Reduced Pressure Principle Backflow Prevention Device Assembly Relief Valve
The relief valve is located within the zone and when it opens to the atmosphere, it provides an air gap between the two check valves. The air gap is actuated by a spring loaded relief valve which opens up to the atmosphere. The relief valve is held closed by supply or inlet pressure by the way of the sensing line and a spring is trying to force the relief valve to open. The relief valve will not open if the RPZ is in a flow or dynamic state such as a demand downstream. When the RPZ is in a static state, the relief valve will stay closed if the supply or inlet pressure is at least 5 PSI greater than the pressure in the zone. The relief valve will open with the assistance of the spring when the water pressure in the zone is equal to or greater than the supply or inlet water pressure. The relief valve will also open when the supply or inlet pressure is 0 PSI or sub-atmospheric. If water is discharging from the relief valve and the RPZ is in a flow state, the relief valve is most likely malfunctioning. Interchanged or broken springs will also cause the relief to discharge.
