these factors.

Way fire protection .

UGP are designed to create a gas environment in the protected room (volume) that does not support combustion. Therefore, there are two methods of fire extinguishing: volumetric and local volumetric. The vast majority use the volumetric method. The volume-local method is economically advantageous in the case when the equipment being protected is installed in a large area, which, according to regulatory requirements, is not required to be completely protected.

NPB 88-2001 provides regulatory requirements for the local volumetric fire extinguishing method 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 greater than the conventionally allocated volume occupied by the equipment to be protected by fire extinguishing equipment, then in this case, a local fire extinguishing method in terms of volume is economically more profitable than a volumetric fire extinguishing method.

Gas extinguishing agent.

Choice of gas fire extinguishing agent should be carried out only on the basis of a feasibility study. All other parameters, including the effectiveness and toxicity of GFFS cannot be considered as decisive for a number of reasons.
Any of the fire extinguishing agents approved for use is quite effective and the fire will be extinguished if the standard fire extinguishing concentration is created in the protected volume.
An exception to this rule is extinguishing materials prone to smoldering. Research conducted at the Federal State Institution VNIIPO EMERCOM of Russia under the leadership of A.L. Chibisov showed that complete cessation of combustion (flame and smoldering) is possible only when three times the standard amount of carbon dioxide is supplied. This amount of carbon dioxide allows you 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 prohibited to release a gaseous fire extinguishing agent into a room if there are people there. And this limitation is correct. Statistics on the causes of death in fires show that in more than 70% of cases of death, death occurred as a result of poisoning by combustion products.

The cost of each 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 for sure that protecting 1 m 3 of volume with fire extinguishing agents N 2, Ar and Inergen costs 1.5 times or more more than other gaseous fire extinguishing agents. This is due to the fact that the listed GFCIs are stored in modules gas fire extinguishing in a gaseous state, which requires a large number of modules.

There are two types of UGP: 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 the fire extinguishing station can be placed.

When protecting 3 or more premises at one site, located at a distance of no further than 100 m from each other, from an economic point of view, centralized UGPs are 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, the centralized fire extinguishing unit has a number of disadvantages compared to the modular one, namely: the need to fulfill a large number of requirements of NPB 88-2001 for the fire extinguishing station; the need to lay pipelines through the building from the fire extinguishing station to the protected premises.

Gas fire extinguishing modules and batteries.

Gas fire extinguishing modules (GFM) and batteries are the main element of a gas fire extinguishing installation. They are designed for storing and releasing GFFS into the protected area.
The MGP consists of a cylinder and a shut-off and release device (ZPU). Batteries, as a rule, consist of 2 or more gas fire extinguishing modules, united by a single factory-made manifold. Therefore, all the requirements for IHL are similar for batteries.
Depending on the gas extinguishing agent used in the fire extinguishing agent, the fire extinguishing agent must meet the requirements listed below.
MGP filled with refrigerants of all brands must ensure a release time of GFFS not exceeding 10 s.
The design of gas fire extinguishing modules filled with CO 2 , N 2 , Ar and Inergen should ensure a release time of GFFS not exceeding 60 s.
During the operation of the MGP, control of the mass of the filled GFFS must be ensured.

The mass of freon 125, freon 318C, freon 227ea, N 2, Ar and Inergen is controlled using a pressure gauge. When the pressure of the propellant gas in cylinders with the above listed refrigerants decreases by 10%, and N 2, Ar and Inergen by 5% of the nominal MGP, it must be sent for repair. The difference in pressure loss is caused by the following factors:

When the pressure of the propellant gas decreases, the mass of the freon in the vapor phase is partially lost. However, this loss is no more than 0.2% of the initially charged mass of refrigerant. Therefore, the pressure limitation equal to 10% is caused by an increase in the time of release of GFFS from the UGP 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 original value is an indirect method of losing the mass of GFFE by the same amount.

Control of the mass loss of GFFS displaced from the module under the pressure of its own saturated vapors (freon 23 and CO 2) should be carried out by a direct method. Those. The gas fire extinguishing module, filled with freon 23 or CO 2, must be installed on a weighing device during operation. At the same time, the weighing device must ensure control of the loss of mass of the gas fire extinguishing agent, and not the total mass of the fire 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 movements of which change the properties of the strain gauge. Reacts to these changes electronic device, which produces alarm signal when the load cell parameters change above the set threshold. The main disadvantages of the strain gauge device are the need to ensure free movement of the cylinder on a durable metal-intensive structure, as well as negative impact external factors - connecting pipelines, periodic shocks and vibration during operation, etc. The metal consumption and dimensions of the product increase, and installation problems increase.
The modules MPTU 150-50-12 and MPTU 150-100-12 use a high-tech method for monitoring the safety of GFFS. The electronic mass control device (UMD) is built directly into the locking and starting device (LSD) of the module.

All information (fuel mass, calibration date, service date) is stored in the UCM memory device and, if necessary, can be output to a computer. For visual control, the module's control unit is equipped with an LED, which provides signals about normal operation, a reduction in the mass of the gas fuel by 5% or more, or a malfunction of the control unit. 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 strain gauge weighing device with a control device.

Isothermal module for liquid carbon dioxide (MIZHU).

MIZHU consists of a horizontal tank for storing CO 2, a shut-off and starting device, instruments for monitoring the amount and pressure of CO 2, refrigeration units and a control panel. The modules are designed to protect premises with a volume of up to 15 thousand m 3. The maximum capacity of MIZHU is 25 tons of CO 2. As a rule, the module stores working and reserve CO 2 reserves.

An additional advantage of the MIZHU is the ability to install it outside the building (under a canopy), which allows for significant savings production area. Only MIZHU control devices and UGP distribution devices (if available) are installed in a heated room or warm block-box.

MGP with a cylinder capacity of up to 100 liters, depending on the type of combustible load and the filled flammable fuel, allows you to protect a room with a volume of no more than 160 m 3. To protect larger premises, the installation of 2 or more modules is required.
A technical and economic comparison showed that to protect premises with a volume of more than 1500 m 3 in the UGP, it is more expedient to use isothermal modules for liquid carbon dioxide (ILC).

The nozzles are designed for uniform distribution of GFFS into the volume of the protected room.
The placement of nozzles in the protected room is carried out in accordance with the manufacturer's specifications. The number and area of ​​the outlet openings of the nozzles is determined by hydraulic calculation taking into account the flow coefficient and spray map specified in the technical documentation for the nozzles.
The distance from the nozzles to the ceiling (ceiling, suspended ceiling) should not exceed 0.5 m when using all GFFS, with the exception of N 2.

Piping.

The layout of pipelines in the protected area, as a rule, should be symmetrical with equal distance of nozzles from the main pipeline.
The installation pipelines are made from metal pipes. The pressure in the installation pipelines and diameters are determined by hydraulic calculations using methods agreed upon in the prescribed manner. Pipelines must withstand pressure during strength and tightness tests of at least 1.25 Rwork.
When using freons as a gas flue gas, the total volume of pipelines, including the manifold, should not exceed 80% of the liquid phase of the working reserve of freons in the installation.

The routing of distribution pipelines for installations using freon should be done only in a horizontal plane.

When designing centralized installations using refrigerants, you should pay attention to the following points:

• the main pipeline of the room with the maximum volume should be connected closer to the battery with GFFE;
• when batteries with a main and reserve reserve are connected in series to the station manifold, the main reserve should be the furthest away from the protected premises, subject to the condition of the maximum release of refrigerant from all cylinders.

The correct choice of UGP gas fire extinguishing installation depends on many factors. Therefore, the purpose of this work is to show the main criteria that influence the optimal choice of UGP and the principle of its hydraulic calculation.
Below are the main factors influencing the optimal choice of UGP. Firstly, the type of flammable load in the protected premises (archives, storage facilities, radio-electronic equipment, technological equipment etc.). Secondly, the size of the protected volume and its leakage. Thirdly, the type of gas fire extinguishing agent GOTV. Fourthly, the type of equipment in which GFFS should be stored. Fifthly, the type of UGP: centralized or modular. The last factor can only occur if there is a need for fire protection of two or more premises at one facility. Therefore, we will consider the mutual influence of only the four factors listed above. Those. on the assumption that the facility requires fire protection for only one room.

Certainly, right choice UGP should be based on optimal technical and economic indicators.
It should be especially noted that any of the fire extinguishing agents approved for use extinguishes a fire, regardless of the type of combustible material, but only when the standard fire extinguishing concentration is created in the protected volume.

The mutual influence of the above factors on the technical and economic parameters of the UGP will be assessed from the condition that the following GFFS are allowed for use in Russia: freon 125, freon 318C, freon 227ea, freon 23, CO 2, N 2, Ar and a mixture (N 2, Ar and CO 2), which has the trademark "Inergen".

According to the method of storage and methods of control of fire extinguishing substances in MGP gas fire extinguishing modules, all gas fire extinguishing agents can be divided into three groups.

Group 1 includes freon 125, freon 318C and freon 227ea. These refrigerants are stored in the 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. The amount of refrigerant during operation of the installation is monitored using a pressure gauge installed on the MGP.

Freon 23 and CO 2 make up the 2nd group. They are also stored in 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 GFFS must have a working pressure of at least 14.7 MPa. During operation, the modules must be installed on weighing devices that provide continuous monitoring of the mass of freon 23 or CO 2.

The 3rd group includes N 2, Ar and Inergen. GFFS data are stored in the 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 mass of group 3 GFFS is controlled using 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 in accordance with 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 these rules.

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

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

Example 1. It is required to protect radio-electronic equipment in a room with a volume of 60 m 3 . The room is conditionally sealed. Those. K2 = 0. We summarize the calculation results in table. 1.

Table 1

The economic justification of the table in specific figures has some difficulty. This is due to the fact that the cost of equipment and GFFS among manufacturers and suppliers has different prices. However, there is a general tendency that as the cylinder capacity increases, 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 refrigerants. Analysis of the table 1 shows that the cost of UGP with freon 125 and CO 2 is comparable in value. Despite the significantly higher cost of freon 125 compared to carbon dioxide, the total price of freon 125 - MGP with a cylinder with a capacity of 40 liters will be comparable or even slightly lower than the set of carbon dioxide - MGP with a cylinder of 80 liters - a weighing device. We can definitely state that the cost of UGP with nitrogen is significantly higher compared to the two previously considered options. Because Requires 2 modules with maximum capacity. More space will be required to place 2 modules in the room and, naturally, the cost of 2 modules with a volume of 100 liters will always be more than a module with a volume of 80 liters with a weighing device, which, as a rule, is 4 - 5 times less expensive than the module itself.

Example 2. The room parameters are similar to example 1, but it is not the electronic equipment that needs to be protected, but the archive. The calculation results are similar to the 1st example and presented in table. 2 will be tabulated. 1.

table 2

Based on the analysis of table. 2 can be said unequivocally, and in in this case EGP with nitrogen is significantly more expensive 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 an MGP with a cylinder capacity of 80 l and 100 l, the price of 56 kg of refrigerant 125 significantly exceeds the cost of a weighing device.

Similar dependencies will be observed if the volume of the protected space increases and/or its leakage increases. Because all this causes a general increase in the amount of any type of flammable fuel.

Thus, based only on 2 examples, it is clear that choosing the optimal UGP for fire protection of a room is possible only after considering at least two options with various types GOTV.

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

Such restrictions primarily include the protection of particularly important facilities in seismic zones (for example, nuclear power facilities, etc.), where the installation of modules in earthquake-resistant frames is required. In this case, the use of freon 23 and carbon dioxide is excluded, since modules with these GFFS must be installed on weighing devices that prevent their rigid fastening.

For fire protection of premises with constantly present personnel (air traffic control rooms, rooms with control panels of nuclear power plants, etc.), restrictions on the toxicity of GFFS are imposed. In this case, the use of carbon dioxide is excluded, since the volumetric fire extinguishing concentration of carbon dioxide in the air is lethal 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 the MIL, compared to all other GFFS.

After conducting a feasibility study, the amount of fire fighting substances required to extinguish the fire and the preliminary amount of MGP becomes known.

Nozzles must be installed in accordance with the spray maps 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, with the exception of N 2.

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

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

A cross-shaped connection is possible only if the consumption of GFFS G1 and G2 is equal in value (Fig. 3).

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

There are no restrictions imposed on the spatial connection of pipes when designing UGP piping when using fire extinguishing agents belonging to groups 2 and 3. And for the piping of UGP with GFFS of the 1st group there are a number of restrictions. This is caused by the following:

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

After opening the shut-off and starting device ZPU of the gas fire extinguishing module, under the pressure of the propellant gas, the refrigerant with partially dissolved nitrogen flows through the piping to the nozzles and through them exits into the protected volume. In this case, the pressure in the system (modules - piping) decreases as a result of the expansion of the volume occupied by nitrogen in the process of displacing the freon and the hydraulic resistance of the piping. Partial release of nitrogen occurs from the liquid phase of the refrigerant and a two-phase environment is formed (a mixture of the liquid phase of the refrigerant and gaseous nitrogen). Therefore, a number of restrictions are imposed on the piping of the UGP using the 1st group of GFFE. The main meaning of these restrictions is aimed at preventing the separation of the two-phase medium inside the pipework.

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

and is prohibited from being performed in the forms shown in Fig. 6a, 6b, 6c. In the figures, arrows show the direction of flow of GFFS through the pipes.

In the process of designing the UGP, the piping diagram, pipe length, number of nozzles and their elevations are performed in axonometric form. For determining internal diameter pipes and the total area of ​​the outlet openings 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 optimal option for controlling automatic gas fire extinguishing installations, you must be guided by the technical requirements, features and functionality of the protected objects.

Basic 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 variations are derived from these standard designs.

To protect local (separately standing) premises in one, two and three directions of gas fire extinguishing, as a rule, it is justified to use autonomous 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 alarms, and devices for remote and automatic start-up of a gas fire extinguishing installation (GFE). 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 post to the station’s remote display panel.

Rice. 1. Autonomous gas fire extinguishing control systems

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 complex security system of the facility or a newly designed one. Signals from the autonomous gas fire extinguishing control station are sent to addressable units and control modules, which then transmit information to the central control post at the central station fire alarm. A feature of decentralized gas fire extinguishing control is that if individual elements of the facility’s integrated security system fail, the autonomous gas fire extinguishing control station remains in operation. This system allows you to integrate into your system any number of gas fire extinguishing directions, which are limited only by the technical capabilities of the fire alarm station itself.

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

The third diagram is a diagram of centralized control of gas fire extinguishing systems (Fig. 3). This system is used when fire safety requirements are a 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 air exhaust ventilation(smoke coming from the street), strong wind etc. Prevention of false positives in addressable analogue systems carried out by monitoring the dust level of sensors.

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

The signal from addressable analogue fire detectors is sent to the central fire alarm station, after which the processed data through addressable modules and blocks enters the autonomous gas fire extinguishing control system. Each group of sensors is logically linked to its own direction of gas fire extinguishing. Centralized system gas fire extinguishing control is designed only for the number of station addresses. Let's take, for example, a station with 126 addresses (single-loop). Let's calculate the number of addresses required for maximum protection of the premises. Control modules - automatic/manual, gas supplied and fault - 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 an increase in the cost of the system, but significantly increases its reliability, makes it possible to analyze the situation (control of dust levels in sensors), and also reduces the cost of its Maintenance and exploitation. The need to install a centralized (decentralized) system arises with additional management of engineering systems.

In some cases, in centralized and decentralized gas fire extinguishing systems, 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. In Fig. Figure 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 option for installing gas fire extinguishing depends on a large number of initial data. An attempt to summarize the most significant parameters of gas fire extinguishing systems and installations is presented in Fig. 5.

Rice. 5. Selecting the optimal option for installing gas fire extinguishing systems according to technical requirements

One of the features of AGPT systems in automatic mode is the use of addressable analogue and threshold fire detectors as devices that register a fire, and when triggered, the fire extinguishing system is launched, i.e. release of fire extinguishing agent. And here it should be noted that the performance of the entire expensive complex depends on the reliability of the fire detector, one of the cheapest elements of the fire alarm and fire extinguishing system fire automatics and, consequently, the fate of the protected object! In this case, the fire detector must satisfy two main requirements: early detection of fire and the absence of false alarms. What determines the reliability of a fire detector as an electronic device? From the level of development, 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 focus on price and the availability of a certificate, although, unfortunately, it is not a guarantee of quality today. Only a few fire detector manufacturers openly publish failure rates; for example, according to the Moscow manufacturer System Sensor Fire 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 analogue system allows the customer to be absolutely confident in the performance of all its elements: smoke and heat sensors that monitor the protected premises are constantly polled by the fire extinguishing control station. The device monitors the condition of the loop and its components; if the sensitivity of the sensor decreases, 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. The system is believed to be operational, but in reality the fire control station will not respond appropriately in the event of a real fire. Therefore, when installing automatic gas fire extinguishing systems, it is preferable to use addressable analogue systems. Their relatively high cost is offset by unconditional reliability and a qualitative reduction in the risk of fire.

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

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 selected gas fire extinguishing agent and propellant gas, if any, is indicated. For freon and mixtures of gas fire extinguishing agents, the fire safety certificate number is reported. The type of MGP gas fire extinguishing modules (batteries) selected for storing the gas fire extinguishing agent and the number of the fire safety certificate are given. A brief description of the main elements of the module (battery) and the method of controlling the mass of GFFS is given. The parameters of the electric start of the MGP (battery) are given.
1. General Provisions.

In chapter general provisions the name of the object for which the working design of the UGP has been completed and the rationale for its implementation are given. Regulatory and technical documents on the basis of which the design documentation was prepared are provided.
The list of main regulatory documents used in the design of the UGP is given below. NPB 110-99
NPB 88-2001 as amended No. 1
Due to the fact that constant work is being carried out to improve regulatory documents, designers must constantly adjust this list.

2. Purpose.

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

3. Brief description of the protected object.

This section provides a general overview of the premises subject to UGP protection and their geometric dimensions (volume). The presence of raised floors and ceilings is reported with a volumetric fire extinguishing method, or the configuration of the object and its location with a local volumetric method. Information is provided on 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 maximum permissible pressures in the protected premises. Data is provided on the main types of fire load, categories of protected premises and zone classes.

4. Basic design solutions. This section has two subsections.

The selected type of nozzles for uniform distribution of the gaseous fire extinguishing agent in the protected volume and the accepted standard time for release of the calculated mass of fire extinguishing agent are reported.

For centralized installation the type is given distribution devices and fire safety certificate number.

Formulas are given that are used to calculate the mass of the gas fire extinguishing agent UGP, and the numerical values ​​of the main quantities used in the calculations: accepted standard fire extinguishing concentrations for each protected volume, the density of the gas phase and the remainder of the fire extinguishing agent in the modules (batteries), a coefficient taking into account the loss of the gas fire extinguishing agent from modules (batteries), the remaining GFSF in the module (battery), the height of the protected room above sea level, the total area of ​​constantly open openings, the height of the room and the time of GFSF supply.

A calculation of the time for evacuating people from premises that are protected by gas fire extinguishing installations is given and the time for stopping ventilation equipment, closing fire-preventing valves, air dampers, etc. is indicated. (if available). When evacuating people from a room or stopping ventilation equipment, closing fire-preventing valves, air dampers, etc. less than 10 s, it is recommended that the delay time for the release of GFFS be 10 s. If all or one of the limiting parameters, namely, the estimated time of evacuation of people, the time of stopping ventilation equipment, closing fire-preventing valves, air dampers, etc. exceeds 10 s, then the delay time for the release of GFFS must be taken at a higher value or close to it, but in a larger direction. It is not recommended to artificially increase the delay time for the release of GFFS for the following reasons. Firstly, UGP are designed to eliminate the initial stage of a fire, when the destruction of the enclosing structures and, above all, windows does not occur. The appearance of additional openings as a result of the destruction of enclosing structures during a developed fire, which were not taken into account when calculating the required amount of fire extinguishing agent, will not allow creating the standard fire extinguishing concentration of the gas extinguishing agent in the room after the activation of the fire extinguishing agent. Secondly, artificially increasing the free burning time leads to unjustifiably large material losses.

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

1. • Electrical part.

     This subsection informs you on the basis of what principles fire detectors were selected, their types and fire safety certificate numbers are given. The type of control and control 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. Operating principle of the installation.

   This section has 4 subsections, which describe: the “Automatic on” mode;

   • "Automation disabled" mode;
   • remote start;
   • local start.
3. Electricity supply.

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

4. 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, the location 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 for their installation are given. The brands of cables, wires and the conditions for their installation are reported.

5. Professional and qualified composition of persons working at the facility for maintenance and operation of the installation automatic fire extinguishing.

The contents of this section include requirements for the qualifications of personnel and their number when servicing the designed automatic gas fire extinguishing installation.

1. Measures for labor protection and safe operation.

   This section provides regulatory documents on the basis of which installation and commissioning work and maintenance of an automatic gas fire extinguishing installation must be carried out. Requirements are given for persons permitted to service automatic gas fire extinguishing installations.

The measures that must be taken after the activation of the UGP in the event of a fire are described.

BRITISH STANDARDS REQUIREMENTS.

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 basic provisions that determine the effectiveness of the system must be the same. The following is a commentary on British Standard BS 7273-1:2006 Part 1 for electrically activated gaseous fire extinguishing systems.

British BS 7273-1:2006 replaced BS 7273-1:2000. Fundamental differences new standard from the previous version are noted in its preface.

• BS 7273-1:2006 is a separate document, but it (unlike the current NPB 88-2001* in Russia) contains references to the regulatory documents with which it should be used. These are the following standards:
• BS 1635 "Guidelines for graphic symbols 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 relating to fire detection and warning systems for buildings. Part 1: "Norms and rules for the design, installation and maintenance of systems";
• BS 6266 Code of Practice for Fire Protection in Electronic Equipment Installations;
• BS ISO 14520 (all parts), Gas fire extinguishing systems;
• BS EN 12094-1, "Fixed fire protection systems- components of gas fire extinguishing systems" - 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, with BS 7273 defining only a few of the terms listed below.

• Mode switch automatic/manual and manual only - a means of transferring the system from an automatic or manual activation mode to a manual activation mode only (and 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 a separate door lock, but in any case it must be possible to switch the system activation mode from automatic/manual to manual only or vice versa):
  • automatic mode (in relation to a fire extinguishing system) is an operating mode in which the system is initiated without manual intervention;
  • manual mode is one in which the system can only be initiated through manual control.
• Protected area - the area protected by the fire extinguishing system.
• Coincidence is the logic of the system operation, according to which the output signal is given in the presence of at least two independent input signals simultaneously present in the system. For example, the output signal to activate fire extinguishing is generated only after a fire has been detected by one detector and, at least, when another independent detector in the same protected area 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 component automatic fire alarm and fire extinguishing system).

System design

The standard also notes that the requirements for the protected area must 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, insurance company experts, responsible person from the health department, as well as representatives of any other interested departments. In addition, it is necessary to pre-plan the actions that must 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. These types of actions should be discussed at the design stage and implemented in the proposed system.

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

System operation

In accordance with this standard, an algorithm for the operation of the fire extinguishing system must be generated, which is presented in graphical form. An example of such an algorithm is given in the appendix to this standard. As a rule, to avoid unwanted release of gas in the 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 should, at a minimum, result in the Fire mode being indicated in the fire alarm system and an alarm being activated within the protected area.

The release of gas from the extinguishing system must be controlled and indicated by the control device. To control the release of gas, a gas pressure or gas flow sensor must be used, located in such a way as to control its release from any cylinder in the system. For example, if there are mating 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 shall not affect the operation of the fire detectors or the operation of the fire alarm system.

Requirement for increased performance

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

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

Rice. 1. System with two parallel radial stubs

Indeed, if there is a break or even a short circuit in one of the two radial loops, the second loop remains in in working condition. In this case, the placement of detectors must ensure 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 insulators. In this case, in the event of a break, the ring loop is automatically converted into two radial loops, the break point is localized and all sensors remain operational, which maintains the functioning of the system in automatic mode. When a 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 also remain operational.

Rice. 3. Broken ring loop

Rice. 4. Ring short circuit

A short circuit isolator usually consists of two symmetrically connected electronic switches, between which a fire sensor 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 call points and into functional modules. If necessary, a short circuit isolator can be used, made in the form of a separate module.

Rice. 5. Short circuit isolator in sensor base

It is obvious that the systems often used in Russia with one “double-threshold” loop do not meet this requirement. If such a loop breaks certain part the protected area remains unmonitored, and in the event of a short circuit, monitoring is completely absent. A “Fault” signal is generated, but until the fault is eliminated, the “Fire” signal is not generated by any sensor, which makes it impossible to turn on the fire extinguishing system manually.

False alarm protection

Electromagnetic fields from radio transmitting devices can cause false signals in fire alarm systems and lead to the activation of electrical initiation processes for the release of gas from fire extinguishing systems. Almost all buildings use equipment such as portable radios and cell phones, and base transceiver stations of several cellular operators may 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 may arise if the system is installed in areas of high field strength - for example, near airports or radio transmitting stations.

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

Table 1. LPCB and VdS requirements for sensor immunity to electromagnetic interference.

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

European requirements meet modern conditions operation and several times exceed the requirements even for the highest (4th degree) rigidity according to NPB 57-97 "Instruments and equipment for 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 lower compared to European tests, although the "effectiveness" of interference on a fire detector with with increasing frequency it usually increases.

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 the effects of electromagnetic fields with a degree of severity not lower than the second.

Table 2. Requirements for detector immunity to electromagnetic interference according to NPB 57-97

Frequency ranges and electromagnetic field strength levels when tested according to NPB 57-97 do not take into account the presence of several cellular communication systems with a huge number of base stations and mobile phones, nor an increase in the power and number of radio and television stations, nor other similar interference. 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 various masts. Typically, a large number of antennas of several cellular operators are located at one site, which increases the level of electromagnetic interference several times.

In addition, according to the European standard EN 54-7 for smoke detectors, tests for these devices are mandatory:
- 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 an atmosphere of SO 2 gas 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 detector loops cover several protected areas, then the signal to initiate the release of fire extinguishing agent into the protected area where the fire was detected should not lead to the release of fire extinguishing agent into another protected area whose detection system uses the same loop.

Activation of manual call points must also not in any way affect the start of gas.

Establishing the fact of fire

The fire alarm system must comply with the recommendations given in BS 5839-1:2002 for the relevant system category, unless other standards are more applicable, for example BS 6266 for the protection of electronic equipment installations. Detectors used to control the gas release of an automatic fire extinguishing system must operate in match mode (see above).

However, if the danger is of such a nature that the slow response 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 alarms and detectors is low, or that no people can be present in the protected area (for example, spaces behind suspended ceilings or under raised floors, control cabinets).

In general, precautions should be taken to avoid unexpected gas releases due to false alarms. Coincidence of two automatic detectors is a method of minimizing the likelihood of a false trigger, which is essential in the event of the possibility of a false alarm on 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 coincidence mode, the use of one loop is allowed (provided that the signal from each detector can be independently identified).

Note: In areas protected by traditional addressless systems, after activation of the first detector, up to 50% of the detectors (all other detectors in 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. Address systems provide control of the situation by a signal coming from each detector and after activation of the first fire detector, which ensures maximum efficiency system by using all other detectors in coincidence mode to confirm a fire.

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

Type of detector used

The selection of detectors should be made in accordance with BS 5839-1. In some circumstances, two different detection principles may be required for earlier fire detection - for example, optical smoke detectors and ionization smoke detectors. In this case, an even distribution of detectors of each type must be ensured throughout the protected area. Where match mode is used, it must usually be possible to match the 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 to protect a premises and these are two optical smoke detectors and two ionization smoke detectors, each loop must have one optical detector and one ionization detector.

However, it is not always necessary to use different physical principles for fire recognition. For example, depending on the type of fire expected and the required speed of fire detection, it is acceptable to use one type of detector.

Detectors should be located in accordance with the recommendations of BS 5839-1, according to the required system category. However, when using coincidence mode, the minimum detector density should be 2 times that recommended in this standard. To protect electronic equipment, the fire detection level must comply with BS 6266.

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

Control and display

Mode switch

The mode switching device - automatic/manual and only manual - must ensure a change in the operating mode of the fire extinguishing system, that is, when personnel access an unattended area. The switch must be manually operated and equipped with a key that can be removed in any position and must be located near the main entrance to the protected area.

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

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

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

Manual start device

The operation of the manual fire extinguishing device must initiate the release of gas and requires two separate actions to prevent accidental activation. The manual release device must be predominantly yellow in color and be marked to indicate the function it performs. Typically, the manual start button is covered with a cover and to activate the system you need to perform two steps: open the cover and press the button (Fig. 8).

Rice. 8. The manual start button on the control panel is located under the yellow cover

Devices that require breaking a glazed cover to access are not desirable due to the potential danger 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 distinguishable 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 the protected area before a gas release occurs. Since the time delay period depends on the potential speed of fire spread 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 prescribed by the relevant department. Activation of the time delay device shall be indicated by an audible warning signal audible in the protected area ("pre-warning signal").

Note: A long start-up delay 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 provided, the system may also be equipped with an emergency interlock device, which must be located near the exit from the protected area. While the button on the device is pressed, the countdown of the pre-start time should stop. When the press is released, the system remains in the alarm state and the timer must be restarted from the beginning.

Emergency interlock and reset devices

Emergency interlock devices must 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 appearance of the "pre-warning buzzer" must be modified to control the activation of the emergency interlock device, and there must also be a visual indication of the activation of this mode on the control unit.
In some environments, fire extinguishing mode reset devices may also be installed. In Fig. Figure 9 shows an example of the structure of a fire extinguishing system.

Rice. 9. Fire extinguishing system structure

Sound and light indication

A visual indication of the system status should be provided outside the protected area and located at all entrances to the premises so that the status 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”.

There should also be a clear visual indication of the operation of the fire alarm system within the protected area when the first detector is activated: in addition to the audible warning recommended in BS 5839-1, warning lights should flash so that people in the building are notified of the possibility of releasing gas. Signal lights must comply with BS 5839-1.

Easily distinguishable sound signals Alerts should be given at the following stages:

• during the gas start delay period;
• at the beginning of gas start-up.

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

Power supply, connection

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

Acceptance and commissioning

Once the installation of the fire extinguishing system is complete, clear instructions describing its use should be prepared for the person responsible for the use of the protected premises.
All responsibilities and responsibilities for using the system must be allocated in accordance with BS 5839-1 standards and management and staff must be familiar with the rules safe handling with 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 on the operation of the fire extinguishing system.
The user must be provided with documentation relating to the various parts of the equipment (junction boxes, piping) and wiring diagrams - that is, all documents relating to the composition of the system, as recommended in BS 5306-4, BS 14520-1, BS 5839- 1 and BS 6266.
These diagrams and drawings shall be prepared in accordance with BS 1635 and shall be updated as the system changes to reflect any modifications or additions made to it.

In conclusion, it can be noted that the British standard BS 7273-1:2006 does not even mention the duplication of fire detectors to improve system reliability. Strict European certification requirements, work of insurance companies, high technological level of fire sensor production, etc. - all this ensures such high reliability that the use of backup fire detectors loses its meaning.

Materials used in preparing the article:

Gas fire extinguishing. British standards requirements.

Igor Neplohov, Ph.D.
Technical Director of GC POZHTEHNIKA for PS.

- Magazine “ , 2007

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

Classification of fires extinguished by gas extinguishing

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

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

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

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

Advantages of the method

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

To the main advantages this method fire fighting include the following factors:

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

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

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

Design and principle of operation of installations

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

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

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

The gas fire extinguishing method occurs automatically:

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

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

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

Types of automatic systems

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

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

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

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

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

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

Requirements for design, calculation and installation work

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

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

When determining the locations of this fire-fighting equipment, special attention must be paid to the amount of oxygen in areas where people gather at the time automatic switching on. The amount of oxygen in these places must meet acceptable standards.
When installing gas equipment, it is necessary to ensure its protection from mechanical influences.

Activities for maintenance of fire fighting equipment

Gas-type automatic fire extinguishing systems require regular preventative maintenance.

Every month it is necessary to check the working condition and tightness of individual elements and the system as a whole.

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

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

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

Advantages and disadvantages of fire extinguishing agents

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

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

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

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

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

Disadvantages of gas fire extinguishing:

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

Gases used to extinguish fires

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

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

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

Note!

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

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

Types of gas fire extinguishing systems

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

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

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

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

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

Top five IHL modules

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

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

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

The use of new gas fire extinguishing agents such as Novec 1230 (fluoroketone group), as a result, the ability to extinguish a fire in the presence of people, has increased the efficiency of the fire extinguishing agent due to early response. And the harmlessness of using GFFE 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.

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

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

Brief characteristics of popular GOTV

CO2

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

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

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

Freon 125

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

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

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

Freon 23

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

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

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

Fluoroketone FK-5-1-12 or “dry water”

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

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

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

Freon 227ea (heptafluoropropane)

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

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

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

Freon 318C

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

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

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

Inergen

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

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

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

AQUAMARINE

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

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

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

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

Recently, in fire safety systems of small objects subject to protection by automatic fire extinguishing systems, automatic gas fire extinguishing systems are becoming increasingly common.
Their advantage lies in fire extinguishing compositions that are relatively safe for humans, complete absence of damage to the protected object when the system is activated, repeated use of equipment and extinguishing fires in hard-to-reach places.
When designing installations, questions most often arise regarding the choice of fire extinguishing gases and the hydraulic calculation of the installation.

In this article we will try to reveal some aspects of the problem of choosing a fire extinguishing gas. All the most commonly used modern installations gas fire extinguishing gas fire extinguishing compositions 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 their mixtures.

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

Gas fire extinguishing agents are used primarily for volumetric fire extinguishing in the initial stage of a fire in accordance with GOST 12.1.004-91. Fire extinguishing agents are also used to phlegmatize explosive environments in the petrochemical, chemical and other industries. Fire extinguishing agents are not electrically conductive, evaporate easily, and do not leave marks on the equipment of the protected facility; in addition, an important advantage of fire extinguishing agents is their suitability for extinguishing expensive fires. electrical installations under voltage.

It is prohibited to use fire extinguishing agent for extinguishing:

a) fibrous, loose and porous materials capable of spontaneous combustion with subsequent smoldering of the layer inside the volume of the substance (sawdust, rags in bales, cotton, grass meal, etc.);
b) chemicals and their mixtures, polymeric materials prone to smoldering and burning without air access (nitrocellulose, gunpowder, etc.);
c) chemically active metals (sodium, potassium, magnesium, titanium, zirconium, uranium, plutonium, etc.);
d) chemicals capable of undergoing authermal decomposition (organic peroxides and hydrazine);
e) metal hydrides;
f) pyrophoric materials (white phosphorus, organometallic compounds);
g) oxidizing agents (nitrogen oxides, fluorine)

It is prohibited to extinguish class C fires if this may release or enter the protected volume of flammable gases with the subsequent formation of an explosive atmosphere. In the case of using GFFE for fire protection of electrical installations, the dielectric properties of gases should be taken into account: dielectric constant, electrical conductivity, dielectric strength. Usually, ultimate voltage, at which it is possible to extinguish without shutting down electrical installations with all fire extinguishing agents, is no more than 1 kV. To extinguish electrical installations with voltages up to 10 kV, you can use only the highest grade CO2 in accordance with GOST 8050.

Depending on the extinguishing mechanism, gas fire extinguishing compositions are divided into two qualification groups:
- 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);
- inhibitors that inhibit 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:

Human safety;
- Technical and economic indicators;
- Preservation of equipment and materials;
- Restriction on use;
- Impact on the environment;
- Possibility of removing GFZ after use.

It is preferable to use gases that:

They have acceptable toxicity in the used fire extinguishing concentrations (suitable for breathing and allow the evacuation of personnel even when gas is supplied);
- thermally stable (form a minimal amount of thermal decomposition products, which are corrosive, irritating to the mucous membrane and toxic when inhaled);
- most effective in fire extinguishing (protect the maximum volume when supplied from a module that is filled with gas to the maximum value);
- economical (provide minimal specific financial costs);
- environmentally friendly (do not have a destructive effect on ozone layer Earth and do not contribute to the creation of the greenhouse effect);
- provide universal methods filling modules, storage and transportation and refilling.

The most effective in extinguishing fires are chemical refrigerant gases. Physico-chemical process 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 88-2001*, the standard fire extinguishing concentration of Freon 125 for class A2 fires is 9.8% vol. This concentration of Freon 125 can be increased to 11.5% vol., while the atmosphere is breathable for 5 minutes.

If we rank GFFS by toxicity in the event of a massive leak, then compressed gases are the least dangerous, since carbon dioxide provides human protection from hypoxia.
The refrigerants used in the systems (according to NPB 88-2001*) are low-toxic and do not exhibit a pronounced pattern of intoxication. In terms of toxicokinetics, freons are similar to inert gases. Only with prolonged inhalation exposure to low concentrations can freons have an adverse effect on the cardiovascular, central nervous system, lungs. With inhalation exposure to high concentrations of freons, oxygen starvation develops.

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

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

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

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

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

Carbon dioxide at concentrations greater than 5% (92 g/m3) has bad influence on human health, the volume fraction of oxygen in the air decreases, which can cause the phenomenon of oxygen deficiency and suffocation. When the pressure drops to atmospheric, liquid carbon dioxide turns into gas and snow at a temperature of minus 78.5 °C, which cause frostbite of the skin and damage to the mucous membrane of the eyes. In addition, when using carbon dioxide automatic fire extinguishing systems, the ambient air temperature working area should not exceed plus 60 °C.

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