RPZ in a Flow or Dynamic State – Second Check Valve Opens
After the first check valve opens, the water pressure will open the second check valve. A loss of pressure of at least 1 PSI is created across the second check valve due to the force loading of the second check valve spring. If there is a demand downstream, the RPZ is would be in a flow or dynamic state and the first and second check valves would be open and inlet pressure is keeping the relief valve closed. The greater the flow (gpm) the more the check valves will open. When the RPZ device is in a flow condition with a demand downstream, the relief valve will not open.