Check valves consist of a valve body, a bonnet and a disk with a hinge or a piston or a ball. Check valves are automatic operate when it reaches the cracking pressure. It will open when forward flow occurs and close when reverse flow occurs.
Check valves are design to operate to flow in only one direction. When the build-up pressure behind the seat exceeds the cracking pressure, the disk or ball will open and allow the fluid to flow through. Once the pressure drops below the cracking pressure, it will close and create a seal to prevent back flowing. Check valves are often used in oil and gas industry when different gases are mixed into one gas stream.
In general, there are two types of check valves: Lift/Piston Check Valve and Swing Check Valve. Each design has its benefit and setup.
Lift – Piston check valves use a globe valve style... More information