Patent ID: 7981289

Claim:
A fluid treatment assembly comprising: a head having a fluid inlet configured to receive fluid into the assembly, and a fluid outlet through which fluid exits the assembly; a shell releasably coupled to the head at a first end, having a shell interior, the shell including a plug cap located at a second end opposite the first end, the plug cap being removable from the second end of the shell, the plug cap including one of a recess and a protuberance; and a cartridge removably received within the shell and releasably coupled to the head, the cartridge shaped to engage the one of the recess and the protuberance of the plug cap when in at least one rotational position within the shell in order to prevent use of an incorrect cartridge, the cartridge having a cartridge wall separating an interior of the cartridge from an exterior of the cartridge, the cartridge wall having substantially uniform properties along the cartridge and between opposite ends of the cartridge and deformable under internal fluid pressure to radially expand against the shell; a cartridge inlet configured to receive fluid from the head; a cartridge outlet through which fluid exits the cartridge to the head; and an internal chamber through which fluid passes from the cartridge inlet to the cartridge outlet, the cartridge configured to retain fluid within the internal chamber and the head and to fluidly isolate the shell interior and the cartridge exterior from fluid passing through the fluid treatment assembly.