Non Return Valves are found everywhere, including the home. If you have a sump pump in the basement, a non return valve is probably in the discharge line of the pump. Outside the home, they are found in virtually every industry where a pump is located.
What are Non Return Valves?
There are a variety of types of non return valve, but their main function is similar at its core. Non return valves basically allow the flow to move in just one direction. As a result, they’re also known as one-way valves. NRVs are also considered a kind of two-port valve as they have two openings: One opening is for exiting and the other is for entering fluids. NRVs usually don’t require manual assistance and function automatically. So most NRVs don’t have stems or handles.
How Does a Non Return Valve Work?
A non-return valve usually only has two openings in the body, with a closing member situated between them. Whenthe fluid enters the valve its pressure holds the closing mechanism open. If the fluid attempts to flow back through the valve in the wrong direction, the closing member is forced back over the entrance of the valve preventing any flow.
Non-return valves work automatically, which means that most are not controlled by a person or an external control but by the media flow itself. Depending on exactly.
Types of Non Return Valves
Depending on the working mechanism, various types of non-return valves are available in the market. Some of those are:
Swing Check Valves: In this type of non-return valve, the movable part that allows/blocks the fluid flow swings on a hinge or trunnion.
Ball Check Valves: The ball type of non-return valve features a movable spherical ball to block the flow. Sometimes they are spring-loaded.
Lift Check Valves: In a lift check valve , a disc known as a lift operates to allow/block the flow. When the inlet pressure is high, the disc is lifted and the flow is allowed. When the pressure drops gravity force or outlet pressure lowers the disc and the flow is stopped. Normally used for high-pressure service.
Wafer Check Valves: Mainly used for gaseous or low-pressure liquid service, this type of non-return valves are made in a wafer body pattern. They are also known as single plate or dual plate check valves.
Tilting Disc Check Valves: Tilting disc types of non-return valves are suitable for turbulent, pulsing, or high-speed flows. The disk of this type of NRV floats within the flow and fluid runs on its top and bottom surfaces.
Stop Check Valves: Stop check valves possess an override control that stops the flow. It does not depend on the fluid pressure or flow direction.
In-line Check Valves: This type of non-return valve uses a spring and the flow is allowed when the upstream pressure exceeds the spring tension. Again when the pressure goes below the pressure to overcome spring tension the flow is blocked.
Diaphragm Check Valves: This type of non-return valve uses a diaphragm (usually made of flexible rubber) that is controlled by fluid pressure.
Applications of Non Return Valves
A non-return valve, also known as a check valve, clack valve, one-way valve or retention valve, is designed to allow fluid to flow in one direction only, therefore preventing the liquid or gas from flowing back upstream of the valve. We take a look below at how a non-return valve operates, and what a non-return valve is used for, including some of the applications in which you might find one.
Non-return valves find a range of applications in industrial and domestic sectors. Some of the uses of nonreturn valves are:
- Pump Discharge: A non-return valve known as a check valve is always installed at the pump discharge piping to prevent the backflow of the fluid.
- Transportation Fluid System: Transportation fluid systems use non-return valves in their pipelines to avoid the backward movement of the fluid.
- Nuclear Industry: Nitrogen feed systems, dump lines.
- Industrial Sampling systems
- Fluid Injection Systems of aircraft, space crafts
- Laboratory Purification system
- Mixing chambers: a non-return valve is installed at each individual line to avoid gas mixing with the original source.
- Domestic Uses like Sprinkler systems, Home heating systems, inflatable mattresses and boats, drip irrigation system, Rainwater harvesting system, Hydraulic jacks, etc.
Advantages of Non Return Valves
- Operates Automatically
- Available In Wide Range of Sizes
- Protects Pump and Compressor Equipment
- Prevents Back Flow
- Helps In Preventing Water Hammering
- Saves Energy
- Reduces Sudden Valve Failure
- Low Maintenance Cost