One, check valve function
The check valve is an automatic valve. Its main function is to prevent the backflow of the medium, prevent the reversal of the pump and drive motor, and discharge the container medium. The check valve can also be used to supply pressure to the auxiliary system which can exceed the system pressure.
Two, the classification of check valve
The check valve can be divided according to its structure and installation method.
1. swing check valve
The valve disc of the swing check valve is disc shaped and rotating around the seat channel. Because of the flow line in the valve channel, the flow resistance is smaller than the lift check valve. It is suitable for a large aperture with low flow velocity and unchangeable flow, but it is not suitable for pulsating flow, and its sealing performance is less than the lifting type. The swing check valve is divided into three types, single valve, double valve and multi half. These three forms are divided mainly according to the valve diameter. The purpose is to prevent the hydraulic shock from stopping the flow or reverse flow of the medium.
2. lift check valve
The valve slid along the vertical center line of the valve body, the lift check valve can only be installed on the horizontal pipe, and the ball can be used on the small caliber check valve on the high pressure small caliber check valve. The body shape of lift check valve is the same as that of globe valve (and can be used with globe valve), so its fluid resistance coefficient is large. The structure is similar to the globe valve, and the valve body and disc are the same as the globe valves. The upper part of the valve and the lower part of the valve cover are machined, and the valve guide can be reduced freely in the guide of the valve. When the medium is flow, the valve is opened by the medium thrust. When the medium stops flow, the valve is landed on the seat by the droop. The vertical lift check valve is perpendicular to the direction of the seat channel, and the vertical lift check valve is the same as the direction of the valve seat channel, and the flow resistance is smaller than that of the direct passage.
3. disc check valve
The check valve is revolving around the pin inside the valve seat. The disc check valve is simple in structure and can only be installed on horizontal pipes, with poor sealing performance.