The RPD Inlet Valves are used on all RPD (Harben) pumps, also known as P Type pumps. There is an inlet valve for each cylinder of the pump. The general symptom that occurs when inlet valves have blown is that the jetting unit won’t get to pressure and the pump is running rough.
It is recommended to change the inlet valves, delivery valves, and diaphragms all together while the pump is disassembled due to the intricate nature of the RPD pump. General recommendation is to change these parts every 1000 hours. If the valves are less than 1000 hours, inspect every valve prior to changing them as they may not all require replacement.
