Water treatment system

Abstract

A water treatment system including a pair of water treatment tanks, each tank defining a flow path extending from a tank inlet to a tank outlet and containing a water treatment material disposed along the flow path for treating water as it travels from the inlet to the outlet. A system controller controls which of the tanks is on-line and which of the tanks is off-line and controls the regeneration of an exhausted tank. A multi-stage, spring-loaded control valve assembly controls the communication of fluid to a regeneration control turbine. The control valve assembly includes a piston head and a seat-carrying stem. An upper end of the stem is coupled to the piston head in an arrangement that allows relative movement between the stem and the piston head. A spring urges the stem away from the piston head. An opposite end of the stem carries a seat. When a signal pressure is applied to the piston head, initial movement of the head compresses the spring but does not produce movement in the stem and, hence, the seat. After a predetermined relative movement of the piston head with respect to the seat, further movement produces movement in the seat, thereby causing the seat to disengage its associated sealing surface, whereupon the spring produces further opening movement in the seat. The present invention improves the operation of the control valve assembly, even in water treatment applications where source water is supplied at a relatively low pressure.

Dependencies are inferred from the claim text.