Patent ID: 7273544

Claim:
A sludge extractor, comprising: a receiving tank having a suction connection connected to a suction element which draws in sludge-containing liquid and a discharge connection connected to a discharge element which discharges the sludge-containing liquid from the receiving tank; a motor connected to a suction device, wherein said motor is operable for driving said suction device such that a negative pressure is created in said receiving tank; a vacuum valve arranged in the discharge element, wherein the negative pressure acts on said vacuum valve and holds said vacuum valve closed until the sludge-containing liquid reaches a predetermined level at which level the pressure of the sludge-containing liquid acting on said vacuum valve surpasses the negative pressure acting on said vacuum valve and said valve opens, said vacuum valve being configured to open while said motor continues to operate said suction device to draw in the sludge containing liquid; and a safety valve installed in said receiving tank proximate a maximum fill level of said receiving tank.