In every piping system, there is a need for backflow prevention. Most piping systems utilize pumps or compressors to generate needed pressure for movement of line fluids or gases. When rotating equipment stops, flow reversal or backflow occurs. Check valves (also non-return valves) are used to stop backflow and protect rotating equipment or other mechanical devices from the sudden backflow surges that may occur.

Our check valves are mechanical valves that permit gases and liquids to flow in only one direction, preventing process flow from reversing. They are classified as one-way directional valves. Fluid flow in the desired direction opens the valve, while backflow forces the valve closed. Our range of non-return valves is suitable for oil, gas, water, refining, power and chemical applications where the prevention of flow reversal is mandatory. Check valves can be supplied with a cast or forged body design for high pressure applications or fully lined to meet specific requirements within the chemical industry.

The VR-100 series are available in a number of design sub-families such as swing check valves, tilting check valves, forged steel lift check valves (flanged or flangeless), nozzle check valves…

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A check valve, non-return valve or one-way valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction. A check valve is an electronic equivalent of a diode which permits the flow of electrical current in one direction only. The various practical applications of check valves are as follows.

Single pump systems

This is the most common application of a check valve where a check valve permits flow from suction tank to the discharge tank and prevents the reverse flow from the discharge tank back to the suction tank during pump stoppage or pump failure.

Parallel pump systems

This is another common application of check valves. In this configuration two or more pumps are connected in parallel. The check valve has two functions in such a scenario:

• The check valve prevents the duty pump, pumping into the standby pumps
• The check valve prevents the discharge tank back flowing into suction tank during pump stoppage.

Series pumping systems

When pumps are connected in series especially when pumping fluids in cross country pipelines then it is recommended to place check valves in parallel to each pump. Under normal operation the discharge pressure of the pump will keep the check valve in closed position. However if any pump fails then the pressure drop across the pump will activate the check valve. This will split the flow in two streams and reduce the hydraulic losses. 

Emergency cooling systems

This is a smart way of using check valves. Under normal operation only a small amount of fluid will go to the header tank and the same amount will overflow and drain back into the suction tank. So in effect the header tank will be always charged with water. The main flow will go through the load. 

Pressure relief systems

Spring loaded check valves are commonly used in gas projects as relief valves for low pressure applications.

Vacuum breaker systems

Check valves can also be used as vacuum breakers. 

Mixing streams

Check valves can also be used to maintain the purity of individual streams before they mix.