Backwashable fluid filter

A backwash filtering device including a housing having an inlet connectable to an upstream fluid pipe and an outlet connectable to a downstream fluid pipe, a filter body having an upstream surface communicating with the housing inlet to intercept dirt particles in the fluid flowing in the foreward direction from the housing inlet to the housing outlet, a backwash nozzle within the housing and having a nozzle inlet disposed adjacent to the upstream surface of the filter body, means for effecting relative movement between the filter body and the backwash nozzle, and means for connecting the backwash nozzle to the atmosphere for backwashing the filter body;

• characterized in that said housing further includes a sleeve axially movable to open or close a passage between the housing inlet and the filter body, said sleeve being axially movable by a piston displaceable in a cylinder, the device further including means for subjecting one face of the piston to atmospheric pressure tending to move the sleeve to open the passage between the housing inlet and the filter body, a control member for subjecting the opposite face of the piston either to the housing inlet pressure tending to move the sleeve to close the said latter passage or to atmospheric pressure, and means effective to move the sleeve to open the latter passage when the control device subjects said opposite face of the piston to atmospheric pressure, said housing further including a conical deflector between the housing outlet and the passage from the housing inlet to deflect the fluid therethrough, said sleeve being coaxial with respect to said deflector.

A backwashable filtering device including a housing having an inlet connectable to an upstream fluid pipe, and an outlet connectable to a downstream fluid pipe, a filter body having an upstream surface communication with the housing inlet to intercept dirt particles in the fluid flowing in the foreward direction from the housing inlet to the housing outlet, a backwash nozzle within the housing and having a nozzle inlet disposed adjacent to the upstream surface of the filter body, and means for connecting the backwash nozzle to the atmosphere for backwashing the filter body said housing outlet and filter body being of coaxial tubular construction;

• characterized in that the device further includes a valve assembly movable to open or close a passage between the filter body and the housing outlet, which passage is defined by an opening through a portion of the tubular outlet adjacent to the filter body;
• said valve assembly including a valve member movable within said tubular outlet to open and close said opening therethrough, and a pressure-responsive device for moving said valve member;
• said filtering device further including a pressure sensor sensing the pressure drop across the filter body and effective to connect the backwash nozzle to the atmosphere for backwashing the filter body when a predetermined pressure drop is sensed, and means connecting said sensor to the pressure-responsive device said valve assembly so as to actuate same to move the valve member to close said passage upon the initiation of a backwashing operation by the sensor.