LECTURE 6
Rice. one . Schemes of water supply networks:
A - dead end;
B - ring;
B - combined
Trunk lines designed to transport transit water within the water supply facility.
distribution lines are laid at the necessary points when transporting water from highways to the consumer. If the water supply network feeds one house, then the functions of the main and distribution lines are combined in one thread.
Schemes of water supply networks are dead-end, ring and combined (Fig. 1).
dead end scheme the grid consists of a main line and branches that depart in the form of dead ends. In a dead-end network, water moves in one direction - to the end of the branch. The dead-end circuit is the shortest in length, but less reliable with respect to uninterrupted water supply.
During an accident on one section of the highway, all sections that are located behind it will not be provided with water supply.
Ring diagram has no dead ends and all its branches are interconnected and closed.
Combined scheme consists of looped and dead-end lines.
Ring and combined schemes of water supply networks are more reliable in operation. In a looped network, water does not stagnate, but constantly circulates. Emergency sections are turned off without stopping the supply of water to other consumers.
The route of water supply networks is linked to the vertical and horizontal planning of the area and taking into account other underground engineering networks. Water supply networks on driveways, as a rule, are laid straight and parallel to the building line, strictly along the highway.
Crossings of pipelines must be carried out at right angles to each other and to the axis of the passages. The placement of water lines in relation to other underground utilities should ensure the possibility of installing networks and prevent washing out of foundations in case of damage to the water supply.
The distance in the plan from water supply networks to parallel buildings and structures must be determined depending on the structures of the foundations of buildings, their depth, diameter and characteristics of networks, water pressure in them, etc.
The external water supply network is one of the main parts of each water supply system. The cost of the water supply network of populated areas is about 50-70% of the cost of the entire water supply system, so much attention should be paid to its tracing, design and construction.
Soviet scientists A. A. Surin, N. N. Geniev, L. F. Moshnin, V. P. Sirotkin, M. M. Andriyashev, V. G. Lobachev, N. N. Abramov, M. V. Kirsanov, F. A. Shevelev and others did a lot of work to develop the theory of calculation, create methods and techniques for calculating water supply networks, improve their performance and reduce costs.
Thanks to the high development of the theory of calculation, conditions were created for the effective use of the possibilities that modern computer technology provides. At present, electronic digital computers - digital computers are used to calculate multi-ring networks.
Water supply networks are divided into main lines and distribution lines.
Main lines serve to transport transit masses of water; distribution lines - for transporting water from mains to individual buildings in which consumers receive water directly from external distribution lines.
The main and distribution lines must have sufficient capacity and provide the necessary water pressure at the points of consumption.
The required throughput and pressures are ensured by the correct selection of pipe diameters during design.
The reliability of the operation of water supply networks is ensured by the good quality of the material of pipes and fittings, as well as laying and installation.
The lowest cost of water supply networks is obtained by laying them along the shortest paths from water sources to places of consumption.
According to the outline in the plan, water supply networks are dead-end, ring.
Dead end network, the diagram of which is shown in rice. 33,a, shorter than an annular ( rice. 33, b), but cannot guarantee uninterrupted
Rice. 33. Water network:
a - branched; b - ring; NS - pumping station; "WB is a water supply tower, because at the time of the liquidation of an accident in one section of the main, all sections following it, together with branches, will not be supplied with water.
Rice. 34. Location of pipelines on a large-width city highway
Ring networks are more reliable in operation, since in the event of an accident on one of the lines, when it is turned off, consumers will be supplied with water through the other line.
Water supply networks, which are fire-fighting, must be ring. As an exception, dead-end lines with a length of not more than 200 m are allowed when measures are taken to prevent freezing of these lines.
The distance of water supply networks to buildings, structures, roads, as well as other networks should be assigned depending on the structures of the foundations of buildings, the type of roads, the depth of the laying, the diameter and nature of the networks, the pressure in them and the size of the wells.
The approximate location of water and other pipes on the street of a large city is shown in Fig. 34.
A water pipeline is a complex of engineering structures and equipment designed to take water from natural sources and supply it to places of consumption, as well as, if necessary, to clean and store it.
Typically, water pipes consist of the following structures:
1) water intakes for water intake from natural sources;
2) pumping stations for lifting water;
3) facilities for water treatment;
4) conduits and water supply networks for supplying water to consumers;
5) water towers and pressure tanks to maintain pressure and regulate water flow;
6) water storage tanks.
The mutual arrangement of individual waterworks, if necessary, lifting, storing and purifying water is shown in fig. 1. Here is a general scheme of the city's water supply from a surface source (river) with a treatment plant.
Water is taken from the river with the help of a water intake 1 and enters the coastal well 3 through gravity pipes 2, and from it, by pumps of the first lift 4, it is supplied to settling tanks 5 and then to filters 6 for cleaning and disinfection.
From the treatment plant, the purified water enters the spare clean water tanks 7, from which it is pumped by the second lift pumps 8 through the conduits 9 to the pressure control structure 10 (above-ground or underground reservoir located on a natural elevation - a water tower or a pneumatic installation), and also in the main pipes 11 of the water supply network of the city, through which water is transported to various districts of the city and through the network of distribution pipes 12 and house inlets 13 - to individual consumers 14.
By appointment, water pipes are divided into the following:
household and drinking - to meet the drinking and household needs of the population;
production - to supply industrial enterprises with water;
fire fighting - supplying water to extinguish a fire;
combined - designed to simultaneously meet various needs, while in some cases household and drinking water pipes can be combined with fire or industrial ones. Such are economic-fire-prevention, industrial-fire-prevention and other systems.
According to the method of water supply, pressure and gravity water pipes are distinguished.
Pressure water pipelines are those in which water is pumped from the source to the consumer; gravity - in which water from a highly located source flows to the consumer by gravity. Such water pipelines are sometimes arranged in the mountainous regions of the country.
Depending on the quality of the water in the source and the requirements for water by consumers, water pipelines are built with and without facilities for water purification and treatment. The first include utility and drinking water pipelines that receive water from surface sources - rivers, lakes, reservoirs. Water supply systems without treatment facilities include household and drinking water supply systems, fed by water from artesian wells. For the technological needs of industrial enterprises, water from surface sources is often suitable without purification.
According to the method of using water by industrial enterprises, industrial water pipelines are arranged with direct-flow, reverse or with sequential use of water.
In the case of direct-flow water supply, the water used in production is discharged into the reservoir without purification, if it is not polluted, or after purification in case of contamination (from gas cleaning, rolling mills, iron casting, etc.).
With circulating water supply, water heated in production is not discharged into a reservoir, but is re-supplied to production after it has been cooled in ponds, cooling towers or spray pools. To replenish water losses (in cooling facilities, in case of leakage, etc.), fresh water from the source is added to the circulation cycle.
A scheme with a rotary use of water is given in fig. 2.6. Pumps 1 water after cooling at facility 2 is supplied through pipes 3 to production units 4. Heated water enters pipelines 5 (shown in dotted lines in the drawing) and discharged to cooling facilities 2 (cooling towers, spray pools, cooling ponds). The addition of fresh water from the source through the water inlet 6 is carried out by pumps 7 through conduits 8.
Circulating (repeated) water supply is usually arranged with a limited debit of a natural source; however, even with a sufficient flow rate, it can be more economical than direct-flow water supply.
Water pipelines with sequential use of water are used if it is possible to use it after one consumer by others. Such water pipes are recommended to be used as widely as possible.
Water pipelines are divided into external and internal. The external water supply includes all facilities for the intake, purification of water and its distribution by the water supply network. Internal water pipes take water from the external network and supply it to consumers in buildings.
Rice. 1 Scheme of the water supply system of the city; a - plan; b - cut
If there is a source of water that meets the requirements of consumers in terms of quality, there is no need to build treatment facilities. Sometimes a second lift pumping station is also not required. In these cases, water from the source is supplied by submerged pumps directly through water conduits and main networks, and through them to consumers. An example of such water supply is water intake from artesian wells ( rice. 2,a).
Rice. 2 a. General scheme of an artesian water supply system: 1 - well; 2 - water supply network; 3 - reservoirs; 4 - pumping station P lifting; ZSO - sanitary protection zone
Rice. 2 b. Water supply scheme with water reuse
Pressure control structures are designed to accumulate excess water supplied by the pumps, which is formed when the water supply by the pumps exceeds its withdrawal from the network, as well as to store the supply of water for fire extinguishing and to supply water to the water supply network in cases where the water withdrawal consumers exceeds its supply by pumps. In addition, on rice. 2 and there are two nodes of structures. In water pipelines with a relatively uniform water consumption, pressure-control structures may not exist. In this case, water is pumped directly into the pipes of the distribution network, and tanks are arranged to store the fire-fighting supply of water, from which water is taken by pumps to extinguish the fire.
§ 4. Determination of the estimated water flow- (All images)
The estimated water flow is its maximum flow, obtained by multiplying the average flow by the coefficient of non-uniformity.
Estimated water consumption for settlements is determined by the following formulas:
Here q is the rate of water consumption in liters per person per day (see Table 1); N is the estimated population; Ksut - coefficient of daily unevenness of water consumption; Кsut - general coefficient of non-uniformity of water consumption, equal to
The estimated consumption of domestic and drinking water in industrial and auxiliary buildings is determined by the following formulas.
Daily water consumption
where q "n is the rate of water consumption per person per shift (see Table 2); Ni is the number of employees per day (separately in cold and hot shops). Water consumption per shift is
where N2 is the number of workers per shift.
Maximum second water consumption in liters per shift
where Kchas is the coefficient of hourly irregularity in water consumption (see Table 2); T is the duration of the shift in hours. The estimated consumption for using a shower in the domestic premises of industrial enterprises is determined using formulas (7), (8) and (9).
Daily water consumption for shower use is equal to
where 9d is the rate of water consumption per procedure (separately by industry); N3 - the number of shower users per day (separated by
productions). Water consumption per shower per shift is equal to
where Nt is the number of shower users per shift.
Second water consumption (shower. Sec in this shift
since the duration of the showers after the shifts should be no more than 45 minutes.
Estimated water consumption for irrigation of a territory with an irrigated area F ha is determined by the formula
where q floor - watering rate l / day per 1 m2. The second water consumption for irrigation is equal to
The average daily amount of water per year Qcp.mx For irrigation can be approximately determined by the formula
(12)
where Tpol is the number of days in a year in which irrigation is carried out, determined taking into account climatic and other local conditions. Water consumption in canteens of industrial enterprises is taken into account especially. The daily consumption of water in canteens is
(13)
where dst - the rate of water consumption in the dining room per diner is taken from 18 to 25 liters with a coefficient of hourly uneven water consumption of 1.5.
The maximum second water consumption in canteens is
where Tn is the number of working hours of canteens.
Water consumption for production needs, both daily and second, is taken according to the data of technologists for each production unit or group of units.
For humidification, dust removal and air conditioning, the water consumption is taken according to the data of the ventilation projects of industrial buildings.
The mode of water consumption depends on the size of the settlement, climatic and other conditions. Fluctuations in hourly water consumption are usually depicted in the form of tables or graphs, which are compiled on the basis of monitoring the water consumption regime in existing water pipelines.
Rice. 3. Schedule of daily water consumption in the city
On fig. 3 shows, as an example, a graph of fluctuations in water consumption in the city during the day. Here, the hours of the day are plotted on the abscissa axis, and the hourly water consumption, expressed as a percentage of its daily consumption, is plotted on the ordinate axis.
Fluctuations in water consumption for production needs in each individual case are set by technologists based on the study of the technological process of this production.
The water supply by a pump operating for 24 hours a day, i.e., supplying 4.17% of the daily consumption every hour, is indicated on the graph by a dotted line.
It follows from this that the excess water supplied by the pumps during hours of less consumption from the network accumulates in the tank of the water tower. This accumulation can also take place in an underground tank or in a pneumatic installation tank.
The regulating supply of water is intended to cover the difference between the withdrawal of water from the network and its supply by the pump during the hours of maximum flow. The volume of the regulating reserve with single-stage operation of pumps in settlements with a population of up to 200 thousand is 10-15% of the daily flow, with two-stage operation of pumps it can be reduced to 1.5-3%.
The reservoirs of water supply systems must contain an emergency supply of water for firefighting needs.
Fluctuations in water consumption for household and drinking needs and sang and during the day with the maximum water consumption are displayed in Table. 5.
The maximum hourly water consumption for household and drinking needs in Table. 5 corresponds to the given coefficient of hourly unevenness Kh = 1.25.
The schedule of water consumption for irrigation is drawn up taking into account the morning, general cleaning of the streets; in addition, it is required that watering does not coincide with the highest water consumption for household and drinking needs.
We accept that an emergency reserve for extinguishing a fire of 500 m3 should be stored in spare tanks. After a fire, it must be replenished in 24 N. Therefore, the water consumption when replenishing the fire water supply increases to 3910 + 500 = 4410 m3/day.
The water supply must be designed to supply this amount of water.
Conduits
Water conduits are intended only for transporting water, water consumers do not join them. By water conduits of the first lift water is transported from the water intake to the water treatment complex, through conduits second rise drinking water is transported from the water treatment complex to the city's water supply network. To increase the reliability of water supply, water conduits are laid in two or more threads parallel to each other.
For water conduits, sanitary protection strips.
The width of the sanitary protection strip of water conduits passing through an undeveloped area is taken from the extreme water conduits:
when laying in dry soils - at least 10 m with a diameter of up to 1000 mm and at least 20 m with large diameters; in wet soils - at least 50 m, regardless of diameter.
When laying water conduits in a built-up area, the width of the strip, in agreement with the sanitary and epidemiological supervision authorities, may be reduced.
The external water supply network of the city is designed both for transporting water and for distributing it to consumers. The water supply network is the most costly element of the water supply system, accounting for more than half of the total cost of the city's water supply system. The efficiency of the water supply network is determined by the reliability and uninterrupted operation of its operation, the degree of provision of estimated costs and free pressure for consumers, energy costs for transporting water and maintaining its quality during transportation.
According to the configuration in terms of water supply networks are divided into branched (dead-end), ring, and combined.
Dead-end networks, fig. 9, are laid to consumers over the shortest distance and require minimal, in comparison with ring and combined networks, costs for the installation of networks. The fundamental disadvantage of dead-end networks is the low reliability of water supply, due to the fact that in the event of an accident at any section of the pipeline system, the water supply to all consumers located behind the accident site in the direction of water movement is interrupted.
Figure 9. Dead-end water networks
4 - building quarters.
Ring networks, fig. 10, compare favorably with dead-end ones in greater reliability of water supply, since they provide for the possibility of supplying water to consumers bypassing the emergency section, however, this is achieved by increasing the total length of water supply networks and increasing their cost.
Figure 10. Ring water networks
1 - conduits; 2 - main water pipelines; 3 - distribution pipelines;
4 - quarters.
Combined networks, fig. 11, are a combination of ring and dead-end networks as part of a single settlement water supply system.
Figure 11. Combined water supply networks
1 - conduits; 2 - main water pipelines; 3 - distribution pipelines;
4 - quarters.
When choosing the configuration of water supply networks, it must be taken into account that they must be ring. Dead-end lines of water supply systems for household and drinking purposes may only be used with a pipe diameter of not more than 100 mm or with a line length of not more than 200 m.
In the water supply network, trunk and distribution lines.
The direction of the main lines coincides with the general direction of the water supply. They are recommended to be laid along elevated sections of the relief, since this reduces the hydrostatic head in the pipelines. The diameters of the main lines are determined by calculation, which is based on data on the maximum water intake and recommended water flow rates. Considering dependency
as well as the fact that the pressure loss of the liquid when it moves through the pipe is proportional to the square of the velocity, it can be concluded that with a constant volume flow and a decrease in the diameter of the pipe, the velocity of the water increases, and, consequently, the pressure loss. This leads to the need to increase the pressure generated by the pump, and, as a result, to an increase in the energy consumption of the pump. Thus, reducing the cost of setting up the network with a decrease in the diameter of the pipelines causes an increase in operating costs due to the increased consumption of electricity by the pumps of the second lift. The best option for choosing the diameters of water pipelines is considered to be one in which the values of the velocities of water in the pipes are in the range from 0.5 to 2 m / s, while lower velocities are accepted for pipes with a diameter of 100 to 300 mm, and larger ones for diameters over 600 mm.
The diameter of the pipes of the water supply system, combined with the fire-fighting one, must be at least 100 mm, in rural settlements - at least 75 mm.
tracing distribution lines and the costs of their arrangement are largely determined by the town-planning decision of the settlement. If the width of the streets within the red lines is 22 m or more, it is recommended to lay water supply networks on both sides of the streets.
Pipelines are laid underground to prevent freezing of water in winter and heating in summer. The minimum pipe laying depth, counting to the bottom, is taken to be 0.5 m more than the calculated depth of penetration into the ground of zero temperature, and is approximately 1.0-1.5 m for the southern regions of Russia, 2.0-3.0 m for the average stripes and 3.0-3.5 m for the northern regions. The minimum distance from the top of the pipe to the ground surface is determined from the conditions of preventing water heating in summer, as well as protection from external loads, and is 0.5 m.
During the heat engineering and feasibility study, ground and above-ground laying, laying in tunnels, as well as laying water lines in tunnels together with other underground utilities are allowed.
When determining the routing and laying depth of water supply networks during underground laying, it is necessary to take into account the conditions for their intersection with other underground structures and communications.
In order to protect water supply lines from external influences, as well as to prevent the negative impact of accidents and leaks on water supply networks, SNiP limit the minimum distances from the outer surface of water pipes to buildings, structures and other external engineering networks.
Water pipes.
Water pipes must meet a number of requirements, the main of which are:
Sanitary safety;
Sufficient strength to ensure the safety of pipelines when exposed to water pressure, soil and transport loads;
Durability and resistance to aggressive soil and groundwater;
The smoothness of the inner surface of the pipes, providing their low hydraulic resistance;
Tightness of pipes and their connections;
Moderate cost.
For water supply networks, it is advisable to use non-metallic pipes (reinforced concrete, asbestos-cement, plastic, etc.). Recently, plastic pipes have been widely used, which favorably differ in strength, durability, low hydraulic resistance and good thermal characteristics. The advantages of plastic pipes can also be attributed to the industrial nature and a high degree of mechanization of work on their laying.
Cast iron pipes are used in the justification for networks within settlements and territories of industrial and agricultural enterprises.
The use of steel pipes is allowed:
In areas with a design internal pressure of more than 1.5 MPa (15 atm.);
For crossings under railways and roads, through water barriers and ravines;
At the intersection of the utility and drinking water supply with sewerage networks;
When laying pipelines along road and city bridges, along overpass supports and in tunnels.
Pipeline accessories.
To ensure the operational reliability of water supply networks, they provide for the installation of shut-off, control and safety pipeline valves:
Gate valves, ball valves and other valves for shutting off individual sections of the network;
Air inlet and outlet valves for emptying and filling pipelines;
Plungers for air release during operation of pipelines;
Releases for water discharge when emptying pipelines;
Check valves to prevent reverse movement of water;
Fire hydrants.
When choosing the location of the plumbing fittings, the following should be considered.
fire hydrants placed along highways at a distance of no more than 2.5 m from the edge of the carriageway, but no closer than 5 m from the walls of buildings. These restrictions are related to the conditions for the intake of water by fire engines and the prevention of soaking of building foundations. The distance between the hydrants is determined by calculation and is approximately 100 - 150 m.
Shut-off valves set to ensure the possibility of disconnecting individual sections of the network for repair work and place it on the network in such a way that during the repair of any section of the network the water supply of objects that do not allow interruptions in water supply does not stop, and more than 5 hydrants do not turn off. The design of shut-off valves should ensure a smooth decrease in water flow or a complete cessation of its movement. This is necessary to prevent the occurrence hydraulic shocks, accompanying a sharp decrease in the speed of water movement in pipelines.
plungers for air release, they are installed on elevated sections of the network.
check valves, preventing the reverse flow of water, are installed on dead ends of the network, where a reverse flow of water is possible when the pumps supplying water to the water supply network are turned off.
When laying underground water pipelines, pipeline fittings are installed in wells. When placing wells on the carriageway, manhole covers must be flush with the surface of the road surface.
Zoning of the water supply network.
The most important task of designing a water supply network is to ensure the required water pressure for consumers, while, based on the conditions for the safety of the internal water supply, the pressure in the water supply network should not exceed the maximum allowable value of 60 m. In some cases, for example, with a very pronounced relief, do this impossible, so separate water network zones, differing from each other in the magnitude of the pressure of water in pipelines. Zoning water supply network is possible in two ways.
Consistent zoning It is applied at strongly expressed relief of building, fig. 12.
Figure 12. Scheme of sequential zoning. 1,2 - lower and higher located building areas; 3 - tank; 4 - pumping station.
With sequential zoning, the pressure in the water supply network serving the higher part of the building exceeds the pressure in the network of the lower part by the amount of pressure created by the pump.
Parallel zoning it is used if there are remote areas of development on the territory of the settlement, fig. thirteen.
Figure 13. Parallel zoning scheme
1 - drinking water tank; 2 - pumping station; 3 - building area located near the pumping station; 4 - building area, remote from the pumping station.
With parallel zoning, water is supplied to the building area close to the pumping station and the area remote from it different pumps that are part of the pumping station. At the same time, pumps serving a remote area create a greater pressure necessary to compensate for pressure losses in long conduits supplying water to a remote area.
As a rule, network zoning increases the cost of the water supply network due to the construction of additional reservoirs and pumping stations, therefore it is considered as a forced measure necessary to ensure the required pressure in all sections of the water supply network.
Influence of planning decisions of settlements on the technical and economic characteristics of water supply networks.
Planning decisions of settlements have a significant impact on the cost characteristics of water supply networks. The following leads to an increase in the length of the network, and, consequently, to an increase in its cost:
Low building density and, as a result, an increase in the built-up area of the settlement;
Territorial disunity of the settlement (the presence of remote building blocks, settlements, etc.);
A large number of wide, more than 22 m streets, on each side of which it is necessary to lay distribution water supply networks;
Remoteness of the pumping station of the second lift from urban areas.
Engineering communications are one of the indispensable components of a modern country house - these are external systems of water supply, heating, sewage disposal and drinking water supply.
First of all, in order to determine your future goals, if external water supply systems are required, you need to decide whether your house will be a permanent or temporary shelter, because summer seasons are one thing, and wintering in a “dacha” is another thing.
Planning such engineering networks certain design organizations are involved (most often - Gorvodokanal). When designing outdoor water supply systems on your own, you must notify the relevant authorities and wait for permission to carry out further work. After installation work, you will need to contact a “specially trained” person to help draw up an acceptance certificate.
External water supply systems, or rather installation work associated with them, imply a list of necessary documentary permits from the relevant authorities.
The device of external water supply systems
Maximum comfort when choosing outdoor water supply systems provides centralized water supply system. In this case, you only need to correctly connect the pipe to the water main and bring water directly to the house. As a rule, plastic or metal-plastic pipes are advised, in any case, they must withstand heat up to one hundred degrees.
Who can not connect to the central water supply, recommend autonomous water supply system.
If you are going to live in a country house temporarily and in the summer, then a good option is to supply water from a well using a pump that supplies water to the internal network. If you are thinking of this house as a permanent residence, then drill a well, in some cases this is done directly under the house. Then external water supply systems are not required.
When installing external sewerage networks, pipes are laid below the level where the soil freezes through. In addition, they need insulation with expanded clay or slag. During the installation work of external sewer systems, plastic pipes are used, the guarantee of proper operation of some will be 50 years. At the trench for the discharge pipe, the shape should be trapezoidal. The bottom of the trench must be covered with rubble and tamped, the pipe must fit tightly on the bottom of the trench, not sag. When constructing external sewage systems, remember that the receiving openings of the treatment plant must be located below the outlet of the discharge pipe.
Country-style houses often cannot be connected to a centralized sewerage system. If you live in the house temporarily, then the external sewerage system is possible according to an abbreviated scheme: a pipe draining from the house, located under a slope, and a cesspool. If you live in a house year-round, then it is best to make a septic tank to settle the waters along with a filter well.
When outdoor water supply systems are installed, it must be remembered that the host wastewater treatment plant opening always located below the outlet of the discharge pipe.
We hope that these tips will help you in installing outdoor water supply and sewerage systems.
An integral part of any housing construction is design, which provides not only for the layout of the premises, but also for the installation of communication systems. Regardless of whether a private house or municipal real estate will be built, the installation of water supply and sewerage is considered a prerequisite for the operation of the building. These systems are placed inside and outside the structure, taking into account the established norms and rules.
General device and purpose
Water supply and sewerage are a single system that combines a number of measures aimed at providing the building with water and draining wastewater. Thanks to a complex of engineering devices and structures, water is supplied to consumers from natural sources, undergoing preliminary purification.
In order for the water supply to be uninterrupted, the communications necessarily provide for the storage of reserves, this allows you to provide water to various economic facilities and settlements. Therefore, the main tasks of the water supply include: obtaining water from the source, controlling its quality according to the requirements of users and direct transportation to sampling points. Such supply, as a rule, is carried out from local or centralized sources and has its own water supply scheme.
The design of communications depends on the choice of water source. For large and industrial facilities, centralized sources are usually chosen, and special tanks are used for local intake. As for the water supply with hot water, it is most often installed in the form of a closed water intake, where heating and subsequent transportation takes place.
For residential premises, the norm of hot water in the water supply system provides for a lower limit of + 60С and an upper limit of + 75С.
Depending on the operational purpose of the building, the following types of water supply are distinguished:
- industrial;
- fireman;
- negotiable;
- economic and drinking;
- for the supply of hot water.
Fire water supply can be combined with other systems, including industrial and drinking water. As for drinking water supply, it cannot be used with facilities that simultaneously transport water that does not meet sanitary standards. In order for communication systems to cope with their tasks, they are provided with the following facilities:
- water intake stations responsible for the intake of water from a natural source object;
- pumping stations that create the required pressure during transportation and supply water to a given height;
- treatment and purification facilities that improve water quality;
- plumbing systems and conduits;
- reserve and control tanks.
outdoor network
Modern plumbing systems are a complex network, the main component of which is considered to be an external pipeline. He is responsible for the supply of water from wells, reservoirs or storage facilities to the consumer, the central water supply system can be laid both on the surface and underground. The first installation option is the cheapest, characterized by quick installation. In this case, the water supply is mounted on elevated supports and additionally covered with insulation. If, when designing a water supply system, main intersections are provided, then pipe laying is carried out in underground tunnels or trenches.
The external network, as a rule, consists of facilities responsible for cleaning, storing water and various pumping equipment. At the same time, filtration is carried out not only in the fence, but also in the outermost water supply system. Depending on where the water will be used, there are several types of outdoor water supply.
- Technical. It is intended exclusively for production facilities. Often, in order to save money, only partial cleaning is installed in technical water pipes, and the processed resource can be reused.
- Fire department. It is used for fire extinguishing systems. Such a network is additionally supplied with special equipment and hydrants. Usually, fire water supply is made dead-end, which allows it to be combined with household and technical supplies.
- Household. The transported water in such a water supply system is used for drinking and is thoroughly cleaned.
internal system
The water supply also has an internal system, consisting of a network of pipes passing inside the building and leading communications to water intake points. Since the external pipeline can have different pressures, internal water supply is arranged in two ways.
- No booster pumps. The water supply in this case is carried out due to the pressure in the external network, and the water supply includes an inlet, a water meter, pipes, a riser and a supply line. This type of supply is ideal for both a private house and city apartments. It is characterized by simplicity, it does not have any additional devices, except for the pipeline.
- With periodic or permanent deposits. Such a system is chosen when the external network is not provided with the necessary pressure for transporting water, or if it is necessary to supply it to high and remote water intake points. As a rule, water supply with pumps is installed in large buildings with a height of more than 50 m, hotels, holiday homes and industrial facilities.
In order for water to flow to consumers uninterruptedly, in addition to pumping units, the water supply system is supplemented with special tanks in which its supply is stored. The volume of tanks is determined depending on household needs, usually their capacity is calculated for 20% of the daily consumption.
Water tanks are the main components of the internal water supply system and are equipped with special pipes and valves. They are recommended to be placed in a well-lit and ventilated room.
If the project provides for zonal supply, then each site must have individual trunk lines, they are usually laid in the technical floors. Inside the building, the water supply network is made open with divorces. In some cases, hidden installation of pipes is also used, located in the shafts and furrows of the walls. To do this, connections are fixed at the installation sites of the reinforcement, and inspection hatches are fixed.
In addition, internal systems must be laid at a slope of 0.002-0.005, this will ensure the withdrawal of water from the mains to suitable pipes and appliances. If the communications are located at the lower points, then it is desirable to make a descender.
During the installation of the internal water supply, attention must be paid to the installation of stop valves. It is placed on connections to faucets, toilet bowls, flush cisterns and wash basins.
Pipe materials
When installing a water pipe, it is important to pay attention to the choice of material from which the pipes are made, since this will not only affect the cost of their installation, but also the service life. In order for the systems to reliably serve for more than a dozen years, during the purchase of pipes, it must be taken into account that they will be subjected to pressure and the chemical effects of water. Therefore, it is recommended to give preference to a durable and reliable material. To date, several types of pipes can be found on sale.
Copper
Such pipes are widely used in various engineering communications, including water supply. The main advantages of copper pipes include:
- high resistance to pressure;
- low and high temperatures;
- no deformation during heating;
- this material provides the line with durability;
- spectacular appearance.
As for the disadvantages, such systems:
- roads in the installation;
- their installation is laborious and requires special soldering technologies;
- if during operation the copper system leaks, then the damaged area must be completely cut out and replaced with a new one.
As a rule, copper water pipes are used for distilled water, as they tend to combine with toxic elements.
Chlorinated water adversely affects the physical characteristics of copper. Copper systems are also rapidly destroyed by stray current.
metal-plastic
They consist of a thin metal tube, covered on the outside and inside with layers of plastic. The advantages of such water pipes are many:
- they have a small diameter;
- easy to repair;
- easy to install;
- tolerate temperature changes very well.
But when choosing the installation of communications from metal-plastic pipes, it is worth considering that they require regular maintenance, are expensive, are afraid of shock and can collapse under the influence of ultraviolet rays.
Steel
Depending on the coating material, products are divided into galvanized and uncoated. The installation of such a water supply system is carried out using special threaded connections, couplings, tees or welding. Steel systems are characterized by high rigidity, strength and long service life. Despite the positive properties of these pipelines, they are subject to the formation of rust and inorganic deposits inside. In addition, their installation is laborious.
Galvanized
Giving preference to this type of pipes, it is important to carefully seal the joints when installing them. This can be done with linen, pre-impregnated with drying oil or paint. Threads must not be processed with synthetic solutions. The advantage of galvanized pipelines is their affordable price and easy installation, the disadvantage is a short service life.
Plastic
They are a good material for the construction of water pipes, as they:
- durable;
- do not corrode;
- have low thermal conductivity;
- light weight.
Plastic systems can be laid with a hidden method. Installation of pipes is quick and easy, but they cannot be used to supply hot water.
HDPE pipes
They are made from low-pressure polyethylene, so they are durable and are excellent for supplying both industrial and drinking water. Such pipes are popular in modern construction, because they have high elasticity and resistance to freezing. At low temperatures, they do not burst and allow you to transport both cold and hot water. In the system, pipes are connected by welding or soldering, installation is easy, since polyethylene bends well.
PVC
Unlike other types of material, these products are characterized by greater rigidity, due to which they are widely used for laying open and closed water supply lines. Pipes are suitable for transporting not only hot and cold water, but also for heating systems, they have a neat appearance and high strength. Pipes are inexpensive, they are connected by gluing and using fittings. There are no visible flaws in polyvinyl chloride.
Polypropylene
In terms of their technical properties, they are in many ways similar to polyethylene pipes, but they are much cheaper and are connected by welding. In addition, such systems are durable, strong, meet all building standards and requirements, but during their joining, you need to pay attention to the quality of soldering, otherwise leakage is possible.
Water treatment facilities
The water pipeline provides transportation of water to the consumer from various natural sources, which may contain organic and mineral elements in a dissolved, colloidal or suspended state. In order for the water quality to meet all standards, during the installation of communications, treatment facilities are additionally built. The most common options are small gravity water treatment plants. Most often they can be found in urban water supply systems.
MIA RUSSIA FEDERAL
FIRE-FIGHTING WATER SUPPLY
L E C T I A
IRKUTSK-2007
MIA RUSSIA FEDERAL
STATE EDUCATIONAL INSTITUTION OF HIGHER PROFESSIONAL EDUCATION "EAST SIBERIAN INSTITUTE OF THE MINISTRY OF INTERNAL AFFAIRS OF THE RUSSIAN FEDERATION" (FSEI VPO VSI MIA RUSSIA)
APPROVED Head of the Department Cand. tech. Sciences, Associate Professor
Colonel of the Internal Service
A.V. Malykhin "____" ______________ 2007
FIRE-FIGHTING WATER SUPPLY
L E C T I A
higher professional education in the specialty 280104.65 - Fire safety
Topic 4. Ensuring the reliability of fire water supply systems
LECTURE 4. "Water pipes and external water supply network"
Irkutsk-2007
Fire water supply: lecture "Water lines and external water supply network" of higher professional education in the specialty 280104.65 - Fire safety. - Irkutsk: FGOU VPO VSI MIA of Russia, 2007 - 18 p.
Prepared by A.Yu. Kochkin, Candidate of Technical Sciences, Senior Lecturer of the Department of Fire Engineering, Automation and Communications
Discussed at the PMS meeting "____" November 2007 Minutes No. ___
© FGOU VPO VSI MIA of Russia, 2007
PURPOSE: To study the purpose, types of arrangement and operation of water conduits and external water supply network
As a result of the lesson, cadets should:
Know: the device of water conduits, methods of redundant water conduits, equipment that is installed on water supply systems to ensure the reliability of operation, as well as devices for taking water for fire extinguishing needs. Placement of fire hydrants in wells. Regulatory requirements for the installation of hydrants on water supply networks.
Be able to: Conduct a survey of fire hydrants, and check them for performance.
Have an idea: about the device of shut-off and control valves, which is located on the water supply network.
Educational goal: to instill in cadets the desire to acquire new knowledge for their application in the practical work of the State Fire Service. Acquisition of note-taking skills. Compliance with military requirements in the classroom.
Time: 2 hours.
Methodological support:
1. Board, chalk;
2. Posters;
3. Kodoscope, slides;
4. SNiP 2.04.02-84* Water supply. External networks and structures.
Issues under consideration:
1. Arrangement of conduits and water supply network;
2. Fittings of the water supply network;
3. Fire hydrants and columns;
4. Fire safety requirements for the installation of fire hydrants;
5. Requirements for the installation of an external water supply network.
Question one. Construction of conduits and water supply network
The external water supply network is one of the most important elements of the water supply system, which consists of water conduits and a water supply network.
Conduits are laid between pumping stations and the water supply network, designed to supply water to it.
The water supply network is a system of lines that distribute water across the territory of a settlement or an industrial facility; it is the final link on the path of water movement from a source to a consumer.
Ensuring the reliable operation of water conduits that supply water from the source to the consumer is an important task. Failure of water conduits at one water feeder can cause failure of the entire water supply system. Most often, redundancy is used to increase the reliability of the operation of water conduits. It can be carried out in two ways: without jumpers and with jumpers (Figure 1).
Figure 1 - The movement of water through conduits and lintels:
a - conduits in good condition; b - in case of failure of one of the sections of water conduits
In the first case, the conduit system consists of several parallel lines without jumpers. Such laying of conduits is used only for conduits of relatively short length, when the conduit lines are laid at a considerable distance from each other.
The use of the second method of laying conduits using jumpers significantly increases the reliability of water supply systems. When installing jumpers in each junction of water conduits, it is necessary to install 3 gate valves, thus, for each jumper
it is necessary to install 6 valves. This allows you to turn off only one damaged section in case of an accident, without stopping the water supply.
Figure 1b shows the movement of water through conduits and in lintels in case of failure of one section of the conduit, to turn off which it is necessary to close two valves, the first and second.
The tracing of the water supply network must, on the one hand, provide sufficient reliability, and on the other hand, be economical.
A branched (dead-end) network (Figure 2a) has a lower cost than a ring network (Figure 2b). However, there is only one path from each node of the dead-end network to the water supply point. For reliable operation, it is necessary to have at least two such paths. This requirement is met by a ring network. The structure of the ring network has a high degree of redundancy of water supply routes and, consequently, high reliability indicators. In addition, the ring water supply network with the same pipe diameters, compared to the dead-end one, has a significantly higher water yield, approximately 2 times.
Figure 2 - Routing of the distribution water supply network: a - dead end; b - ring
The term "reliability" is commonly understood as the property of an object to perform the specified functions, while maintaining the values of the established operational indicators over time within the specified limits, corresponding to the specified modes and conditions of use, maintenance, and repairs.
The reliability of water supply to individual consumers largely depends on their location on the territory of an object or settlement. The farther the consumer is from the point of water supply to the network, the lower the reliability of its water supply.
SNiP 2.04.02-84* establishes the permissible limits for reducing the total water supply in the event of an accident and the lowest pressure in the network at a critical point in an emergency. Violation of these limits is a failure of the water supply system. In networks with a single source
power supply critical (dictating) points usually turn out to be located in the most remote and most highly located points. The choice of critical points should be given taking into account the possibility of supplying the entire network from the source, as well as supplying it simultaneously from the source and from the control tank (water tower). With multiple power sources, the reliability of water supply is improved.
Dead-end water lines are allowed to be used:
- for supplying water for production needs - if a break in water supply is admissible for the period of liquidation of the accident;
- for supplying water to household and drinking needs - with a pipe diameter of not more than 100 mm;
- for supplying water for firefighting or household firefighting needs, regardless of the water consumption for firefighting - with a line length of not more than 200 m;
- in settlements with a population of up to 5000 people and water consumption for outdoor fire extinguishing up to 10 liters× s-1 or if the number of internal fire hydrants in the building is up to 12, dead-end lines with a length of more than 200 m are allowed, provided that fire fighting devices are installed
reservoirs or ponds, a water tower or a counter-reservoir at the end of a cul-de-sac.
Pipes must be laid at a depth that ensures that water does not freeze in winter conditions, excludes the possibility of heating it in summer and prevents damage to pipes under loads from moving vehicles. To ensure non-freezing, the depth of pipe laying Ztr (counting to the bottom of the trench) should be 0.5 m more than the calculated depth Zp of penetration into the soil of zero temperature, i.e.:
Ztr = Zr + 0.5, m (1)
The calculated depth of zero temperature penetration into the soil should be established on the basis of long-term observations.
Conclusion on the issue. Thus, the supply of water to settlements and industrial enterprises depends on the correctness of the device, as well as the method of reserving water conduits and the water supply network.
Question two. Fittings of the water supply network
The following fittings are installed on water supply networks:
- shut-off and regulating(valves, taps, gate valves, locks);
- safety (safety, check and pressure reducing valves, plungers, outlets);
- water intake (water columns, taps and fire hydrants).
Shut-off and control valves. Gate valves and valves (picture 3)
designed to turn off individual sections of the network in case of an accident, repair, as well as in the regulation of costs. Gate valves with manual drive
are installed on pipelines with a diameter of up to 300 mm, with an electric drive - on pipelines with a diameter of 300 mm or more.
Figure 3 - Valve
Protective fittings. Plungers are used for automatic intake and exhaust of air from pipelines. They are installed on pipelines with a diameter of 400 mm or more, at elevated points at a distance of 250 ... 2500 m from each other. If the air is not removed from the pipeline, then air cushions are formed, which reduce the area of the free section of the pipeline.
The plunger (Figure 4) consists of a cast-iron body 1, in which a steel hollow ball 2 with a vertical steel rod is located, the body is closed with a lid 3. The air released from the water accumulates in the upper part of the plunger. Under air pressure, the water level drops along with the ball, which opens the valve 4 connected to it, as a result of which the air comes out. After that, the water filling the plunger raises the ball and closes the valve.
Figure 4 - Plunger: a - section; b – side view; 1 - body; 2 - ball; 3 - cover; 4 - valve
Similar plungers can also be used to let air into the conduit when low pressures are formed in it or when the continuity of the flow breaks during hydraulic shocks.
Check valves (Figure 5) are designed to allow water to flow in one direction only. They are installed on pressure lines, after centrifugal pumps, on lines for shutting off water towers, and in a number of other cases.
Picture 5 - Check valve
Safety valves are used to prevent an increase in pressure in pipes beyond the allowable level in the event of a water hammer in water pipes and water lines as a result of stopping pumps or quickly closing valves in the network.
Figure 6 - The device of the spring safety valve 1 - branch pipe; 2 - stock; 3 - spring; 4 - valve; 5 - connecting flange
Safety valves can be spring-loaded or lever-operated (Figure 6). The principle of operation of the spring-loaded safety valve
is as follows: under the action of increased pressure in the valve, the force of the spring is overcome, and water is thrown out through the pipe. The fittings of the external water supply network are located in special wells. Water wells can be reinforced concrete, concrete, brick, rubble stone. Wells with a diameter of up to 2 m are made in a round shape, large sizes - a rectangular shape.
In cases where groundwater is located above the bottom of the well, waterproofing of the bottom and walls of the well should be provided 0.5 m above the groundwater level. When wells are located on the roadway, well hatches must be located at the level with the road surface. To prevent freezing of fire hydrants, wells (with appropriate justification) are insulated.
Conclusion on the issue. Various equipment is installed on the water supply network, which is designed to protect pipelines, block repair areas, regulate flow, and also take water for fire extinguishing.
Question three. Fire hydrants and columns
Fire hydrants are designed to take water for fire extinguishing from outdoor water supply systems.
Fire hydrants perform ground and underground.
The most widespread in our country is the Moscow-type underground hydrant (Figure 7), the inventor of which is the Russian engineer N.P. Zimin.
The hydrant is installed on the flange of the fire stand 2 of the external water supply network. The height of the cast-iron column of the hydrant 1 can be from 0.75 to 2.5 m. The hydrant is closed with a lid 3. To use the hydrant, the well hatch is opened, then the lid of the hydrant and a fire column is screwed onto its upper end with a thread (Figure 9).
The square head of the column rod will fit into the socket wrench 6 of the hydrant. The rotation of the handle of the column through the rod is transmitted to the rod 8 of the hydrant. The screw thread on the stem 8 of the hydrant enters the copper nut 9 and causes the stem to move in the vertical direction to open and close the associated hollow ball valve 10. The stem 8 is rigidly connected to the discharge valve 11 of the ball valve. When the rod 8 moves down, the unloading valve opens. Through the hole opened in the ball, water will begin to flow first into the ball, and then through hole 13 into the hydrant riser. When the pressure above the ball valve is equal to the pressure of the water mains, the ball valve will open under gravity pressure. In the lower part of the hydrant there is an opening 14 through which water is discharged from the column and the hydrant riser after it is closed, which prevents the water from freezing in winter. During the opening of the hydrant, the hole is automatically closed by a special slider 15 rigidly attached to the rod.
