About the usefulness of check valve

Swing check valve: The valve disc of the swing check valve is disc-shaped and rotates around the shaft of the valve seat channel. Because the channel in the valve is streamlined, the flow resistance ratio increases.The drop check valve is small and suitable for large-diameter occasions with low flow rate and infrequent flow changes, but it is not suitable for pulsating flow, and its sealing performance is not as good as that of the lifting check valve. Swing check valves are divided into three types: single-disc type, double-disc type and multi-half type. These three types are mainly divided according to the caliber of the valve.

Lifting check valve: a check valve whose disc slides along the vertical centerline of the valve body. Lifting check valves can only be installed on horizontal pipelines. Balls can be used as discs on high-pressure small-diameter check valves. The valve body shape of the lift check valve is the same as that of the globe valve, and it can be used in common with the globe valve, so its fluid resistance coefficient is relatively large. Its structure is similar to the globe valve, and the valve body and disc are the same as the globe valve. The upper part of the valve clack and the lower part of the bonnet are processed with ratchet sleeves, and the valve clack guide plate can be lifted and lowered freely in the valve cup guide plate. When the medium flows downstream, the valve clack is opened by the thrust of the medium. Drop down on the valve seat to prevent the reverse flow of the medium. The direction of medium inlet and outlet channel of straight-through lift check valve is perpendicular to the direction of valve seat channel; for vertical lift check valve, the direction of the inlet and outlet channels of the material is the same as that of the valve seat channel, and its flow resistance is smaller than that of straight-through type.

Disc check valve: a check valve in which the disc rotates around a pin in the valve seat. The disc check valve has a simple structure and can only be installed on horizontal pipelines with poor sealing performance.

Compression check valve: This valve [ ] is used as a boiler feed water and steam cut-off valve. It has the comprehensive functions of lift check valve and stop valve or angle valve.In addition, there are some check valves that are not suitable for pump outlet installation, such as bottom valve, spring type, Y type and other check valves.

How Check Valves Work：

Check valve refers to the valve that relies on the flow of the medium itself to automatically open and close the disc to prevent the backflow of the medium, also known as check valve, one-way valve, reverse flow valve and back pressure valve. The check valve is a kind of automatic valve, the main function is to prevent the reverse flow of the medium, prevent the reverse rotation of the pump and the drive motor, and discharge the medium of the container. Check valves are also used on lines that supply auxiliary systems where the pressure may rise above system pressure. Check valves can be mainly divided into swing check valves that rotate according to the center of gravity and lift check valves that move along the axis. The function of this type of valve is to only allow the medium to flow in one direction and prevent the flow in the opposite direction. Usually this kind of valve works automatically. Under the action of fluid pressure flowing in one direction, the valve disc opens; when the fluid flows in the opposite direction, the valve seat is acted on by the fluid pressure and the self-weight of the valve disc to cut off the flow. . Among them, the check valve belongs to this type of valve, which includes swing check valve and lift check valve. The swing check valve has a hinge mechanism, and a door-like disc freely leans on the inclined seat surface. In order to ensure that the valve clack can reach the proper position of the seat surface every time, the valve clack is designed in the hinge mechanism, so that the valve clack has enough swing space, and makes the valve clack truly and comprehensively contact with the valve seat. The disc can be made entirely of metal, or it can be inlaid with leather, rubber, or synthetic covering on the metal, depending on the performance requirements. When the swing check valve is fully open, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. The disc of the lift check valve is located on the sealing surface of the valve seat on the valve body. In addition to the fact that the valve disc can rise and fall freely, the valve is like a globe valve. The fluid pressure makes the valve disc lift from the sealing surface of the valve seat, and the backflow of the medium causes the valve disc to fall back to the valve seat and cut off the flow. According to the conditions of use, the disc can be of all-metal structure, or in the form of inlaid rubber pads or rubber rings on the disc frame. Like the stop valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than that of the swing check valve, and the flow rate of the swing check valve is limited. few restrictions