The diaphragm is hydraulically actuated. Its function is basically that of a partition. The diaphragm material is usually Teflon. There is no leakage of the process fluid as it is hermetically sealed. A rupture detection system can be provided to detect diaphragm failure in order to prevent the contamination of the metered fluid. The diaphragm has a long life as it is always in hydraulic balance with the liquid being pumped on one side and hydraulic oil on the other side.
Working Principle:
The reciprocating plunger displaces hydraulic fluid causing movement of the diaphragm and a like movement of the process liquid. The diaphragm separates Hydraulic fluid and process liquid. A pressure limiting valves prevents overload of the pump. The internal leak age at the plunger is balanced by the leakage replenishment valve. The diaphragm always operates in an optimal operating range. This diaphragm control gives very high operational safety. The diaphragm has a long life as it is always in hydraulic balance with the liquid being pumped on one side and hydraulic oil on the other side. The system is safe guarded by a built- in pressure relief valve on the hydraulic side.