Method of removing residual concrete from hopper and delivery pipe of piston type pump - involves running pump empty to create air pressure expelling part of residual concrete and then pumping water behind sponge to expel remainder

摘要

After the feeding of concrete, the pump is driven empty to produce a pneumatic pressure that expels part of the residual concrete from the end of the delivery pipe (3). A sponge plug (11) is then introduced into the delivery pipe via the hopper (1) and pump cylinder (12) and the hopper filled with water. The pump is again actuated until the remaining residual concrete has been expelled by hydraulic pressure. After residual concrete has been expelled the pump is reversed to return the cement laden water to the hopper, where it can be pumped to drainage or a cement mixer. ADVANTAGE - Operator's task is simplified. Contamination of ground is avoided. Raw material wastage is reduced.