Patent ID: 6837254

Claim:
A system for cleaning a drainage pipe provided in movable equipment comprising: a reservoir tank containing a cleaning liquid; a feed pipe connecting the reservoir tank and a downstream side of the drainage pipe of the movable equipment and including feed pump means for feeding the cleaning liquid to the downstream side of the drainage pipe from the reservoir tank; a suction pipe connecting an upstream side of the drainage pipe and the reservoir tank; and vacuum pump means for sucking gas from the reservoir tank; wherein the suction pipe is provided with gas separation means for separating gas from gas, liquid and solid sucked from the drainage pipe; wherein a gas suction pipe for feeding the separated gas back into the reservoir tank is connected parallel to the suction pipe between the gas separation means and the reservoir tank; wherein the feed pump means and the vacuum pump means are actuated to maintain the inside of the drainage pipe at a negative pressure, to feed the cleaning liquid into the drainage pipe from the reservoir tank through the feed pipe, and to cause the cleaning liquid to flow toward the upstream side of the drainage pipe, whereby scale deposited in the drainage pipe is removed and the removed scale is sucked together with the cleaning liquid through the suction pipe and, after only the gas is separated from the gas, the liquid and the solid by the gas separation means, the liquid and the solid are fed back into the reservoir tank through the suction pipe, and the gas is fed back into the reservoir tank through the gas suction pipe.