Check Valves
Check valves are valves that only allow water to flow in one direction and are designed to be drip tight. Check valves are components of backflow prevention device assemblies. The check valves incorporated into design of the backflow prevention device assemblies are spring loaded which force the check valves to a closed position. Check valves in backflow prevention device assemblies can be found in several configurations depending on the manufacture preference and design standards. The design standards require the check valves to be equipped with elastomer disks to seal against the seat creating a drip tight closure. Elastomers are a natural material such as rubber or a synthetic material such as polyvinyl that has elastic properties.
If no water is flowing through the check valve, the force of the check valve spring closes the check valve. If backpressure is present, the check valve will close due to the force of the spring and backpressure. If there is a demand downstream and water is flowing through the check valve, the check valve will open when the inlet pressure is greater than the force of the spring. Although check valves are used in backflow prevention device assemblies, a single check valve is not an approved backflow prevention method for cross-connection control.