External fire water supply ensures the supply of water of the desired pressure during extinguishing a fire. At the same time, the water supply complex itself must be reliable and not fail at a crucial moment.
general information
External fire water supply is usually represented by water towers.
Water towers, as well as other pressure-regulating structures, are necessary when the village does not consume water in the same way during the daily hours and pumps it. Such buildings are used as a "warehouse" of water in case of possible fire fighting.
The water supply system at an industrial enterprise provides it with water for all needs, from household to fire extinguishing.
Hydraulics
To extinguish a fire , foam and water jets are used. They must have a certain pressure, fly far, despite the high consumption. External fire water supply just provides the necessary pressure of such jets. What is needed for this?
The jets of the necessary pressure and impact are provided by the nozzle on the hose. It has conical and cylindrical parts. The first part of the nozzle increases the speed of the jet at the outlet, and the second, in the form of a cylinder, does not allow water to spray.
If you tilt the hose at an angle of thirty degrees, then the distance that the water stream flies increases. To extinguish a source of ignition on the street, the compact part of the jet should not be less than seventeen meters.
Water hammer means a sharp increase in pressure in the fire hoses, the result of which is an increase in the speed of the water inside. Water hammer is especially dangerous in long pipelines. A large amount of water moves in them at high speed, and water hammer can lead to pipe rupture. Typically, the risk of this phenomenon occurs if you suddenly open or close the fire barrel, which has a cork crane. The pressure from the shock will propagate through the pipeline in a strong wave, the speed of which depends on the strength of the pipe walls and the strength of the water. For example, a water hammer in a fire hose is unlikely to provoke a speed of more than 120 meters per second, while water in a reinforced concrete pipe can reach 1300 meters per second. The waves arising in the control device propagate “against the wool” of the water flow. When they reach a free surface or pump, they change their direction and move in the opposite direction. If the control device stops working, then the water hammer decays because its energy is dissipated. If the valve is closed for longer than the wavelength, the pressure in the pipelines does not increase to the maximum level.
Water consumption
External fire water supply depends on many factors. For example, the population, the number of floors in the village, the average number of fires. Settlements are an extensive network of artificial pools, to which there is a comfortable exit and a parking lot for fire engines. The smallest supply of water should correspond to three thousand cubic meters per one square kilometer of urban development. If there are many sources of external fire water supply near the city, the water supply in one fire pool can be no more than one and a half thousand cubic meters per square kilometer. The estimated number of simultaneous fires may depend on the area they occupy. If the fire area is less than 150 hectares, then this is considered one fire. And if more than 150 hectares, then in two fires.
When calculating the water flow rate to extinguish a fire, take into account the fire resistance level of the building, its width and volume, how fire hazardous the production is. As an example, experts calculated how much water is spent to extinguish one fire at a factory, and it turned out up to one hundred liters per second. Whereas an agricultural enterprise will need only thirty liters. The minimum extinguishing time there and there is at least three hours.
Types of water supply
Sources of external fire water supply are divided into two types: waterless and water supply.
Wireless fire water supply is the use of water from artificial pools and natural reservoirs. On the banks install water intake devices or equip parking areas for special vehicles.
Tap fire water supply is based on the use of water from dead-end networks or fire ring hydrants.
Water pipes can be divided according to purpose. They are railway, township, agricultural and industrial.
There are still gravity and pressure pipes. The first includes those from which water itself flows to the consumer. Such a system is used most of all in mountainous regions, where the water is very clean, spring. Pressure pipelines include those that conduct water using pumps.
Requirements
All buildings and territories near potentially hazardous facilities should be equipped with a joint venture. external fire water supply.
Sources of such water supply can be natural and artificially created pools, internal and external pipelines. How much you need to use natural pools, create artificial pools, use devices that help in the abstraction of water, determines the Federal Law.
Must be a joint venture. sources of fire external water supply around and in the territories of settlements, cities. All settlements are necessarily equipped with fire water pipelines, which can be combined with a drinking water supply or industrial.
Outdoor Water Sources
These include:
- external water supply networks with fire hydrants;
- water bodies that are used for fire fighting in accordance with the legislation of our country.
In settlements where there are fewer than five thousand inhabitants, as well as in individual buildings no more than a thousand cubic meters that do not have a ring fire water supply, in buildings with production categories G, V, D for fire risks, in rooms with refrigeration units, in vegetable storage facilities, feed warehouses and fertilizer warehouses are allowed to use artificial pools and natural reservoirs.
External fire extinguishing at production facilities with one and two floors, whose height is not more than eighteen meters, with steel structures or asbestos-cement sheets present, consumes about ten liters per second according to the regulations.
In sp. external fire water supply sources that have high pressure, stationary pumps must be with timers that delay the start of the pumps for more than five minutes in case of fire.
Even at low pressure in the fire water supply, the water pressure should not be less than ten meters.
If the pressure in the water supply is high, then the height of the water stream should not be less than twenty meters.
Fire hydrants are installed along the route no more than two and a half meters from the curb. They should be no closer than five meters from buildings. According to the law, the arrangement of hydrants on the roadway is permissible. But you can not install hydrants on the branches of the pipeline.
Arrange the units in such a way that in case of fire it was possible to extinguish the building from at least two structures at a flow rate of more than fifteen liters per second or from one hydrant if the flow rate is less than fifteen liters.
Requirements for sources at the production facility
Production facilities also need to provide cn. external fire water supply. The hydrants must be located so that from any of them it was possible to extinguish the building, which is served by this water supply network.
Water reserves for extinguishing fires in artificial pools are determined by the calculations of the waste of water on external fire extinguishing and the extinguishing time.
Fire Extinguisher
A hydrant, together with a fire column, is a water intake device that is installed on the pipeline network and is used to extinguish fires. It is used as a water supply for the pump of special equipment or an external crane, if necessary, connection to a fire hose to extinguish a fire.
Fire station - a removable device that is installed on an underground hydrant so that it can be opened or closed.
Column structure:
- head;
- AL-6 cast from an aluminum alloy;
- socket wrench;
- directly housing.
At the bottom of the column there is a bronze ring with a thread, which puts the column on the hydrant.
A hydrant column is a kind of hybrid of two devices. Water intake on it can be carried out using a pressure hose, the diameter of which is 66 millimeters. Water is supplied directly to special equipment or the fire barrel.
This device can be used not only as a means to extinguish fires, but also for household or drinking purposes.
Fire Water Check
So that, if necessary, fire water sources are always ready, timely inspections of external fire water supply are carried out. In case of violations, the following activities are carried out:
- careful reception of only constructed water supply systems;
- reconstruction as necessary;
- repair as required;
- preparation of water supply systems for summer-spring and winter-autumn periods;
- testing water return networks;
- establishing a close relationship between plumbing maintenance services.
Inspection of external fire water supply is carried out according to the regulations, which includes:
- Checking the pointer according to GOST standards, compliance with actual data.
- The coincidence of the square on the hydrant rod with the square coupling from the fire column is checked. It also turns out whether the position of the neck of the well corresponds to the hydrant.
- Starting water by opening the valve using a fire column.
- Check if there is an entrance that is at least 3.5 meters wide.
- Compliance of the operation of the drainage hole with the established standards. Does the neck of the well close with a lid?
- At the end of the audit, they draw up an act.
In addition to these points, a check of the operability of external fire water supply sources includes a check of water supply networks for water return, which is carried out once a year. After all the tests, an act is drawn up, which is signed by the representative of the water utility and the head of the guard.
The guard on duty performs a GHG check in the summer at any time, and in winter it is permissible to let water only at a temperature not lower than -10 degrees Celsius. If the temperature reaches -20 degrees, then only an external inspection of the installations can be carried out. The frequency of checking external fire water supply is also regulated by the time of year. For example, at temperatures below -20 degrees Celsius it is forbidden to open the covers of the wells where the hydrant is located. All this is done to maintain heat.
Do not use a socket wrench to check to open the fire hydrant. If the external inspection showed any defects that could subsequently affect the operation of the fire hydrant, they constitute a special act. The dispatcher must notify the operating company of all problems found by fax. The exact address of the installation with problems is registered in the fax, what the malfunction is, the name of the dispatcher, the date the information was sent, the name of the receiving fax. The frequency of checking sources of external fire water supply is not specified, it is carried out as needed. But, for example, if malfunctions occur too often in one area, then it is taken under control. The timelines for troubleshooting are set out in Appendix Six. When the malfunction of the fire hydrant is eliminated, this is reported to the fire department. The guard on duty performs a check and notes its results in a special journal. After marking the device is designated as serviceable.
Any checks in the summer of the fire hydrant are made by the representative of the water utility and the guard on duty. In winter, after an external inspection and finding defects, they invite a representative and draw up an act of verification of sources of external fire water supply. If the site is disconnected from the network, then only five fire hydrants can be disabled.
When it becomes necessary to disconnect sections of the water supply system, on which more than five units are located, the representative of the water supply company must appear five days before disconnecting from the State Fire Service Unit and agree with their chief.
Each year, the director of the branch, together with the director of the water utility, agree on a combination of fire hydrant inspections and water return tests.
Requirements for New Sources
There is a set of rules "Sources of external fire water supply", which regulates the reception of new sources. Here are some of them:
- The pipeline should be laid half a meter more than indicated in the calculations.
- An external fire-fighting pipeline must be provided as an annular circular system with a constant filling of water. You cannot make deadlock networks.
- Checking the internal and external fire water supply will reveal a violation if the installed hydrants are not of the Norilsk type and are located closer than one hundred meters from each other.
- The main length of the pipeline can be no further than 2.5 meters from the curb. All fire hydrants must be protected from drifts by booths.
- Where aggregates are installed, the width of the carriageway should ensure unhindered entry of special vehicles. According to the rules of fire water supply, the outdoor air supply must be connected without problems to the fire engine, and for this there must be a comfortable entrance. Also, the pipeline must be separated during repair by valves.
Requirements for water storage tanks
Checking the internal and external fire water supply includes monitoring the fire tanks. The latter should be necessarily insulated and heat water to +5 degrees Celsius. They should be equipped with devices for pumping water with special equipment pumps.
The amount of water in unclosed pools must be considered with possible evaporation and ice formation. The edge of the outdoor pool cannot be more than half a meter above the water level. Fire tanks should not be less than two, open reservoirs, too. Each of the containers should contain half of the water necessary to extinguish a fire.
Water Inspection
When checking the operability of external fire water supply, they will take into account:
- availability of an entrance convenient for special equipment to a fire reservoir;
- is the pointer installed according to GOST 12.4.009PZ, are the data consistent.
The access to the fire reservoir should have a width of not less than four meters. Also, according to the verification of sources of external fire water supply, a site equipped for a turn is needed nearby. It should be a square with a side of twelve meters. Ventilation and sunroof must be present at the inspection site.
Water return tests
This procedure is carried out by a guard on duty and a representative of the water utility. The purpose of such tests is to understand whether it will be possible to use water unhindered in the event of a fire. External and internal fire water supply must always be ready for operation, and defective devices replaced.
Theoretical training is carried out once a year and most often in the spring-summer period.
In order to test a section of a pipeline with low pressure, you only need a fire column with a smooth-bore nozzle, with a diameter of 65 millimeters and a length of 500 millimeters. You also need a plug and a pressure gauge.
After the water has been supplied, they count down two minutes and look at the indicators of the pressure gauge. The results are checked with the table and thus calculate the water flow.
How to exploit
Fire devices are placed along the streets at an equal (equal) distance. The external fire water supply system, as a rule, provides a comfortable access to any of the hydrants. To make it easier to find it, on adjacent buildings, a reflective plate is attached with the direction of the location of the device.
A fire engine can only pump water from two devices at a time, with two arms each. It is important to know how to open the valve of the device:
- Initially, the socket wrench handle is rotated two or three turns and filled with water.
- When the noise stops, pause, and then continue to rotate the socket wrench handle until the device valve is fully open.
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Technical regulations
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- It is allowed not to organize external water supply if no more than fifty people live in the village and there are no two-story buildings.
- The quality of water from fire sources must comply with the methods of extinguishing a fire and the conditions for using specialized equipment.
- It is necessary to create an artificial fire pool of low pressure. There must be a base for high pressure in the pond. But in a settlement with a population of no more than five thousand inhabitants, it is necessary to equip a fire pipeline with high pressure only.
- The free head in the network of the combined pipeline should not be less than ten meters and more than sixty.
In JV 2009 "Sources of external fire water supply" there are many more requirements and nuances. Every fireman and even a water utility worker should know them, because the life of many people depends on this.
Labor protection during operation of the GHG
To use a fire hydrant, the lid must be opened with a crowbar or hook. It is very important to approach this action calmly, without panic. Do not drop the manhole cover to your feet, which may result in personal injury.
When the air temperature reaches -15 degrees Celsius, only an external examination of the device is carried out. If the temperature has dropped even lower, it is strictly forbidden to open the hatches. Devices with a water start-up are tested using a column, because using socket wrenches or other devices can cause an accident.
Network Routes
First of all, they depend on how the roads and enterprises are located. With the help of an internal fire water supply, the local fires are extinguished until special equipment arrives. Such a water supply system consists of pipeline networks and risers, on which internal fire hydrants are installed. The risers are always in the public domain, for example, on or near stairwells. The internal fire pipeline in buildings is usually looped and receives power only from the external pipeline.
Before starting the construction, they carefully form the fire water supply. It must meet the following requirements:
- The water stream from the fireman’s crane should be consumed no less than 2.5 liters per second.
- The compact part of the jet should reach the farthest point in the room.
- Fire hydrants are located only in rooms with heating and not lower than one and a half meters from the floor.
- In the case of installing taps in a place where freezing is possible, water is supplied only in an insulated place.
- Cranes should be on each floor in a heated room near the exits or in public areas.
- Cranes are stored in lockers, with them there is a fire hose and a barrel. An inscription must be hanging above such a cabinet, which indicates what is inside.
Multi-storey buildings
For each floor of a building or premises for various purposes, the water flow during fire fighting must be calculated separately. But water should be calculated based on the structural features:
- buildings that do not have fire walls in the total volume of the structure;
- buildings that are separated by fire walls of the first and second type (in that part of the structure where most of the water is needed).
If buildings with the first and second degree of fire resistance are interconnected by transitions from non-combustible materials, then the water consumption is considered separately.
Rules for installing fire cabinets
The organization of control over external fire water supply systems has established the rules for the placement of fire cabinets. First you need to figure out what cabinets are. They are divided into attached, mounted, built-in.
Wall mounted fire cabinets are installed on the walls inside the premises and structures.
Built-in structures are placed in niches of buildings.
Attached type fire cabinets can be installed in niches and near flat walls. The legs of the cabinets are on the floor.
Shut-off valves must provide:
- easy connection of the sleeve, no creases on the sleeve;
- ease of coverage of the flywheel valve and its turns with one hand.
Complete fire cabinets
In such a cabinet should be:
- fire pressure hoses;
- shut-off fire valves;
- connecting heads;
- portable fire extinguishers;
- fire manual trunks.
What is fire water supply, everyone should know. It is equally important to comply with all fire regulations and requirements. And it is not necessary to have information at the professional level, it will be enough to obtain general information. We need all this in order not to get confused and not to panic in an emergency situation, but to start fire fighting before the arrival of special services. Thus, you can not only put out a fire and save human lives, but also prevent a fire and avoid casualties. This is the most important duty of all citizens.