Spill-Resistant Pressure Vacuum Breaker Backflow Prevention Device Assembly – Pressure Loss Across the Check Valve – Dynamic State
In a flow or dynamic state with the upstream and downstream shut-off valves open, the check valve is open and the air inlet valve is closed. The differential pressure across the check valve is 1.0 psi less than supply pressure or equal to the tensile strength or loading of check valve spring. If the supply pressure is 60 psi and the check valve spring is loaded to 1.0 psi, the pressure loss will be 1.0 psid and the pressure downstream of the check valve will be 59 psi. The maximum allowable pressure loss at any flow rate is 10 psi.