I am designing a resin dosing & mixing room for a production plant. This will use pneumatic diaphragm pumps to pump the resin & additives, flow meters to measure the dose, and pneumatic ball valves to shut off flow when the correct does is reached.
Talking with pump suppliers, Google etc, everyone suggests that pressure relief valves should be incorporated, since the system can potentially shut off flow via the pneumatic ball valve while the pump is still pressurising the line. This seems like a logical safety measure to me as well. However, the experienced maintenance fitters at my work say that if the fittings and pipe in the process line are all rated higher than the pump output pressure, there is no need for PRV because the pump will just reach dead-head pressure and stall. This reasoning seems sound to me, and it would reduce a LOT of cost and complexity to remove the PRV return lines (about 14 in total), but it also feels uncomortable removing a safety measure which seems like common practice to include.
System specs for reference: Pneumatic diaphragm pump maximum output = 115psi (needs 120psi air supply to achieve this), Air supply = 100psi maximum, poly process line MOP (safety factors included) = 115psi, poly compression fittings = 180psi, The rest of the components (SS fittings, flow meters etc) are rated to at least 1000psi.