High pressure check valve is to rely on the flow of the medium itself and automatically open and close the valve flap, used to prevent the media back to the valve, also known as check valve, check valve, counterflow valve, and back pressure valve. Check valve is an automatic valve, its main role is to prevent media backflow, to prevent the pump and drive motor reversal, and the release of container media. Check valves can also be used on lines where the pressure may rise above the system pressure on the auxiliary system. Check valve can be divided into spin-check valve (according to the center of gravity rotation) and the lift check valve (along the axis of movement). One female check valve, butterfly check valve belongs to this type of valve, which includes the swing check valve and lift check valve. Swing check valves have a hinged hinge mechanism and a flap-like flap freely rests against the slanted seat surface. To ensure that the valve flap reaches the proper seating surface every time, the valve flap is designed in the hinge mechanism so that the valve flap has enough swivel-open space for true and complete valve flap contact. The valve flap can be made entirely of metal, or it can be fitted with a leather, rubber or synthetic cover over the metal, depending on the performance requirements. Swing check valve in the fully open condition, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. Lift check valve seat is located on the valve seat sealing surface. In addition to the valve flap valve can be freely up and down, the rest of the same as the cut-off valve, the fluid pressure from the valve seat sealing surface lift up, the media back to the valve seat caused by the valve back down and cut off the flow. Depending on the conditions of use, the valve disc can be of all-metal construction or it can be in the form of a rubber gasket or rubber ring inlaid on the valve disc holder. Like the shut-off valve, the passage of the fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than the swing check valve and there is very little restriction on the flow through the cryogenic check valve . High-pressure check valve structure and installation: 1, high-pressure check valve disc was disc-shaped, around the valve seat passage for rotation shaft movement, because the valve into the streamline linear flow resistance than the butterfly-type stop Check the valve is small, suitable for low flow rate and flow of small changes in occasions, but not suitable for pulsating flow, the sealing performance is less than lift. Butterfly check valve single-valve, double-valve and most of the three, these three forms are mainly based on the valve caliber, the purpose is to prevent the media stop flowing or backwards, weakened the hydraulic impact. 2, check the high-pressure valve along the valve body vertical centerline sliding check valve, internal thread check valve can only be installed on the level of the pipeline, in the high-pressure small-caliber check valve on the disc can be used ball. Butterfly check valve body shape and the same cut-off valve (common with the cut-off valve), so it has a larger fluid resistance coefficient. Its structure is similar to the cut-off valve, the valve body and the valve and the cut-off valve the same. The upper part of the valve plate and the lower part of the valve cover are machined with a guide sleeve which is simple and can be freely guided and guided by the valve guide. When the medium flows downstream, the valve plate is opened by the medium thrust. When the medium is stopped, Drop falling on the valve seat, play a role in blocking the media countercurrent. Straight through butterfly check valve medium inlet and outlet channel direction and seat channel vertical; vertical lifting check valve, the media import and export channel direction and valve seat channel in the same direction, the flow resistance than the straight-through small. 3, high pressure check valve: valve around the valve seat within the rotation of the check valve. Disc check valve structure is simple, can only be installed on the horizontal pipe, sealing better. 4, high-pressure check valve: valve along the valve body centerline sliding valve. Pipeline check valve is a new type of valve, its small size, light weight, good processing technology, is one of the development direction of the check valve. But the fluid resistance coefficient is slightly larger than the swing check valve. 5, high pressure check valve: This valve is used as a boiler feed water and steam cut valve, it has a lift check valve and globe valve or angle valve of the integrated function. In addition, there are - some do not apply to the pump outlet installed check valve, such as the end of the valve, spring, Y-type check valve.