Quarter turn stop cock safety interlock - has spring forcing button to register in notch of downstream union sleeve

摘要

A cover knob is retained by two half shells surrounding the valve body and also holding in place a sleeve covering the downstream union. A sliding button registers in a notch in the skirt of the cover knob when the valve is closed and is itself held in this position by a ball. The ball locks the button by being forced upwards into a recess in the base of the button, by the action of a ring rotated by the cover sleeve, which can then be removed. When the tap is turned on, a spring automatically forces the button to register in a notch in the sleeve and lock it in position. Removal of the sleeve thus requires two hands, and accidental removal is impossible.