Abstract: A filtration system which may include multiple filters capable of being individually washed of clogging filtrate material by a "blow-down" or flushing operation, is regulated by a blow-down controller device. Each filter has a blow-down discharge valve which is normally maintained closed by a required level of fluid pressure in a pilot line connected to the valve. This pressure is supplied by the controller device, which draws pressure from an inlet line feeding all the filters. When the controller relieves pressure in one of the pilot lines, the filter associated with that pilot line is subjected to blow-down for a predetermined time period. To determine when blow-down of one or more filters is required, the controller senses pressure differential between the common inlet line and a common filter outlet line. When the pressure differential reaches a certain level, it indicates that the filters are sufficiently clogged by filtrate to require blow-down.

Abstract: A combination flow control, shutoff and pressure relief device comprises a body with a movable spool and inlet and outlet portions. The spool supports a spring loaded valve head that forms an internal fluid chamber around one end when the handle fixed to the other end is in the closed position. An orifice in the body inlet portion is progressively opened from a complete shutoff position by rotation of the spool within the body to provide flow into the fluid chamber. When fluid pressure within the internal chamber exceeds a preselected spring force on the valve head, the latter opens to provide pressure relief. Regulation of the fluid pressure in the chamber and thus in the outlet can be maintained at the preselected level by controlling the size of the inlet orifice at a point just below the actuation level of the valve spring.