A check valve, non-return valve, reflux valve, or one-way valve is a valve that normally allows fluids to flow through it in only one direction and these are available in Bronze / Brass / Cast Iron and Ductile iron Construction. The valve that used to prevent backflow in a piping system is known as a check valve. It is also regarded as a non-return valve or NRV. The pressure of the fluid passing through a pipeline opens the valve, while any reversal of flow will close the valve. The valve allows completely unobstructed flow and automatically shuts as pressure decreases. The exact operation will vary depending on the mechanism of the valve.
Check valves are mainly used in a piping system to prevent backflow. The discharge line of rotary equipment such as pump and compressor always fitted with a check valve to prevent backflow. Different types available are swing type, Lift Type, Wafer style, Globe style. Typical applications are Commercial, Industrial and HVAC.
The disc in a swing type of valve is unguided as it fully opens or closes. This valve operates when there is flow in the line and gets fully closed when there is no flow. Turbulence and pressure drop in the valve is very low. Disk and seat designs are mainly of metal to metal or metal to composite. The seating angle which is the angle between the seat and the vertical plane varies from 0 to 45 degrees. Usually, the seat angles are in the range of 5-7 degrees. Larger seat angles reduce the disc travel which results in quick closing, thus minimizing the possibility of water hammer. The swing check valve allows full, unobstructed flow and automatically closes as pressure decreases.
Lift Check valves are mainly suitable for high-pressure service where the velocity of flow is very high. The disk is set on the seat with full contact and these valves are suitable for installation in horizontal or vertical pipelines with upward flow. When the flow enters below the seat, a disk is raised from the seat by the pressure of the upward flow. When the flow stops or reverses, the backflow and gravity forced the disk downward to set on the seat. These are commonly used in piping systems that used globe valves as flow control valves.
In a Dual Check valve, as the name suggests, two halves of the disc move towards centreline with the forward flow and reverse flow two halves open and rest on the seat to close the flow. Use of Dual Plate Check Valve is popular in low-pressure liquid and gaseous services. Its lightweight and compact construction make it a preferable choice when space and convenience are important. It is 80 to 90% lighter than the conventional full body check valve. Frequently used in systems that used butterfly valves. The cost of installation & maintenance is very low compared to other types.
Silent check valves have double guided spring-loaded poppet system which maximizes efficiency and reduces water hammer while preventing flow reversal. Assured drop tight closure with specially lapped bronze to bronze seats. Long maintenance-free operation is provided by the stainless.
Swing Check Valve - DZR Brass
Lift Check Valve - Brass
Swing Check Valve - Brass
Swing Check Valve - Bronze
Swing Check Valve - Ductile Iron
Dual Plate Check Valve - Ductile Iron
Silent Check Valve - Ductile Iron
Lift Check Valve - Bronze