Spill-Resistant Pressure Vacuum Breaker Backflow Prevention Device Assembly – No Flow or Static State
The check valve will start to close as the inlet rate of flow decreases to a static state. When the SRPVB is in a static state, the check valve, if operating properly, will close and the air inlet valve will remain closed due to the supply pressure. The water pressure downstream of the check valve is less than the supply pressure. The differential pressure across the check valve is based on the tensile strength or loading of the check valve spring which shall be at least 1.0 psi.
If the downstream shut-off valve is closed drip tight and the upstream shut-off valve is open no water is flowing through a pressurized SRPVB, a static state within the body of the SRPVB exists. In a static state with the SRPVB pressurized, the check valve is closed and the air inlet valve is closed. The water pressure downstream of the check valve is less than the supply pressure. The differential pressure across the check valve is based on the tensile strength or loading of the check valve spring which shall be at least 1.0 psi.
