High pressure reciprocating plunger water pump - has oil filled sealing chamber in place of stuffing box

摘要

The pump has a plunger (3) reciprocating inside a casing (2). The working chamber (6) has water inlet and discharge connections (7, 8) with automatic valves. The cylinder casing has an internally projecting annulus (11) fitting closely round the plunger with a small gap (13) between them. Below this a space (9) is formed which is filled with oil at a pressure always higher than that of the water. The oil is supplied from a pump (14) through a non return valve (16) and a pressure relief valve (15) set at slightly more than the maximum water pressure. Oil is pumped in on the plunger downstroke at a pressure above water suction pressure. On the upstroke the non return valve (16) closes and the oil pressure rises with the water pressure.