This is also known as one way valve which allow the fluid flow in one direction only. As its name implies non return means there is only one direction flow.All the assembly are provided with a valve bonnet.This valves are generally USED in pump discharges and steam water pipe LINES.This device ensures there is no back flow of fluid from the SOURCE. It has TWO lines one is inlet line and other is outlet line.There is a direction symbol provided on the valve which show the direction of flow fluid.

Types of NRV:-

1. Tilting disc check valve-This is a disc type check valve.The disc provided fixed with a hinge which swing up and down. As the fluid flow in the line it lift by the fluid force and allow the fluid to flow in the pipe. When there is no fluid flow in the circuit it closes due to gravitational force.
2. Ball check valve- Here a spherical ball is used to fervent the fluid flow. The ball is spring loaded which close the valve when there is no fluid flow in the line. The PRESSURE of fluid lift the ball and let the fluid to flow.
3. Diaphragm type NRV – This is consists of a rubber diaphragm clapper ,Which works on the differential pressure When the pressure in the upstream is more it open the diaphragm and allow the fluid to flow and when the pressure is equalize is closes diaphragm and prevent to fluid.
4. Stop check valve- It’s construction is same as the swing check valve except that here is a external control mechanism of handle or lever provided.
5. Lift check valve- Here a lift or disc is provided which operates on the working pressure of the fluid.

This is also known as one way valve which allow the fluid flow in one direction only. As its name implies non return means there is only one direction flow.All the assembly are provided with a valve bonnet.This valves are generally used in pump discharges and steam water pipe lines.This device ensures there is no back flow of fluid from the source. It has two lines one is inlet line and other is outlet line.There is a direction symbol provided on the valve which show the direction of flow fluid.

Types of NRV:-