What is a check valve?

Check valve refers to the opening and closing parts for the round valve and relies on their own weight and media pressure to produce action to block the medium backflow of a valve. Is an automatic valve, also known as a check valve, check valve, back valve, or isolation valve.

Principle of operation:

A check valve, also known as a one-way valve or check valve, prevents the backflow of media in the pipeline.

The opening and closing parts rely on the flow of media and the power to open or close, to prevent the backflow of the media valve called a check valve.

Check valve belongs to the automatic valve class, mainly used for the one-way flow of media on the pipeline, only allowing the media to flow in one direction to prevent accidents.

A check valve must be installed in the pump outlet, the only special is the bottom valve, pump suction port of the bottom valve also belongs to the check valve class. Bottom valve is installed on the inlet pipe of the pump, the role is to prevent the pump from stopping the work of the pump pipe in the water flow, so that the pump in the next work will not have to fill the pumping pipe again, improve the efficiency of the work.

Nominal pressure or pressure level: PN1.0-16.0MPa, ANSI CLASS 150-900, JIS10-20K 

Nominal diameter or calibre: DN15~900, NPS 1/4 ~36 

Applicable temperature: -196℃~540 

Valve body material: ductile iron, carbon steel, 304 316, titanium alloy, chromium molybdenum steel

Medium: Selection of different materials, check valves can be applied to water, steam, oil, nitric acid, acetic acid, oxidizing media, urea, and other media.

Check valves can be divided into threaded, flanged, welded, and clamped according to the connection form.

Check valves can be divided into lift check valves, swing check valves, butterfly check valves, and others according to the structure.

1. Lift check valve is divided into vertical and horizontal two kinds.

2. Swing check valve is divided into single-valve type, double-valve type, and multi-valve type.

3. Butterfly check valve is straight-through type.

Lift check valve:

Fluid is introduced from the low end, due to the pressure difference between the valve and the fluid after the valve produced by the thrust is greater than the gravity of the valve flap and the valve flap top rise, the fluid by the valve flap and seal ring ring ring through the high end of the flow out of the valve body; but the fluid backflow occurs, the pressure at the outlet end is greater than the inlet end pressure, the valve flap in the gravity and the pressure difference between the action of the valve flap down and seated in the seal ring, to stop the reverse flow of fluids.

The swing check valve consists of a valve body, valve cover, valve flap, valve seat, and rocker.

The valve flap is shaped like a disc and rotates around the pin outside the valve seat channel.

Working Principle: 

The valve flap and rocker of the swing check valve are connected and can rotate around the pin at a certain angle. When the pipeline fluid flows in the specified direction (from left to right), the valve inlet pressure is higher than the outlet pressure, the valve is pushed away from the valve seat, rotating around the pin in a certain position, and the valve is open. When the pressure difference between the two sides of the valve flap is reduced to a certain point, the valve falls back to the closed state.

The valve channel into a streamlined flow resistance is smaller than the straight-through lift check valve, suitable for large-diameter pipelines. But at low pressure, its sealing performance is not as good as the lift check valve. To improve the sealing performance can be used to assist the spring or the use of heavy hammer structure to assist the sealing.

Swing check valve.

The swing check valve consists of a valve body, valve cover, valve flap, valve seat, and rocker.

The valve flap is shaped like a disc and rotates around the pin outside the valve seat channel.

Working Principle: 

The valve flap and rocker of the swing check valve are connected and can rotate around the pin at a certain angle. When the pipeline fluid flows in the specified direction (from left to right), the valve inlet pressure is higher than the outlet pressure, the valve is pushed away from the valve seat, around the pin to rotate a specific position, and the valve is open. When the pressure difference between the two sides of the valve flap is reduced to a certain point, the valve falls back to the closed state.

The valve channel into a streamlined flow resistance is smaller than the straight-through lift check valve, suitable for large diameter pipelines. But at low pressure, its sealing performance is not as good as the lift check valve. To improve the sealing performance, auxiliary springs can be used or the use of a heavy hammer structure to assist the seal.

1.Do not make the check valve in the pipeline to bear the weight, the large check valve should be independently supported so that it is not affected by the pressure generated by the pipeline system.

2.Installation, pay attention to the direction of media flow should be consistent with the direction of the arrow marked on the valve body.

3.Lifting vertical flap check valve should be installed in the vertical pipeline.

4.Lifting horizontal flap check valve should be installed in the horizontal pipeline.

5.Swing-opening check valve installation position is not restricted, usually installed in the horizontal pipeline, but can also be installed in the vertical pipeline or dumping pipeline.

6.The installation of check valves, should pay special attention to the direction of media flow, and should make the normal flow of media direction and the direction of the arrow indicated on the valve body. Otherwise, it will cut off the normal flow of media. The bottom valve should be installed at the bottom of the pump suction line.

7.Check valve closure, which will produce water hammer pressure in the pipeline, which can lead to serious damage to the valve, pipeline, or equipment, especially for large port pipelines or high-pressure pipeline

WESDOM Group specializes in pipeline fluid systems: R&D, production and sales of valves, pipe fittings, water meters, flow meters, etc. The products cover cast iron, cast steel, stainless steel, copper, plastics and other materials, which are widely used in hydropower stations, heat, buildings, Water supply and drainage, petroleum, chemical industry, electric power, medical and other fields.

Why more and more customers are choosing wesdom valves:

1. There is a professional technical team, and quality is guaranteed

2. Independent factory, more favorable price

3. Extensively trained employees are well-versed in all aspects of flow control technology

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