When arranging an autonomous water supply system, one has to carefully select not only the pump, but also a variety of protective pipe fittings. Among the important devices, one of the most significant places is the non-return valve for the pumping station, which helps maintain a stable pressure in the hydraulic system.
It prevents premature wear of pumping equipment and prevents malfunctions.
The content of the article:
- Types and purpose of the back-stop valves
- Bottom check valve
-
Pressure Support Check Valve
- Constructive types of products
- Classification by type of attachment
- Variations in the production of material
- Installation of valves with pumping station
- Conclusions and useful video on the topic
Types and purpose of the back-stop valves
The size of the check valve is small, but without this little pressure in the plumbing system support will be impossible. It belongs to the category of pipeline fittings, whose main task is to prevent reversal of the flow of water in the pipes of the water supply system.
Household pumping equipment is not designed for its movement in an abnormal direction.
A non-return valve is used to pass water flow in only one direction, blocking it completely the way back (+)
There is a market pumping station models, the package which manufacturers put the presence of a check valve. These options come with a suction hose with a built-in check valve. But in most cases, these valves must be purchased independently.
Similar closures are placed both on the suction line and at the inlet into the in-house water supply system immediately behind the pump with a hydroaccumulator or in front of the pumping station.
Depending on the installation location in the water supply system, check valves are divided into:
- Bottom. Prevent the reverse movement of water raised from the source when turning off the pumping equipment. Create conditions for the operation of the unit without constant filling with water before running it and the suction line.
- Pipeline. Among them are axial and cuspid species. Prevent a drop in the working value of pressure in the system.
If there is no non-return valve at the end of the suction pipe of the pumping station, then when the pump stops, the water will flow back under the action of gravity. As a result, air traffic jams will form in the pipeline, and in the “dry run” conditions, seals will break down. As a result, water will penetrate into the electric pump and cause it to burn out.
Not only the starting point of the suction line can be equipped with a non-return valve. To ensure the pressure is maintained, it is installed in the pipeline in front of the pumping station or in front of the hydraulic tank when it is placed separately.
Most modern pumps have protection against such processes. But water for starting them will have to fill in after each stop of the unit.
In some models of pumps, reverse rotation of the impeller is possible, which may entail its failure. The installation of this valve on the line of fluid intake from the source is obligatory, otherwise no electronic protection for the water-pressure unit will help.
When connecting several pumping stations into a single unit, the check valves protect the switched off unit from the pressure of operating devices
With a pipeline check valve, the situation is somewhat different. Here he no longer protects the pump, but the water distribution system inside the house. By locking the water in the pipes, preventing it from returning back to the hydraulic accumulator, the reverse valve helps to maintain the required value in the system. working head. Without it, the water will tend back into the storage tank, forcing it to work in abnormal mode.
Check valves improve the efficiency and reliability of the pumping station, while protecting the pump, plumbing and plumbing from water hammering. In general - an indispensable device. But the water has to be wasted on opening the gate, which reduces the flow pressure after its passage by 0.1–0.3 atm.
Bottom check valve
Bottom varieties of check valves are installed at the inlet of the water evacuating line. Used to equip surface pumping systems to protect against pressure drop.
The task of the bottom check valve is to maintain water in the system and maintain the operating pressure level (+)
By design specificity bottom check valves are divided into:
- Spring. Their working locking mechanism consists of a spring and a disk, which, when the spring is reduced under the pressure of water, is displaced along the body of the device and allows flow through.
- Swing. The main body consists of one or two transverse flaps, opening under the pressure of the pumped water and returning to the site when it is stopped.
According to the method of attachment to the end of the suction hose or pipe bottom valves are divided into coupling and flange. In tandem with household pumping units, a clutch type is most often used.
Under the pressure of water, the spring of the device is compressed, and the locking disk attached to it opens the way to the flow in one direction only.
Coupling check valve connections are easier to install, but require periodic monitoring of the condition, especially when working with a vibratory pump
The swing check valve is the easiest-to-work repairable version of the device, the flap of which opens only in one direction under the pressure of the pumped water (+)
A strainer is recommended before the bottom check valve. He is obliged to exclude penetration into the pumping system of biological contaminants and solid particles with an abrasive effect.
The device must be installed according to the direction indicated by the arrow on the body. The distance from the bottom of the water intake to the check valve should be at least 0.5 - 1.0 m, depending on the class of the unit and the manufacturer's recommendations. Between the water mirror in the well or well and the valve should be a water column of at least 0.3 m.
Pumping systems with submersible pump equip the check valve without filter, because They are equipped with built-in cleaning devices to protect the functional “filling” from friction. The check valve in this case is installed in front of the supply pipe immediately after the pump unit. It is used to prevent pressure drop in the network.
A check valve in a pumping system with a submersible pump is installed immediately after the unit at the inlet of the suction pipe
Pressure Support Check Valve
There are several designs of check valves for pipelines with a general principle of operation. All of them must ensure the unidirectional movement of the working fluid, for which they have a locking mechanism inside. It opens in the direction of flow, without interfering with it, and when you try to reverse the flow of water immediately closes.
With the direct movement of water, the closure element in the valve moves to the side, and at the reverse - closes the pipe tightly (+)
A typical check valve consists of:
- enclosures;
- shut-off and regulatory element (working body);
- springs (in some models it is missing).
The energy of the flow of water flowing in the forward direction, squeezes the locking element from the saddle, thereby creating a working window for the smooth movement of fluid. And when the current is reversed, this valve under the action of the spring and water pressure returns to its original position, blocking the pipeline.
Products of this type of pipe fittings differ structurally, the materials used in stamping, as well as the method of fasteners to the pipes. At the same time, almost all types of check valves can be used in the installation of pumping stations, but this is not always practical and expedient.
Constructive types of products
The locking element can move in parallel, perpendicular and at an angle to the axis of the pipeline. Most often with dry pipes it sinks into its saddle under its own weight. The device provides normal pressure in the water supply, preventing the reverse current supplied to the water collection of water.
Therefore, when installing individual models of check valves, it is necessary to monitor not only the direction arrow flow, but also for the correct location of the lid, where the guide for moving the locking part.
Depending on the design, the valve inside the check valve moves, turns or rises (+)
Internal constipation in the check valve can be made in the form:
- spool consisting of stem and locking plates;
- whole or divided into two leaf disc;
- ball with spring mechanism and sealing gaskets.
In valves with a diameter greater than 400 mm, the disc hits the body sufficiently when it returns to the saddle, which inevitably leads to device breakage. To avoid premature wear of valves, these valves are equipped with hydraulic dampers that make the course of the disk smooth.
However, in everyday life such unstressed check valves are not used. On sale there are more simple and cheap analogues.
If the check valve is needed small, then the model should choose either a ball or double. In the first case, a small ball moves in and out along the movement of water, while in the second, the pipe overlaps at the expense of two halves of a disk fixed on one rod. The case of both products is small due to the lack of a moving inside with a wide displacement step.
There are also non-return type designs with forced opening / closing of the shutter. Flow control in this case is carried out by mechanical or manual devices. However, such a back-stop valves in everyday life with pumping stations is not applicable. It is simply not needed for pumps.
Classification by type of attachment
In addition to the design differences in the operating element, check valves used to plants with pumping stations, differ in the method of attachment. The choice here depends on the material of the pipelines and the technology of their connection.
Coupling check valve with lifting-spring mechanism consists of a brass body with threaded thread (1, 2), a spool (3), a spring (4), a spool valve-lock (5) and a gasket (6)
According to the method of connection with pipes, check valves are divided into:
- Coupling.
- Flanged.
- Interflange.
- Navarny (under welding).
The first version of the pipeline is connected through a threaded junction, and the second is connected through the flanges with seals. Wafer check valves do not have their own fasteners, they are fixed between the flanges of other elements of the aqueduct with the help of long studs.
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Coupling devices by their design and method of installation are more suitable for installation on water pipes
Flanged valves are not typical for domestic use, but are often used in industrial applications.
Wafer type check valves are good because they can be installed both horizontally and vertically
Welding valves are made of stainless steel grade 304 or 316 and equipped with a clamp clamp
Coupling check valve for water supply systems
Cast Iron Flanged Check Valve
Wafer type disc valve
Non-return valve for welding
The variant for welding is more intended for use in pipelines through which aggressive media are pumped. They are not mounted on pumping stations. Wafer type check valves are available only in a disk or double-leaf version.
For water supply systems most often selected check valves with lifting and spring mechanism of the constipation and the coupling connection. They are easier to install and dismantle, as well as repair them by replacing the spring, which is the weakest link in the pipe fittings.
Wafer products differ in small dimensions and rather high price; they can be installed on pipes both horizontally and vertically
Variations in the production of material
The check valve body can be:
- bronze;
- brass;
- cast iron;
- steel stainless steel;
- plastic.
The most durable models are stainless steel, they are least susceptible to corrosion processes. Cast iron return valves are cumbersome, so they are rarely found in everyday life. They are mainly used on pipes with a large cross section. These pipes are not connected to household pumping stations.
The most popular products are made of brass. This metal is relatively cheap, does not rust, and is optimally suited to all types of pipes. Plastic products should be taken only for low-pressure pipelines and polypropylene pipelines.
The main failure of the check valves are due to spring wear, for a cottage it is worth picking up a product with the possibility of replacing it with your own hands (+)
The working locking element is made of:
- stainless steel;
- aluminum;
- plastics.
In principle, all these materials are equally good. The locking parts are small in size and are always high strength and durable. Failures most often occur in the spring mechanism. Therefore, in the overwhelming majority of models, the springs are made of stainless steel, which is famous for its anti-corrosion characteristics and reliability.
In stores you can also find a combined check valve, the body and cover of which are made of different materials. Each manufacturer seeks to reduce the cost of its products and offer the market any new product. Fortunately, all valves are tested, it is only necessary to require a certificate of conformity to the relevant norms and standards.
To ensure the tightness of the shutter when lowering it into the saddle, we use rubber, plastic seals and hard metal alloy cladding in various combinations.
Installation of valves with pumping station
When choosing a check valve, it is necessary to take into account its nominal pressure, flow capacity and flow diameter. All these data are contained in the technical passport.
Installation can be performed independently, following the instructions for the pumping station. The manufacturer must indicate the recommended places for the installation of all necessary fixtures.
Installation option OK on a submersible centrifugal pump:
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We select the part by the size of the hose / adapter (for example, 1 inch), check the quality of workmanship: there are no scratches, chips, internal damage
The direction in which water should flow is usually indicated by an arrow. If not, then you can use the method of blowing
Screw the check valve on the adapter. To create a tight joint, we use FUM tape or linen strand.
To make the connection as strong and tight as possible, tighten the valve with a gas wrench.
Step 1 - Select and check the check valve
Step 2 - Determining the Right Installation Direction
Step 3 - Winding the valve onto the adapter thread
Step 4 - tighten the gas key
The main thing here is to find out the presence / absence of a check valve in the pumping station unit. If it is already a regular element of the water supply installation, then you should not put these valves in addition.
In this case, constipation will only reduce the capacity of the pipes, and there is no benefit from it. Spending money and time to install an unnecessary element, which also will create even small difficulties in the flow of water, is not worth it.
Standard locations for the installation of check valves are the lowest bottom point of the suction pipe and the entrance to the pressure line immediately behind the pump station.
If the scheme of the water supply system suggests the possibility of emptying the pressure pipe or work pump in reverse mode, the upper check valve can not be installed after the water-pumping unit. He simply will not allow such actions, blocking the flow of water to the water-pressure unit.
The sequence of installation of the “valve + gate” ligament depends on the technology of starting the pump. There are models that were originally designed to run on a closed valve. In these cases, the check valve must be installed after the stopcock.
Reverse constipation in the “lower” position manufacturers recommend to install in all cases, together with the mesh coarse filter. Water must first be cleaned from sand. The internal parts of the system will wear out faster from contact with abrasive particles.
It is better to immediately take back the constipation with a removable or non-removable mesh. It will protect the device from sand, with it you will not have to install an additional filter.
When choosing a mounting point for a check valve, consider:
- water flow direction;
- availability of fittings for subsequent repair and maintenance;
- restrictions on the strict horizontal or vertical installation of some types of reverse constipation;
- the presence of sand in the water, which can lead to clogging.
The spring check valves with a lifting shut-off element are the least susceptible to contamination. Faster and easiest to install pipe fittings with interflange type of connection. But more often for plumbing in private homes are selected inexpensive counterparts with flange or socket mounting.
When using a submersible pump, the check valve is mounted on the end of the pipe, lowered into the water intake, in front of the pumping device
When installing a check valve, it is important to install it correctly. The axis of the spool should be strictly vertical. And when installing a rotary product, the axis of rotation “flaps” should always be higher than the axial line of the water flow.
To control the direction of water flow and the correct location of the check valve allows the arrow on its body. It is difficult not to notice, it is even more difficult to make a mistake with the installation of the locking device in the desired position.
Conclusions and useful video on the topic
Video # 1. All about the installation technology of a check valve for water:
Video # 2. Overview of stop valves blocking reverse flow:
Video # 3. Which option of the check valve is preferred for the cottage water supply system:
The use of check valves simplifies the operation of pumping stations and reduces the risk of accidents in the plumbing system. You should not save on this small but important product.
Manufacturers are now offering the masses of variants of this reinforcement of different sizes, the mode of actuation of the constipation and the type of fastening. For any system of water supply and the type of pump you can easily find the optimal solution.
We will be glad to know your opinion. Those who wish to clarify difficult technical issues, share experiences or point out a flaw in the material in the block below can leave comments.
