THROUGH BORE VALVE

摘要

A valve head assembly comprises an inlet (3), an outlet (4) and a valve disc (20). The valve disc (20) is operatively moveable from a closed position in which it engages the inlet (3) so as to close it against the passage of liquid therethrough and an open position in which it is disengaged from the inlet (3) so as to allow the passage of liquid from the inlet (3) to the outlet (4). The inlet (3) and outlet (4) are substantially aligned so as to form a substantially straight chamber (10) therebetween. In the open position of the valve disc (20), it is substantially completely withdrawn from the chamber (10) between the inlet (3) and outlet (4) so as to allow free passage from the outlet (4) to the inlet (3).