Patent ID: 7662283

Claim:
In the combination of a replaceable water filter cartridge having a filter body with an axially extending neck on one end, the neck having an inlet and an outlet for water, and a filter head having an outer housing defining a cylindrical interior wall having an inlet opening for water to be treated and an outlet opening for treated water, and a valve spindle disposed in the outer housing for reciprocal rotary movement on the filter body axis between flow and no-flow positions, providing connection and disconnection of the outer housing inlet opening and outlet opening with the cartridge inlet and outlet, respectively, the spindle having an interior chamber for receipt of the cartridge neck to provide said connection and disconnection, an arrangement for assuring compatibility and operative connection of the cartridge to the filter head comprising: at least one detent carried by the outer housing and biased into locking engagement with the valve spindle to prevent rotary movement thereof; and, at least one key carried on the cartridge neck and positioned to engage the detent in response to insertion of the cartridge neck into the spindle to bias the detent out of locking engagement.