What is the structure and working principle of the check valve?

<> check valve is simply a one-way valve that allows liquid to flow from one side to the other and not back! As shown in the figure, there will be a rubber round pad in the upper flange, and when the liquid flows into the valve from the left side, the rubber pad of the check valve is flushed open, and the liquid flows through. If the liquid flows back, the force of the liquid will block the rubber mat and the liquid will not flow from the right side to the left side.

Check valve refers to a valve that automatically opens and closes the valve disc by relying on the flow of the medium itself to prevent the medium from backflowing. Check valves can be divided into 1

Lift Check Valve: A check valve 2Swing check valve:

Check valve 3Disc Check Valve: A check valve 4

In-line check valve: A valve in which the disc slides along the centerline of the valve body.

Check valve (cheek valve): Check valve, also known as check valve or check valve, is used to prevent the backflow of media in the pipeline. The foot valve of the suction off of the water pump also belongs to the category of check valves.

The opening and closing parts rely on the flow and force of the medium to open or close by themselves, so as to prevent the medium from flowing backwards. Check valves belong to the automatic valve category, which are mainly used on pipelines where the medium flows in one direction, and only allow the medium to flow in one direction to prevent accidents.

According to the structure, the check valve can be divided into three types: lifting check valve, swing check valve and butterfly check valve. Lifting check valves can be divided into vertical and horizontal types. There are three types of swing check valves: single-petal, double-petal and multi-petal.

The butterfly check valve is a straight-through type, and the above check valves can be divided into three types: threaded connection, flange connection and welding.

To put it simply, when the liquid flows, the pressure flushes the valve open. When it doesn't flow, the reverse liquid can't rush through the valve, and you can understand it as a one-way door with a spring, and the person pushes the door forward and walks forward. But on the other side of the door, you can't push, you can only pull to get through.

I don't know if this metaphor is appropriate, so welcome to continue the discussion.

Under the action of fluid pressure flowing in one direction, the disc opens; When the fluid flows in the opposite direction, the fluid pressure and the self-closing disc of the disc act on the valve seat, thus cutting off the flow.

Among them, check valves belong to this type of valve, which includes swing check valves and lifting check valves. The swing check valve has a medium hinge mechanism and a door-like disc resting freely against the sloping seat surface.

In order to ensure that the disc reaches the right position on the seat surface every time, the disc is designed with a hinge mechanism so that the disc has enough room to swing and that the disc is in true and full contact with the seat.

The disc can be made entirely of metal, or it can be inlaid with leather, rubber, or synthetic overlay, depending on the performance requirements.

When fully open, the fluid pressure is virtually unhindered, so the pressure drop through the valve is relatively small. The disc of the lift check valve is located on the seat seal on the valve body.

Except for the disc that can be raised and lowered freely, the rest of the valve is like a globe valve, the fluid pressure lifts the disc from the sealing surface of the valve seat, and the backflow of the medium causes the disc to fall back to the valve seat and cut off the flow.

Depending on the conditions of use, the disc can be an all-metal construction or in the form of a rubber pad or rubber ring inlaid on the disc holder. Like globe valves, the passage of fluid through a lift check valve is narrow, so the pressure drop through a lift check valve is greater than that of a swing check valve, and the flow rate of the swing check valve is less restricted.

Check Valve Usage:

1. The check valve can prevent the medium from backflowing

The check valve has only one flow direction, that is, it can only flow in the direction of the water inlet, preventing the water from flowing in the opposite direction. The flow medium flows in from the inlet and out from the outlet. The valve is opened when the inlet pressure is greater than the sum of the disc weight and its flow resistance.

Conversely, the valve is closed when the medium flows backwards.

2. The check valve can prevent the pump and the drive motor from reversing

The check valve works automatically, and the disc opens under the action of fluid pressure flowing in one direction; When the fluid flows in the opposite direction, the fluid pressure and the self-closing disc of the disc act on the valve seat, thus cutting off the flow.

3. Check valves can also be used to supply pipelines to auxiliary systems where the pressure may rise to more than the system pressure

Check valves can be mainly divided into swing check valves and lifting check valves. They are all used on pipes where the medium flows in one direction, and the medium is only allowed to flow in one direction to prevent accidents.

Check valves are used in various water supply and drainage pipelines to prevent the water in the pipeline from flowing back.

1. Check valve refers to a valve that has a circular disc and relies on its own weight and medium pressure to produce after-impulse action to block the backflow of medium. It is an automatic valve, also known as a check valve, a check valve, a return valve or an isolation valve. The disc movement mode is divided into lifting type and swing type.

The lift check valve is similar in structure to the globe valve, with only the stem that drives the disc missing.

2. The medium flows in from the inlet end (lower side) and flows out from the outlet end (upper side). The valve is opened when the vertical inlet pressure is greater than the sum of the disc weight and its flow resistance. Conversely, the valve is closed when the medium flows backwards.

3. The swing-type check valve has an oblique disc that can rotate around the shaft, and the working principle is similar to that of the lifting check valve. Check valves are often used as foot valves for pumping devices to stop the backflow of water. The combination of a check valve and a shut-off valve can play a role in safety isolation.

The disadvantage is that the resistance is high and the sealing is poor when closed.

Here are some of the well-known brands recognized in the valve industry, which are widely recognized and have a high reputation. While rankings may vary depending on time and market conditions, the following brands are generally considered to be among the top brands in the valve industry:

The following are the top ten domestic first-line valve brand manufacturers in 2022-2023, but for reference only: Suzhou Neway Valve Co., Ltd., Shanghai Guanlong Valve Machinery, Shanghai Qizhong Valve Manufacturing Co., Ltd., Sanhua, Su Yan, Shentong, Su Valve, Nanfang, Jiang.

First, the word Yao. The above manufacturers are only estimates and references, and the specific situation may vary or fluctuate at any time due to changes in a series of factors such as changes in the market, the size of the competition pattern, and the stability of product quality. As an indispensable key device in industrial production and civil facilities, the quality and reputation of the valve brand directly affect the satisfaction and trust of users.

These brands are known in the valve industry for their innovative technology, high-quality products and reliability. It's worth noting that market and industry developments are changing rapidly, and different rankings may vary depending on time and region. For the most up-to-date ranking information, it is recommended to refer to industry reports, professional organizations or market research data for more detailed and accurate information.

The working principle of the check valve is that under the effect of the fluid pressure running in a single direction, the disc is opened, and when the fluid runs in the opposite direction, because the fluid pressure and the self-weight of the disc are combined, the valve seat is affected, so that the flow is disconnected. The check valve is a disc that uses the flow of the medium itself to control the switch, which can avoid the backflow of the medium, so it can also be called a check valve. Common check valves are swivel and lifting, with a hinge structure on the swivel type and a gate-like disc that can be arbitrarily leaned against the surface of the inclined seat.

What are the types of check valves?

1. Lifting check valve: vertical and horizontal. The body shape of the lift check valve is the same as that of the shut-off valve, so it has a high fluid resistance.

The disc slides along the vertical centerline of the body. When the medium flows downstream, the disc is opened by the thrust of the medium, and when the medium stops, the disc falls on the valve seat by self-sagging.

1. Vertical lifting check valve. The direction of the medium inlet and outlet channel is the same as that of the valve seat channel, and its flow resistance is smaller than that of the straight-through type. Vertical lift check valves are installed in vertical lines.

2. The straight-through lift check valve can only be installed in the horizontal pipeline. Due to the limitation of installation requirements, DN50 is commonly used in small diameter applications.

2. Swing-open check valve: The disc of the swing-open check valve is disc-shaped, and the rotating motion is made around the rotating shaft of the valve seat channel, because the channel in the valve is streamlined, the flow resistance is smaller than that of the lifting check valve, which is suitable for small and medium-caliber, low-pressure and large-diameter pipelines (low-flow velocity and large-diameter occasions where the flow does not change often). The sealing performance is not as good as that of the lifting type.

1. The swing-type check valve is divided into three types: single-valve type, double-valve type and multi-half type, which are mainly divided according to the diameter of the valve, in order to prevent the medium from flowing or reversing and weakening the hydraulic impact. Single-lobe swing check valves are generally suitable for medium caliber applications. When a single-valve swing-open check valve is selected for large-diameter pipelines, it is best to use a slow-closing check valve that can reduce the water hammer pressure in order to reduce the water hammer pressure.

The double-valve swing check valve is suitable for large and medium diameter pipelines. The double-valve swing check valve is small in structure and light in weight, and is a fast-growing check valve; Multi-lobe swing check valves are suitable for large diameter pipelines.

2. The installation position of the swing check valve is not limited, and it can be installed on horizontal, vertical or inclined pipelines.

3. Butterfly check valve: straight-through. The structure of a butterfly check valve is similar to that of a butterfly valve.

Its structure is simple, the flow resistance is small, and the water hammer pressure is also small. A check valve in which the disc rotates around a pin shaft inside the seat. The disc check valve has a simple structure and can only be installed on a horizontal pipeline, which has poor sealing.

Fourth, diaphragm check valve: there are a variety of structural forms, all use diaphragm as the opening and closing parts, because of its waterproof hammer performance, simple structure, low cost, in recent years rapid development. However, the operating temperature and pressure of diaphragm check valves are limited by the diaphragm material.

Diaphragm check valve is suitable for pipelines that are prone to water hammer, diaphragm can well eliminate water hammer generated when the medium is reversed, it is generally used in low-pressure and normal temperature pipelines, especially for tap water pipelines.