Also known as a non-return valve or one-way valve, a check valve allows pressurized media to flow in one direction through a system and prevents reverse flow.
How Do Check Valves Work?
The valve opens when the upstream pressurized media reaches a higher threshold than the downstream pressure inside the valve. Check valves close when the upstream pressure drops below a certain level relative to the downstream pressure. The closure prevents backflow in the system.
Types of Check Valves
Swing check valve: A swing check valve uses a hinged pivoting disc to open the valve upon actuation. The disc and hinge are suspended in the valve body by a pin, allowing it to swing open or closed.
Lift check valve: A lift valve has a spring-loaded vertical weighted piston that moves up to allow media into the valve body. Gravity pushes the piston down into its sealed position when media pressure drops. Lift check valves are ideal for applications with high pressure and flow rates.
Ball check valve: A weighted ball sits at the valve opening until the media reaches cracking pressure, lifting the ball out of its seat to allow free flow. The ball remains suspended while the air or fluid going through the valve maintains a high pressure. It returns to the seat once the flow pressure drops to stop backflow.
Wafer check valve: Wafer check valves have thin discs inside the valve body that move back and forth to allow and prevent flow. Media moves in one direction after it pushes the disc up and away from the opening.
Dual plate check valve: Also known as a butterfly valve, a dual plate valve features discs that are split down in the center. The discs fold toward each other to allow forward media movement and sealing flexibility. The discs separate and close the orifice with reverse flow.
Diaphragm check valve: A rubber diaphragm flexes to allow forward media flow, while reverse flow seals the disc in a mating seat area.
Piston check valve: A spring-loaded piston is biased away from its sealing surface for forward flow and engages the sealing surface during reverse flow.
Pilot-operated check valve: Also known as a check valve with override, this valve functions as a check valve when it’s not pilot-operated. It allows flow in both directions during pilot operation.
Benefits of Check Valves
Check valves are designed to seal and prevent backflow from contaminating or damaging a system during operation. They’re self-actuating and fast-acting, which enhances application performance and efficiency.
Other check valve benefits:
- Compact size, typically spliced into piping or tubing
- Horizontal and vertical operation
- Few moving parts
- Reliable
- Easy to troubleshoot and maintain
- Lowers operating costs
- Reduced risk of sudden valve failure
Applications of Check Valves
You’ll find check valves in the following applications:
- Medical and analytical
- Irrigation
- Water treatment
- Pumps and compressors
- Oil and gas
- Fire protection
- Chemical processing
Durable Check Valves from Humphrey Products
We offer TAC miniature check valves and pilot-operated check valves from our classic diaphragm-poppet series. Humphrey quick exhaust valves can also function as an excellent check valve by plugging the exhaust port. Contact our team to learn more about our products and request a quote.