Hydraulic calculation of gas fire extinguishing online calculator. Method for calculating gas fire extinguishing
No need to rush to conclusions!These formulas only show consumption in numbers.
Let's digress from the "candy wrappers" and pay attention to the "candy" and its "stuffing". And "candy" is formula A.16. What does she describe? Losses in the pipeline section, taking into account the flow of nozzles. Let's take a look at it, or rather what is in brackets. The left side describes the wiring of the main part of the pipeline and the processes in a cylinder or a gas fire extinguishing station, it is of little interest to us now, as a certain constant for wiring, while the right one is of particular interest! This is the whole highlight with the sum sign! Let's simplify the notation, let's transform the rightmost part inside the bracket space: (n^2*L)/D^5,25 into this form: n^2*X. Let's say you have six nozzles in a pipeline section. In the first section to the first nozzle (counting from the side of the cylinder), you have GOTV flowing to all six nozzles, then the losses in the section will be the losses to the nozzle plus what will leak further along the pipeline, the pressure will be less than if there was a plug after the nozzle. Then the right side will look like: 6 ^ 2 * X1 and we will get the parameter "A" for the first nozzle. Next, we come to the second nozzle and what do we see? And the fact that part of the gas is consumed by the first nozzle, plus what was lost in the pipe on the way to the nozzle, and what will leak further (taking into account the flow rate at this nozzle). Now the right side will already take the form: 6 ^ 2 * X1 + 5 ^ 2 * X2 and we will get the parameter “A” on the second nozzle. Etc. Here you also have expenses on each nozzle. Summing up these costs, you will get the cost of your installation and the time of release of GOTV. Why is everything so difficult? Very simple. Let's assume that the wiring has the same six nozzles and a branch (let's say that the right shoulder has two nozzles, and the left - 4), then we will describe the sections:
1) GOTV flows through it to all nozzles: 6 ^ 2 * X1;
2) flows along it to two nozzles on the right shoulder 6^2*X1+2^2*X2 - Parameter "A" for the first nozzle;
3) Parameter "A" for the second nozzle on the right shoulder 6^2*X1+2^2*X2+1^2*X3;
4) Parameter "A" for the third piping nozzle or the first nozzle on the left arm: 6^2*X1+4^2*X4;
5) and so on "according to the text."
I deliberately “teared off a piece” of the main pipeline to the first section for greater readability. In the first section, the flow rate is for all nozzles, and in the second and fourth sections, only for two on the right shoulder and four on the left, respectively.
Now you can see in the figures that the flow rate on 20 nozzles is always more than on one with the same parameters as 20.
In addition, with the naked eye you can see what is the difference between the flow rates between the “dictating” nozzles, that is, the nozzles located in the most advantageous place in the piping (where there are the least losses and the highest flow rate) and vice versa.
That's all!
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.
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.
Appendix 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 allowable 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 IN determined by Figure 1.
IN
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 IN 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 by 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
Emergencies and Disaster Management (1)
Document...) Groups premises (productions And technological processes) on degree danger development fire in dependencies from them functional destination And fire department loads combustible materials Group premises List of characteristic premises, productions ...
General provisions for the design and construction of gas distribution systems from metal and polyethylene pipes SP 42-101-2003 ZAO Polymergaz Moscow
abstract... on prevention them development. ... premises categories A, B, C1 fire and explosion fire department danger, in buildings of categories below III degree ... materials. 9.7 On the territory of cylinder warehouses (SB) in dependencies from technological process ...
Terms of reference for the provision of services for the organization of the exposition during the XXII Olympic Winter Games and the XI Paralympic Winter Games 2014 in the city of Sochi General information
Technical task... from them functional ... materials with indicators fire department danger premises. Everything combustible materials ... technological process fire department ...
For the provision of services for the organization of an exhibition exposition and presentation of projects of Rosneft Oil Company during the XXII Olympic and XI Paralympic Winter Games of 2014 in Sochi
Document... from them functional ... materials with indicators fire department danger allowed for use in these types premises. Everything combustible materials ... technological process. All Partner employees must know and comply with the requirements of the rules fire department ...
When designing gas fire extinguishing systems, the problem arises of determining time to enter the room the required amount of fire extinguishing agent for the given parameters of the hydraulic system. The possibility of carrying out such a calculation makes it possible to select the optimal characteristics of a gas fire extinguishing system that provides the required time for the release of the required amount of fire extinguishing agent.
In accordance with clause 8.7.3 of SP 5.13130.2009, at least 95% of the mass of the gas fire extinguishing agent required to create the standard fire extinguishing concentration in the protected room must be supplied over a time interval not exceeding 10 s for modular installations and 15 s for centralized gas fire extinguishing installations in which liquefied gases (except carbon dioxide) are used as a fire extinguishing agent of a fire extinguishing agent.
In connection with lack of approved domestic methods, allowing to determine the time of release of the fire extinguishing agent into the room, this method for calculating gas fire extinguishing was developed. This technique allows using computer technology to carry out calculation of the exit time of the fire extinguishing agent for gas fire extinguishing systems based on freons, in which the fire extinguishing agent is in cylinders (modules) in a liquid state under the pressure of a propellant gas, which provides the necessary rate of gas exit from the system. Wherein the fact of dissolution of the propellant gas in the liquid fire extinguishing agent is taken into account. This method of calculating gas fire extinguishing underlies the computer program TACT-Gas, in its part concerning the calculation of gas fire extinguishing systems based on freons and new extinguishing agent Novec 1230(freon FK-5-1-12).
The calculation of gas fire extinguishing is carried out during the development of projects and is carried out by a specialist - a design engineer. It provides for determining the amount of substance required for extinguishing, the required number of modules, and hydraulic calculation. It also includes work on setting a suitable pipeline diameter, determining the time it will take to supply gas to the room, taking into account the width of the openings and the area of \u200b\u200beach protected room.
Calculating the mass of a gas fire extinguishing agent allows you to calculate the required amount of freon used for. The following fire extinguishers are used to extinguish fire:
- carbon dioxide;
- nitrogen;
- argon inergen;
- sulfur hexafluoride;
- freons (227, 23, 125 and 218).
Depending on the principle of action, fire extinguishing compositions are divided into groups:
- Deoxidants are substances that act like a fire extinguishing concentration that creates a dense cloud around the flame. This concentration prevents the access of oxygen necessary to maintain the combustion process. As a result, the fire is extinguished.
- Inhibitors are special fire-extinguishing compositions that are capable of interacting with burning substances. As a result, combustion slows down.
Calculation of the mass of gas fire extinguishing agent
The calculation of the standard volume concentration allows you to determine what mass of a gaseous substance is required to extinguish a fire. The calculation of gas fire extinguishing is carried out taking into account the main parameters of the protected premises: length, width, height. You can find out the required mass of the composition using special formulas, which take into account the mass of freon necessary to create the gas concentration necessary for fire extinguishing in the volume of the room, the density of the compositions, as well as the concentration leakage coefficient for fire extinguishing from containers and other data.
Designing a gas fire extinguishing system
The design of a gas fire extinguishing system is carried out taking into account the following factors:
- number of rooms in the room, their volume, installed structures in the form of suspended ceilings;
- location of openings, as well as the number and width of permanently open openings;
- temperature and humidity in the room;
- features , the number of people at the facility.
Scheme of operation of the gas fire extinguishing system Other factors are also taken into account, depending on the individual design features, target affiliation, staff work schedule, if we are talking about an enterprise.
Selection and location of gas fire extinguishing modules
The calculation of gas fire extinguishing also provides for such a moment as the choice of a module. This is done taking into account the physical and chemical properties of the concentrate. The charging factor is determined. More often this value is from the range: 0.7-1.2 kg / l. Sometimes it is required to install several modules to one collector. In this case, the volume of the pipeline is important, the cylinders must match in size, one type of filler is selected, the same pressure of the propellant gas. The location is allowed in the protected room itself, or outside it - in the immediate vicinity. The distance from the gas tank to the heating system object is at least one meter.
Connected module of gas fire extinguishing system in production
After choosing the location of gas fire extinguishing installations, a hydraulic calculation should be made. During the hydraulic calculation, the following parameters are determined:
- pipeline diameter;
- train exit time from the module;
- nozzle outlet area.
You can make a hydraulic calculation both independently and using special programs.
When the results of the calculation are received and the installation is completed, it is necessary to instruct the personnel in accordance with. Special attention is paid to the regulatory framework, the preparation and placement of an evacuation plan, familiarization with the instructions.
Staff briefing and training on the use of personal protective equipment in case of fire
Authorized supervisory authorities
Instances exercising control:
- state fire supervision;
- safety department;
- fire-technical commission.
Compact gas extinguishing module for small spaces
Tasks of the controlling authorities
Responsibilities include monitoring compliance with the regulatory framework, ensuring the proper level of security, security of facilities. These institutions require:
- bringing the working conditions of employees to the established standards;
- installation of warning systems and automatic fire extinguishing systems;
- exclusion of the use of flammable materials for repairs and decoration;
- the requirement to eliminate any violations of fire safety.
Conclusion
Upon completion of the process, the company draws up project documentation in accordance with existing norms and requirements. The results of the work are provided to the customer for review.