Ball-and-seat valve Definition


Ball-and-seat valve:

A device used to restrict fluid flow to one direction.

It consists of a polished sphere, or ball, usually or metal, and an annular piece, the seat, ground and polished to form a seal with the surface of the ball.

Gravitational force or the force of a spring holds the ball against the seat.

Flow in the direction of the force is presented, while flow in in the opposite direction overcomes the force and unseats the ball.