Plunger pump with viscous fluid seals - has pneumatic auxiliary pump to supply viscous fluid at high pressure (SW 9.10.78)

摘要

A plunger pump(1) has a plunger(2) sliding in a sleeve(3). The sleeve(3) has two annular spaces (6, 7) connected by a narrow clearance(8). The annular space (6) is connected by small holes (23) to a non return valve(21). The non-return valve(21) is connected to a smaller plunger pump(11) which draws a fluid with a very high viscosity from the tank(10). This highly viscous fluid fills the annular spaces and acts as a seal against the fluid being pumped by the plunger pump(1). Surplus viscous fluid flows into the annulus(9) and returns to the tank(10) through the pipe(30). The viscous fluid pump(11) is actuated by admitting compressed air to each side of the piston(16) alternately.