3.19.4.2 Pump Relief Valve

Each pump or group of pumps shall be equipped with one or more relief valves conforming to the following requirements:

(a) Type and Location. The relief valve shall be located between the pump and the check valve and shall be of a type and so installed in the bypass connection that the valve cannot be shut off from the hydraulic system.

(b) Size. The size of the relief valve and bypass shall be sufficient to pass the maximum rated capacity of the pump without raising the pressure more than 50% above the working pressure. Two or more relief valves shall be permitted to be used to obtain the required capacity.

(c) Sealing. Relief valves shall be sealed after being set to the correct pressure.

No relief valve is required for centrifugal pumps driven by induction motors, provided the shutoff, or maximum pressure that the pump can develop, is not greater than 135% of the working pressure at the pump.