Non-return valve

Non-return valve (NRV), also called check valves, allow drinking water to flow in pipes, pumps and fittings in one direction only and prevent a possible reversal of the flow direction. If the direction of flow is reversed, they close automatically and open again when the direction of flow is correct. In this way, non-return valves prevent pipes and tanks from running empty and pumps from experiencing reverse flows. Examples of non-return prevention include valves, flaps, check valves, non-return valves and gravity brakes.

For drinking water supply, the non-return valve is located between the water filter and after the water metre to prevent the metre from being reversed. In combination with an atmospheric vacuum breaker, non-return valves also help to prevent the back flow of used water. Non-return valves are also required by utilities in front of the safety valve in the cold water inlet of the storage tank, so that no hot water can get into the higher quality cold water. In heating technology, non-return valves are used to prevent heat buoyancy and mixing of water in different heating circuits.

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