Sprinkler fire extinguishing - the main characteristics of the system. Automatic water fire extinguishing systems Fire extinguishing sprinkler working principle
1. WATER AND AQUEOUS SOLUTIONS
No one will doubt that water is the most famous substance for extinguishing fire. The element resisting fire has a number of advantages, such as high specific heat capacity, latent heat of vaporization, chemical inertness to most substances and materials, availability and low cost.
However, along with the advantages of water, its disadvantages should also be taken into account, namely, low wetting ability, high electrical conductivity, insufficient adhesion to the extinguishing object, and also, importantly, causing significant damage to the building.
Extinguishing a fire from a fire hose with a direct stream is not the best way to fight a fire, since the main volume of water is not involved in the process, only cooling of the fuel occurs, and sometimes the flame can be extinguished. You can increase the efficiency of extinguishing a fire by spraying water, but this will increase the cost of obtaining water spray and delivering it to the source of the fire. In our country, a water jet, depending on the arithmetic mean diameter of the droplets, is divided into atomized (droplet diameter more than 150 µm) and finely atomized (less than 150 µm).
Why is water spraying so effective? With this extinguishing method, the fuel is cooled by diluting the gases with water vapor; in addition, a finely atomized jet with a droplet diameter of less than 100 microns is capable of cooling the chemical reaction zone itself.
To increase the penetrating ability of water, so-called water solutions with wetting agents are used. Additives are also used:
- water-soluble polymers to increase adhesion to a burning object (“viscous water”);
- polyoxyethylene to increase the throughput of pipelines (“slippery water”, abroad “fast water”);
- inorganic salts to increase the efficiency of extinguishing;
- antifreeze and salts to reduce the freezing point of water.
Water should not be used to extinguish substances that enter into chemical reactions with it, as well as toxic, flammable and corrosive gases. Such substances include many metals, organometallic compounds, metal carbides and hydrides, hot coal and iron. Thus, under no circumstances use water or aqueous solutions with the following materials:
- organoaluminum compounds (explosive reaction);
- organolithium compounds; lead azide; alkali metal carbides; hydrides of a number of metals - aluminum, magnesium, zinc; calcium, aluminum, barium carbides (decomposition with release of flammable gases);
- sodium hydrosulfite (spontaneous combustion);
- sulfuric acid, thermites, titanium chloride (strong exothermic effect);
- bitumen, sodium peroxide, fats, oils, petrolatum (intensified combustion as a result of emission, splashing, boiling).
Also, jets should not be used to extinguish dust to avoid the formation of an explosive atmosphere. Also, when extinguishing oil products, spreading and splashing of the burning substance may occur.
2. SPRINKLER AND DEUTCH FIRE FIGHTING INSTALLATIONS
2.1. Purpose and design of installations
Installations of water, foam low expansion, as well as water fire extinguishing with a wetting agent are divided into:
- Sprinkler installations used for local fire extinguishing and cooling of building structures. Typically used in rooms where a fire may develop and release a large amount of heat.
- Deluge installations are intended to extinguish a fire over the entire given area, and also create water curtain. They irrigate the source of fire in the protected area, receiving a signal from fire detection devices, which allows eliminating the cause of the fire in the early stages, faster than sprinkler systems.
These fire extinguishing installations are the most common. They are used to protect warehouses, shopping centers, premises for the production of hot natural and synthetic resins, plastics, rubber products, cable ropes, etc. Modern terms and definitions in relation to water AUP are given in NPB 88-2001.
The installation contains a water source 14 (external water supply), a main water supply (working pump 15) and an automatic water supply 16. The latter is a hydropneumatic tank (hydropneumatic tank), which is filled with water through a pipeline with a valve 11.
For example, the installation diagram contains two different sections: a water-filled section with a control unit (CU) 18 under the pressure of a water feeder 16 and an air section with a CU 7, the supply pipelines 2 and distribution 1 of which are filled with compressed air. Air is pumped by compressor 6 through check valve 5 and valve 4.
The sprinkler system is activated automatically when the room temperature rises to a predetermined level. The fire detector is a thermal lock of the sprinkler sprinkler. The presence of a lock ensures sealing of the sprinkler outlet. At the beginning, the sprinklers located above the fire are turned on, as a result of which the pressure in the distribution 1 and supply 2 wires drops, the corresponding control unit is activated and water from the automatic water feeder 16 through the supply pipeline 9 is supplied for extinguishing through the opened sprinklers. The fire signal is generated by alarm device 8 УУ. When the control device 12 receives a signal, it turns on the working pump 15, and if it fails, the backup pump 13. When the pump reaches the specified operating mode, the automatic water feeder 16 is turned off using the check valve 10.
Let's take a closer look at the features of the deluge installation:
It does not contain a thermal lock, like a sprinkler, and therefore is equipped with additional fire detection devices.
Automatic activation is ensured by the incentive pipeline 16, which is filled with water under the pressure of the auxiliary water feeder 23 (for unheated rooms, compressed air is used instead of water). For example, in the first section, incentive-start valves 6 are connected to pipeline 16, which in the initial state are closed using a cable with thermal locks 7. In the second section, distribution pipelines with sprinklers are connected to a similar pipeline 16.
The outlets of the deluge sprinklers are open, so the supply 11 and distribution 9 pipelines are filled atmospheric air(dry pipes). The supply pipeline 17 is filled with water under the pressure of the auxiliary water feeder 23, which is a hydraulic pneumatic tank filled with water and compressed air. Air pressure is controlled using an electric contact pressure gauge 5. In this image, the source of water for the installation is an open reservoir 21, water is taken from which by pumps 22 or 19 through a pipeline with a filter 20.
The control unit 13 of the deluge installation contains a hydraulic drive, as well as a pressure indicator 14 of the SDU type.
The installation is automatically switched on as a result of the activation of sprinklers 10 or the destruction of thermal locks 7, the pressure in the stimulating pipeline 16 and the hydraulic drive unit УУ 13 drops. Valve УУ 13 opens under water pressure in the supply pipeline 17. Water flows to the deluge sprinklers and irrigates the room protected installation section.
The deluge installation is manually started using ball valve 15. The sprinkler installation cannot be turned on automatically, because Unauthorized supply of water from fire extinguishing systems will cause great damage to the protected premises in the absence of a fire. Let's consider a sprinkler installation diagram that allows you to eliminate such false alarms:
The installation contains sprinklers on the distribution pipeline 1, which under operating conditions is filled with compressed air to a pressure of about 0.7 kgf/cm2 using a compressor 3. The air pressure is controlled by a signaling device 4, which is installed in front of a check valve 7 with a drain valve 10.
The installation control unit contains a valve 8 with a membrane-type shut-off element, a pressure or liquid flow indicator 9, and a valve 15. Under operating conditions, the valve 8 is closed by the pressure of water, which enters the starting pipeline of the valve 8 from the water source 16 through the open valve 13 and the throttle 12. The starting pipeline is connected to the manual start valve 11 and to the drain valve 6, equipped electric drive. The installation also contains technical means (TS) of automatic fire alarm(APS) - fire detectors and control panel 2, as well as starting device 5.
The pipeline between valves 7 and 8 is filled with air with a pressure close to atmospheric, which ensures the functionality of shut-off valve 8 (main valve).
Mechanical damage that could cause a leak in the installation's distribution pipeline or thermal lock will not cause water supply, because valve 8 is closed. When the pressure in pipeline 1 decreases to 0.35 kgf/cm2, the alarm 4 generates an alarm signal about a malfunction (depressurization) of the distribution pipeline 1 of the installation.
A false activation of the alarm system will also not trigger the system. The control signal from the APS, using an electric drive, will open the drain valve 6 on the starting pipeline of the shut-off valve 8, as a result of which the latter will open. The water will flow into distribution pipeline 1, where it will stop in front of the closed thermal locks of the sprinklers.
When designing AUVP, TS APS are selected so that the inertia of sprinklers is higher. This is done for this purpose. So that in the event of a fire, the APS fires earlier and opens shut-off valve 8. Next, water will flow into pipeline 1 and fill it. This means that by the time the sprinkler is activated, the water is already in front of it.
It is important to clarify that the submission of the first alarm signal from the APS allows you to quickly eliminate small fires with primary fire extinguishing means (such as fire extinguishers).
2.2. Composition of the technological part of sprinkler and deluge water fire extinguishing installations
2.2.1. Source of water supply
The source of water supply for the system is a water supply system, a fire tank or a reservoir.
2.2.2. Water feeders
In accordance with NPB 88-2001, the main water supply ensures the operation of the fire extinguishing installation with a given pressure and flow rate of water or aqueous solution for the estimated time.
A water supply source (pipeline, reservoir, etc.) can be used as the main water supply if it can provide the calculated flow rate and water pressure for the required time. Before the main water feeder enters operating mode, the pressure in the pipeline is automatically ensured auxiliary water feeder. As a rule, this is a hydropneumatic tank (hydropneumatic tank), which is equipped with float and safety valves, level sensors, visual level gauges, pipelines for releasing water when extinguishing a fire, and devices for creating the necessary air pressure.
An automatic water feeder provides the pressure in the pipeline necessary to activate the control units. Such a water feeder can be water pipes with the necessary guaranteed pressure, a hydropneumatic tank, or a jockey pump.
2.2.3. Control unit (CU)- this is a combination pipeline fittings with locking and signaling devices and measuring instruments. They are intended for starting a fire-fighting installation and monitoring its performance; they are located between the supply and supply pipelines of the installations.
Control nodes provide:
- supply of water (foam solutions) to extinguish fires;
- filling supply and distribution pipelines with water;
- draining water from supply and distribution pipelines;
- compensation of leaks from the AUP hydraulic system;
- checking the alarm about their activation;
- alarm when the alarm valve is activated;
- pressure measurement before and after the control unit.
Thermal lock as part of a sprinkler system, it is triggered when the temperature in the room rises to a predetermined level.
The heat-sensitive element here are fusible or explosive elements, such as glass flasks. Locks with an elastic “shape memory” element are also being developed.
The principle of operation of a lock using a fusible element is the use of two metal plates soldered with low-melting solder, which loses strength as the temperature rises, as a result of which the lever system becomes unbalanced and opens the sprinkler valve.
But the use of a fusible element has a number of disadvantages, such as the susceptibility of a low-fusible element to corrosion, as a result of which it becomes brittle, and this can lead to spontaneous operation of the mechanism (especially under vibration conditions).
Therefore, sprinklers using glass flasks are now increasingly used. They are technologically advanced to manufacture, resistant to external influences, prolonged exposure to temperatures close to the nominal ones does not in any way affect their reliability, and are resistant to vibration or sudden fluctuations in pressure in the water supply network.
Below is a diagram of the design of the sprinkler with an explosive element - S.D. flask. Bogoslovsky:
1 - fitting; 2 - arms; 3 - socket; 4 - clamping screw; 5 - cap; 6 - thermoflask; 7 - diaphragm
A thermoflask is nothing more than a thin-walled, hermetically sealed ampoule containing a heat-sensitive liquid, for example, methylcarbitol. This substance expands vigorously under the influence of high temperatures, increasing the pressure in the flask, which leads to its explosion.
Thermal flasks are the most popular heat-sensitive element in sprinklers these days. The most common thermoflasks from Job GmbH are types G8, G5, F5, F4, F3, F 2.5 and F1.5, Day-Impex Lim types DI 817, DI 933, DI 937, DI 950, DI 984 and DI 941, Geissler type G and "Norbert Job" type Norbulb. There is information about the development of production of thermoflasks in Russia and by the Grinnell company (USA).
Zone I- These are thermoflasks of the Job G8 and Job G5 types for operation under normal conditions.
Zone II- these are thermoflasks of type F5 and F4 for sprinklers placed in niches or hidden.
Zone III- these are thermal flasks of type F3 for sprinklers in residential premises, as well as in sprinklers with an increased irrigation area; thermoflasks F2.5; F2 and F1.5 - for sprinklers, the response time of which must be minimal according to the conditions of use (for example, in sprinklers with fine atomization, with an increased irrigation area and sprinklers intended for use in explosion prevention installations). Such sprinklers are usually marked with the letters FR (Fast Response).
Note: the number after the letter F usually corresponds to the diameter of the thermoflask in mm.
List of documents that regulate the requirements, application and testing methods of sprinklers
GOST R 51043-97
NPB 87-2000
NPB 88-2001
NPB 68-98
The designation structure and marking of sprinklers in accordance with GOST R 51043-97 is given below.
Note: For deluge sprinklers pos. 6 and 7 are not indicated.
Main technical parameters of general purpose sprinklers
|
Type of sprinkler |
Nominal diameter of the outlet, mm |
External connecting thread R |
Minimum operating pressure before the sprinkler, MPa |
Protected area, m2, not less |
Average irrigation intensity, l/(s m2), not less |
|
0,020 (>0,028) |
|||||
|
0,04 (>0,056) |
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|
0,05 (>0,070) |
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Notes:
(text) - edition according to the GOST R project.
1. The specified parameters (protected area, average irrigation intensity) are given when installing sprinklers at a height of 2.5 m from the floor level.
2. For sprinklers with mounting location V, N, U, the area protected by one sprinkler must have the shape of a circle, and for location G, Gv, Gn, Gu - the shape of a rectangle measuring at least 4x3 m.
3. The size of the external connecting thread is not limited for sprinklers with an outlet whose shape differs from the shape of a circle and a maximum linear size exceeding 15 mm, as well as for sprinklers intended for pneumatic and mass pipelines, and special-purpose sprinklers.
The protected irrigation area is assumed to be equal to the area, the specific flow rate and uniformity of irrigation of which is not lower than the established or standard one.
The presence of a thermal lock imposes some restrictions on time and operating temperature limits on sprinklers.
The following requirements are established for sprinklers:
Rated response temperature- the temperature at which the thermal lock reacts and water is supplied. Established and specified in the standard or technical documentation for this product
Rated operating time- the sprinkler response time specified in the technical documentation
Conditional response time- time from the moment the sprinkler is exposed to a temperature exceeding the nominal temperature by 30 °C until the thermal lock is activated.
Rated temperature, conditional response time and color coding sprinklers according to GOST R 51043-97, NPB 87-2000 and the planned GOST R are presented in the table:
Rated temperature, conditional response time and color marking of sprinklers
|
Temperature, °C |
Conditional response time, s, no more |
Marking color of the liquid in a glass thermoflask (explosive temperature-sensitive element) or sprinkler arms (with a fusible and elastic temperature-sensitive element) |
|
|
rated operation |
maximum deviation |
||
|
Orange |
|||
|
Violet |
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|
Violet |
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Notes:
1. At a nominal operating temperature of the thermal lock from 57 to 72 °C, the sprinkler arms may not be painted.
2. When using a thermoflask as a heat-sensitive element, the sprinkler arms may not be painted.
3. “*” - only for sprinklers with a fusible heat-sensitive element.
4. “#” - sprinklers with both a fusible and explosive heat-sensitive element (thermal flask).
5. Values of the nominal response temperature not marked with “*” and “#” - the thermosensitive element is the thermoflask.
6. GOST R 51043-97 does not have temperature ratings of 74* and 100* °C.
Elimination of fires with high heat generation intensity. It turned out that conventional sprinklers installed in large warehouses, for example, of plastic materials, cannot cope due to the fact that the powerful heat flows of a fire carry away small drops of water. From the 60s to the 80s in Europe, 17/32” sprinklers were used to extinguish such fires, and after the 80s they switched to the use of extra large orifice (ELO), ESFR and “big drop” sprinklers. Such sprinklers are capable of producing drops of water that penetrate the convective flow that occurs in a warehouse during a powerful fire. Outside our country, sprinkler carriers of the ELO type are used to protect plastic packaged in cardboard at a height of about 6 m (except for flammable aerosols).
Another quality of the ELO sprinkler is that it is able to operate with low water pressure in the pipeline. Sufficient pressure can be provided in many water sources without the use of pumps, which affects the cost of sprinklers.
Sprinklers of the ESFR type are recommended for the protection of various products, including non-foamed plastic materials packaged in cardboard, stored at a height of up to 10.7 m with a room height of up to 12.2 m. Such qualities of the system as quick response to the development of fire and intense flow water, allows you to use fewer sprinklers, which has a positive effect on reducing wasted water and damage caused.
For rooms where technical structures disturb the interior of the room, we have developed following types sprinklers:
In-depth- sprinklers, the body or arms of which are partially hidden in the recesses of a suspended ceiling or wall panel;
Secret- sprinklers in which the bow body and partly the heat-sensitive element are located in a recess in the suspended ceiling or wall panel;
Hidden- sprinklers covered with a decorative cover
The operating principle of such sprinklers is shown below. After the cover is activated, the sprinkler socket, under its own weight and the influence of a stream of water from the sprinkler, moves down along two guides to such a distance that the recess in the ceiling in which the sprinkler is mounted does not affect the nature of the distribution of water.
In order not to increase the response time of the AUP, the melting temperature of the solder of the decorative cover is set below the response temperature of the sprinkler system, so in case of fire decorative element will not interfere with the flow of heat to the thermal lock of the sprinkler.
Design of sprinkler and deluge water fire extinguishing installations.
The design features of water-foam AUPs are described in detail in the training manual. In it you will find the features of creating sprinkler and deluge water-foam fire extinguishing systems, fire extinguishing installations with finely sprayed water, fire extinguishing systems for preserving high-rise rack warehouses, rules for calculating fire extinguishing systems, examples.
The manual also sets out the main provisions of modern scientific and technical documentation for each region of Russia. The statement of development rules is subject to detailed consideration terms of reference for design, formulation of the main provisions for the coordination and approval of this task.
The training manual also discusses the content and rules for preparing a working draft, including an explanatory note.
To simplify your task, we present an algorithm for designing a classic water fire extinguishing installation in a simplified form:
1. According to NPB 88-2001, it is necessary to establish a group of premises (production or technological process) depending on its functional purpose and the fire load of combustible materials.
An extinguishing agent is selected, for which the effectiveness of extinguishing flammable materials concentrated in protected objects with water, aqueous or foam solution is determined according to NPB 88-2001 (Chapter 4). Check the compatibility of materials in the protected area with the selected fire extinguishing agent - there are no possible chemical reactions with fire extinguishing agents, accompanied by an explosion, strong exothermic effect, spontaneous combustion, etc.
2. Taking into account the fire danger (speed of flame spread), choose the type of fire extinguishing installation - sprinkler, deluge or AUP with finely atomized (atomized) water.
Automatic switching on of deluge units is carried out based on signals from fire alarm systems, an incentive system with thermal locks or sprinklers, as well as from sensors of technological equipment. The drive of deluge units can be electric, hydraulic, pneumatic, mechanical or combined.
3. For a sprinkler AUP, depending on the operating temperature, the type of installation is determined - water-filled (5°C and above) or air. Note that NPB 88-2001 does not provide for the use of water-air AUP.
4. According to Ch. 4 NPB 88-2001 take the irrigation intensity and the area protected by one sprinkler, the area for calculating water consumption and the estimated operating time of the installation.
If water is used with the addition of a wetting agent based on a general-purpose foaming agent, then the irrigation intensity is 1.5 times less than for water AUP.
5. Based on the sprinkler’s passport data, taking into account the efficiency factor of the consumed water, the pressure that must be provided at the “dictating” sprinkler (the most remote or highly located) and the distance between the sprinklers (taking into account Chapter 4 of NPB 88-2001) are established.
6. The calculated water consumption for sprinkler systems is determined from the condition of simultaneous operation of all sprinklers in the protected area (see Table 1, Chapter 4 of NPB 88-2001), taking into account the efficiency of the water used and the fact that the consumption of sprinklers installed along distribution pipes, increases with distance from the “dictating” sprinkler.
Water consumption for deluge installations is calculated based on the condition of simultaneous operation of all deluge sprinklers in the protected warehouse (5, 6 and 7 groups of the protected object). The area of rooms of the 1st, 2nd, 3rd and 4th groups to determine water consumption and the number of simultaneously operating sections is determined depending on the technological data.
7. For warehouses(5, 6 and 7 groups of the object of protection according to NPB 88-2001) the intensity of irrigation depends on the height of storage of materials.
For the area of receiving, packaging and sending goods in warehouses with a height of 10 to 20 m with high-altitude rack storage, the values of intensity and protected area for calculating the consumption of water, foaming agent solution for groups 5, 6 and 7, given in NPB 88-2001, are increased from calculation of 10% for every 2 m of height.
The total water consumption for internal fire extinguishing of high-rise rack warehouses is taken according to the highest total consumption in the rack storage area or in the area of receiving, packaging, picking and dispatching goods.
In this case, it is necessary to take into account that space-planning and Constructive decisions warehouses must comply with SNiP 2.11.01-85, for example, racks are equipped with horizontal screens, etc.
8. Based on the estimated water consumption and the duration of fire extinguishing, the estimated amount of water is calculated. The capacity of fire reservoirs (reservoirs) is determined, while taking into account the possibility of automatic replenishment with water during the entire time of extinguishing the fire.
The calculated amount of water is stored in tanks for various purposes if devices are installed that prevent the consumption of the specified volume of water for other needs.
At least two fire tanks must be installed. It is necessary to take into account that at least 50% of the volume of water for fire extinguishing must be stored in each of them, and water supply to any point of the fire is provided from two adjacent reservoirs (reservoirs).
With a calculated water volume of up to 1000 m3, it is permissible to store water in one tank.
Free access for fire engines with a lightweight, improved road surface must be created to fire tanks, reservoirs and boreholes. You will find the location of fire tanks (reservoirs) in GOST 12.4.009-83.
9. In accordance with the selected type of sprinkler, its flow rate, irrigation intensity and the area protected by it, plans for the placement of sprinklers and an option for routing the pipeline network are developed. For clarity, depicted (not necessarily to scale) axonometric diagram pipeline network.
It is important to consider the following:
9.1. Within one protected room, sprinklers of the same type with the same outlet diameter should be placed.
The distance between sprinklers or thermal locks in the incentive system is determined by NPB 88-2001. Depending on the group of the room, it is 3 or 4 m. The only exceptions are sprinklers under beam ceilings with protruding parts of more than 0.32 m (for fire hazard classes of the ceiling (covering) K0 and K1) or 0.2 m (in other cases) . In such situations, sprinklers are installed between the protruding parts of the floor, ensuring uniform irrigation of the floor.
In addition, it is necessary to install additional sprinklers or deluge sprinklers with an incentive system under barriers (technological platforms, boxes, etc.) with a width or diameter of more than 0.75 m, located at a height of more than 0.7 m from the floor.
The best performance indicators were obtained when the area of the sprinkler arms was placed perpendicular to the air flow; with a different placement of the sprinkler due to shielding of the thermoflask with arms from the air flow, the response time increases.
Sprinklers are installed in such a way that water from one sprinkler does not touch neighboring ones. The minimum distance between adjacent sprinklers under a smooth ceiling should not exceed 1.5 m.
The distance between sprinklers and walls (partitions) should not be more than half the distance between sprinklers and depends on the slope of the coating, as well as the fire hazard class of the wall or coating.
The distance from the ceiling (covering) plane to the sprinkler socket or thermal lock of the cable incentive system should be 0.08...0.4 m, and to the sprinkler reflector installed horizontally relative to its type axis - 0.07...0.15 m.
Placement of sprinklers for suspended ceilings - in accordance with TD on this type sprinkler
Deluge sprinklers are located taking into account their technical characteristics and irrigation maps to ensure uniform irrigation of the protected area.
Sprinkler sprinklers in water-filled installations are installed with sockets up or down, in air-filled installations - with sockets only up. Sprinklers with a horizontal reflector are used in any sprinkler installation configuration.
If there is a danger of mechanical damage, the sprinklers are protected by casings. The design of the casing is chosen so as to prevent a decrease in the area and intensity of irrigation below standard values.
Features of placing sprinklers to produce water curtains are described in detail in the manuals.
9.2. Pipelines are designed from steel pipes: according to GOST 10704-91 - with welded and flanged connections, according to GOST 3262-75 - with welded, flanged, threaded connections, and also according to GOST R 51737-2001 - with detachable pipeline couplings only for water-filled sprinkler installations for pipes with a diameter of no more than 200 mm.
Supply pipelines are allowed to be designed as dead-end pipes only if the structure contains no more than three control units and the length of the external dead-end wire is no more than 200 m. In other cases, supply pipelines are created as rings and are divided into sections by valves at the rate of up to 3 controls per section.
Dead-end and ring supply pipelines are equipped with flushing valves, valves or taps with a nominal diameter of at least 50 mm. Such shut-off devices are equipped with plugs and installed at the end of a dead-end pipeline or in the place most remote from the control unit - for ring pipelines.
Valves or valves installed on ring pipelines must allow water to pass in both directions. The presence and purpose of shut-off valves on supply and distribution pipelines is regulated by NPB 88-2001.
On one branch of the distribution pipeline of installations, as a rule, no more than six sprinklers with an outlet diameter of up to 12 mm inclusive should be installed, and no more than four sprinklers with an outlet diameter of more than 12 mm.
In deluge AUPs, supply and distribution pipelines can be filled with water or an aqueous solution to the level of the lowest located sprinkler in a given section. With special caps or plugs on deluge sprinklers, the pipelines can be completely filled. Such caps (plugs) must release the outlet of the sprinklers under the pressure of water (aqueous solution) when the AUP is activated.
It is necessary to provide thermal insulation for water-filled pipelines laid in places where they may freeze, for example, above gates or doorways. If necessary, additional devices for draining water are provided.
In some cases, it is possible to connect internal fire hydrants with manual barrels and deluge sprinklers with an incentive switching system to the supply pipelines, and to the supply and distribution pipelines - deluge curtains for irrigating door and technological openings.
As mentioned earlier, the design of pipelines made of plastic pipes has a number of features. Such pipelines are designed only for water-filled AUP according to technical specifications, developed for a specific facility and agreed upon with the Main Directorate for State Traffic Safety of the Ministry of Emergency Situations of Russia. The pipes must be tested at the Federal State Institution VNIIPO EMERCOM of Russia.
The average service life of plastic pipelines in fire extinguishing installations should be at least 20 years. Pipes are installed only in premises of categories B, D and D, and their use in external fire extinguishing installations is prohibited. Installation of plastic pipes is provided both open and hidden (in the space of false ceilings). Pipes are laid in rooms with a temperature range from 5 to 50 ° C, the distances from pipelines to heat sources are limited. Intrashop pipelines on the walls of buildings are located 0.5 m above or below window openings.
It is prohibited to lay intra-shop pipelines made of plastic pipes in transit through premises performing administrative, household and economic functions, switchgears, electrical installation rooms, control and automation system panels, ventilation chambers, heating points, staircases, corridors, etc.
Sprinklers with an operating temperature of no more than 68 °C are used on branches of plastic distribution pipelines. At the same time, in rooms of categories B1 and B2, the diameter of bursting flasks of sprinklers does not exceed 3 mm, for rooms of categories B3 and B4 - 5 mm.
When sprinklers are placed openly, the distance between them should not be more than 3 m; for wall-mounted ones, the permissible distance is 2.5 m.
When the system is hidden, the plastic pipeline is hidden ceiling panels, whose fire resistance is EL 15.
The working pressure in the plastic pipeline must be at least 1.0 MPa.
9.3 The pipeline network must be divided into fire extinguishing sections - a set of supply and separation pipelines on which sprinklers are located, connected to a control unit (CU) common to all.
The number of sprinklers of all types in one section of a sprinkler installation should not exceed 800, and the total capacity of pipelines (only for an air sprinkler installation) should not exceed 3.0 m3. The pipeline capacity can be increased to 4.0 m3 when using a control unit with an accelerator or exhauster.
To eliminate false alarms, a delay chamber is used in front of the pressure switch CU of the sprinkler installation.
To protect several rooms or floors with one section of the sprinkler system, it is possible to install liquid flow detectors on supply pipelines, with the exception of ring ones. In this case, shut-off valves must be installed, information about which you will find in NPB 88-2001. This is done to issue a signal specifying the location of the fire and turn on the warning and smoke removal systems.
The liquid flow switch can be used as a signal valve in a water-filled sprinkler installation if a check valve is installed behind it.
A sprinkler section with 12 or more fire hydrants must have two inlets.
10. Drawing up hydraulic calculations.
The main task here is to determine the water flow for each sprinkler and the diameter of the various parts of the fire pipeline. Incorrect calculation of the AUP distribution network (insufficient water flow) often becomes the cause of ineffective fire extinguishing.
In hydraulic calculations, it is necessary to solve 3 problems:
a) determine the pressure at the inlet to the opposite water supply (on the axis of the outlet pipe of a pump or other water supply), if the calculated water flow rate, pipeline routing diagram, their length and diameter, as well as the type of fittings are specified. The first step is to determine the pressure loss when water moves through the pipeline at a given design stroke, and then determine the brand of pump (or other type of water supply source) capable of providing the required pressure.
b) determine the water flow based on the given pressure at the beginning of the pipeline. In this case, the calculation should begin by determining the hydraulic resistance of each element of the pipeline, as a result of which, establish the estimated water flow depending on the obtained pressure at the beginning of the pipeline.
c) determine the diameter of the pipeline and other elements protective system pipelines based on the calculated water flow and pressure losses along the length of the pipeline.
The manuals NPB 59-97, NPB 67-98 discuss in detail how to calculate the required pressure in a sprinkler with a set irrigation intensity. It should be taken into account that when the pressure in front of the sprinkler changes, the irrigation area can either increase, decrease or remain unchanged.
The formula for calculating the required pressure at the beginning of the pipeline after the pump for the general case is as follows:
where Rg is the pressure loss on the horizontal section of the AB pipeline;
Pv - pressure loss in the vertical section of the BD pipeline;
Po is the pressure at the “dictating” sprinkler;
Z is the geometric height of the “dictating” sprinkler above the pump axis.
1 - water feeder;
2 - sprinkler;
3 - control units;
4 - supply pipeline;
Pr - pressure loss on the horizontal section of the AB pipeline;
Pv - pressure loss in the vertical section of the BD pipeline;
Рм - pressure loss in local resistances (shaped parts B and D);
Ruu - local resistance in the control unit (signal valve, gate valves, shutters);
Po - pressure at the “dictating” sprinkler;
Z - geometric height of the “dictating” sprinkler above the pump axis
Maximum pressure in pipelines of water and foam fire extinguishing- no more than 1.0 MPa.
Hydraulic pressure loss P in pipelines is determined by the formula:
where l is the length of the pipeline, m; k - pressure loss per unit length of the pipeline (hydraulic slope), Q - water flow, l/s.
The hydraulic slope is determined from the expression:
where A is the resistivity, depending on the diameter and roughness of the walls, x 106 m6/s2; Km - specific characteristics of the pipeline, m6/s2.
As operating experience shows, the nature of the change in pipe roughness depends on the composition of the water, air dissolved in it, operating mode, service life, etc.
The resistivity value and specific hydraulic characteristics of pipelines for pipes of various diameters are given in NPB 67-98.
Estimated water flow (foaming agent solution) q, l/s, through the sprinkler (foam generator):
where K is the performance coefficient of the sprinkler (foam generator) in accordance with the TD for the product; P - pressure in front of the sprinkler (foam generator), MPa.
Productivity coefficient K (in foreign literature synonymous with performance coefficient - "K-factor") is an aggregate complex depending on the flow coefficient and outlet area:
where K is the flow coefficient; F - outlet area; q is the acceleration of free fall.
In the practice of hydraulic design of water and foam AUP, the calculation of the performance coefficient is usually carried out from the expression:
where Q is the flow rate of water or solution through the sprinkler; P - pressure in front of the sprinkler.
The relationships between performance coefficients are expressed by the following approximate expression:
Therefore, when performing hydraulic calculations according to NPB 88-2001, the value of the performance coefficient in accordance with international and national standards must be taken equal to:
However, it must be taken into account that not all dispersed water enters directly into the protected area.
The figure shows a diagram of the area of the room affected by the sprinkler. On the area of a circle with radius Ri the required or standard value of irrigation intensity is provided, and for the area of a circle with a radius Rosh all the fire extinguishing agent dispersed by the sprinkler is distributed.
The mutual arrangement of sprinklers can be represented in two patterns: in a checkerboard or square pattern
a - chess; b - square
Placing sprinklers in a staggered pattern is beneficial in cases where linear dimensions controlled zone are multiples of the radius Ri or the remainder is not more than 0.5 Ri, and almost the entire water consumption falls on the protected zone.
In this case, the configuration of the calculated area has the form of a regular hexagon inscribed in a circle, the shape of which tends to the area of the circle irrigated by the system. This arrangement creates the most intensive irrigation of the sides. BUT with a square arrangement of sprinklers, the area of their interaction increases.
According to NPB 88-2001, the distance between sprinklers depends on the groups of protected premises and is no more than 4 m for some groups, no more than 3 m for others.
Only 3 ways of placing sprinklers on the distribution pipeline are realistic:
Symmetrical (A)
Symmetrically looped (B)
Asymmetrical (B)
The figure shows diagrams of three methods for assembling sprinklers; let’s look at them in more detail:
A - section with symmetrical arrangement of sprinklers;
B - section with asymmetrical arrangement of sprinklers;
B - section with a looped supply pipeline;
I, II, III - rows of the distribution pipeline;
a, b…јn, m - nodal design points
For each fire extinguishing section, we find the most remote and highest protected zone; hydraulic calculations will be carried out specifically for this zone. The pressure P1 at the “dictating” sprinkler 1, located further and higher than other sprinklers in the system, should not be lower than:
where q is the flow rate through the sprinkler; K - productivity coefficient; Pmin slave - the minimum permissible pressure for a given type of sprinkler.
The flow rate of the first sprinkler 1 is the calculated value of Q1-2 in the section l1-2 between the first and second sprinkler. Pressure loss P1-2 in section l1-2 is determined by the formula:
where Kt is the specific characteristic of the pipeline.
Therefore, the pressure at the sprinkler 2 is:
Sprinkler 2 consumption will be:
The estimated flow rate in the area between the second sprinkler and point “a”, i.e. in area “2-a” will be equal to:
Pipeline diameter d, m, is determined by the formula:
where Q is water flow, m3/s; ϑ - speed of water movement, m/s.
The speed of water movement in water and foam AUP pipelines should not exceed 10 m/s.
The diameter of the pipeline is expressed in millimeters and increased to the nearest value specified in the RD.
Based on the water flow Q2-a, the pressure loss in section “2-a” is determined:
The pressure at point "a" is equal to
From here we get: for the left branch of the 1st row of section A, it is necessary to ensure the flow rate Q2-a at pressure Pa. The right branch of the row is symmetrical to the left, so the flow rate for this branch will also be equal to Q2-a, therefore, the pressure at point “a” will be equal to Pa.
As a result, for row 1 we have a pressure equal to Pa and water consumption:
Row 2 is calculated according to the hydraulic characteristic:
where l is the length of the design section of the pipeline, m.
Since the hydraulic characteristics of the rows, made structurally identical, are equal, the characteristics of row II are determined by the generalized characteristics of the design section of the pipeline:
Water consumption from row 2 is determined by the formula:
All subsequent rows are calculated similarly to the calculation of the second until the result of the calculated water consumption is obtained. Then the total flow rate is calculated from the condition of placing the required number of sprinklers necessary to protect the calculated area, including if it is necessary to install sprinklers under technological equipment, ventilation ducts or platforms that prevent irrigation of the protected area.
The calculated area is taken depending on the group of premises according to NPB 88-2001.
Due to the fact that the pressure in each sprinkler is different (the most distant sprinkler has a minimum pressure), it is also necessary to take into account the different water flow from each sprinkler with the corresponding water efficiency.
Therefore, the estimated consumption of the AUP should be determined by the formula:
Where QAUP- estimated consumption of AUP, l/s; qn- consumption of n-th sprinkler, l/s; fn- coefficient of flow utilization at the design pressure of the n-th sprinkler; in- average irrigation intensity with the nth sprinkler (not less than the normalized irrigation intensity; Sn- standard irrigation area by each sprinkler with normalized intensity.
The ring network is calculated similarly to the dead-end network, but at 50% of the calculated water flow for each half-ring.
From point “m” to the water feeders, the pressure loss in the pipes is calculated along the length and taking into account local resistances, including in control units (signal valves, valves, shutters).
For approximate calculations, all local resistances are assumed to be equal to 20% of the resistance of the pipeline network.
Pressure losses in control units of installations Ruu(m) is determined by the formula:
where yY is the pressure loss coefficient in the control unit (accepted according to the TD for the control unit as a whole or for each signal valve, gate or gate valve individually); Q- calculated flow rate of water or foaming agent solution through the control unit.
The calculation is made so that the pressure in the control unit does not exceed 1 MPa.
The approximate diameters of the distribution rows can be determined by the number of installed sprinklers. The table below shows the relationship between the most common pipe diameters of distribution rows, pressure and the number of sprinklers installed.
The most common mistake in hydraulic calculations of distribution and supply pipelines is determining the flow rate Q according to the formula:
Where i And For- respectively, the intensity and area of irrigation for calculating flow rates, taken according to NPB 88-2001.
This formula cannot be applied because, as stated above, the intensity in each sprinkler is different from the others. This happens due to the fact that in any installations with a large number of sprinklers, when they are activated simultaneously, pressure losses occur in the pipeline system. Because of this, both the flow rate and the irrigation intensity of each part of the system are different. As a result, the sprinkler located closer to the supply pipeline has greater pressure, and consequently greater water flow. The specified unevenness of irrigation is illustrated by the hydraulic calculation of rows, which consist of sequentially located sprinklers.
d - diameter, mm; l - pipeline length, m; 1-14 - serial numbers of sprinklers
Row flow and pressure values
|
Row design number |
Diameter of pipe sections, mm |
Pressure, m |
Sprinkler consumption l/s |
Total row consumption, l/s |
|||||||||||
|
Uniform irrigation Qp6= 6q1 |
Uneven irrigation Qф6 = qns |
||||||||||||||
Notes:
1. The first design scheme consists of sprinklers with holes with a diameter of 12 mm with a specific characteristic of 0.141 m6/s2; the distance between sprinklers is 2.5 m.
2. Design diagrams for rows 2-5 are rows of sprinklers with holes with a diameter of 12.7 mm with a specific characteristic of 0.154 m6/s2; the distance between sprinklers is 3 m.
3. P1 indicates the design pressure in front of the sprinkler, and
P7 - design pressure in the row.
For design scheme No. 1, water consumption q6 from the sixth sprinkler (located near the feed pipeline) 1.75 times more than the water flow q1 from the final sprinkler. If the condition of uniform operation of all sprinklers in the system were met, then the total water flow Qp6 would be found by multiplying the water flow of the sprinkler by the number of sprinklers in the row: Qp6= 0.65 6 = 3.9 l/s.
If the water supply from sprinklers were uneven, the total water consumption Qf6, according to approximate table method calculation, would be calculated by sequential addition of expenses; it is 5.5 l/s, which is 40% higher Qp6. In the second calculation scheme q6 3.14 times more q1, A Qf6 more than twice as high Qp6.
An unreasonable increase in water flow for sprinklers, the pressure in front of which is higher than in the others, will only lead to an increase in pressure losses in the supply pipeline and, as a consequence, to an increase in the unevenness of irrigation.
The diameter of the pipeline has a positive effect on both reducing the pressure drop in the network and the calculated water flow. If you maximize the water flow of a water feeder with uneven operation of the sprinklers, the cost of construction work for the water feeder will greatly increase. this factor is decisive in determining the cost of work.
How can you achieve uniform water flow, and, ultimately, uniform irrigation of the protected area at pressures that vary along the length of the pipeline? There are several available options: arrangement of diaphragms, use of sprinklers with outlet openings varying along the length of the pipeline, etc.
However, no one canceled existing standards(NPB 88-2001), which do not allow the placement of sprinklers with different outlets within the same protected room.
The use of diaphragms is not regulated by documents, since when they are installed, each sprinkler and row has constant flow, calculation of supply pipelines, the diameter of which determines the pressure loss, the number of sprinklers in a row and the distance between them. This fact greatly simplifies the hydraulic calculation of the fire extinguishing section.
Thanks to this, the calculation is reduced to determining the dependence of the pressure drop in sections of the section on the diameters of the pipes. When choosing pipeline diameters in individual sections, it is necessary to comply with the condition under which the pressure loss per unit length differs little from the average hydraulic slope:
Where k- average hydraulic slope; ∑ R- pressure loss in the line from the water feeder to the “dictating” sprinkler, MPa; l- length of design sections of pipelines, m.
This calculation will demonstrate that the installation power of the pumping units required to overcome pressure losses in the section when using sprinklers with the same flow rate can be reduced by 4.7 times, and the volume of the emergency water reserve in the hydraulic pneumatic tank of the auxiliary water feeder can be reduced by 2.1 times. The reduction in metal consumption of pipelines will be 28%.
However, the training manual stipulates that installing diaphragms of different diameters in front of sprinklers is inappropriate. The reason for this is the fact that during the operation of the AUP the possibility of rearranging the diaphragms is not excluded, which significantly reduces the uniformity of irrigation.
For internal fire-fighting separate water supply systems in accordance with SNiP 2.04.01-85* and automatic fire extinguishing installations in accordance with NPB 88-2001, the installation of one group of pumps is permitted, provided that this group provides a flow rate Q equal to the sum of the needs of each water supply system:
where QVPV QAUP are the costs required for the internal fire water supply system and the AUP water supply system, respectively.
In the case of connecting fire hydrants to supply pipelines, the total flow rate is determined by the formula:
Where QPC- permissible flow from fire hydrants (accepted according to SNiP 2.04.01-85*, Table 1-2).
The operating time of internal fire hydrants, which include manual water or foam fire nozzles and are connected to the supply pipelines of the sprinkler installation, is assumed to be equal to its operating time.
To speed up and increase the accuracy of hydraulic calculations of sprinkler and deluge AUPs, it is recommended to use computer technology.
11. Select a pumping unit.
What are pumping units? In the irrigation system, they perform the function of the main water supply and are intended to provide water (and water-foam) fire extinguishing systems with the required pressure and flow of fire extinguishing agent.
There are 2 types of pumping units: main and auxiliary.
Auxiliary ones are used in permanent mode, as long as large amounts of water are not required (for example, in sprinkler systems for a period until no more than 2-3 sprinklers operate). If the fire takes on a larger scale, then the main pumping units are started (in the NTD they are often referred to as the main fire pumps), which provide water flow for all sprinklers. In deluge AUPs, as a rule, only the main fire pumping units are used.
Pumping units consist of pumping units, a control cabinet and a piping system with hydraulic and electromechanical equipment.
The pump unit consists of a drive connected through a transmission coupling to the pump (or pump block) and a foundation plate (or base). Several working pumping units can be installed in the AUP, which affects the required water flow. But regardless of the number of installed units, one backup must be provided in the pumping system.
When using no more than three control units in an automatic control system, pumping units can be designed with one input and one output, in other cases - with two inputs and two outputs.
Schematic diagram a pumping unit with two pumps, one inlet and one outlet is shown in Fig. 12; with two pumps, two inputs and two outputs - in fig. 13; with three pumps, two inputs and two outputs - in fig. 14.
Regardless of the number of pumping units, the pumping installation circuit must ensure the supply of water to the AUP supply pipeline from any input by switching the corresponding valves or gates:
Directly through the bypass line, bypassing the pumping units;
- from any pumping unit;
- from any set of pumping units.
Valves are installed before and after each pumping unit. This allows for repair and maintenance work to be carried out without disrupting the operation of the AUP. To prevent the reverse flow of water through pumping units or a bypass line, check valves are installed at the outlet of the pumps, which can also be installed behind the valve. In this case, when reinstalling the valve for repairs, there will be no need to drain water from the conducting pipeline.
As a rule, centrifugal pumps are used in AUP.
The appropriate type of pump is selected according to the Q-H characteristics, which are given in the catalogs. In this case, the following data is taken into account: the required pressure and flow (based on the results of hydraulic calculation of the network), dimensions pump and the relative orientation of the suction and pressure pipes (this determines the layout conditions), the mass of the pump.
12. Placement of the pumping station pumping unit.
12.1. Pumping stations are located in separate rooms with fire partitions and ceilings with a fire resistance limit of REI 45 according to SNiP 21-01-97 on the first, ground or basement floors, or in a separate extension to the building. It is necessary to ensure a constant air temperature from 5 to 35 °C and a relative humidity of no more than 80% at 25 °C. The specified room is equipped with working and emergency lighting in accordance with SNiP 23-05-95 and telephone communication with the fire station room; a light sign “Pumping station” is placed at the entrance.
12.2. The pumping station should be classified as:
According to the degree of water supply security - to the 1st category according to SNiP 2.04.02-84*. The number of suction lines to the pumping station, regardless of the number and groups of installed pumps, must be at least two. Each suction line must be designed to handle the full design flow of water;
- in terms of reliability of power supply - to the 1st category according to the PUE (power supply from two independent power supply sources). If it is impossible to fulfill this requirement, it is allowed to install (except in basements) backup pumps driven by internal combustion engines.
Typically, pumping stations are designed to be controlled without permanent maintenance personnel. Local control must be taken into account if automatic or remote control is available.
Simultaneously with the switching on of the fire pumps, all pumps for other purposes, powered into this main line and not included in the fire control system, must be automatically switched off.
12.3. The dimensions of the pumping station machine room should be determined taking into account the requirements of SNiP 2.04.02-84* (section 12). Take into account the requirements for the width of aisles.
In order to reduce the size of the pumping station in plan, it is possible to install pumps with right and left rotation of the shaft, and the impeller should rotate in only one direction.
12.4. The elevation of the pump axis is determined, as a rule, based on the conditions for installing the pump casing under the fill:
In the container (from the upper water level (determined from the bottom) of the fire volume for one fire, average (for two or more fires;
- in a water intake well - from the dynamic level of groundwater at maximum water intake;
- in a watercourse or reservoir - from the minimum water level in them: with a maximum supply of calculated water levels in surface sources - 1%, with a minimum - 97%.
In this case, it is necessary to take into account the permissible vacuum suction height (from the calculated minimum water level) or the necessary pressure on the suction side required by the manufacturer, as well as pressure loss (pressure) in the suction pipeline, temperature conditions and barometric pressure.
To obtain water from a reserve tank, it is necessary to install pumps “under the flood”. When installing pumps in this way above the water level in the reservoir, pump priming devices or self-priming pumps are used.
12.5. When using no more than three control units in the automatic control system, pumping units are designed with one input and one output, in other cases - with two inputs and two outputs.
It is possible to install suction and pressure manifolds in the pumping station, if this does not entail an increase in the span of the machine room.
Pipelines in pumping stations are usually made of welded steel pipes. Provide for a continuous rise of the suction pipeline to the pump with a slope of at least 0.005.
The diameters of pipes and fittings are taken on the basis of a technical and economic calculation, based on the recommended water flow rates indicated in the table below:
|
Pipe diameter, mm |
Speed of water movement, m/s, in pipelines of pumping stations |
|
|
suction |
pressure |
|
|
St. 250 to 800 |
||
On the pressure line, each pump requires a check valve, valve and pressure gauge; on the suction line, a check valve is not needed, and when the pump operates without support on the suction line, a valve with a pressure gauge is dispensed with. If the pressure is external network water supply is less than 0.05 MPa, then a receiving tank is placed in front of the pumping unit, the capacity of which is specified in section 13 of SNiP 2.04.01-85*.
12.6. In the event of an emergency shutdown of the working pumping unit, automatic switching on of the backup unit powered into this line must be provided.
The start-up time for fire pumps should not be more than 10 minutes.
12.7. To connect the fire extinguishing installation to mobile fire fighting equipment, pipelines with branch pipes are brought out, which are equipped with connecting heads (if at least two fire fighting vehicles are connected at the same time). Bandwidth The pipeline must provide the highest calculated flow rate in the “dictating” section of the fire extinguishing installation.
12.8. In buried and semi-buried pumping stations, measures must be taken against possible flooding of units in the event of an accident within the turbine room at the largest pump in terms of productivity (or at shut-off valves, pipelines) in the following ways:
- location of pump electric motors at a height of at least 0.5 m from the floor of the turbine room;
- gravity release of an emergency amount of water into the sewer or onto the surface of the earth with the installation of a valve or gate valve;
- pumping water from the pit with special or basic pumps for industrial purposes.
It is also necessary to take measures to remove excess water from the turbine room. To do this, the floors and channels in the hall are installed with a slope towards the collection pit. On the foundations for pumps, sides, grooves and tubes are provided for water drainage; If it is impossible to drain water by gravity from the pit, drainage pumps should be provided.
12.9. Pumping stations with a machine room size of 6-9 m or more are equipped with an internal fire-fighting water supply with a water flow rate of 2.5 l/s, as well as other primary fire extinguishing means.
13. Select an auxiliary or automatic water feeder.
13.1. In sprinkler and deluge installations, an automatic water feeder is used, usually a vessel (vessels) filled with water (at least 0.5 m3) and compressed air. In sprinkler systems with connected fire hydrants for buildings with a height of more than 30 m, the volume of water or foam solution is increased to 1 m3 or more.
The main task of a water supply system installed as an automatic water feeder is to provide a guaranteed pressure numerically equal to or exceeding the design pressure, sufficient to trigger the control units.
You can also use a feed pump (jockey pump), which includes a non-redundant intermediate tank, usually a membrane one, with a water volume of more than 40 liters.
13.2. The volume of water in the auxiliary water feeder is calculated from the condition of ensuring the flow rate required for the deluge installation (the total number of sprinklers) and/or the sprinkler installation (for five sprinklers).
It is necessary to provide an auxiliary water feeder for each installation with a manually started fire pump, which will ensure operation of the installation with the design pressure and flow rate of water (foaming agent solution) for 10 minutes or more.
13.3. Hydraulic, pneumatic and hydropneumatic tanks (vessels, containers, etc.) are selected taking into account the requirements of PB 03-576-03.
Tanks should be installed in rooms with walls whose fire resistance is at least REI 45, and the distance from the top of the tanks to the ceiling and walls, as well as between adjacent tanks, should be 0.6 m. Pumping stations must not be placed adjacent to rooms where large crowds of people are possible, such as concert halls, stages, wardrobes, etc.
Hydropneumatic tanks are located on technical floors, and pneumatic tanks are also located in unheated rooms.
In buildings whose height exceeds 30m, the auxiliary water supply is placed on the upper floors for technical purposes. Automatic and auxiliary water feeders must be turned off when the main pumps are turned on.
The training manual discusses in detail the procedure for developing a design assignment (Chapter 2), the procedure for developing a project (Chapter 3), coordination and general principles examination of AUP projects (Chapter 5). Based on this manual, the following applications have been compiled:
Appendix 1. List of documentation provided by the developer organization to the customer organization. Composition of design and estimate documentation.
Appendix 2. An example of a detailed design of an automatic sprinkler installation for water fire extinguishing.
2.4. INSTALLATION, ADJUSTMENT AND TESTING OF WATER FIRE FIGHTING INSTALLATIONS
When performing installation work, you must observe General requirements given in Chap. 12.
2.4.1. Installation of pumps and compressors produced in accordance with working documentation and VSN 394-78
First of all, it is necessary to carry out incoming control and draw up a report. Then remove excess grease from the units, prepare the foundation, mark and level the platform for the plates for the adjusting screws. When aligning and fastening, it is necessary to ensure that the axes of the equipment are aligned in plan with the axes of the foundation.
The pumps are aligned using the adjusting screws provided in their supporting parts. Compressor alignment can be done with adjusting screws, stock jacks, locating nuts on foundation bolts, or metal shim packs.
Attention! Before the final tightening of the screws, no work should be carried out that could change the aligned position of the equipment.
Compressors and pumping units that do not have a common foundation slab are mounted in series. Installation begins with a gearbox or a larger machine. The axles are aligned along the coupling halves, the oil lines are connected and, after alignment and final fastening of the unit, the pipelines are connected.
The placement of shut-off valves on all suction and pressure pipelines must provide the possibility of replacing or repairing any of the pumps, check valves and main shut-off valves, as well as checking the characteristics of the pumps.
2.4.2. Control units are delivered to the installation area in an assembled state in accordance with the wiring diagram (drawings) adopted in the project.
For control units, a functional diagram of the piping is provided, and in each direction there is a plate indicating the operating pressures, the name and category of explosion and fire hazard of the protected premises, the type and number of sprinklers in each section of the installation, the position (state) of the shut-off elements in standby mode.
2.4.3. Installation and fastening of pipelines and equipment during their installation is carried out in accordance with SNiP 3.05.04-84, SNiP 3.05.05-84, VSN 25.09.66-85 and VSN 2661-01-91.
Pipelines are attached to the wall with holders, but they cannot be used as supports for other structures. The distance between pipe fastening points is up to 4 m, with the exception of pipes with a nominal bore of more than 50 mm, for which the pitch can be increased to 6 m, if there are two independent fastening points built into the building structure. And also when laying a pipeline through sleeves and grooves.
If risers and branches on distribution pipelines exceed 1 m in length, they are secured with additional holders. The distance from the holder to the sprinkler on the riser (outlet) is at least 0.15 m.
The distance from the holder to the last sprinkler on the distribution pipeline for pipes with a nominal diameter of 25 mm or less does not exceed 0.9 m, with a diameter of more than 25 mm - 1.2 m.
For air sprinkler installations, the slope of the supply and distribution pipelines towards the control unit or drainage devices is provided: 0.01 - for pipes with an outer diameter of less than 57 mm; 0.005 - for pipes with an outer diameter of 57 mm or more.
If the pipeline is made of plastic pipes, then it must be tested at a positive temperature 16 hours after welding the last connection.
Do not install production and sanitary equipment to the supply pipeline of the fire extinguishing installation!
2.4.4. Installation of sprinklers on protected objects carried out in accordance with the project, NPB 88-2001 and TD on specific type sprinkler
Glass thermoflasks are very fragile and therefore require delicate handling. Damaged thermoflasks can no longer be used, as they cannot fulfill their direct responsibility.
When installing sprinklers, it is recommended to orient the planes of the sprinkler arms sequentially along the distribution pipeline and then perpendicular to its direction. On adjacent rows, it is recommended to orient the planes of the arms perpendicular to each other: if on one row the plane of the arms is oriented along the pipeline, then on the next row - across its direction. Guided by this rule, you can increase the uniformity of irrigation in the protected area.
For accelerated and high-quality installation of sprinklers on the pipeline, use various devices: adapters, tees, clamps for hanging pipelines, etc.
When securing the piping in place using clamp connections, it is necessary to drill several holes in the desired locations in the distribution piping to center the unit. The pipeline is secured with a bracket or two bolts. The sprinkler is screwed into the outlet of the device. If you need to use tees, then in this case you will need to prepare pipes of a given length, the ends of which will be connected by tees, then secure the tee tightly to the pipes with a bolt. In this case, the sprinkler is installed in the tee outlet. If you have chosen plastic pipes, then special clamp hangers are required for such pipes:
1 - cylindrical adapter; 2, 3 - clamp adapters; 4 - tee
Let's take a closer look at clamps, as well as the features of fastening pipelines. To prevent mechanical damage to the sprinkler, it is usually covered with protective casings. BUT! Keep in mind that the casing may interfere with the uniformity of irrigation due to the fact that it can distort the distribution of the dispersed liquid over the protected area. In order to avoid this, always ask the seller for certificates of conformity of this sprinkler with the attached casing design.
a - clamp for hanging a metal pipeline;
b - clamp for hanging a plastic pipeline
Protective enclosures for sprinklers
2.4.5. If the height of equipment control devices, electric drives and flywheels of valves (gates) is more than 1.4 m from the floor, additional platforms and blind areas are installed. But the height from the platform to the control devices should not be more than 1 m. It is possible to widen the equipment foundation.
The location of equipment and fittings under the installation platform (or service platforms) is not excluded at a height from the floor (or bridge) to the bottom of protruding structures of at least 1.8 m. In this case, a removable covering of the platforms or openings is made above the equipment and fittings.
AUP starting devices must be protected from accidental activation.
These measures are necessary in order to maximally protect the AUP starting devices from unintentional operation.
2.4.6. After installation, individual tests are carried out elements of a fire extinguishing installation: pumping units, compressors, tanks (automatic and auxiliary water feeders), etc.
Before testing the control unit, air is removed from all elements of the installation, then filled with water. In sprinkler installations, open the combined valve (in air and water-air valves), you must make sure that the alarm device is activated. In deluge installations, close the valve above the control unit, open the manual start valve on the incentive pipeline (turn on the electric valve start button). The activation of the control valve (electrically driven valve) and the signaling device is recorded. During testing, the operation of pressure gauges is checked.
Hydraulic tests of containers operating under compressed air pressure are carried out in accordance with TD for the container and PB 03-576-03.
Run-in of pumps and compressors is carried out in accordance with TD and VSN 394-78.
Test methods for the installation upon acceptance into operation are given in GOST R 50680-94.
Now, according to NPB 88-2001 (clause 4.39), it is possible to use plug valves at the upper points of the pipeline network of sprinkler installations as air release devices, as well as as a valve under a pressure gauge to control the sprinkler with minimum pressure.
It is useful to prescribe such devices in the installation project and use them when testing the control unit.
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1 - fitting; 2 - body; 3 - switch; 4 - cover; 5 - lever; 6 - plunger; 7 - membrane
2.5. OPERATIONAL MAINTENANCE OF WATER FIRE FIGHTING INSTALLATIONS
The serviceability of the water fire extinguishing installation is monitored by round-the-clock security of the building territory. Access to the pumping station must be limited to unauthorized persons; sets of keys are issued to operational and maintenance personnel.
The sprinklers must NOT be painted; they must be protected from paint during cosmetic repairs.
Such external influences as vibration, pressure in the pipeline, and, as a result, the impact of sporadic water hammer due to the operation of fire pumps, seriously affect the operating time of sprinklers. The consequence may be a weakening of the thermal lock of the sprinkler, as well as their loss if the installation conditions were violated.
Often the temperature of the water in the pipeline is higher than average, this is especially true for rooms where the type of activity causes elevated temperatures. This may cause sticking locking device in a sprinkler due to precipitation in the water. That is why, even if the device looks undamaged on the outside, it is necessary to inspect the equipment for corrosion and sticking, so that false alarms and tragic situations do not occur if the system fails during a fire.
When activating the sprinkler, it is very important that all parts of the thermal lock fly out without delay after destruction. This function regulates the membrane diaphragm and levers. If the technology was violated during installation, or the quality of the materials leaves much to be desired, the properties of the spring-disc membrane may weaken over time. Where it leads? The thermal lock will partially remain in the sprinkler and will not allow the valve to fully open; water will only ooze out in a small stream, which will not allow the device to fully irrigate the area it protects. To avoid such situations, the sprinkler is equipped with an arc-shaped spring, the force of which is directed perpendicular to the plane of the arches. This ensures that the heat lock is completely released.
Also, when using, it is necessary to exclude the impact of lighting fixtures on sprinklers when they are moved during repairs. Eliminate any gaps between the pipeline and electrical wiring.
When determining the progress of maintenance and repair work, you should:
Carry out an external inspection of the installation components daily and monitor the water level in the tank,
Perform a weekly test run of pumps with electric or diesel drive for 10-30 minutes using remote start devices without water supply,
Once every 6 months, drain the sediment from the tank, and also make sure that the drainage devices that ensure the drainage of water from the protected premises (if any) are in good working order.
Check the flow characteristics of the pumps annually,
Turn drain valves annually
Annually replace the water in the tank and pipelines of the installation, clean the tank, flush and clean the pipelines.
Conduct hydraulic tests of pipelines and hydraulic pneumatic tank in a timely manner.
The main regulatory work that is carried out abroad in accordance with NFPA 25 provides for a detailed annual inspection of the elements of the air defense system:
- sprinklers (absence of plugs, type and orientation of sprinkler in accordance with the design, absence of mechanical damage, corrosion, clogging of outlet holes of deluge sprinklers, etc.);
- pipelines and fittings (no mechanical damage, cracks in fittings, damage to the paintwork, changes in the slope angle of pipelines, serviceability of drainage devices, sealing gaskets must be tightened in clamping units);
- brackets (absence of mechanical damage, corrosion, reliability of fastening of pipelines to brackets (fastening units) and brackets to building structures);
- control units (position of valves and gate valves in accordance with the design and operating instructions, operability of signaling devices, gaskets must be tightened);
- check valves (correct connection).
3. WATER FIRE FIGHTING UNITS
HISTORICAL REFERENCE.
International studies have proven that when water droplets are reduced, the effectiveness of finely atomized water increases dramatically.
Finely atomized water (FW) includes jets of droplets with a diameter of less than 0.15 mm.
Note that TRV and its foreign name “water fog” are not equivalent concepts. According to NFPA 750, water mist is divided into 3 classes based on the degree of dispersion. The “fine” water mist belongs to class 1 and contains droplets with a diameter of ~0.1…0.2 mm. Class 2 combines water jets with a droplet diameter of predominantly 0.2...0.4 mm, class 3 - up to 1 mm. using conventional sprinklers with a small outlet diameter at a slight increase in water pressure.
So, in order to obtain water mist of the first class, high water pressure is required, or the installation of special sprinklers, while obtaining a dispersion of the third class is achieved using conventional sprinklers with a small outlet diameter with a slight increase in water pressure.
Water mist was first installed and used on passenger ferries in the 1940s. Now interest in it has increased due to recent research, which has proven that water mist does an excellent job of providing fire safety in those rooms where halon or carbon dioxide fire extinguishing systems were previously used.
In Russia, fire extinguishing installations using superheated water were the first to appear. They were developed by VNIIPO in the early 1990s. The stream of superheated steam quickly evaporated and turned into a stream of steam with a temperature of about 70 ° C, which transferred a stream of condensed fine droplets over a considerable distance.
Now fire extinguishing modules with finely sprayed water and special sprayers have been developed, the principle of operation of which is similar to the previous ones, but without the use of superheated water. Delivery of water droplets to the fire is usually carried out by propellant gas from the module.
3.1. Purpose and design of installations
According to NPB 88-2001, fire extinguishing installations with finely sprayed water (UPTRV) are used for surface and local extinguishing of fires of classes A and B. These installations are used in premises of categories A, B, B1-B3, as well as in archive rooms of museums, offices, retail and warehouse premises, that is, in cases where it is important not to harm material assets with fire retardant solutions. Typically such installations are modular in design.
For extinguishing both ordinary solid materials (plastics, wood, textiles, etc.) and more dangerous materials such as foam rubber;
Combustible and flammable liquids (in the latter case, use a fine spray of water);
- electrical equipment, for example, transformers, electrical switches, rotating motors, etc.;
Gas jet fires.
We have already mentioned that the use of water fog greatly increases the chances of saving people from a flammable room and simplifies evacuation. The use of water fog is very effective when extinguishing aviation fuel spills, because it significantly reduces the heat flow.
The general requirements applicable in the United States to specified fire extinguishing installations are given in NFPA 750, Standard on Water Mist Fire Protection Systems.
3.2. To obtain finely atomized water They use special sprinklers called sprayers.
Spray- a sprinkler designed for spraying water and aqueous solutions, the average diameter of the droplets in the flow is less than 150 microns, but does not exceed 250 microns.
Spray sprinklers are installed in the installation at a relatively low pressure in the pipeline. If the pressure exceeds 1 MPa, then a simple rosette sprayer can be used as sprayers.
If the diameter of the sprayer socket is larger than the outlet, then the socket is mounted outside the arms; if the diameter is small, then between the arms. The jet can also be crushed on a ball. To protect against contamination, the outlet of deluge nozzles is covered with a protective cap. When water is supplied, the cap is thrown off, but its loss is prevented by a flexible connection with the body (wire or chain).
Nozzle designs: a - AM 4 type nozzle; b - sprayer type AM 25;
1 - body; 2 - arms; 3 - socket; 4 - fairing; 5 - filter; 6 - calibrated outlet (nozzle); 7 - protective cap; 8 - centering cap; 9 - elastic membrane; 10 - thermoflask; 11 - adjusting screw.
3.3. As a rule, UPRVs are modular designs. Modules for UPRV are subject to mandatory certification for compliance with the requirements of NPB 80-99.
The propellant gas used in the modular sprinkler is air or other inert gases (for example, carbon dioxide or nitrogen), as well as pyrotechnic gas-generating elements recommended for use in fire fighting equipment. No parts of gas-generating elements should get into the fire extinguishing agent; this should be provided for by the design of the installation.
In this case, the propellant gas can be contained both in one cylinder with OTV (injection type modules) and in a separate cylinder with an individual shut-off and starting device (ZPU).
Operating principle of modular UPTV.
As soon as the fire alarm detects an extreme temperature in the room, a control pulse is generated. It enters the gas generator or squib cartridge of the cylinder, the latter contains a propellant gas or OTV (for injection-type modules). A gas-liquid flow is formed in the cylinder with fire extinguishing agent. It is transported through a network of pipelines to sprayers, through which it is dispersed in the form of a finely dispersed droplet medium into the protected room. The installation can be activated manually from the trigger element (handle, button). Typically, the modules are equipped with a pressure alarm, which is designed to transmit a signal about the operation of the installation.
For clarity, we present to you several UPRV modules:
General view of the module for the fire extinguishing installation with finely sprayed water MUPTV "Typhoon" (NPO "Plamya")
Fire extinguishing installation module for finely sprayed water MPV (Moscow Experimental Plant Spetsavtomatika JSC):
a - general view; b - locking and starting device
The main technical characteristics of domestic modular UPTRV are given in the tables below:
Specifications modular installations fire extinguishing with finely sprayed water MUPTV "Typhoon".
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Indicators |
Indicator value |
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MUPTV 60GV |
MUPTV 60GVD |
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Fire extinguishing capacity, m2, no more: class A fire fire class B flammable liquids with flash point vapors up to 40 °C fire class B flammable liquids with flash point vapors 40 °C and above |
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Duration of action, s |
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Average consumption of fire extinguishing agent, kg/s |
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Weight, kg, and type of fire protection equipment: Drinking water according to GOST 2874 water with additives |
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Mass of propellant gas ( liquid dioxide carbon according to GOST 8050), kg |
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Volume in the propellant cylinder, l |
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Module capacity, l |
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Working pressure, MPa |
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Technical characteristics of modular fire extinguishing installations with finely sprayed water MUPTV NPF "Safety"
Technical characteristics of modular water mist fire extinguishing installations MPV
Much attention in regulatory documents is paid to ways to reduce foreign impurities in water. For this reason, filters are installed in front of the nozzles, and anti-corrosion measures are taken for modules, pipelines and UPRV nozzles (the pipelines are made of galvanized or of stainless steel). These measures are extremely important because The flow sections of the UPTRV nozzles are small.
When using water with additives that precipitate or form a phase separation during long-term storage, the installations provide devices for mixing them.
All methods for checking the irrigated area are described in detail in the technical specifications and technical documentation for each product.
In accordance with NPB 80-99, the fire extinguishing efficiency of using modules with a set of sprayers is checked during fire tests, where model fires are used:
- class B, cylindrical baking sheets with an internal diameter of 180 mm and a height of 70 mm, flammable liquid - n-heptane or A-76 gasoline in the amount of 630 ml. Free burning time of flammable liquid is 1 min;
- class A, stacks of five rows of bars, folded in the form of a well, forming a square in horizontal section and fastened together. Three bars are laid in each row, having a square cross-section measuring 39 mm and a length of 150 mm. The middle bar is laid in the center parallel to the side edges. The stack is placed on two steel angles mounted on concrete blocks or rigid metal supports so that the distance from the base of the stack to the floor is 100 mm. A metal pan measuring (150x150) mm with gasoline is placed under the stack to set the wood on fire. Free burning time is about 6 minutes.
3.4. Design of UTPVR performed in accordance with Chapter 6 of NPB 88-2001. According to the amendment No. 1 to NPB 88-2001 “calculation and design of installations are carried out on the basis of regulatory and technical documentation of the installation manufacturer, agreed upon in the prescribed manner.”
The design of the UPRV must comply with the requirements of NPB 80-99. The placement of sprayers, the diagram of their connection to the piping, the maximum length and diameter of the pipeline, the height of its placement, fire class and protected area and other necessary information are usually indicated in the manufacturer's TD.
3.5. Installation of UPRV is carried out in accordance with the manufacturer's design and installation diagrams.
Observe the spatial orientation specified in the project and TD during installation of sprayers. Installation diagrams for AM 4 and AM 25 sprayers on the pipeline are presented below:
In order for the product to serve for a long time, it is necessary to promptly carry out the necessary repair work and technical specifications given in the manufacturer’s technical documentation. You should especially carefully follow the schedule of measures to protect the nozzles from clogging, both external (dirt, intense dust, construction debris during repairs, etc.) and internal (rust, mounting sealing elements, sediment particles from water during storage, etc. .) elements.
4. INTERNAL FIRE-PROOF WATER PIPELINE
The ERW is used to deliver water to the fire hydrant of the premises and, as a rule, is included in the internal water supply system of the building.
Requirements for ERW are defined by SNiP 2.04.01-85 and GOST 12.4.009-83. The design of pipelines laid outside buildings to supply water for external fire extinguishing should be carried out in accordance with SNiP 2.04.02-84. Requirements for ERW are defined by SNiP 2.04.01-85 and GOST 12.4.009-83. The design of pipelines laid outside buildings to supply water for external fire extinguishing should be carried out in accordance with SNiP 2.04.02-84. General issues of using ERW are discussed in the work.
The list of residential, public, auxiliary, industrial and warehouse buildings that are equipped with ERW is presented in SNiP 2.04.01-85. The minimum required water flow for fire extinguishing and the number of simultaneously operating jets are determined. The consumption is affected by the height of the building and the fire resistance of building structures.
If the ERV cannot provide the required water pressure, it is necessary to install pumps that increase the pressure, and a pump start button is installed near the fire hydrant.
The minimum diameter of the sprinkler installation supply pipeline to which a fire hydrant can be connected is 65mm. Cranes are placed in accordance with SNiP 2.04.01-85. Indoor fire hydrants do not require a remote fire pump start button.
The methodology for hydraulic calculation of ERW is given in SNiP 2.04.01-85. In this case, the water consumption for using showers and watering the territory is not taken into account; the speed of water in pipelines should not exceed 3 m/s (except for water fire extinguishing installations, where a water speed of 10 m/s is allowed).
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Water consumption, l/s |
Water movement speed, m/s, with pipe diameter, mm |
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The hydrostatic head should not exceed:
In the system of a combined utility and fire-fighting water supply system, at the level of the lowest location of the sanitary fixture - 60 m;
- in a separate fire water supply system at the level of the lowest fire hydrant - 90 m.
If the pressure in front of the fire hydrant exceeds 40 m of water. Art., then a diaphragm is installed between the tap and the connecting head, which reduces the excess pressure. The pressure in the fire hydrant must be sufficient to create a jet that affects the most distant and highest parts of the room at any time of the day. The radius and height of the jets are also regulated.
The operating time of fire hydrants should be 3 hours, when supplying water from the building’s water tanks - 10 minutes.
Internal fire hydrants are installed, as a rule, at the entrance, on staircase landings, in the corridor. The main thing is that the place should be accessible, and the crane should not interfere with the evacuation of people in case of fire.
Fire hydrants are placed in wall boxes at a height of 1.35. The cabinet has openings for ventilation and inspection of the contents without opening.
Each tap must be equipped with a fire hose of the same diameter, 10, 15 or 20 m long, and a fire nozzle. The hose must be laid in a double roll or “accordion” and attached to the tap. The procedure for maintaining and servicing fire hoses must comply with the “Instructions for the operation and repair of fire hoses” approved by the Main Directorate for the Operation of the Ministry of Internal Affairs of the USSR.
Fire hydrants are inspected and tested for functionality by running water at least once every 6 months. The results of the check are recorded in a log.
The exterior design of fire lockers must include a red signal color. Lockers must be sealed.
Among all the existing methods of fighting fires, the fire sprinkler system stands apart. Its peculiarity lies in the simplicity of its design and the absence of complex automation.
Its action is based on the automatic opening of water. The system reacts to an increase in room temperature. When it reaches critical values, water is supplied from the sprinkler.
A little history
The first sprinkler systems were developed in the early 19th century. Over such a long period of time, they have changed, but the principle of operation remains the same. They owe their survivability to the simplicity of their design. They do not contain complex semiconductor or digital elements.
Simplicity also determines the reliability of devices. The main changes affected the materials used in the production of systems, increasing their power, installation modern elements. Only the basic principle of operation of the fire sprinkler system remains unchanged.
Structurally, the system looks like a branched pipeline with water under pressure. The outlets of the working fluid are hermetically sealed with caps that can be destroyed under the influence of high temperature. Simplified operation of the system can be described as follows. If a fire occurs in the room, the temperature rises and the material of the hood melts. Water sprays from the pipe system. The design changes affected not the principle of operation, but its improvement. IN modern systems sprinkler is used. In fact, this is a sprinkler, thanks to which the extinguishing liquid is sprayed under pressure.
Advantages:
- Can be used in residential, office, administrative, industrial buildings.
- Quick response to fire.
Works well with smoke detectors. The latter increase the efficiency of the system due to timely notification of increased smoke levels. Their use without fire extinguishing devices is not justified; their effectiveness is not always high.
The decrease in efficiency is explained by the following factors:
- The alarm signal may simply not be heard.
- People do not always have time to evacuate from a burning building.
Installing a fire sprinkler system together with smoke detectors allows you to increase the efficiency of both elements significantly. Sensors sound an alarm, and the fire extinguishing system instantly responds to a fire by spraying water.
Additional benefits come from using tap water as an extinguishing liquid:
- Low cost.
- No shortage of water.
- Environmentally friendly, non-toxic.
- Safety for humans.
- Good extinguishing ability.
Schemes of modern systems
Schemes of fire sprinkler systems are developed based on the use modern materials. Plastic pipes are used for pipeline installation. This is an economically viable choice. The cost of installing a plastic pipeline is several times lower than the cost of metal structures.
Installing plastic pipes makes it possible to forget about any problems for many years. There is no limescale deposited on their internal surfaces. The pipe clearance will maintain its original values for a long time. Plastic pipes are lightweight and do not increase the load on building structures. They are very easy to install.
The main disadvantage of water fire extinguishing is the negative impact on many materials, for example, wood, paper. This required the development of systems whose use does not increase damage. Since the cap is destroyed under the influence of temperature, the use of modern materials ensured the gradual operation of the sprayers. The elements located as close as possible to the source of fire always start working first.
The fire extinguishing system pipeline is connected to the water supply network. To maintain the required pressure, check valves are installed. The result is a completely autonomous, non-volatile system, ready to start at any time. The activation of one of the sprayers leads to a sharp drop in pressure. After this, pressure sensors are triggered, starting pumping equipment that provides the necessary backup water supply.
Water sprinkler fire extinguishing can effectively protect a room within a radius of 12 m. If the triggered sprayer fails to control the source of fire, the air temperature continues to rise. Neighboring sprinklers turn on.
Restrictions
Automatic fire sprinklers have some limitations on their use. Firstly, they are associated with the possibility of using water to extinguish fires of different classes. For example, for server and industrial facilities, the choice of such a system is not justified, since water cannot be used to extinguish electrical equipment.
Other disadvantages include:
- Inertia of the system. The water in the pipeline cools the hood. Its destruction and operation of the system begins with a slight delay.
- Dependence on the reliability of the water supply system.
- The operation of the sprinkler system is dependent on the ambient temperature, which can increase not only as a result of a fire.
- Wetting surrounding surfaces with water. This parameter can be considered both as an advantage and as a negative point in the operation of the system. On the one hand, water damages things. On the other hand, wetting the surfaces prevents the spread of fire.
Dry systems
Classic sprinkler systems have limitations on their use. They require water to operate. If there is no constant, uninterrupted supply of water, the system will be useless. Sprinklers should not be used at low temperatures either. Water freezes at subzero temperatures and can lead to complete destruction of the system and pipe ruptures. It is not always possible to solve the problem using additives that can lower the freezing point. They form a coating on the inner surface of the pipes, narrowing their lumen. Over time, the pipes can become clogged to such an extent that the system completely loses its functionality.
The development of dry systems allowed the problem to be solved. While the system is in standby mode, it is filled with compressed air. When the sprinkler is activated, air escapes, creating a vacuum. Under its influence, water is supplied to the valves of the water system and to the pipes. To speed up the work, additional devices are installed that provide an almost instantaneous decrease in pressure and rapid filling of pipes with water.
Their operation is as follows: when one sprinkler is activated, other valves automatically open. As a result, the pressure in the system instantly drops and water flows faster.
Installation of dry systems is only possible with plastic pipes. Metal constructions are destroyed by exposure to oxygen.
Despite their apparent simplicity, sprinklers are in constant operation, in standby mode. As a result, installation and maintenance of the system must be carried out by a specialized company licensed to carry out such work.
Deluge systems are a type of water fire extinguishing system. Sometimes they are considered independent structures, sometimes called a type of sprinkler. Their main similarity is in the installation diagram of the pipeline in which the water is located. Deluge and sprinkler fire extinguishing systems differ in the way they operate. The signal to start working in deluge fire extinguishing is given from the central control panel or detector. This method of excitation made it possible to get rid of the main drawback of water systems - inertia.
This type can be mounted on any objects. Their type and purpose do not matter. In unheated facilities, deluge systems are installed with dry pipelines filled with air.
You cannot install dry fire extinguishing systems at facilities where there is a risk of explosion, intense fire with a high rate of fire spread.
Examples and prices
Sprinkler and deluge systems are some of the most affordable fire suppression equipment on the market. It is impossible to name a specific price for the device.
It consists of different components:
- Room area.
- Required number of sprinklers with thermal locks.
- Pipes.
- Shut-off valves (check valves).
- Pump equipment.
- Backup water storage.
The main pricing parameter still remains the area of the premises. The amount of materials and components depends on it. Prices for the services of companies designing and installing fire systems can also vary significantly.
On average, for a small room up to 500 sq. meters, project development and installation of all elements will cost 65,000 rubles.
Automatic deluge fire extinguishing system
Fire is disaster, which causes great harm and often takes the lives of many people. To prevent this, fire sprinklers are installed. The first such systems appeared in late XIX centuries and worked on the principle of destroying heat-sensitive locks. Due to its imperfections, the installation was triggered already during a severe fire, and sometimes false activity was observed.
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Work principles
IN modern designs Automatic fire extinguishing is installed; its detectors can detect fires even before a fire starts. But the principle of operation of the fire sprinkler system remains unchanged. Water constantly flows through the pipes under high pressure. In their holes there is a lock made of low-melting material, which melts under the influence of high temperature, as a result of which the liquid is sprayed.
Each system, regardless of its type, has a built-in sprinkler equipped with a thermal lock. Under the influence of a certain temperature, the substance begins to melt in the flask, which eventually collapses and depressurizes the pipeline. After this, the system works according to the algorithm:
Fire sprinkler system testing
The sprinkler is designed to eliminate local fires. In rooms where the temperature has not reached a critical point, the lock will not collapse and water will not be sprayed. Modern designs combine several devices - a fire alarm, which gives an alert when a fire is detected and ensures the evacuation of personnel, a control system that activates smoke protection, and pumps that maintain pressure in quiet mode and during fire extinguishing.
Scope of application
According to the decree “On the fire safety regime” and some production documentation, the installation of sprinkler fire extinguishing must be carried out in some structures. Among them are:
PUMPING STATION OF SPLINCLER FIRE FIGHTING SYSTEM...
Advantages and disadvantages
Before purchasing and installing equipment, you must familiarize yourself with its technical characteristics and features. Many businesses install a sprinkler system because of its benefits. These include:
- low cost;
- efficiency;
- Possibility of installation in any room;
- quick installation.
The design itself, its installation and maintenance will not require large financial costs. The system quickly copes with fires, eliminating their local sources. The equipment can be installed in a room of any shape and size. During installation, there is no need to change the layout of the building or disturb load-bearing structures or partitions.
There are also several disadvantages:
- restrictions temperature regime;
- possible losses from using large amounts of water;
- the need to replace devices after use;
- System activation time may be delayed.
Distribution and supply pipes filled with water are used in rooms with temperatures above 5 degrees. If the indicator is negative, only supply structures are allowed to be filled with liquid. Water escaping from equipment during operation can cause significant damage to property in the building.Sprinklers are considered disposable devices because they must be replaced after the first activation or the system will not be able to return to standby mode. If the room is heavily smoky, the design will not work, because it only reacts to high temperatures.
System structure
Supply pipelines are connected to the system on both sides. One of them is filled with water, the second with liquid and air. There are two types of sprinklers on the pipelines - SVV, directed with the rosette upward, and SVV, turned downwards. On one pipe there is a water supply control sensor, on the second there are detachable couplings.
Attached below are the system control units: water-filled direct flow and air with SKD valve. Near the tank with the fire extinguishing liquid there is a sensor that monitors the water level in the tank. In the center there is a device with which the entire system is controlled and monitored. There are also several other elements in the design:
- check valve;
- control cabinet for automatic maintenance of water supply;
- automatic pipe pressure support sensor;
- container with water;
- main, backup and pump-out pumps;
- compressor and drainage pit.
The main working element responsible for the efficiency of the entire system is the sprinkler. All activity depends on a capsule with heat-sensitive contents that responds to an indicator within the range of 57-340 degrees. Different models of sprayers contain parts that are triggered at a certain mark. They differ in the color of the liquid they contain:
- orange - from 57 degrees;
- red - from 68;
- yellow - from 79;
- green - from 93;
- blue - from 141;
- purple - from 182.
The first two types are considered low-temperature. Such sprinklers operate within five minutes after identifying a fire. The activity of the following begins after 10-15 minutes. Sprinkler designs are divided according to several criteria - jet direction, position and speed of action.
Impressive fire extinguishing system test
The parts can be arranged with a rosette down and up, the water passes at a certain angle, which increases the spray area. The system creates a liquid curtain or thin stream designed to extinguish fires in rooms with property that may be damaged by water. Increased speed is necessary to identify the lesion in the early stages. Such models are installed in buildings with high ceilings (up to 20 m).
Requirements and Standards
Equipment requirements are set out in the fire sprinkler system installation code. The main one is the rate of fluid supply in the early stages of a disaster. The fire should not intensify and spread to other rooms, therefore, during installation of equipment, make sure that it complies with all GOSTs, SNiP standards and the requirements of the Ministry of Emergency Situations. You only need to purchase quality system, which must be confirmed by certificates and technical passports.According to the standards, the activation time of the thermal flask depends on the temperature regime. The higher the indicator, the faster the sprinkler should work. At temperatures above 79 degrees, the maximum time should not exceed five minutes. The distance between the irrigation heads is determined in accordance with SNiP standards. During installation, possible malfunctions of some parts of the assembly are taken into account. To avoid breakdowns, install an additional pump, a water tank and a power source. These include:
Among the disadvantages is the possibility of inertial operation. The system will not work effectively if electrical appliances catch fire.
Items in the room can be damaged by exposure to water. In such buildings, a structure with air-filled pipelines is installed.
In standby mode, the system is filled not with water, but with compressed air. If the fire sensor is triggered, a special valve opens, oxygen escapes, and water is poured into the pipes under pressure. She enters the burning area using a sprinkler. For water-filled systems, sprinklers are mounted with rosettes down and up, as well as in a horizontal position. In models of other types, it is possible to install sprinklers only vertically. The shortcomings of the system are not serious excuses for refusing to purchase such systems.
Installation of sprinkler structure
To install a fire sprinkler system, pipelines coated with a zinc sheath on the outside and inside are used. It is also possible to use suture products. They are attached to the ceiling using elastic clamps, keeping a step of 1.5 m. The pipes are connected to each other using a welding machine or crimped with special fittings, electric and pneumatic tools. After preparing these elements, sprinklers are attached according to the model and design of the system.IN separate room- in the basement or utility room - install distribution units and a container for fire extinguishing liquid. The control element is mounted there, but its duplicate is displayed on the security console. Since water sprinkler fire extinguishing pipelines are under high pressure, all seams and joints of parts must be as tight as possible. Otherwise, the system will experience leaks and damage.
Sprinkler fire extinguishing structures are convenient to use in large industrial and entertainment premises - warehouses, workshops, restaurants and theaters. With proper installation, you can achieve maximum efficiency of the system, while you need to apply minimal physical effort, and the financial costs will be insignificant.
In office premises, administrative or commercial buildings, you can often see small sensors on the ceiling - sprinklers. They are thermosensitive, that is, they react to increased temperature. The result of activation of sprinklers is the automatic start of the fire extinguishing process.
A system that combines sprinklers, the network of pipelines on which they are installed, and pumping equipment is called a fire sprinkler system (AFS).
Principle of operation
The devices and equipment included in the ASPT are improved over time, thanks to which modern sprinkler systems are highly efficient, respond quickly and are reliable. As for the operating principle of ASPT, it has not changed since the invention of this method of water fire extinguishing.
The operating scheme of ASPT is simple:
- during a fire, the temperature in the room rises;
- sensors react to excess heat and are destroyed;
- the pipeline, constantly filled with water under pressure, depressurizes;
- pressure booster pumps are automatically turned on;
- The extinguishing agent is sprayed through all activated sprinklers, extinguishing the fire in the room.
Since the sprinkler system is automatic and most often connected with other fire and security systems of the building, simultaneously with the start of fire extinguishing, an emergency message is sent to the security console, the warning and evacuation control system is turned on, the ventilation is turned off, the elevators are called to the 1st floor and blocked after opening the doors.
Device
The fire sprinkler system is based on the water supply present in the building. In heated buildings, the pipes are constantly filled with water (unless another type of waste water is used), which is under a certain pressure thanks to pumping equipment. If the ASPT is activated and the process of spraying water over the protected volume begins, the pumps will provide pressure in the system at a sufficient level to extinguish the fire.
In those buildings that are not heated in winter, provision is made for draining the water supply during the cold season. This prevents water in the pipes from freezing. In winter, the pipeline is filled with compressed air. If a fire occurs, air is quickly released from the system and the pipes are filled with fire extinguishing agent. The only drawback with such a dry sprinkler system is the increase in time from the receipt of a fire signal to the start of extinguishing the fire.
Calculation
In order for the fire extinguishing system at a facility to be effective, that is, to clearly and effectively perform its assigned functions, each of its elements must be carefully thought out at the design stage.
The designer, in particular, is required to determine:
- water consumption if a fire occurs;
- intensity of irrigation of the protected space;
- compliance of the 2nd parameter with standard values;
- water feeder pressure;
- optimal pipe diameter.
Taking into account all the necessary indicators, the specialist calculates the fire sprinkler system with optimal indicators for a particular facility.
Trial
After the ASPT has been designed and installed at the site, it must be tested before it is put into operation. Such work is carried out by specialists from specialized service companies. The testing procedure must comply with GOST 50680-94 and other rules and regulations.
The purpose of the tests is to establish compliance of the system with the regulatory parameters specified in GOST.
Sprinkler installations are tested in 2 stages:
- Fire simulation (using a heat pulse) to test the functionality of sprinklers.
- Replacement of sprinklers in the test area with deluges, manual start of ASPT.
Flaws
Despite the fact that sprinkler fire extinguishing is a simple, effective and inexpensive way to protect a building from fire, such systems have their drawbacks:
- limited use at low temperatures;
- the need to replace sprinklers after they are activated;
- the system’s reaction only to an increase in heat, without taking into account smoke in the room and other fire factors;
- water, like OTV, is not suitable for all types of objects.
To select a suitable fire extinguishing system, the best solution would be to seek help from specialists with experience in the design and installation of fire extinguishing equipment.
Theoretical knowledge and practical experience in the field of ensuring fire safety of different types of buildings is a guarantee that you will be advised of a truly reliable, effective and profitable method of protection for your facility.
The use of automatic water fire extinguishing systems, both in industrial and public buildings, and in residential buildings, has a number of advantages. Economic advantages lie in the low cost of the fire extinguishing agent - water, its availability and high fire extinguishing efficiency. The second point is the technical advantages of the system itself:
- water fire extinguishing can be used for almost any type of premises;
- ease of installation, relatively low cost of the system and its further maintenance;
- versatility;
There are also special advantages of a water fire extinguishing system over powder or gas extinguishing systems. This is possible for use in public places where many people are concentrated or in buildings where people with disabilities are located: hospitals, nursing homes, hospices.
At the moment, there are several types of water fire extinguishing systems. Two of them are considered the most effective and widespread - sprinkler and deluge.
WATER FIRE FIGHTING SPRINKLER SYSTEM
The sprinkler installation for automatic water fire extinguishing is a system of pipelines filled with pressurized water. Sprinklers with fusible plugs for the outlet openings are embedded into the pipes at certain intervals.
The operating principle of a water fire extinguishing sprinkler system is as follows. When a fire occurs, the temperature in the room rises. The heat-sensitive liquid in the interlock expands and destroys the capsule, allowing the extinguishing agent to enter the room. After water spraying begins, the pressure in the system drops and a special relay turns on the autonomous water supply pump group.
For the pipeline system, not only steel pipes are used, but plastic pipes that can withstand high temperatures and significant pressure. Constant high pressure in the pipeline is maintained using a group of check valves installed at key points.
In the event of a malfunction in the main water supply system, the sprinkler system maintains a working pressure level, and the reservoir with the fire extinguishing agent will provide the necessary amount of water to eliminate the source of fire in the early stages.
Sprinklers.
Sprinkler sprinklers can have an upper (for an open method of laying pipes) and a lower (for pipelines hidden behind a false ceiling) installation scheme. Manufacturers produce many models designed for more efficient operation and spraying, including directional spraying. The area that one sprayer can effectively control is, on average, 12 m2.
Advantages and disadvantages of a water fire extinguishing sprinkler system:
The advantages of the fire extinguishing systems under consideration include:
- work in autonomous mode, operation in the absence of power supply;
- elimination of complex feedback and fire control systems that are prone to false alarms;
- constant readiness for operation;
- significant service life of the installation with minimal costs for service.
The disadvantages of such a system are:
- dependence on the performance of the centralized water supply network;
- dependence on room temperature, minor fires can damage a significant amount of material assets;
- It cannot be used to extinguish electrical wiring or connected electrical appliances.
Dry fire sprinkler installation.
Sprinkler installations for automatic water fire extinguishing have significant limitations in use. They cannot be operated at subzero temperatures, since the water in the pipes will freeze, not only paralyzing the operation of the installation, but also compromising the integrity of the pipes. To solve this problem, dry (air-filled) sprinkler systems were developed.
By the way, the use of solutions with chemical additives instead of water that give it antifreeze properties has not found widespread use for two reasons:
- firstly, the high cost of the fire extinguishing agent obtained in this way;
- secondly, the resulting sedimentary components can significantly clog the pipeline and sprinkler nozzles.
The underwater pipeline of a dry sprinkler installation for water fire extinguishing is filled with compressed air. In most cases, such systems consist of plastic underwater pipes located directly above the controlled area. They are filled with compressed air and, thanks to the material, are not subject to corrosion. Steel pipes are used in the water supply line of the underwater pipeline.
The principle of operation of a dry installation is completely similar to a water-filled one. After one of the heat-sensitive locks is destroyed, the pressure in the pipe decreases and the valve of the water system located in the heated room is activated. Water is then supplied to the fire site.
Some modern installations equipped with accelerated purge devices, which forcefully open all pressure valves regardless of where the actuation occurred.
AUTOMATIC WATER FIRE FIGHTING SYSTEM
The main difference between deluge systems and sprinkler systems is the activation method. The deluge automatic fire extinguishing installation is triggered by a signal from fire alarm sensors installed in the building. They activate the main pumps, which fill a network of dry pipes with water.
Irrigation is carried out over the entire area controlled by the installation. This has both a positive effect on the speed of fire extinguishing and localization of the flame - the fire does not spread across areas, and a negative effect - material assets located in rooms not affected by the fire get wet and deteriorate.
The scope of application of deluge water fire extinguishing systems is quite wide. They can be used to extinguish fires both in unheated rooms and in open areas. The only limitation is the possibility of an explosion or sudden intense fire.
Another area of application is water curtains. Depending on the design and installation location, such systems can keep not only the flame, but other combustion products from spreading for a long time:
- thermal radiation;
- toxic substances.
A significant advantage of the deluge installation is the ability to use more than effective foam. Such a change will not require significant modernization costs, but will greatly increase the effectiveness of fire extinguishing and will allow it to be used to eliminate fire in premises previously unsuitable for this: warehouses with flammable liquid substances, operating electrical equipment, etc.
WATER FIRE FIGHTING INSTALLATION
The design and installation of water fire extinguishing is carried out in accordance with the following standards:
- SP 5.13130. 2009 “Fire protection systems...”;
- NPB 88-01 “Fire extinguishing and alarm installations...”;
- SNiP 2.04.09-84 “Fire automatics of buildings and structures...”.
You can familiarize yourself with some of them on the REGULATIVE DOCUMENTS ON FIRE SAFETY page.
The algorithm for calculating an automatic fire extinguishing installation (AUP) includes the following steps:
1. The type of fire extinguishing mixture suitable for extinguishing materials located in the controlled premises is determined:
- water;
- water with fire retardant additives;
- foam solution (taking into account the foam expansion ratio).
2. The type of system is selected taking into account the speed of fire spread through the structure of the structure and the operating temperature inside the room:
- sprinkler;
- deluge;
- modular.
3. Select the required irrigation intensity in accordance with the standards.
4. The operating pressure of the system is calculated based on the indicators of the most distant sprinkler (dictating sprinkler).
5. In accordance with the type of sprinkler, the consumption of fire extinguishing agent and the controlled area, the diameter of the pipes, the number and location of sprinklers and the routing of pipelines are determined.
6. Based on the hydraulic calculation of the pipeline, the power of the pump pair is selected.
When used as a base for pipelines polymer materials they must be fireproof (AntiFire) with the PRR marking. They can be used in rooms of groups 1 and 2, fire hazard categories B, D and D. In this case, the calculated fire load should not exceed 1400 MJ/m2.
In places of possible physical contact that could damage the pipeline, a metal casing is mounted on it with a protrusion of 50 cm beyond the area of expected contact on each side. The frequency of attachment to load-bearing structures or pipe supports depends on their diameter. It must exclude the possibility of sagging, deformation from temperature loads, or vibration during operation.
MAINTENANCE OF WATER FIRE FIGHTING SYSTEM
Maintenance of automatic fire extinguishing systems must be carried out by a company that has the appropriate license to perform this type of work. In accordance with current regulations, testing the performance of an automatic water fire extinguishing installation should be carried out once every 3 years with all systems turned on for 1.5-2 minutes.
Once every six months The electrical circuit is checked and a test operation of the control unit is carried out (at idle with the pump dampers closed) from an external fire detector.
Once a quarter it is necessary to check the condition of the shut-off valves of water intakes and measuring devices of the water intake well. In the piping system it is necessary to check:
- no pipe bending or leaks;
- the presence of a pipeline slope (for pipes with a diameter of up to 50 mm no less than 0.01, more than 50 mm 0.005);
- reliability of pipe fastening to racks and supporting structures;
- condition of painting and presence of corrosion lesions (for metal pipes).
Once a month– pumps and other power equipment are checked for damage and cleaned of dust and dirt. A test transfer of power equipment (pumps) from the main to the backup power supply line is carried out.
Important! All actions for routine and emergency maintenance of an automatic water fire extinguishing system must be recorded in a special log, which is kept by the responsible person.
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