Are check valves and non-return valves the same thing?

Irrespective of what a device is called, for the purposes of the water fittings regulations, byelaws in Scotland, the important factor is whether it provides protection against backflow.

There are two ways to verify the backflow protection capabilities of a device, both rely on satisfying a specification including performance testing. These are:

• Conformity with BS EN 13959, the British Standard for both single and double checks valves, this also includes provision for fittings incorporating these devices.

  or

• Conformity with all of the tests from the Regulators Specification for fittings applicable to devices intended to be used as a single or double check valve.

Both of these routes include endurance tests intended to demonstrate the device continues to operate correctly over its lifetime.

Example of a check valve

Example of a non-return valve

The terms ‘check valve’ and ‘non-return’ valve are both commonly used to describe a device which allows flow from upstream to downstream but not the reverse. Only valves, or fittings incorporating devices, which conform with one of the above specifications can claim to provide backflow protection.

Those meeting the requirements of a single check valve can be used for fluid category 2 backflow protection, whereas those satisfying the requirements for a double check valve can be used for up to fluid category 3 backflow protection.