Abstract: A modular filter system using replaceable filter cartridges includes matching adaptor rings in the filter head and on the filter cartridge placed at selected circumferential positions to ensure proper cartridge fit and to provide a proprietary cartridge construction for selected users. The adaptor rings operate only to control cartridge to filter head fit and are not used to drive the rotary valve spindle.

Abstract: A modular filter system using replaceable filter cartridges includes a locking arrangement that prevents rotation of the flow control valve spindle in the filter head, but includes an unlocking arrangement on the cartridge that unlocks the locking arrangement if the proper replacement cartridge is used. The locking arrangement may include spring biased locking pins carried on the filter head and matching unlocking pins on the filter cartridge to operate through an intermediate adaptor ring that is set on assembly to match the positions of the locking and unlocking pins.

Abstract: A modular filter system using replaceable filter cartridges includes a mounting bracket for each filter cartridge and corresponding filter head that includes keyed attachment of the head to the mounting ring on the mounting bracket and modular attachment of the mounting bracket to the modular back plate. Back plates are also modular to permit assembly of a variety of multi-cartridge systems.

Abstract: A rotary valve spindle for flow control in the head of a filter includes a unitary dual function seal that is carried by the spindle and seals against the inner surface of the filter head during spindle rotation between flow and no-flow positions. The dual function seal greatly simplifies manufacture and assembly of the valve.

Abstract: A modular filter system using replaceable filter cartridges includes matching adaptor rings in the filter head and on the filter cartridge placed at selected circumferential positions to ensure proper cartridge fit and to provide a proprietary cartridge construction for selected users. The adaptor rings operate only to control cartridge to filter head fit and are not used to drive the rotary valve spindle.

Abstract: A modular filter system using replaceable filter cartridges includes a locking arrangement that prevents rotation of the flow control valve spindle in the filter head, but includes an unlocking arrangement on the cartridge that unlocks the locking arrangement if the proper replacement cartridge is used. The locking arrangement may include spring biased locking pins carried on the filter head and matching unlocking pins on the filter cartridge to operate through an intermediate adaptor ring that is set on assembly to match the positions of the locking and unlocking pins.

Abstract: The valve spindle for a reverse osmosis (RO) filter system is housed in a filter head and attached to a mounting ring that also carries the replaceable RO cartridge. The RO spindle is locked in the head during normal operation, but can be easily removed, after removal of the cartridge, to permit spindle replacement or repair without disassembly of the head from the mounting bracket.

Abstract: An assembly method and related subassembly for a water filter element in the housing of a replaceable filter cartridge provides for filter element insertion into the open bottom end of the housing and subsequent attachment of a retaining ring to the upper end of the element such that the element is secured against vertical drop-out until the bottom end of the cartridge can be enclosed with an end cap. The method and subassembly are particularly well adapted to cartridges in which the lower end cap is attached by spin welding. The enclosing end cap may also be provided with end rings to enhance the user's grip in cartridge installation and removal. The end rings may also be color coded for each of cartridge identification and matching to the filter head.