Towards a Common Metamodel for Web Applications

The specification discloses a ball valve comprising a valve body having a ball receiving cavity with aligned inlet and outlet passages leading thereto. Located in the cavity are two ring-shaped seats and a ball rotatably supported in the seats. The ball has an opening formed therethrough. Means is provided for rotating the ball to an open position where its opening is aligned with the inlet and outlet passages and to a closed position where its opening is out of alignment with the inlet and outlet passages. The ball is coated with chrome oxide and the ball seats are formed of cast iron. The ball and seats are lapped to a close tolerance fit. O-rings are provided for forming a seal between the back side of the seats and the valve body.