That the water supply system functioned correctly and effectively, it is not enough to simply connect the pipes, it is also necessary to equip it with a number of additional elements, one of which is a check valve or any other type. The presence of such an element in the water supply system allows to protect it from such undesirable phenomena, both countercurrent and hydraulic shock. Check valves, which by the method of installation can be coupling, flange or interflange type, are mounted both on separate sites of pipeline systems, and at pumping stations.
Brass check valve coupling type
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There are two main elements in the design of any check valve:
- frame, for the manufacture of which various metals can be used;
- locking element, the position of which in the closed state is provided by a special spring.
Regardless of the type, all reverse shutters work on the following principle. Water flow, entering such a device under a certain pressure, affects the locking element, squeezing the spring and opening it. If the water flow pressure decreases or it starts to move in the wrong direction, the spring returns the locking element to its original position, not allowing fluid to pass through the shutter.
The principle of operation of water meters of various designs
In those cases, when non-return valves are used to equip the pump, by means of which water is pumped out of a well or well, the purpose of such devices is also, to prevent the liquid from returning back to the water source at that time, when the pump is not running. When installed on water supply pipelines, such valves do not allow the water flow pressure to decrease then, when users open taps on one or more sections of the system. in addition, as mentioned above, the use of water meters protects the pipelines from the effects of hydraulic shocks.
Types of check valves
A wide variety of check valves are available on the market today, which differ in both design and technical characteristics, and material of manufacture.
According to the type of locking element, there are devices of the following types.
lifting
The locking element of such shutters is a spool, moves freely along the vertical axis. Lifting the spool (and, in accordance, shutter opening) occurs under the pressure of the fluid flow, and closing in case of decrease in flow pressure - under the influence of own weight of a spool, which at such a moment simply falls to its seat. The big disadvantage of such water meters is that, that they can be installed only on vertical sections of pipelines.
Scheme of the coupling lifting check valve
spherical
The locking element of these shutters is a spring-loaded ball. When the required fluid pressure is reached, entering the valve, the spring is squeezed, and the bullet opens the through hole, allowing the water to move freely in the right direction. In accordance, when the fluid pressure drops or it starts to move in the wrong direction, the spring returns the ball to its seat.
Ball check valve device
disk
The shut-off element of these valves is a metal plate - sash, located on the spring-loaded axis. The most significant disadvantage of such shutters is, that when closing their locking element creates significant shock loads. This adversely affects the technical condition of the valve device itself and can lead to such an undesirable phenomenon., as a hydraulic shock.
The disc check valve is spring-loaded
bivalves
In these shutters two spring-loaded leaves are used as a locking element at once. Double-leaf check valves due to their design features are compact in size and light weight.
Drawings of the two-leaf check valve
mounting methods
There are non-return valves and methods of installation in pipelines. So, depending on this parameter is allocated:
- flange shutters, which are installed on the pipeline (mostly of significant diameter) by means of flanges, welded to their body;
- flange check valves, which are mounted between two flanges, fixed on the selected section of the pipeline;
- check valves of coupling type, which are established by means of threaded couplings (Coupling valves are most often mounted on domestic pipelines);
- close, which are established by means of welding.
Check valves are spring coupling type
For installation in household pipelines, as mentioned above, use mainly check valves of the coupling type. Mandatory parts of coupling valves (as well as other valve devices) there is a locking element and a spring, which holds it in position.
The check valve is spring coupling with a metal saddle
Depending on the material of manufacture, check valves of the coupling type can belong to devices of one of the following categories.
- The check valve is spring brass. Brass material is used to make such water meters, which is not subject to corrosion. These are the most popular clutches, used for installation in domestic piping systems. The check valve brass practically does not demand regular service and can be used for installation on pipes of any type..
- Check valves, the case of which is made of cast iron. Cast iron is prone to corrosion and deposits, which significantly limits the use of such devices. Coupling shutters, made of cast iron, usually, installed on pipelines, differing in significant diameter.
- Check valves, parts of which are made of stainless steel. Such couplings are the most reliable, but also the most expensive. They are not prone to corrosion, and deposits do not accumulate on their inner surface.
- Check valves, made of combined materials, which can be brass and stainless steel. Shut-off elements of such coupling valves, usually, are made of polymeric materials.
The check valve is spring coupling with a plastic saddle
To equip domestic pipelines usually choose a brass coupling valve, which at high reliability differs and affordable cost, if you compare it with models of similar devices, made of stainless steel.
Coupling type check valves in domestic piping systems, usually, are installed after water meters, which prevents such devices from rotating in the opposite direction. in addition, installation of coupling valve devices on separate sections of the pipeline allows to protect such sections from emptying at that moment, when water drains from the system or the pump stops, who submits it.
The design of the spring clutch check valve is arranged as follows, that it can be disassembled into two halves. This may be required for its maintenance.
Check valve disassembled
Valves for submersible pumps
Check valves are required to equip pumping equipment, by which water is pumped out of underground sources. The use of return valves protects such systems from backflow of water, and to facilitate the process of starting pumping equipment after it is stopped. Place of installation, as well as the type of valve devices in such cases is chosen depending on, what kind of pumping equipment needs to be equipped with them.
Placing the non-return valve in front of the submersible pump
Models of modern pumping units are already equipped with non-return valves, which are installed on the input and output lines of such equipment. When purchasing such pumps, it is not necessary to additionally equip them with return valves.
In that case, if vacuum pumping equipment is used to pump water from a well or well, the non-return valve is installed in front of the accumulator. Non-return valves are optimal for this, relating to the spherical and spool type. If the vacuum pump is installed on the ground, outside the source of water supply, then use two check valves at once, one of which is installed at the end of the water supply from the well hose, and the second - in front of the accumulator. In most cases, the manufacturers of pumping equipment indicate in the instructions, which check valves can be used with it.
Check valve with mesh at the end of the pipeline, giving
When equipping pumping stations, check valves are installed after the ratchet and mounted mainly on the suction pipe.. If a non-return valve is installed directly in front of the pump station, you can face that, that the water flow pressure will be weaker, than when installing such a device on the suction line.
In that case, if a vibrating pump is used to pump water, the non-return valve is best installed in front of the receiver. Choosing a place to mount the shutter, that fact should be taken into account, that such a device must be serviced regularly, therefore, direct access to it must be provided.
Installing a butterfly valve in front of the receiver
Before installing the non-return valve, shut off the water supply and turn off all electrical equipment. Fittings and couplings of appropriate diameter should also be selected, and be careful when making threaded connections, to make them as airtight as possible.
Particular attention should be paid to its technical parameters before installing the coupling check valve, the main of which are the working pressure and the diameter of the conditional passage. From that, how correctly the non-return valve will be selected, depends on how it works, and the efficiency of the entire pipeline.
Some important conclusions
so, check valves (including clutch) allow to solve such tasks effectively:
- to ensure stable operation of the entire pipeline system;
- minimize the risk of air entering the water supply;
- save electricity, if such a valve is installed in a hot water supply system, which is served by an electric water heater;
- provide water use for some time even in that case, if the supply pump is switched off.