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Method for calculating the mass of gaseous fire extinguishing agent for installationAnovok gas fire extinguishing when extinguishing by volumetric method
1. Estimated mass of GOTV, which must be stored in the installation, is determined by the formula
where 
- the mass of GFEA, intended to create a fire extinguishing concentration in the volume of the room in the absence of artificial air ventilation, is determined by the formulas:
for GOTV - liquefied gases, except for carbon dioxide
;
(2)
for GOTV - compressed gases and carbon dioxide
,
(3)
where 
- the estimated volume of the protected premises, m 3.
The calculated volume of the room includes its internal geometric volume, including the volume of the ventilation, air conditioning, air heating system (up to hermetic valves or dampers). The volume of equipment located in the room is not deducted from it, with the exception of the volume of solid (impermeable) building elements (columns, beams, foundations for equipment, etc.);
- coefficient taking into account leakage of gaseous fire extinguishing agent from vessels; 
- coefficient taking into account the loss of gas fire extinguishing agent through the openings of the room; 
- the density of the gaseous fire extinguishing agent, taking into account the height of the protected object relative to sea level for the minimum temperature in the room 
,
kg m -3, is determined by the formula
,
(4)
where 
is the vapor density of the gaseous extinguishing agent at a temperature 
\u003d 293 K (20 С) and atmospheric pressure 101.3 kPa; 
- minimum air temperature in the protected room, K; 
- correction factor taking into account the height of the object location relative to sea level, the values of which are given in Table 11 of Appendix 5; 
- normative volume concentration, % (vol.).
The values of standard fire extinguishing concentrations () are given in Appendix 5.
Mass of the rest of GOV in pipelines 
, kg, is determined by the formula
,
(5)
where - the volume of the entire piping of the installation, m 3; 
- the density of the GFFS residue at the pressure that exists in the pipeline after the end of the outflow of the mass of the gas fire extinguishing agent into the protected room.
- the product of the remainder of GOTV in the module ( M b), which is accepted according to TD per module, kg, per number of modules in the installation 
.
Note. For liquid combustible substances not listed in Appendix 5, the standard volumetric fire extinguishing concentration of GFEA, all components of which are in the gas phase under normal conditions, can be determined as the product of the minimum volumetric fire extinguishing concentration and a safety factor equal to 1.2 for all GFFS, for except for carbon dioxide. For CO 2 the safety factor is 1.7.
For GFFS that are in the liquid phase under normal conditions, as well as GFFS mixtures, at least one of the components of which is in the liquid phase under normal conditions, the standard fire extinguishing concentration is determined by multiplying the volumetric fire extinguishing concentration by a safety factor of 1.2.
Methods for determining the minimum volumetric fire extinguishing concentration and fire extinguishing concentration are set out in NPB 51-96 *.
1.1. The coefficients of equation (1) are determined as follows.
1.1.1. Coefficient taking into account leakage of gaseous extinguishing agent from vessels:
.
1.1.2. Coefficient taking into account the loss of gas extinguishing agent through the openings of the room:
,
(6)
where 
- parameter that takes into account the location of openings along the height of the protected premises, m 0.5 s -1 .
The numerical values of the parameter are selected as follows:
0.65 - when the openings are located simultaneously in the lower (0 - 0.2) 
and the upper zone of the room (0, 8 - 1.0) or simultaneously on the ceiling and on the floor of the room, and the areas of the openings in the lower and upper parts are approximately equal and make up half of the total area of the openings; \u003d 0.1 - when openings are located only in the upper zone (0.8 - 1.0) of the protected room (or on the ceiling); = 0.25 - when openings are located only in the lower zone (0 - 0.2) of the protected premises (or on the floor); = 0.4 - with an approximately uniform distribution of the opening area over the entire height of the protected premises and in all other cases.
- parameter of leakage of the room, m -1,
where 
- total area of openings, m 2 .
Room height, m; 
- normative time of GOTV supply to the protected premises.
1.1.3. Extinguishing fires of subclass A 1 (except for smoldering materials specified in clause 7.1) should be carried out in rooms with a leakage parameter of not more than 0.001 m -1.
The value of the mass M p for extinguishing fires of subclass A 1 is determined by the formula
M p \u003d K 4. M p-hept,
where M p-hept - the value of the mass M p for the standard volumetric concentration of CH when quenching n-heptane, is calculated by formulas 2 or 3;
K 4 - coefficient taking into account the type of combustible material. The values of the coefficient K 4 are taken equal to: 1.3 - for extinguishing paper, corrugated paper, cardboard, fabrics, etc. in bales, rolls or folders; 2.25 - for premises with the same materials, to which access of firefighters is excluded after the end of the work of the AUGP, while the reserve stock is calculated at a value of K 4 equal to 1.3.
The supply time of the main stock of GOTV with a value of K 4 equal to 2.25 can be increased by a factor of 2.25. For other fires of subclass A 1, the value of K 4 is assumed to be 1.2.
Do not open the protected room or violate its tightness in any other way for at least 20 minutes (or until the arrival of fire departments).
When opening the premises, primary fire extinguishing equipment must be available.
For premises where access of fire departments is excluded after the end of the work of the AUGP, CO 2 should be used as a fire extinguishing agent with a coefficient of 2.25.
1. Average pressure in the isothermal tank over the time of carbon dioxide supply 
, MPa, is determined by the formula
,
(1)
where 
- pressure in the tank during storage of carbon dioxide, MPa; 
- pressure in the tank at the end of the release of the calculated amount of carbon dioxide, MPa, is determined from Figure 1.
2. Average consumption of carbon dioxide 
,
(2)
where 
- estimated amount of carbon dioxide, kg; 
- normative time of carbon dioxide supply, s.
3. The inner diameter of the supply (main) pipeline, m, is determined by the formula
where k 4 - multiplier, determined according to table 1; l 1 - the length of the supply (main) pipeline according to the project, m.
Table 1
|
Factor k 4 |
4. Average pressure in the supply (main) pipeline at the point of its entry into the protected room
,
(4)
where l 2 - equivalent length of pipelines from the isothermal tank to the point where the pressure is determined, m:
,
(5)
where 
- the sum of the coefficients of resistance of the fittings of pipelines.
5. Medium pressure
,
(6)
where R 3 - pressure at the point of entry of the supply (main) pipeline into the protected room, MPa; R 4 - pressure at the end of the supply (main) pipeline, MPa.
6. Average flow through nozzles Q m, kg s -1 , is determined by the formula
where 
- coefficient of flow through nozzles; A 3
- area of the nozzle outlet, m 2 ; k 5
- coefficient determined by the formula
. (8)
7. Number of nozzles 
is determined by the formula
.
8. Distribution pipe inner diameter 
, m, is calculated from the condition
,
(9)
where 
- nozzle outlet diameter, m.
R 
R 1 =2,4
Figure 1. Graph for determining the pressure in an isothermal
tank at the end of the release of the calculated amount of carbon dioxide
Note. Relative mass of carbon dioxide 
is determined by the formula
,
where 
- initial mass of carbon dioxide, kg.
Annex 7
Method for calculating the area of the opening for relieving excess pressure in rooms protected by gas fire extinguishing installations
Opening area for overpressure relief 
, m 2 , is determined by the formula
,
where 
- maximum permissible excess pressure, which is determined from the condition of maintaining the strength of the building structures of the protected premises or the equipment located in it, MPa; 
- atmospheric pressure, MPa; 
- air density in the operating conditions of the protected premises, kg m -3 ;
-
safety factor taken equal to 1.2; 
- coefficient taking into account the change in pressure when it is supplied; 
- GFFS supply time, determined from the hydraulic calculation, s; 
- the area of permanently open openings (except for the discharge opening) in the enclosing structures of the room, m 2.
Values 
,
, are determined in accordance with Appendix 6.
For GOTV - liquefied gases, the coefficient To 3 =1.
For GOTV - compressed gases, the coefficient To 3 is taken equal to:
for nitrogen - 2.4;
for argon - 2.66;
for the “Inergen” composition - 2.44.
If the value of the expression on the right side of the inequality is less than or equal to zero, then the opening (device) for relieving excess pressure is not required.
Note. The value of the opening area is calculated without taking into account the cooling effect of GFFS-liquefied gas, which can lead to some reduction in the opening area.
General provisions for the calculation of powder fire extinguishing installations of a modular type.
1. The initial data for the calculation and design of installations are:
geometric dimensions of the room (volume, area of enclosing structures, height);
the area of open openings in the enclosing structures;
operating temperature, pressure and humidity in the protected room;
a list of substances, materials in the room, and indicators of their fire hazard, the corresponding fire class according to GOST 27331;
type, size and scheme of fire load distribution;
availability and characteristics of ventilation, air conditioning, air heating systems;
characteristics and arrangement of technological equipment;
presence of people and ways of their evacuation.
technical documentation for modules.
2. Installation calculation includes the definition of:
the number of modules designed to extinguish a fire;
evacuation time, if any;
operating time of the installation;
the necessary stock of powder, modules, components;
the type and required number of detectors (if necessary) to ensure the operation of the installation, signal-starting devices, power supplies to start the installation (for cases according to clause 8.5).
Method for calculating the number of modules for modular powder fire extinguishing installations
1. Extinguishing the protected volume
1.1. Extinguishing the entire protected volume
The number of modules to protect the volume of the room is determined by the formula
, (1)
where 
-
the number of modules required to protect the premises, pcs.; 
- the volume of the protected premises, m 3; 
- the volume protected by one module of the selected type is determined according to the technical documentation (hereinafter referred to as the appendix-documentation) for the module, m 3 (taking into account the geometry of the spray - the shape and size of the protected volume declared by the manufacturer); 
=
11.2 - coefficient of uneven spraying of the powder. When placing spray nozzles on the border of the maximum allowable (according to the documentation for the module) height to 
=
1.2 or determined by the documentation for the module.
- safety factor that takes into account the shading of a possible source of fire, depending on the ratio of the area shaded by the equipment 
,
to the protected area S y, and is defined as:
at 
,
Shading area - is defined as the area of the part of the protected area where the formation of a fire is possible, to which the movement of powder from the spray nozzle in a straight line is blocked by structural elements that are impermeable to the powder.
At 
it is recommended to install additional modules directly in a shaded area or in a position that eliminates shading; when this condition is met k 
is taken equal to 1.
-
coefficient taking into account the change in the fire extinguishing efficiency of the powder used in relation to the combustible substance in the protected area in comparison with A-76 gasoline. Determined according to Table 1. In the absence of data, it is determined experimentally according to the methods of VNIIPO.
- coefficient taking into account the degree of leakage of the room. = 1 + B
F neg
,
where F neg = F/F pom- the ratio of the total area of leaks (openings, slots) F to the general surface of the room F pom, coefficient AT determined by Figure 1.
AT
20
Fн/ F , Fв/ F
Figure 1 Graph for determining the coefficient B when calculating the coefficient .
F n- leak area in the lower part of the room; F in- leak area in the upper part of the room, F-total area of leaks (openings, slots).
For impulse fire extinguishing installations, the coefficient AT can be determined from the documentation for the modules.
1.2. Local fire extinguishing by volume
The calculation is carried out in the same way as for extinguishing over the entire volume, taking into account paragraphs. 8.12-8.14. Local volume V n protected by one module is determined according to the documentation for the modules (taking into account the geometry of the spray - the shape and size of the local protected volume declared by the manufacturer), and the protected volume V h defined as the volume of an object increased by 15%.
In local quenching, the volume is taken to be =1,3, it is allowed to take other values given in the documentation for the module.
2. Fire fighting by area
2.1. Extinguishing throughout the area
The number of modules required for fire extinguishing over the area of the protected premises is determined by the formula
- the local area protected by one module is determined according to the documentation for the module (taking into account the geometry of the spray - the shape and size of the local protected area declared by the manufacturer), and the protected area
defined as the area of an object increased by 10%. In case of local extinguishing over the area, it is assumed = 1.3, it is allowed to take other values to 4 given in the documentation for the module or justified in the project.
As S n the area of the maximum rank of a class B source, which is extinguished by this module, can be taken (determined according to the documentation for the module, m 2).
Note. If fractional numbers are obtained when calculating the number of modules, the next larger integer in order is taken as the final number.
When protecting by area, taking into account the design and technological features of the protected object (with justification in the project), it is allowed to launch modules according to algorithms that provide zone protection. In this case, a part of the area allocated by design (driveways, etc.) or constructive non-combustible (walls, partitions, etc.) solutions is taken as the protected zone. In this case, the operation of the installation should ensure that the fire does not spread beyond the protected zone, calculated taking into account the inertia of the installation and the speed of fire propagation (for a specific type of combustible materials).
Table 1.
Coefficient comparative efficiency of fire extinguishers
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Hydraulic calculation is the most difficult stage in the creation of AUGPT. It is necessary to choose the diameters of the pipelines, the number of nozzles and the area of the outlet section, to calculate the real time of the exit of the GFFS.
How will we count?
First you need to decide where to get the methodology and formulas for hydraulic calculation. We open the set of rules SP 5.13130.2009, Appendix G and see there only the methodology for calculating low-pressure carbon dioxide fire extinguishing, but where is the methodology for other gas fire extinguishing agents? We look at paragraph 8.4.2 and see: "For the rest of the installations, it is recommended that the calculation be carried out according to the methods agreed upon in the prescribed manner."
Programs for calculation
Let us turn to the manufacturers of gas fire extinguishing equipment for help. In Russia, there are two methods for hydraulic calculations. One was developed and copied many times by leading Russian equipment manufacturers and approved by VNIIPO, on its basis the ZALP, Salyut software was created. The other was developed by the TACT company and approved by the DND of the Ministry of Emergency Situations, and the TACT-gas software was created on its basis.
The methods are closed to most design engineers and are for internal use by manufacturers of automatic gas fire extinguishing installations. If you agree, they will show it to you, but without special knowledge and experience, it will be difficult to perform a hydraulic calculation.
Currently, gas fire extinguishing is an effective, environmentally friendly and universal way to fight fire at an early stage of a fire.
The calculation of the installation of gas fire extinguishing systems is widely used at facilities where it is undesirable to use other fire fighting systems - powder, water, etc.
Such objects include premises with electrical equipment placed inside, archives, museums, exhibition halls, warehouses with explosive substances located there, etc.
Gas fire extinguishing and its undeniable advantages
In the world, including Russia, gas fire extinguishing has become one of the widely used methods for eliminating a fire source due to a number of undeniable advantages:
- minimizing the negative impact on the environment due to the release of gases;
- ease of removal of gases from the room;
- accurate distribution of gas over the area of the entire room;
- non-damage to property, valuables and equipment;
- functioning in a wide temperature range.
Why is a gas fire extinguishing calculation necessary?
To select a particular installation in a room or on an object, a clear calculation of gas fire extinguishing is required. So, there are centralized and modular complexes. The choice of one or another type depends on the number of rooms that need to be protected from fire, the area of \u200b\u200bthe object and its variety.
Taking into account these parameters, gas fire extinguishing is calculated, with the obligatory consideration of the mass of gas necessary to eliminate the source of ignition in a certain area. For such calculations, special methods are used, taking into account the type of fire extinguishing agent, the area of \u200b\u200bthe entire room and the type of fire installation.
For and calculation, the following parameters must be taken into account:
- area of the room (length, ceiling height, width);
- object type (archive, server rooms, etc.);
- the presence of open openings;
- type of combustible substances;
- fire hazard class;
- the degree of removal of the security console from the premises.
The need to calculate gas fire extinguishing
Fire extinguishing calculation is a preliminary stage before installing a gas fire extinguishing system at the facility. To ensure the safety of people and the safety of property, it is necessary to carry out a clear calculation of the equipment.
The validity of the calculation of gas fire extinguishing and subsequent installation at the facility is determined by the regulatory documentation. Be sure to use this system in server rooms, archives, museums and data centers. In addition, such installations are mounted in closed parking lots, in repair shops, and warehouse-type premises. The calculation of fire extinguishing directly depends on the size of the room and the type of goods stored in it.
The undeniable advantage of gas fire extinguishing over powder or water installations is the lightning-fast response and operation in the event of a fire, while the objects or materials in the room are reliably protected from the negative effects of fire extinguishing agents.
At the design stage, the amount of fire extinguishing agent required to eliminate the fire is calculated. The further functioning of the complex depends on this stage.
E.1 Estimated mass of GOTV, which must be stored in the installation, is determined by the formula
where - the mass of GFEA, intended to create a fire extinguishing concentration in the volume of the room in the absence of artificial air ventilation, is determined by the formulas:
For GOTV - liquefied gases, except for carbon dioxide:
For GOTV - compressed gases and carbon dioxide
here - the estimated volume of the protected premises, m. The estimated volume of the premises includes its internal geometric volume, including the volume of the ventilation, air conditioning, air heating system (up to hermetic valves or dampers). The volume of equipment located in the room is not deducted from it, with the exception of the volume of solid (impermeable) building elements (columns, beams, foundations for equipment, etc.);
Coefficient taking into account leakage of gaseous extinguishing agent from vessels;
Coefficient taking into account the loss of gas fire extinguishing agent through the openings of the room;
The density of the gas fire extinguishing agent, taking into account the height of the protected object relative to sea level for the minimum room temperature , kg/m, is determined by the formula
here is the vapor density of a gas fire extinguishing agent at a temperature of 293 K (20 °C) and an atmospheric pressure of 101.3 kPa;
Minimum air temperature in the protected room, K;
Correction factor taking into account the height of the object location relative to sea level, the values of which are given in Table E.11 of Appendix D;
Normative volume concentration, % (vol.).
The values of standard fire extinguishing concentrations are given in Appendix D.
The mass of the rest of GOV in pipelines, kg, is determined by the formula
where - the volume of the entire pipeline distribution of the installation, m;
Density of the GFFS residue at the pressure that exists in the pipeline after the end of the outflow of the mass of the gaseous fire extinguishing agent into the protected room;
The product of the remainder of DHW in the module, which is accepted according to the TD per module, kg, by the number of modules in the installation.
Note - For liquid combustible substances not listed in Appendix D, the standard volumetric fire extinguishing concentration of GFEA, all components of which are in the gas phase under normal conditions, can be determined as the product of the minimum volumetric fire extinguishing concentration and a safety factor equal to 1.2 for all GFFS except for carbon dioxide. For CO, the safety factor is 1.7.
For GFFS that are in the liquid phase under normal conditions, as well as GFFS mixtures, at least one of the components of which is in the liquid phase under normal conditions, the standard fire extinguishing concentration is determined by multiplying the volumetric fire extinguishing concentration by a safety factor of 1.2.
Methods for determining the minimum volumetric fire extinguishing concentration and fire extinguishing concentration are set out in GOST R 53280.3.
E.2 The coefficients of equation (E.1) are determined as follows.
E.2.1 Coefficient taking into account leakage of gaseous fire extinguishing agent from vessels 1.05.
E.2.2 Coefficient taking into account the loss of gas fire extinguishing agent through the openings of the room:
where is a parameter that takes into account the location of openings along the height of the protected room, m s.
The numerical values of the parameter are selected as follows:
0.65 - when openings are located simultaneously in the lower (0-0.2) and upper zones of the room (0.8-1.0) or simultaneously on the ceiling and on the floor of the room, and the areas of the openings in the lower and upper parts are approximately equal and make up half of the total area of openings; 0.1 - when openings are located only in the upper zone (0.8-1.0) of the protected room (or on the ceiling); 0.25 - when openings are located only in the lower zone (0-0, 2) the protected premises (or on the floor); 0.4 - with an approximately uniform distribution of the opening area over the entire height of the protected premises and in all other cases;
Leakage parameter of the room, m,
where is the total area of openings, m;
Room height, m;
Normative time for the supply of GOTV to the protected premises, s.
E.3 Subclass A fires (except for smoldering materials specified in 8.1.1) should be extinguished in rooms with a leakage parameter of not more than 0.001 m.
The mass value for extinguishing fires of subclass A is determined by the formula
where - the value of the mass for the standard volumetric concentration when extinguishing n-heptane, is calculated by formulas (2) or (3);
Coefficient taking into account the type of combustible material.
The values of the coefficient are taken equal to: 1.3 - for extinguishing paper, corrugated paper, cardboard, fabrics, etc. in bales, rolls or folders; 2.25 - for rooms with the same materials, in which access to firefighters after the end of the work of the AUGP is excluded. For other division A fires, other than those listed in 8.1.1, the value is assumed to be 1.2.
In this case, it is allowed to increase the standard time for the supply of GOTV in times.
If the estimated amount of GFEA is determined using a coefficient of 2.25, the reserve of GFEA can be reduced and determined by calculation using a coefficient of 1.3.
It is not necessary to open the protected room, to which access is allowed, or violate its tightness in any other way within 20 minutes after the operation of the AUGP (or before the arrival of the fire department).
Annex G
Fill in the form fields to find out the cost of a gas fire extinguishing system.
The preference of domestic consumers in favor of effective fire extinguishing, in which gas fire extinguishing agents are used to eliminate fires in electrical equipment and fires of class A, B, C (according to GOST 27331), is explained by the advantages of this technology. Fire extinguishing with the use of gas, in comparison with the use of other fire extinguishing agents, is one of the most non-aggressive methods of eliminating fires.
When calculating the fire extinguishing system, the requirements of regulatory documents, the specifics of the facility are taken into account, and the type of gas installation is determined - modular or centralized (the possibility of extinguishing a fire in several rooms).
Automatic gas fire extinguishing installation consists of:
- cylinders or other containers intended for the storage of a gaseous fire extinguishing agent,
- pipelines and directional valves that provide the supply of a fire extinguishing agent, gas (freon, nitrogen, CO2, argon, sulfur hexafluoride, etc.) in a compressed or liquefied state to the source of ignition,
- detection and control devices.
When making an application for the supply, installation of equipment or a full range of services, the clients of our company "CompaS" are interested in an estimate for gas fire extinguishing. Indeed, the information that this species is among the "expensive" ways to extinguish a fire is true. However, an accurate calculation of the fire extinguishing system, made by our specialists, taking into account all the conditions, demonstrates that in practice an automatic gas fire extinguishing installation can be the most effective and beneficial for the consumer.
Fire extinguishing calculation - the first stage of installation design
The main task for those who order gas fire extinguishing is to calculate the cost of the mass of gas that will be required to extinguish the fire in the room. As a rule, fire extinguishing is calculated by area (length, height, width of the room), under certain conditions, other parameters of the object may be required:
- type of premises (server room, archive, data center);
- the presence of open openings;
- if there is a raised floor and a false ceiling, indicate their heights;
- minimum room temperature;
- types of combustible materials;
- type of extinguishing agent (optional);
- explosion and fire hazard class;
- remoteness of the control room / security console from the protected premises.
Our company's customers can pre-order.
