Abstract: A ball valve includes a valve casing accommodating therein an upstream ball seat and a downstream ball seat and defining a cavity between the two ball seats, a ball provided with a through hole, accommodated in the cavity and brought into sealing contact with the two ball seats at the outer periphery thereof, a valve stem having one end thereof fixed to the ball, a valve handle fixed to the other end of the valve stem, a check valve accommodated in the through hole of the ball and biased toward the upstream side, a path formed on the ball and, when the ball valve is closed, causing the downstream side and the cavity to communicate with each other, and a connection port formed on the valve casing so as to communicate with the cavity and having a free end thereof connected to one end of a nipple having the other end thereof covered with a cap. The ball opens and closes the ball valve through the valve stem by a rotating operation of the valve handle.

Abstract: A ball valve with a built-in check valve includes a valve casing having a passageway for a fluid, a ball having a through hole formed therein, also having a valve seat formed inside thereof at a position in the vicinity of one end of the through hole, and rotatably housed in the valve casing so that the through hole is capable of communicating with the passageway, a guide bush provided within the through hole for guiding the check valve, a spiral spring wound on the guide bush for biasing the check valve in the direction of forming a seal contact between the check valve and the valve seat, and rubber or resin damping members attached to the check valve. The check valve is received within the through hole for cutting off the communication between the passageway and the through hole and preventing a counter flow of the fluid, and has a sealing contact portion and a shoulder portion.