Reciprocating sludge pump unit - has auxiliary piston providing protective clean fluid flow to moving parts of sludge piston

摘要

The pump has a sludge cylinder n2) continuing in a clean fluid cylinder (1) of a larger diameter. In this cylinder assembly sludge piston (5) with peripheral gap (18) and clean fluid piston (4) are fitted on the same piston rod (3) and operate together. The working space of the sludge cylinder is on its free end (9) and contains suction valve (7), discharge valve (8), protective bell-shaped baffle plate (11) with gap (12) around piston rod, clean fluid inlet valve (16), gland (10) and clean fluid bypass connection (13). During the suction stroke sludge cylinder is filled via valve (7) with solids-laden fluid, while clean fluid on the other side of the sludge piston (5) is discharged via outlet and bypass into space between protective baffle and sludge cylinder head (9). At the same time clean fluid piston (4) due to its larger size draws in clean fluid in excess of the volume being discharged into the bypass.