JPS6054081B

PURPOSE:To provide the titled apparatus automatically controlled until a flow amount reaches a definite value or less, in the flow amount control part of a precoat type filter apparatus, by subjecting a liquid to be filtered to constant flow amount control up to the specific value of filter resistance differential pressure while subjecting the same to constant differential pressure control after the specific pressure treatment. CONSTITUTION:A backwashing valve 24 is opened to remove the contaminated precoat on the surface of a filter body Ic and a switch SW3 is closed while a valve 16 is opened to send a precoat liquid to precoat the surface of the filter body Ic. A switch SW1 is closed and the filter body Ic is brought to a pressurized state by a pump 13 while an operation treatment part 10 is turned ON to open the switch SW3. A switch SW2 is closed and water is sent by a pump 3 while a flow amount control part 4 is subjected to constant flow amount control on the basis of the value of a flow amount measuring part 6 as a parameter by the operation treatment part 10. If the differential pressure of a differential pressure measuring part 9 reaches a specific value or more, the operation treatment part 10 subjects the flow amount control part 4 to constant pressure control.