E.1 The estimated mass of GFFS, which must be stored in the installation, is determined by the formula
where is the mass of fire extinguishing agent intended to create a fire extinguishing concentration in the volume of the room in the absence of artificial air ventilation, determined by the formulas:
For GOTV - liquefied gases, excluding carbon dioxide:
For GOTV - compressed gases and carbon dioxide
here - the calculated volume of the protected room, m. The calculated volume of the room includes its internal geometric volume, including the volume of the ventilation, air conditioning, air heating system (up to sealed valves or dampers). The volume of equipment located in the room is not deducted from it, with the exception of the volume of solid (impenetrable) building elements (columns, beams, foundations for equipment, etc.);
Coefficient taking into account leaks of gas extinguishing agent from vessels;
A coefficient that takes into account the loss of gas extinguishing agent through room openings;
Gas density fire extinguishing agent taking into account the height of the protected object relative to sea level for the minimum room temperature, kg/m, determined by the formula
here is the vapor density of the 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;
A correction factor that takes into account the height of the object relative to sea level, the values of which are given in Table E.11 of Appendix E;
Standard volume concentration, % (vol.).
The values of standard fire extinguishing concentrations are given in Appendix D.
The mass of GFFS residue in pipelines, kg, is determined by the formula
where is the volume of the entire piping of the installation, m;
The density of the residual fire extinguishing agent at the pressure that exists in the pipeline after the end of the flow of the mass of gaseous fire extinguishing agent into the protected room;
The product of the remaining GFFS in the module, which is accepted according to the TD per module, kg, by the number of modules in the installation.
Note - For liquid flammable substances not listed in Appendix E, the standard volumetric fire extinguishing concentration of GFFS, 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 by a safety factor equal to 1.2 for all GFFS , with the exception of carbon dioxide. For SO, the safety factor is 1.7.
For GFFS that are in the liquid phase under normal conditions, as well as mixtures of GFFS, 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 leaks of gas extinguishing agent from vessels 1.05.
E.2.2 Coefficient taking into account the loss of gas extinguishing agent through room openings:
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 floor of the room, and the areas of the openings in the lower and upper parts are approximately equal and constitute half of the total area of the openings; 0.1 - when the openings are located only in the upper zone (0.8-1.0) of the protected room (or on the ceiling); 0.25 - when the openings are located only in the lower zone (0-0, 2) the protected room (or on the floor); 0.4 - with an approximately uniform distribution of the area of openings over the entire height of the protected room and in all other cases;
Room leakage parameter, m,
where is the total area of openings, m;
Room height, m;
Standard time for supplying GFFS to the protected premises, s.
E.3 Extinguishing fires of subclass A (except for smoldering materials specified in 8.1.1) should be carried out in rooms with a leakage parameter of no more than 0.001 m.
The mass value for extinguishing fires of subclass A is determined by the formula
where is the mass value for the standard volumetric concentration when extinguishing n-heptane, calculated using formulas (2) or (3);
A coefficient that takes into account the type of combustible material.
The coefficient values 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 for firefighters after the end of the AUGP operation is excluded. For other fires of subclass A, except those specified in 8.1.1, the value is assumed to be 1.2.
In this case, it is allowed to increase the standard time for supplying GFFS by a factor.
If the estimated quantity of GFFS is determined using a factor of 2.25, the GFFS reserve can be reduced and determined by calculation using a factor of 1.3.
You should not open the protected room to which access is permitted, or break its tightness in any other way within 20 minutes after the activation of the AUGP (or until the fire department arrives).
Appendix G
Hydraulic calculation is the most difficult stage in creating an AUGPT. It is necessary to select the diameters of the pipelines, the number of nozzles and the outlet cross-sectional area, and calculate real time GOTV output.
How will we count?
First you need to decide where to get the methodology and formulas for hydraulic calculations. We open the set of rules SP 5.13130.2009, Appendix G and see there only the method for calculating carbon dioxide fire extinguishing low pressure, and where is the methodology for other gaseous fire extinguishing agents? We look at paragraph 8.4.2 and see: “For other installations, it is recommended to carry out calculations using methods agreed upon in the prescribed manner.”
Calculation programs
Let's turn to equipment manufacturers for help gas fire extinguishing. In Russia, there are two methods for hydraulic calculations. One developed and copied many times by leading Russian manufacturers equipment and approved by VNIIPO, on its basis created software"VALUE", "Salute". The other was developed by the TACT company and approved by the DND of the Ministry of Emergency Situations, on its basis the TACT-gaz software was created.
The techniques are closed to most design engineers and serve to internal use manufacturers of automatic gas fire extinguishing systems. If you agree, they will show it to you, but without special knowledge and experience it will be difficult to perform hydraulic calculations.
Currently, gas fire extinguishing is an effective, environmentally friendly and universal method of fighting fire at the early stage of a fire.
Calculation of the installation of gas fire extinguishing systems is widely used at facilities where the use of other fire fighting systems – powder, water, etc. – is undesirable.
Such objects include premises with electrical equipment, 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 of eliminating the source of fire due to a number of undeniable advantages:
- minimization negative influence on the environment due to the release of gases;
- ease of removing gases from the room;
- precise distribution of gas over the entire area of the room;
- non-damage to property, valuables and equipment;
- functioning over a wide temperature range.
Why is a gas fire extinguishing calculation necessary?
To select a particular installation for a room or facility, a clear calculation of gas fire extinguishing is required. Thus, a distinction is made between centralized and modular complexes. The choice of one type or another depends on the number of premises that need to be protected from fire, the area of the facility and its type.
Taking these parameters into account, gas fire extinguishing is calculated, with mandatory consideration of the mass of gas required to eliminate the source of fire in certain area. For such calculations we use special techniques, taking into account the type of fire extinguishing agent, the area of the entire room and the type of fire-fighting installation.
For calculations, the following parameters must be taken into account:
- room area (length, ceiling height, width);
- object type (archive, server rooms, etc.);
- the presence of open openings;
- type of flammable substances;
- Class fire danger;
- degree of distance of the security console from the premises.
The need to calculate gas fire extinguishing
Fire extinguishing calculations – preliminary stage before installing a gas fire extinguishing system on site. 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 regulatory documentation. The use of this system in server rooms, archives, museums and data centers is mandatory. In addition, such installations are installed in car parks closed type, in repair shops, 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 its lightning-fast response and operation in the event of a fire, while 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 extinguish the fire is calculated. The further functioning of the complex depends on this stage.
1. The estimated mass of GFSF M_g, which must be stored in the installation, is determined by the formula
M = K, (1)
where M is the mass of GFFS intended to create in volume
premises of fire extinguishing concentration in the absence of artificial
air ventilation is determined by the formulas:
for GFFS - liquefied gases, with the exception of carbon dioxide
M = V x po x (1 + K) x ──────────;
(2)
р р 1 2 100 - C
for GOTV - compressed gases and carbon dioxide
(2)
M = V x po x (1 + K) x ln ──────────, (3)
where V is the estimated volume of the protected room, m3.
The calculated volume of the room includes its internal geometric volume, including the volume of the ventilation, air conditioning, and air heating systems (up to sealed valves or dampers). The volume of equipment located in the room is not deducted from it, with the exception of the volume of solid (impenetrable) building elements (columns, beams, foundations for equipment, etc.); K_1 - coefficient taking into account leaks of gas extinguishing agent from vessels; K_2 - coefficient taking into account the loss of gas extinguishing agent through room openings; ro_1 - 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 T_m, kg x m(-3), determined by the formula
rho = rho x ──── x K, (4) where po_0 is the vapor density of the gas fire extinguishing agent at temperature T_0 = 293 K (20°C) and atmospheric pressure 101.3 kPa; T_m - minimum air temperature in the protected room, K; K_3 - correction factor taking into account the height of the object relative to sea level, the values of which are given in table 11
appendices 5; S_n - standard volume concentration, % (vol.).
The values of standard fire extinguishing concentrations С_н are given in Appendix 5.
The mass of the remaining GFFS in pipelines M_tr, kg, is determined by the formula
M = V x rho, (5)
where V is the volume of the entire installation piping, m3;
po is the density of the GFFS residue at the pressure that exists in
pipeline after the expiration of the mass of gas fire extinguishing agent
substances M into the protected area; M x n - product of the remainder of the GFSR in
module (M), which is accepted according to TD per module, kg, per quantity
There are n modules in the installation.
Note. For liquid flammable substances not listed in Appendix 5, the standard volumetric fire extinguishing concentration of GFFS, 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 by a safety factor equal to 1.2 for all GFFS, with the exception of carbon dioxide. For CO2, the safety factor is 1.7.
For GFFS that are in the liquid phase under normal conditions, as well as mixtures of GFFS, 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. Equation coefficients (1) are defined as follows.
1.1.1. Coefficient taking into account leaks of gas extinguishing agent from vessels:
1.1.2. Coefficient taking into account the loss of gas extinguishing agent through room openings:
K = P x delta x tau x square root (H), (6)
where P is a parameter that takes into account the location of openings along the height of the protected room, m(0.5) x s(-1).
The numerical values of the parameter P are selected as follows:
P = 0.65 - when openings are located simultaneously in the lower (0-0.2) N and upper zones of the room (0.8-1.0) N or simultaneously on the ceiling and on the floor of the room, and the areas of the openings in the lower and upper the parts are approximately equal and make up half the total area of the openings; P = 0.1 - when openings are located only in the upper zone (0.8-1.0) N of the protected room (or on the ceiling); P = 0.25 - when openings are located only in the lower zone (0-0.2) N of the protected room (or on the floor); P = 0.4 - with an approximately uniform distribution of the area of openings over the entire height of the protected room and in all other cases;
delta = ───────── - room leakage parameter, m(-1),
where the sum F_H is the total area of the openings, m2, H is the height of the room, m; tau_pod - standard time for supplying GFFS to the protected premises, s.
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 no more than 0.001 m(-1).
The value of mass М_р for extinguishing fires of subclass A_i is determined by the formula
r 4 r-hept
where M is the value of mass M for the standard volume concentration C
r-hept r n
when extinguishing n-heptane, calculated by formulas (2) or (3) ;
K is a coefficient that takes 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 AUGP operation, while the reserve stock is calculated at a K_4 value of 1.3.
The supply time of the main stock of GFFS with a K_4 value of 2.25 can be increased by 2.25 times. For other fires of subclass A_1, the value of K_4 is taken equal to 1.2.
You should not open the protected room to which access is permitted, or break its tightness in any other way within 20 minutes after the activation of the AUGP (or until the fire department arrives).