Relief Valve Will Not Open During Dynamic or Static State
The relief valve may become stuck open or stuck closed because the sensing line is plugged. The relief valve will not open if the sensing line is filled with water and plugged. The relief valve will not close if the sensing line is void of water and plugged. If the relief valve is not working, the device becomes a double check valve assembly. The sensing line, which provides high-pressure water to keeps the relief valve closed, can become plugged. A plugged sensing line will cause the relief valve to stay closed under all backflow conditions. The relief valve diaphragm is unable to move because high-pressure water, which cannot be compressed, is trapped in the sensing line. If the sensing line is plugged, the relief valve will stay open and water will continually discharge from the relief valve during start-up after a repair or internal inspection. Dewatering of the device during a repair or internal inspection released the high-pressure water from the sensing line.