What is NRV | How NRV works | Non-Return Valve

How an NRV (Non-Return Valve) Works

A Non-Return Valve (NRV), also known as a check valve, is a mechanical device that allows fluid (liquid or gas) to flow in only one direction. Its primary function is to prevent backflow in piping systems, which can damage equipment or contaminate clean fluid lines.

Working Principle:

An NRV operates automatically using pressure differences. When fluid flows in the desired direction, the pressure pushes the valve open, allowing passage. If the flow reverses, the pressure causes the valve to close, blocking the backward movement of fluid.

There are different types of NRVs, such as swing check valves, lift check valves, and ball check valves, but the basic principle remains the same—flow in one direction, block in the other.

Key Components:

• Body: The outer casing that houses internal parts.

• Disc or Flap: The movable part that opens with forward flow and closes with reverse flow.

• Spring (in some types): Assists in closing the valve quickly.

Applications:

NRVs are used in water supply systems, HVAC systems, pump discharge lines, and gas pipelines to protect pumps, compressors, and maintain system integrity.

In summary, NRVs are simple yet essential components that ensure unidirectional flow, protect equipment, and maintain safety and efficiency in fluid systems.