A clack valve or flap valve is a type of valve employed for pumps. It consists of a metal disk, or a weighted disk of leather or rubber, hinged at one side, making contact with a flat metal seat.
[n] - a simple valve with a hinge on one side
clack noun a simple valve with a hinge on one side; allows fluid to flow in only one direction
a valve having a hinged flap permitting flow only in the direction in which the flap opens. Also called