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What is the function of a non-return valve?

Underground Drain Sewer Pipe Non Return Valve Dek DrainMany of our customers have asked us what is the function of a non-return valve? Also known as check valves or one-way valves, non-return valves (NRVs) appear in many varieties. This article sets out to explain the primary function of a common non-return valve.

How do non-return valves function?

The main function of an NRV is to allow fluid (either liquid or gas) to flow in a single direction. These two-port valves have two openings in the body: one for the fluid to enter, and the other for the fluid to leave.

NRVs work without the need to be controlled by a person or an external switch. Consequently, most do not have a valve handle or stem. However, there are a few ranges in which a manual switch on the valve can be used instead. This allows for full control.

Another function that NRVs have is helping to protect your drains from rodents. The one-way access restricts fluid to passing out of the valve, preventing irritating pests such as rats and mice getting into the pipes and causing damage.

Different types of non-return valves

Swing check non-return valves

These have a movable part which swings on a hinge to block flow in the opposite direction. Although swing check NRVs can come in numerous sizes, they are often larger.

WAR Water & Rodent Non-Return ValveBall non-return valves

Ball NRVs feature a movable ball to block the opposite flow. This is often spring-loaded to help keep it closed, otherwise reverse flow is required to move the ball toward the seat and create a seal. Ball check valves are often very small, simple and inexpensive.

Stop check non-return valves

These feature override control to stop flow, regardless of direction or pressure. As well as closing in response to inadequate forward pressure or backflow, they can also be intentionally shut by an external mechanism.

If you require any extra assistance or help selecting the right non-return valve for your project, feel free to give our experts a call on 01752 692 221.


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