A check valve is an indispensable element of the equipment of autonomous pumping stations, which provides a constant direction of medium movement. The water check valve for the pump shuts off the pipeline section, the pump or other equipment in case of an emergency situation. The device is triggered automatically by the energy of the working environment, and is a valve of direct action.
The purpose and principle of the check valve on water
The purpose of the check valve is to protect the water supply system against critical changes in flow parameters. Drainage of water into the well or well, when the pump stops, leads to the reverse unwinding of the impeller, and the unit breakage.
The valve actuator prevents the return flow of water, protects the piping system and sanitary equipment from water hammering. Spring-loaded hermetic shut-off valve of the backflow of water retains the filling of the pipes, increases the efficiency of the work of submersible and self-priming pumps.
The design and material of the implementation of protective valves, which are used for autonomous water supply systems, takes into account existing regulatory requirements. Technical characteristics (nominal, working, test and closing pressure, connection diameter, conditional throughput, tightness class) are specified by the manufacturer in the technical passport of products.
The conditional passage of spring check valves for domestic purposes is 15? 50 mm. Compact protective devices provide high throughput, operational reliability, low noise level in the working position.
Important! Spring tension counteracts the flow force. Opening the valve reduces the pump pressure by 0.25 ± 0.5 atmospheres.
The material for stamping elements of the precast body is brass. The alloy is resistant to aggressive substances (oxygen, mineral salts, sulfur, manganese, iron compounds, organics, etc.) that are dissolved or suspended in water. The outer surface of the product is galvanized (nickel plated).
Details of the spool are made of copper-zinc alloy or high-strength polymer. The material of the gasket between the locking discs – rubber or silicone. The spring is made from a special grade of stainless steel.
Common structural elements of spring check valves:
- composite housing (elements of the coupling connection with internal thread at the inlet and outlet, spool chamber);
- the working body is a movable valve consisting of a stem, two spool plates and a sealed interdisk pad;
- the actuator of the lock is a spring, which is located between the valve plates and the seat (a stop in the body of the body).
The working body of the check valve makes reciprocating movements in the spool chamber. Plates slide on the spool rod. The flow is distributed over a channel that has a constant cross section. Water washes evenly locking body on all sides.
If the flow pressure exceeds the spring resistance, then the movable part of the valve opens a gap for the passage of water in a given direction. When equalizing the overpressure before and after the protective device, or when the predetermined pressure is exceeded after the valve, the spring moves the plates to the saddle.
The collapsible cylindrical body consists of two parts having a threaded connection. The movable slide valve is formed from a plastic rod, an upper and lower brass plate. The elements of the shutter is separated by an airtight sealing gasket. The tension of the steel spring counteracts the flow head through the disc spool mechanism.
A distinctive feature of the check valve device for water, with the spherical shape of the spool chamber, is a large flow rate compared to traditional fittings.
A female threaded nozzle for the air vent is mounted on the housing, above the receiving area of the spool chamber. The air is vented by means of a Mayevsky crane.
The drainage pipe with internal thread and plug is located on the opposite side of the body, at the outlet of the check valve.
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With vertical mounting, the device allows the discharge of water after the valve, and the removal of air plugs from the pipeline before the gate. When the horizontal installation of the combined device pipe for air removal is used to install the pressure gauge.
Combined non-return valve reduces the number of installation connections, reduces the total hydraulic resistance of valves, increases system reliability, and facilitates installation and maintenance of the system.
The check valves in the propylene housing are used for water supply systems made of propylene pipes. Externally, the fitting resembles a slanting outlet. Protective reinforcement of propylene attached to the pipeline by polyfusion welding. For the convenience of servicing the non-separable joint, the saddle and the locking spool mechanism are removed from the perpendicular plane of the spool chamber. The constructive position allows you to get the valve locking mechanism for cleaning and repair, without compromising the integrity of the body and system.
In the centralized water supply pipelines use petal, disc, valve, ball and interflange check valves. For connecting large diameter valves, flanges and wafer fasteners on tie rods are used. For installation of check valves in piping of propylene pipes used contact heat welding.
Protective armature is used in autonomous water supply systems, in-house water supply networks in apartment buildings, with a separate centralized supply of hot and cold water. Check valves are installed on the suction line of surface and deep pumps, in front of water meters, boilers, and capacitive water heaters.
Spring-loaded backpressure water valves do not have friction surfaces, so they can be installed in any position (vertically, horizontally or obliquely). The arrow on the body of the product indicates the direction of movement of the medium; its vector must coincide with the mounting position of the protective armature.
The device needs regular maintenance. Install the check valve in an accessible place for cleaning, revision, repair or replacement.
For pumping stations, a check valve is a mandatory element, but a safety valve is not included in the presale package of a household installation. When buying a check valve, pay attention to the connecting dimensions of the device.
If protective reinforcement is installed on the suction line of the pipeline, then its diameter must coincide with the diameter of the pipe. When installing the valve on the suction nozzle of a submersible pump, the dimensions of the parts should ensure the tightness of the connection.
Important! The deposition of mechanical impurities flow on the internal surface of the valve limits the capacity of the device, and violates the tightness of the shutter.
Manufacturers of protective valves took care of how to install a check valve on the pump:
- before the check valve for the water pump recommend the installation of coarse mechanical filters;
- modern models of submersible and well pumps are equipped with direct protective valves at the equipment development stage;
- Special protection is required for the receiving check valve for a well pump that is installed in the suction line from a well, a well or an open reservoir. Mesh or perforated stainless steel ferrule is connected to a non-return valve using a thread.
The check valve for the surface pumping station performs the same functions as the safety device for the downhole unit. The difference lies in the fact that the device is installed on the suction inlet of a self-priming supercharger of pressure.
Do-it-yourself check valve assembly is theoretically possible. Consumables set of fittings bought in the plumbing department of the nearest store of household supplies.
For the realization of creative ideas will require:
- tee with internal thread (non-return valve body);
- coupling with external thread (forms a seat for the bolt);
- steel spring of sufficient stiffness, suitable diameter and length (for free-running turns inside the tee);
- steel ball, the diameter of which is slightly less than the conditional passage of the tee;
- deaf cap – spring stop (“dad”);
- seal of threaded connection (fum, flax);
- set of plumbing keys.
The flow of water enters from the side of the coupling and changes its direction at the exit at an angle of 90 °.
The complexity of self-assembly check valve is the choice of the actuator and parts. If the tightness of the joints will provide the experience and skills in the production of plumbing works, then the quality of components is difficult to guarantee.
For the actuator of the factory non-return valve, special spring steel is used. The movement of the spring-loaded locking discs duplicates the guide rod. Materials for the manufacture of the valve have compatibility in the process of equipment operation. Technical parameters of the products comply with the requirements specified in generally accepted regulatory documents. The manufacturer provides a guarantee for manufactured products.
Important! To ensure the reliability and quality of operation of a check valve assembled at home is impossible.
The prices of existing protective fittings depend on the brand of the manufacturer, throughput (diameter) and structural modification of the valve. The cost of the main armature exceeds the prices of household appliances dozens of times.
Comparative table of prices of check valves for water from different manufacturers:
|Price per unit, rubles
|Polypropylene check valve
|Pipeline AQUA-S systems
|Backpressure check valve clutch
|Danfoss CO (Denmark)
|Combined spring check valve with drainage and air vent
|Spring-cage check valve with brass valve
Analyzing the information provided on the websites of official representatives and companies that produce protective armature, we can conclude: check valves for water for pumps increase the level of reliability and quality of operation of autonomous water supply systems.