Abstract: A valve body with a tapered annular recess for receiving a correspondingly tapered valve seat retainer forms a valve assembly wherein the retainer may be easily removed for maintenance purposes by field service personnel without special tools. The retainer has a radially extending protruberance on an outer circumferential leg, which leg is inwardly radially flexible as the retainer is axially moved into the annular recess of the valve body. When fully inserted, the protruberance is positioned within an annular cavity spaced from the face of the valve body.

Abstract: A method and apparatus for cleaning a reusable litter in a pet animal litter box which utilizes a relatively heavy non-porous, non-absorbent gravel litter material which is cleansed of animal excrements in the litter box. The excrements are dispersed in a volume of water which is rapidly transferred from a first to a second compartment of the litter box to remove the dispersed waste materials.