High pressure reciprocating plunger pump - has floating sleeves round plunger to form seal imposing low hydraulic forces on cylinder

摘要

The pump has a plunger which is carried through a thin wall cylinder (4). A series of sealing sleeves (6) is fitted round the plunger between it and the cylinder. The pressure falls along a small gap (2) between the plunger and the sleeves and forms the seal. Each sleeve is sealed to the cylinder wall by O-rings (7, 12) at its axial ends. Radial holes (13) at its lower end admit liquid at the lower end pressure to the back of the sleeve. As the working pressure rises, the sleeves deform conically (15) and the pressure on the cylinder is kept down so that it can have a thin wall.