Usage of relief valve and safety valve

Positive displacement pumps including the reciprocating types show much higher discharge pressure than the centrifugal pumps. When operating the metering pump, discharge line can be blocked by the foreign matters, or eduction crystal matters. Also when the pump is operated accidentally with closing the discharge line valve, too much pressure can be charged, and cause the damage of diaphragm, motor, or piping. In this case, relief valve discharges the over pressure and consequently protects the overall system. Especially, after a long time that main pump and spare pump is installed, users can accidentally operate the system without opening the discharge line valve. To handle this kind of situation, relief valve installation is strongly necessary.