Check Valve or Non Return Valve is an automatic valve, that opening is with flow and closing is with return of flow. In fact, pressure of flow causes the valve to opening,
Check valve is in different shapes and different sizes. without flange called Wafer, flanged, with Socket, threaded & welded.
Types of check valves:
Swing Check Valve , Piston Type Check valve, Ball Check valve, Check Valve with counter & weight , Tilting Type Check Valve, Stop Check Valve, Spring Loaded Check Valve, Non Slam Check Valve, Nozzle Check Valve , ....
Swing Check Valve includes Body, Bonnet and disc connected to a Hinge , the disc will be fully open or fully closed, it is not guided, when the disc is separated from the seat, allow the fluid to flow when the flow is interrupted or the disc is sitting on the seat does not allow the fluid to flow vice versa, turbulence and pressure drop in this type of valve is very low
Piston Type Check Valve disc is shaped like a piston and in Ball Check Valve disc is shaped like a ball, these two types are suitable for high pressure services, when the flow rate is high, the valve disc is guided entirely in fixed valve's containers , the valves are suitable for both vertical and horizental modes,
Selected check valve on working conditions
Check valve, the valves are automatically opened when the flow is in forward and the return of flow closes the fluid passage. Although the check valve has a simple structure, but choosing the wrong type of check valve will cause a crisis in the collection.
The first step in selecting a check valve, full compliment of facilities and operators that affect the valve, including temperature, type of fluid, minimum and maximum transmission of fluid , allowable pressure drop through the valve, the flow, sealing requirements, space limitations and the situation of valve in the piping system.