Lift type check valve is to rely on media automatically open and close the valve flap, is used to prevent fluid reversal, also called as non-return valve, one-way valve, reflux valve, and back pressure valve. Check Valve is an automatic valve, the main role is to prevent the fluid reversal, to prevent pump and motor driver reverse, and container medium discharge. Check valve can also be used to the pressure which may rise to exceed the system supply pressure of the auxiliary system of pipeline. Check valve can be divided into swing check valve (rotated around the center of gravity) and lift check valves (moved along the axes). This type of valve is for fluid flowd in only one direction, prevent the fluid reverse. Usually the valve is automatically work, in a direction of flowd fluid pressure, the flap open. Lift check valves plate cylindrical shaped, rotated around the seat channel axis, because the valve channel into a streamlined, flow resistance ratio rose butterfly valve, suitable for low flow rate and flow infrequently changes in large-caliber occasion, but not for the pulsating flow, the sealing performance is less than lift. Butterfly Check points unicuspid type, two-valve type, and most of type three, three by the valve diameter to form the main points, the purpose is to prevent the media to stop flow, or reflux, the weakening of the hydraulic shock. Note installation direction of media flow valve should be consistent with the direction the arrow votes. Source: Valvehardware