Check valve structure introduction

The structure of the check valve is mainly composed of the valve body, valve disc, spring (some check valves have) and possible auxiliary parts such as the seat, valve cover, valve stem, hinge pin, etc. The following is a detailed description of the check valve structure:

First, valve body

Function: The valve body is the main part of the check valve, and the internal channel is the same as the inner diameter of the pipeline, which does not affect the pipeline flow when used.

Material: The valve body is usually made of metal (such as cast iron, brass, stainless steel, carbon steel, forged steel, etc.) or non-metallic materials (such as plastic, FRP, etc.), the specific material selection depends on the characteristics of the medium and the working pressure.

Connection method: The valve body is usually connected to the piping system by flange connection, threaded connection, welded connection or clamp connection.

Second, the valve disc

Function: The disc is a key component of the check valve, which is used to block the backflow of the medium. It relies on the force of the working medium to open, and when the medium tries to reverse flow, the valve disc will close under the action of factors such as the pressure difference of the medium and its own gravity.

Shape and material: The disc is usually round or disk-shaped, and the material selection is similar to that of the body, and may also be inlaid with leather, rubber, or synthetic covers on metal to improve sealing performance.

Motion mode: The motion mode of the valve disc is divided into lifting type and swinging type. The lift check valve disc moves up and down the axis, while the swing check valve disc rotates around the rotating shaft of the seat passage.

Third, spring (some check valves have)

Function: In some types of check valves, such as piston or cone check valves, springs are used to assist disc closing to prevent water hammer and counterflow. When the forward speed slows down, the spring begins to assist in closing the disc; When the forward inlet speed is zero, the disc closes the seat before return occurs.

Fourth, auxiliary components

Seat: with the valve disc to form a sealing surface to ensure the sealing performance of the check valve.

Bonnet: Covers the body to protect internal components such as disc and spring (if available).

Stem: In some types of check valves (such as some variants of lift check valves), the stem is used to connect the disc to the actuator (such as a manual lever or an electric actuator) for manual or automatic control of the opening and closing of the disc. Note, however, that not all check valves have stems.

Hinge pin: In swing check valves, the hinge pin is used to connect the disc to the body, allowing the disc to rotate around it.

Fifth, structure classification

Lift check valve: The disc moves up and down the axis and can usually only be installed on horizontal pipes.

Swing check valve: The disc rotates around the shaft of the seat channel and can be installed in horizontal or vertical pipe (depending on the design).

Butterfly check valve: The disc rotates around the pin in the seat, the structure is simple but the sealing is poor.

Other types: Also include heavy weight check valves, bottom valves, spring check valves, etc., each type has its specific structure and application scenarios.

Sixth, installation and maintenance

Installation: When installing the check valve, ensure that the direction of the medium flow is consistent with the direction of the arrow marked on the valve body. At the same time, for large check valves or special types of check valves (such as swing check valves), the installation position and support mode should also be considered to avoid unnecessary weight or pressure.

Maintenance: The maintenance of the check valve is relatively simple, mainly including regular inspection of the sealing performance of the valve disc and seat, cleaning up accumulated impurities and replacing severely worn parts. For check valves with springs, the elasticity and working status of the springs should also be checked regularly.

In summary, the structure of the check valve is designed to ensure that the medium can only flow in one direction and prevent backflow. By reasonable selection of the body, disc and other components of the material and structural form, as well as the correct installation and maintenance of the check valve, it can ensure its long-term stable operation and play the expected function.