Determination of system operating parameters.

Hydraulic calculation of a sprinkler network is aimed at determining water flow, as well as determining the required pressure at water feeders and the most economical pipe diameters.
According to NPB 88-2001*, the required amount of water to extinguish a fire is equal to:

Q = q*S, l/s

Where q – required irrigation intensity, hp/m2;
S – area for calculating water consumption, m.

The actual consumption of the fire extinguishing agent is determined based on the technical characteristics of the selected type of sprinkler, the pressure in front of it, the conditions for placing the required number of sprinklers to protect the design area, including if it is necessary to install sprinklers under technological equipment, platforms or ventilation ducts, if they interfere irrigation of the protected surface. The calculated area is accepted in accordance with NPB 88-2001, depending on the group of premises.
When determining the actual water flow, many designers either take the minimum required flow rate as the calculated flow rate, or stop the calculation when the required amount of fire extinguishing agent is reached.
The mistake is that in this way irrigation of the entire standard design area with the required intensity is not ensured, since the system is not calculated and does not take into account the actual operation of the sprinklers on the design area. Consequently, the diameters of the main and supply pipelines are incorrectly determined, pumps and types of control units are selected.
Let's look at the above with a small example.

It is necessary to protect the premises S=50 m2, with the required intensity q=0.08 l/s*m2

According to NPB 88-2001*, the required amount of water to extinguish a fire is equal to: Q=50*0.08=4 l/s.
According to clause 6. App. 2 NPB 88-2001*, the design water flow Qd, l/s, through the sprinkler is determined by the formula:

Where k– sprinkler performance coefficient, accepted according to the technical documentation for the product, k=0.47(for this option); N– free pressure in front of the sprinkler, H=10 m.

Since it is impossible to describe in detail the hydraulic calculation in the scope of one article, taking into account all the necessary factors affecting the operation of the system - linear and local losses in pipelines, the configuration of the system (ring or dead-end), in this example we will take the water flow as the sum of the costs through the most distant sprinkler .

Qф=Qd*n,

Where n– number of sprinklers placed on the protected area

Qf=1.49*8=11.92 l/s.

We see that the actual consumption Qf significantly exceeds the required amount of water Q, therefore, for normal operation of the system, ensuring all the required conditions, it is necessary to provide for all possible factors affecting the operation of the system.

Automatic water sprinkler fire extinguishing installation combined with fire hydrants.

Sprinklers and fire hydrants are two fire protection systems that have the same purpose, but a different functional structure, so combining them causes some confusion, since you have to be guided by different regulatory documents to build a common system.
According to clause 4.32 of NPB 88-2001*, “In water-filled sprinkler installations on supply pipelines with a diameter of 65 mm or more, the installation of fire hydrants in accordance with SNiP 2.04.01-85* is allowed.”
Let's look at one of the most common options. This example often comes across in multi-storey buildings, when, at the request of the customer and in order to save money, they combine an automatic sprinkler fire extinguishing system with an internal fire water supply system.
According to clause 9.1 of SNiP 2.04.01-85*, if the number of fire hydrants is 12 or more, the system should be a ring one. Ring networks must be connected to the outer ring network with at least two inputs.

Errors made in the diagram on the image 2:
? Sections of the supply pipeline to sections with more than 12 PCs “A+B” and “G+D” are dead ends. The floor ring does not meet the requirements of clause 9.1 of SNiP 2.04.01-85*.
“Internal cold water plumbing systems should be:
– dead-end, if a break in the water supply is allowed and the number of fire hydrants is up to 12;
– ring or with looped inputs with two dead-end pipelines with looped inputs with two dead-end pipelines with branches to consumers from each of them to ensure continuous water supply.
Ring networks must be connected to the outer ring network with at least two inputs.”
P. 4.34. NPB 88-2001*: “A section of a sprinkler installation with 12 or more fire hydrants must have two inputs.”
? According to clause 4.34. NPB 88-2001*, “for sprinkler installations with two sections or more, the second input with a valve may be made from an adjacent section.” Section “A+G” is not such an input, since after it there is a dead-end section of the pipeline.
? The requirements of clause 6.12 are violated. SNiP 2.04.01-85*: the number of jets supplied from one riser exceeds the standard values. “The number of jets supplied from each riser should be no more than two.”
This scheme is appropriate when the number of fire hydrants in the sprinkler section is less than 12.

On Figure 3 Each section of a sprinkler installation with more than 12 fire hydrants has two inputs, the second input is made from the adjacent section (Section “A+B”, which does not contradict the requirement of clause 4.34 of NPB 88-2001*).
The risers are looped with horizontal jumpers, creating a single ring, therefore clause 6.12. SNiP 2.04.02-84* “The number of jets supplied from each riser should be no more than two” is not violated.
This scheme implies uninterrupted supply of water to the system according to reliability category I.

Water supply for automatic water fire extinguishing installation.

Fire extinguishing systems are intended to ensure the safety of people and property, so they must be in working condition at all times.
If it is necessary to install booster pumps on the system, it is necessary to provide them with electricity and water supply under uninterrupted conditions, i.e. according to reliability category I.
Water fire extinguishing systems belong to category I. According to clause 4.4, the requirements for the system are:
“Category I - it is allowed to reduce the water supply for household and drinking needs by no more than 30% of the calculated consumption and for production needs up to the limit established by the emergency work schedule of enterprises; The duration of the reduction in supply should not exceed 3 days. An interruption in the water supply or a reduction in supply below the specified limit is allowed while the reserve elements of the system (equipment, fittings, structures, pipelines, etc.) are turned off, but not more than for 10 minutes.”
One of the errors encountered in projects is that the automatic water fire extinguishing system is not provided with category I water supply reliability.
This arises due to the fact that clause 4.28. NPB 88-2001* states “Supply pipelines may be designed as dead-end pipelines for three or fewer control units.” Guided by this principle, designers often, when the number of control units is less than three, but the installation of fire booster pumps is required, they provide one input to the fire extinguishing systems.
This decision is not correct, since pumping stations of automatic fire extinguishing systems should be classified as reliability category I, according to Note. 1 clause 7.1 SNiP 2.04.02-84 “Pumping stations that supply water directly to the fire-fighting and combined fire-fighting water supply network should be classified as category I.”
According to clause 7.5 of SNiP 2.04.02-84, “The number of suction lines to the pumping station, regardless of the number and groups of installed pumps, including fire pumps, must be at least two. When one line is turned off, the rest must be designed to pass the full design flow for pumping stations of categories I and II.”
Based on all of the above, it is advisable to pay attention to the fact that, regardless of the number of control units of the automatic fire extinguishing installation, if the system has a pumping unit, it must be provided with reliability category I.
Since at this time the design documentation is not approved by the State Fire Supervision authorities before the start of construction and installation work, correcting errors after the installation is completed and the facility is handed over to the supervisory authorities entails unjustified costs and an increase in the time it takes to put the facility into operation.

S. Sinelnikov, Technos-M+ LLC

We select the parameters of the main water feeders for a water fire extinguishing installation protecting a wood storage warehouse (P = 180 kg/m 3).

Water irrigation intensity I=0.4 l/(m 2 . s) according to table 5.2 for group 6 of premises according to the degree of fire hazard.

Irrigation area with a sprinkler F op =12 m 2. The routing of pipelines and the location of sprinklers on the plan are shown on sheet 1 of the graphic part.

We select the type of sprinkler and its main parameters. To do this, we will determine the required pressure and flow rate at the dictating sprinkler.

Based on the calculations obtained, we use the SVN-15 sprinkler in the designed installation.

Let's check the flow rate from the sprinkler:

We accept l/s with a certain safety factor (although this procedure is not prescribed by any regulatory document, and therefore the consumption may not be increased).

Thus, we obtain the initial hydraulic parameters of the dictating sprinkler:

For the left branch of the distribution pipeline, we accept the following pipeline parameters:

section 1-2: mm;

section 2-3: mm;

section 3-4: mm;

section 4-a: mm.

When designing distribution, supply and supply networks, it is necessary to proceed from the considerations that water and foam AUPs are operated, as a rule, for quite a long time without replacing pipelines. Therefore, if we focus on the specific hydraulic resistance of new pipes, after a certain time their roughness increases, as a result of which the distribution network will no longer correspond to the calculated parameters for flow and pressure. In this regard, the average roughness of the pipes is accepted. The resistivity value A is taken from Table V.1. of this manual.

The flow rate of the first sprinkler 1 is the calculated value in the area between the first and second sprinklers.

Thus, the pressure drop in the area will be:

Pressure at sprinkler 2:

Sprinkler flow rate 2:

The estimated flow rate in the area between the first and second sprinklers, i.e. on the site will be:

Sprinkler pressure 3:

Sprinkler consumption 3:

Estimated flow rate in the area between the first and third sprinklers, i.e. on the site will be:

Based on water flow, pressure losses in the area are determined:

The pressure loss in the water pipeline section at mm is very high, so we take the pipeline diameter in mm in the section. Then:

Sprinkler pressure 4:

Sprinkler consumption 4:

Thus, even a slight change in the specification of the distribution and supply pipelines towards a decrease in diameter leads to a fairly significant change in pressure, which requires the use of a fire pump with a high supply pressure.

The estimated flow rate in the area between the first and fourth sprinklers, i.e. on the site will be:

Based on water flow, the pressure loss in the area (m) is determined:

Pressure at point a:

We accept the site as similar to the site, i.e. the diameters and lengths of the pipelines will be equal:

section a-5: mm; m;

section 5-6: mm; m;

section 6-7: mm; m.

In row I, the right branch is asymmetrical to the left branch. The specific hydraulic resistance (or specific hydraulic characteristic) of the right branch of the distribution pipeline depends on the diameters of the pipeline section between sprinklers 7-6, 6-5 and between sprinkler 5 and t.a (5-a).

The pressure of the right branch of row I with sprinklers 5-7 in point a should be equal to the pressure of the left branch of row I with sprinklers 1-4, i.e. MPa.

The flow rate in the right branch of row I at a pressure of 0.272 MPa will be:

where B a-7 is the hydraulic characteristic of the right branch of row I.

Provided that the left and right branches of row I are symmetrical (three sprinklers in each branch), the flow rate should be similar to the flow rate, i.e. =7.746 l/s.

The pressure of sprinkler 5 is similar to the pressure of sprinkler 3, i.e. MPa.

Then the pressure in point a for the right branch of row I will be:

Hydraulic characteristics of the right branch of row I:

Thus, the estimated flow rate of the right branch of row I will be:

Total consumption of row I:

those. the true maximum flow rate of the AUP will be not 10, but 29.2 l/s.

The diameter of the supply pipeline in the area is assumed to be mm.

The flow rate determines the pressure loss in the area:

Since the pressure loss in the area is quite large, we assume the diameter of the supply pipeline is mm.

Then the pressure loss in the area will be:

The pressure in point b will be:

Total consumption of two rows:

The calculation of all subsequent rows, if they are constructed in the same way, is carried out using a similar algorithm.

Since the hydraulic characteristics of the rows, made structurally identical, are equal, the characteristic of row II is determined by the generalized characteristic of the design section of the pipeline of row I:

Water consumption from row II is determined by the formula:

Relative coefficient of expenditure of rows II and I:

The flow rate determines the pressure loss in the area:

The pressure in t.s will be:

Since the hydraulic characteristics of the rows, made structurally identical, are equal, the characteristic of row III is determined by the generalized characteristic of the design section of the pipeline of row II:

Water consumption from row III is determined by the formula:

Total consumption of three rows:

According to the previously existing NPB 88, the consumption of sprinkler AUP is determined as the product of the standard irrigation intensity by the area for calculating water consumption, i.e. consumption should be equal to:

If for a sprinkler AUP the area for calculating the flow rate is assumed to be 160 m 2, then its total flow rate from three rows will not be l/s, but 93.2 l/s.

The required pressure (pressure) that the pumping unit must provide is determined by the formula

P=P O +P T +P M +P УУ +P H +P Z +P ВХ

It is required to select a pump for a sprinkler installation with the following hydraulic network parameters:

total AUP consumption is 36 m 3 /h

pressure at the dictating sprinkler P O =0.075 MPa

linear pressure loss in the supply and supply pipelines P T =0.942 MPa

local pressure loss in the pipeline P M =0.001 MPa

pressure loss in the sprinkler control unit P УУ =0.19 MPa

pressure loss in the pumping unit P H =0.6 MPa

pressure equivalent to the geometric height of the dictating sprinkler P Z =0.0036 MPa

pressure of the external main network P ВХ =0.642 MPa

Р=0.075+0.942+0.001+0.19+0.6+0.0036-0.642=1.17 MPa

Based on flow rate Q = 93.2 l/s and pressure P = 1.17 MPa, we select from the catalog two pumps TP(D) 200 - 660 (with a speed of 2900 rpm), one main, the second backup.

The water fire extinguishing sprinkler system is practical and functional. It is used within entertainment facilities, utility and industrial buildings. The main feature of sprinkler lines is the presence of sprinklers with polymer inserts. Under the influence of high temperatures, the insert fuses, activating the fire extinguishing process.

Fire sprinkler system diagram

A typical system includes the following elements.

• Control modules.
• Pipeline.
• Sprinklers.
• Control module.
• Valves.
• Pulse module.
• Compressor equipment.
• Measuring instruments.
• Pumping installation.

When calculating fire extinguishing systems, the parameters of the room (area, ceiling height, layout), requirements of industry standards, and requirements of technical specifications are taken into account.

Calculation of water fire extinguishing sprinkler systems must be carried out by qualified specialists. They have specialized measuring instruments and the necessary software.

System advantages

Fire sprinkler systems have many advantages.

• Automatic activation in case of fire.
• Simplicity of basic operating schemes.
• Maintaining performance characteristics over a long period of time.
• Ease of maintenance.
• Reasonable price.

Disadvantages of the system

The disadvantages of sprinkler systems include:

• Dependence on standard water supply line.
• Impossibility of use at facilities with a high degree of electrification.
• Difficulties when used in conditions of negative temperatures (requires the use of air-water solutions).
• Sprinklers are unsuitable for reuse.

An example of calculating a water fire extinguishing sprinkler installation

Hydraulic calculation of a fire sprinkler system allows you to determine operating pressure indicators, optimal pipeline diameter and line performance.

When calculating sprinkler fire extinguishing in terms of water consumption, the following formula is used:

Q=q p *S, where:

• Q—sprinkler productivity;
• S is the area of ​​the target object.

Water flow is measured in liters per second.

The sprinkler productivity is calculated using the formula:

q p = J p * F p , where

• J p is the irrigation intensity established by regulatory documents in accordance with the type of room;
• F p is the coverage area of ​​one sprinkler.

The sprinkler performance coefficient is presented as a number and is not accompanied by units of measurement.

When calculating the system, engineers determine the diameter of the sprinkler outlets, material consumption, and optimal technological solutions.

If you require a calculation of a fire sprinkler system, contact the Teploognezashchita staff. Specialists will quickly cope with the task and provide recommendations for solving standard and non-standard issues.

Selecting an automatic fire extinguishing system

The type of automatic extinguishing installation, the method of extinguishing, the type of fire extinguishing agents, the type of equipment for fire automatic fire installations are determined by the design organization depending on the technological, structural and space-planning features of the protected buildings and premises, taking into account the requirements of Appendix A “List of buildings, structures, premises and equipment , subject to protection by automatic fire extinguishing installations and automatic fire alarms" (SP 5.13130.2009).

Thus, as a designer, we install a water fire extinguishing sprinkler system in the carpentry shop. Depending on the air temperature in the warehouse of electrical goods in combustible packaging, we accept a water-filled fire extinguishing sprinkler system, since the air temperature in the carpentry shop is more than + 5 ° C (clause 5.2.1. SP 5.13130.2009).

The fire extinguishing agent in a water fire extinguishing sprinkler installation will be water (handbook by A.N. Baratov).

Hydraulic calculation of a water sprinkler fire extinguishing installation

4.1 Selection of standard data for calculation and choice of sprinklers

Hydraulic calculations are carried out taking into account the operation of all sprinklers on a minimum sprinkler AUP area of ​​at least 90 m2 (Table 5.1 (SP 5.13130.2009)).

We determine the required water flow through the dictating sprinkler:

where is the standard irrigation intensity (Table 5.2 (SP 5.13130.2009));

Design area for sprinkler irrigation, .

1. The estimated water flow through the dictating sprinkler located in the dictating protected irrigated area is determined by the formula:

where K is the sprinkler performance coefficient, accepted according to the technical documentation for the product;

P - pressure in front of the sprinkler, .

As a designer, we select a water sprinkler model ESFR d=20 mm.

We determine the water flow through the dictating sprinkler:

Checking the condition:

the condition is met.

We determine the number of sprinklers involved in the hydraulic calculation:

where is the AUP consumption, ;

Consumption of 1 sprinkler, .

4.2 Placement of sprinklers in the plan of the protected room

4.3 Pipeline routing

1. The diameter of the pipeline in section L1-2 is assigned by the designer or determined by the formula:

Consumption in this area, ;

Speed ​​of water movement in the pipeline, .

4.4 Hydraulic network calculation

According to Table B.2 of Appendix B “Methodology for calculating the parameters of the fire extinguishing system for surface fire extinguishing with water and low expansion foam” (SP 5.13130.2009), we take the nominal diameter of the pipeline equal to 50 mm; for steel water and gas pipes (GOST - 3262 - 75) the specific characteristic of the pipeline is equal to .

1. Pressure loss P1-2 in section L1-2 is determined by the formula:

where is the total consumption of waste water of the first and second sprinkler, ;

Length of the section between 1 and 2 sprinklers, ;

Specific characteristics of the pipeline, .

2. The pressure at sprinkler 2 is determined by the formula:

3. The flow rate of sprinkler 2 will be:

8. Pipeline diameter at the site L 2-a will be:

accept 50 mm

9. Pressure loss R 2-a Location on L 2-a will be:

10. Point pressure A will be:

11. Estimated flow rate in the area between 2 and point A will be equal to:

12. For the left branch of row I (Figure 1, section A) it is required to provide flow at pressure. The right branch of the row is symmetrical to the left, so the flow rate for this branch will also be equal, and therefore the pressure at the point A will be equal.

13. Water consumption for branch I will be:

14. Calculate the branch coefficient using the formula:

15. Pipeline diameter at the site L a-c will be:

we accept 90 mm, .

16. The generalized characteristic of branch I is determined from the expression:

17. Pressure loss R a-c Location on L a-c will be:

18. The pressure at point b will be:

19. Water flow from branch II is determined by the formula:

20. Water flow from branch III is determined by the formula:

we accept 90 mm, .

21. Water flow from branch IV is determined by the formula:

we accept 90 mm, .

22. Calculate the row coefficient using the formula:

23. Let's calculate the consumption using the formula:

24. Checking the condition:

the condition is met.

25. The required pressure of the fire pump is determined by the formula:

where is the required pressure of the fire pump, ;

Pressure loss in horizontal sections of the pipeline;

Pressure loss on a horizontal section of the pipeline s - st, ;

Pressure loss in the vertical section of the pipeline DB, ;

Pressure losses in local resistances (shaped parts B And D), ;

Local resistances in the control unit (signal valve, gate valves, shutters), ;

Pressure at the dictating sprinkler, ;

Piezometric pressure (geometric height of the dictating sprinkler above the axis of the fire pump), ;

Fire pump inlet pressure, ;

Pressure required, .

26. Pressure loss on a horizontal section of the pipeline s - st will be:

27. Pressure loss on a horizontal section of the pipeline AB will be:

where is the distance to the fire extinguishing pumping station, ;

28. The pressure loss on the horizontal section of the BD pipeline will be:

29. Pressure losses in horizontal sections of the pipeline will be:

30. Local resistance in the control unit will be:

31. Local resistance in the control unit (signal valve, valves, shutters) is determined by the formula:

where is the pressure loss coefficient, respectively, in the sprinkler control unit (accepted individually according to the technical documentation for the control unit as a whole);

Water flow through the control unit, .

32. Local resistance in the control unit will be:

We select an air sprinkler control unit - УУ-С100/1.2Вз-ВФ.О4-01 TU4892-080-00226827-2006* with a pressure loss coefficient of 0.004.

33. The required pressure of the fire pump will be:

34. The required pressure of the fire pump will be:

35. Checking the condition:

the condition is not met, i.e. installation of an additional tank is required.

36. According to the obtained data, we select a pump for the AUPT - a 1D centrifugal pump, series 1D250-125, with an electric motor power of 152 kW.

37. Determine the water supply in the tank:

where Q us is the pump flow rate, l/s;

Q water network - water supply network consumption, l/s;

Calculation of automatic water feeder

Minimum pressure in automatic water feeder:

N av = N 1 + Z + 15

where H 1 is the pressure at the dictating sprinkler, m.v.s.;

Z-geometric height from the pump axis to the sprinkler level, m;

Z= 6m (room height) + 2 m (pump room floor level below) = 8m;

15 - reserve for operation of the installation until the backup pump is turned on.

N av =25+8+15=48 m.v.s.

To maintain the pressure of the automatic water feeder, we select a CR 5-10 jockey pump with a pressure of 49.8 m.w.s.

Ministry of Education and Science of the Russian Federation

Ufa State Aviation Technical University

Department of Fire Safety

Calculation and graphic work

Topic: Calculation of automatic water fire extinguishing installation

Supervisor:

department assistant

“Fire Safety” Gardanova E.V.

Executor

student of group PB-205 vv

Gafurova R.D.

Gradebook No. 210149

Ufa, 2012

Exercise

In this work, it is necessary to make an axonometric diagram of a water automatic fire extinguishing system, indicating on it the sizes and diameters of pipe sections, locations of sprinklers and the necessary equipment.

Carry out hydraulic calculations for selected pipeline diameters. Determine the design flow rate of an automatic water fire extinguishing installation.

Calculate the pressure that the pumping station must provide and select equipment for the pumping station.

fire extinguishing installation pipeline pressure

annotation

The RGR course “Industrial and fire automatics” is aimed at solving specific problems in the installation and maintenance of fire automatics installations.

This paper shows ways to apply theoretical knowledge to solve engineering problems related to the creation of fire protection systems for buildings.

During the work:

technical and regulatory documentation regulating the design, installation and operation of fire extinguishing installations was studied;

a method of technological calculations is given to ensure the required parameters of the fire extinguishing installation;

shows the rules for using technical literature and regulatory documents on the creation of fire protection systems.

Carrying out RGR contributes to the development of students' independent work skills and the formation of a creative approach to solving engineering problems related to the creation of fire protection systems for buildings.

annotation

Introduction

Initial data

Calculation formulas

Basic principles of fire extinguishing installation

1 Operating principle of the pumping station

2 Operating principle of a sprinkler system

Design of a water fire extinguishing installation. Hydraulic calculation

Equipment selection

Conclusion

Bibliography

Introduction

Automatic water fire extinguishing systems are currently the most widespread. They are used over large areas to protect shopping and multifunctional centers, administrative buildings, sports complexes, hotels, businesses, garages and parking lots, banks, energy facilities, military and special-purpose facilities, warehouses, residential buildings and cottages.

My version of the assignment presents a facility for the production of alcohols and ethers with utility rooms, which, in accordance with clause 20 of Table A.1 of Appendix A of Code of Practice 5.13130.2009, regardless of the area, must have an automatic fire extinguishing system. In accordance with the requirements of this table, it is not necessary to equip the remaining utility rooms of the facility with an automatic fire extinguishing system. The walls and ceilings are reinforced concrete.

The main types of fire loads are alcohols and ethers. In accordance with the table, we decide that it is possible to use a foaming agent solution for extinguishing.

The main fire load in a facility with a room height of 4 meters comes from the repair area, which, in accordance with the table in Appendix B of the set of rules 5.13130.2009, belongs to group 4.2 of premises according to the degree of fire hazard, depending on their functional purpose and the fire load of combustible materials.

The facility does not have premises of categories A and B for explosion and fire hazards in accordance with SP 5.13130.2009 and explosive zones in accordance with the PUE.

To extinguish possible fires in the facility, taking into account the existing flammable load, it is possible to use a foaming agent solution.

To equip a facility for the production of alcohols and ethers, we will choose an automatic sprinkler-type foam fire extinguishing installation filled with a foaming agent solution. Foaming agents mean concentrated aqueous solutions of surfactants (surfactants) intended to produce special solutions of wetting agents or foam. The use of such foaming agents during fire extinguishing can significantly reduce the intensity of combustion within 1.5-2 minutes. The methods of influencing the source of ignition depend on the type of foaming agent used in the fire extinguisher, but the basic principles of operation are the same for all:

due to the fact that the foam has a mass significantly less than the mass of any flammable liquid, it covers the surface of the fuel, thereby suppressing the fire;

the use of water, which is part of the foaming agent, allows, within a few seconds, to reduce the temperature of the fuel to a level at which combustion becomes impossible;

the foam effectively prevents the hot fumes generated by the fire from spreading further, making re-ignition virtually impossible.

Thanks to these features, foam concentrates are actively used for fire extinguishing in the petrochemical and chemical industries, where there is a high risk of ignition of flammable and flammable liquids. These substances do not pose a threat to human health or life, and traces of them can be easily removed from premises.

1. Initial data

Hydraulic calculations are carried out in accordance with the requirements of SP 5.13130.2009 “Fire extinguishing and alarm installations. Design standards and rules” according to the methodology set out in Appendix B.

The protected object is a room volume of 30x48x4m, in plan - a rectangle. The total area of ​​the facility is 1440 m2.

We find the initial data for the production of alcohols and ethers in accordance with a certain group of premises from Table 5.1 of this set of rules in the section “Water and foam fire extinguishing installations”:

irrigation intensity - 0.17 l/(s*m2);

area for calculating water consumption - 180 m2;

minimum water consumption of fire extinguishing installation - 65 l/s;

the maximum distance between sprinklers is 3 m;

The selected maximum area controlled by one sprinkler is 12m2.

operating time - 60 min.

To protect the warehouse, we select the sprinkler SPO0-RUo(d)0.74-R1/2/P57(68,79,93,141,182).V3-"SPU-15" PO "SPETSAVTOMATIKA" with a performance coefficient k = 0.74 (according to technical .documentation for the sprinkler).

2. Calculation formulas

The estimated water flow through the dictating sprinkler located in the dictating protected irrigated area is determined by the formula

where q1 is the consumption of waste water through the dictating sprinkler, l/s; is the sprinkler performance coefficient accepted according to the technical documentation for the product, l/(s MPa0.5);

P - pressure in front of the sprinkler, MPa.

The flow rate of the first dictating sprinkler is the calculated value of Q1-2 in the section L1-2 between the first and second sprinklers

The diameter of the pipeline in section L1-2 is assigned by the designer or determined by the formula

where d1-2 is the diameter between the first and second sprinklers of the pipeline, mm; -2 is the waste water consumption, l/s;

μ - flow coefficient; - water movement speed, m/s (should not exceed 10 m/s).

The diameter is increased to the nearest nominal value according to GOST 28338.

Pressure loss P1-2 in section L1-2 is determined by the formula

where Q1-2 is the total flow rate of the first and second sprinklers, l/s; t is the specific characteristics of the pipeline, l6/s2;

A is the specific resistance of the pipeline, depending on the diameter and roughness of the walls, c2/l6.

The resistivity and specific hydraulic characteristics of pipelines for pipes (made of carbon materials) of various diameters are given in table B.1<#"606542.files/image005.gif">

The hydraulic characteristics of the rows, made structurally identical, are determined by the generalized characteristics of the design section of the pipeline.

The generalized characteristic of row I is determined from the expression

The pressure loss in section a-b for symmetrical and asymmetrical schemes is found using the formula.

The pressure at point b will be

Рb=Pa+Pa-b.

Water consumption from row II is determined by the formula

The calculation of all subsequent rows until the calculated (actual) water flow rate and the corresponding pressure are obtained is similar to the calculation of row II.

We calculate symmetrical and asymmetrical ring circuits in the same way as a dead-end network, but at 50% of the calculated water flow for each half-ring.

3. Basic principles of operation of a fire extinguishing installation

An automatic fire extinguishing installation consists of the following main elements: an automatic fire extinguishing pumping station with a system of inlet (suction) and supply (pressure) pipelines; - control units with a system of supply and distribution pipelines with sprinklers installed on them.

1 Operating principle of the pumping station

In standby mode, the supply and distribution pipelines of sprinkler systems are constantly filled with water and are under pressure, ensuring constant readiness to extinguish a fire. The jockey pump turns on when the pressure alarm is activated.

In the event of a fire, when the pressure on the jockey pump (in the supply pipeline) drops, when the pressure alarm is triggered, the working fire pump is turned on, providing full flow. At the same time, when the fire pump is turned on, a fire alarm signal is sent to the fire safety system of the facility.

If the electric motor of the working fire pump does not turn on or the pump does not provide the design pressure, then after 10 s the electric motor of the backup fire pump turns on. The impulse to turn on the backup pump is supplied from a pressure switch installed on the pressure pipeline of the working pump.

When the working fire pump is turned on, the jockey pump is automatically turned off. After the fire has been eliminated, the water supply to the system is stopped manually, for which the fire pumps are turned off and the valve in front of the control unit is closed.

3.2 Operating principle of the sprinkler system

If a fire occurs in the room protected by the sprinkler section and the air temperature rises above 68 "C, the thermal lock (glass bulb) of the sprinkler is destroyed. Water, which is under pressure in the distribution pipelines, pushes out the valve that blocks the outlet of the sprinkler, and it opens. Water from the sprinkler enters the room; the pressure in the network drops. When the pressure drops by 0.1 MPa, pressure alarms installed on the pressure pipeline are triggered, and a pulse is given to turn on the working pump.

The pump takes water from the city water supply network, bypassing the water metering unit, and supplies it to the piping system of the fire extinguishing installation. In this case, the jockey pump is automatically switched off. When a fire occurs on one of the floors, liquid flow alarms duplicate signals about the activation of the water fire extinguishing installation (thereby identifying the location of the fire) and simultaneously turn off the power supply system of the corresponding floor.

Simultaneously with the automatic activation of the fire extinguishing installation, signals about a fire, the activation of pumps and the start of operation of the installation in the appropriate direction are transmitted to the premises of the fire post with round-the-clock presence of operational personnel. In this case, the light alarm is accompanied by an audible alarm.

4. Design of a water fire extinguishing installation. Hydraulic calculation

Hydraulic calculations are carried out for the most remote and highly located (“dictating”) sprinkler under the condition that all sprinklers that are furthest from the water feeder and mounted on the design area are activated.

We outline the routing of the pipeline network and the layout plan for sprinklers and select the dictating protected irrigated area on the hydraulic plan diagram of the AUP, on which the dictating sprinkler is located, and carry out a hydraulic calculation of the AUP.

Determination of the estimated water flow over the protected area.

The determination of flow and pressure in front of the “dictating sprinkler” (flow at point 1 on the diagram in Appendix 1) is determined by the formula:

=k √ H

The flow rate of the “dictating” sprinkler must ensure the standard irrigation intensity, therefore:

min = I*S=0.17 * 12 = 2.04 l/s, thus Q1 ≥ 2.04 l/s

Note. When calculating, it is necessary to take into account the number of sprinklers protecting the calculated area. On a calculated area of ​​180 m2 there are 4 rows of 5 and 4 sprinklers, the total flow rate must be at least 60 l/s (see Table 5.2 SP 5.13130.2009 for 4.2 group of premises). Thus, when calculating the pressure in front of the “dictating” sprinkler, it is necessary to take into account that in order to ensure the minimum required flow rate of the fire extinguishing installation, the flow rate (and therefore the pressure) of each sprinkler will have to be increased. That is, in our case, if the flow rate from the sprinkler is taken equal to 2.04 l/s, then the total flow rate of 18 sprinklers will be approximately equal to 2.04 * 18 = 37 l/s, and taking into account the different pressure in front of the sprinklers it will be slightly more, but this value does not correspond to the required flow rate of 65 l/s. Thus, it is necessary to select the pressure in front of the sprinkler so that the total flow rate of 18 sprinklers located on the design area is more than 65 l/s. For this: 65/18=3.611, i.e. the flow rate of the dictating sprinkler should be more than 3.6 l/s. Having carried out several variants of calculations in the draft, we determine the required pressure in front of the “dictating” sprinkler. In our case, H=24 m.v.s.=0.024 MPa.

(1) =k √ H= 0.74√24= 3.625 l/s;

Let's calculate the diameter of the pipeline in a row using the following formula:

From where we get, at a water flow speed of 5 m/s, the value d = 40 mm and take the value of 50 mm for the reserve.

Pressure loss in section 1-2: dH(1-2)= Q(1) *Q(1) *l(1-2) / Km= 3.625*3.625*6/110=0.717 m.w.s.= 0.007MPa;

To determine the flow rate from the 2nd sprinkler, we calculate the pressure in front of the 2nd sprinkler:

H(2)=H(1)+ dH(1-2)=24+0.717=24.717 m.v.s.

Flow from the 2nd sprinkler: Q(2) =k √ H= 0.74√24.717= 3.679 l/s;

Pressure loss in section 2-3: dH(2-3)= (Q(1) + Q(2))*(Q(1) + Q(2))*l(2-3) / Km= 7.304* 7.304*1.5/110=0.727 m.v. With;

Pressure at point 3: Н(3)=Н(2)+ dH(2-3)= 24.717+0.727=25.444 m.v.s;

The total flow rate of the right branch of the first row is Q1 + Q2 = 7.304 l/s.

Since the right and left branches of the first row are structurally identical (2 sprinklers each), the flow rate of the left branch will also be equal to 7.304 l/s. The total flow rate of the first row is Q I = 14.608 l/s.

The flow rate in point 3 is divided in half, since the supply pipeline is made as a dead end. Therefore, when calculating pressure losses in section 4-5, the flow rate of the first row will be taken into account. Q(3-4) = 14.608 l/s.

We will accept the value d=150 mm for the main pipeline.

Pressure loss in section 3-4:

(3-4)=Q(3)*Q(3)*l(3-4)/Km= 14.608 *14.608 *3/36920=0.017 m.v. With;

Pressure at point 4: Н(4)=Н(3)+ dH(3-4)= 25.444+0.017=25.461 m.v. With;

To determine the flow rate of the 2nd row, it is necessary to determine coefficient B:

That is, B= Q(3)*Q(3)/H(3)=8.39

Thus, the consumption of the 2nd row is equal to:

II= √8, 39*24.918= 14.616 l/s;

Total flow rate from 2 rows: QI +QII = 14.608+14.616 =29.224 l/s;

Similarly, I find (4-5)=Q(4)*Q(4)*l(4-5)/Km= 29.224 *29.224*3/36920=0.069 m.v. With;

Pressure at point 5: Н(5)=Н(4)+ dH(4-5)= 25.461+0.069=25.53 m. With;

Since the next 2 rows are asymmetrical, we find the consumption of the 3rd row as follows:

That is, B= Q(1)*Q(1)/H(4)= 3.625*3.625/25.461=0.516lev= √0.516 * 25.53= 3.629 l/s;(5)= 14.616 +3.629 =18.245 l /s= Q(5)*Q(5)/H(5)=13.04III= √13.04 * 25.53= 18.24 l/s;

Total flow rate from 3 rows: Q (3 rows) = 47.464 l/s;

Pressure loss in section 5-6:(5-6)=Q (6) *Q (6) *l(5-6)/Km= 47.464 *47.464 *3/36920=0.183 m.v. With;

Pressure at point 6: Н(6)=Н(5)+ dH(5-6)= 25.53+0.183=25.713 m.v. With;

IV= √13.04 * 25.713= 18.311 l/s;

Total flow rate from 4 rows: Q(4 rows) =65.775 l/s;

Thus, the calculated flow rate is 65.775 l/s, which meets the requirements of regulatory documents >65 l/s.

The required pressure at the beginning of the installation (near the fire pump) is calculated from the following components:

pressure in front of the “dictating” sprinkler;

pressure loss in the distribution pipeline;

pressure loss in the supply pipeline;

pressure loss in the control unit;

difference in elevation between the pump and the “dictating” sprinkler.

Pressure loss in the control unit:

.water.st.,

The required pressure that the pumping unit must provide is determined by the formula:

tr=24+4+8.45+(9.622)*0.2+9.622 =47.99 m.v.s.=0.48 MPa

Total water consumption for sprinkler fire extinguishing: (4 rows) = 65.775 l/s = 236.79 m3/h

Required pressure:

tr = 48 m.v.s. = 0.48 MPa

5. Equipment selection

Calculations were carried out taking into account the selected sprinkler SPOO-RUoO,74-R1/2/R57.VZ-“SPU-15”-bronze with an outlet diameter of 15 mm.

Taking into account the specifics of the facility (a unique multifunctional building with a large number of people), the complex pipeline system of the internal fire-fighting water supply system, the pumping unit is selected with a supply pressure reserve.

The extinguishing time is 60 minutes, which means that 234,000 liters of water must be supplied.

The design solution selected is the Irtysh-TsMK pump 150/400-55/4 speed 1500 rpm, which has a reserve of both H = 48 m.v.s. and Q. of the pump = 65 m.

The operating characteristics of the pump are shown in the figure.

Conclusion

This RGR presents the results of the studied methods for designing automatic fire extinguishing installations, and the calculations necessary for designing an automatic fire extinguishing installation.

Based on the results of hydraulic calculations, the placement of sprinklers was determined in order to achieve a water flow rate for fire extinguishing in the protected area of ​​65 l/s. To ensure the standard intensity of irrigation, a pressure of 48 m.w.c. will be required.

The equipment for the installations was selected based on the standard minimum irrigation intensity, calculated flow rates and required pressure.

Bibliography

1 SP 5.13130.2009. Fire alarm and fire extinguishing installations are automatic. Design norms and rules.

Federal Law No. 123 - Federal Law “Technical Regulations on Fire Safety Requirements” dated July 22, 2008

Design of water and foam automatic fire extinguishing installations / L.M. Meshman, S.G. Tsarichenko, V.A. Bylinkin, V.V. Aleshin, R.Yu. Gubin; edited by N.P. Kopylova. - M: VNIIPO EMERCOM of the Russian Federation, 2002.-413 p.

Websites of manufacturers of fire-fighting equipment