Patent ID: 7250109

Claim:
Backflush filter having several filter chambers which receive filter inserts which can be flushed back by means of a flush filtrate loaded with compressed air, said backflush filter comprising: a filter housing, a backflush device rotatably mounted in said housing around a rotary axis, said backflush device comprises a filtrate pipe connection and a mud drain connecting piece, whereby, for the backflushing, said filtrate pipe connection can be brought into fluid communication with a filtrate chamber of respectively one of said filter chambers which are arranged concentrically around said rotary axis and simultaneously said mud drain connecting piece can be brought into communication with a mud chamber of said respectively one filter chamber, said backflush filter further comprising a pressure chamber for flush gas and a flush valve closing said pressure chamber or releasing it to said backflush device, and said backflush filter further comprising a mud outlet and a mud drain valve closing said mud outlet or releasing it to said mud drain connecting piece wherein said flush valve and said mud drain valve are actuated by a common drive whereas said flush valve only releases the connection to said backflush device when said mud drain valve has already released the connection between said mud drain connecting piece and said mud outlet at least partially, said flush valve and said mud drain valve are ball valves, wherein said flush ball valve has a ball bore which is smaller than a ball bore of said mud drain ball valve.