Ball valves are valves with a hollow ball as a shut-off body. Characteristic for a ball valve is the complete closing within a rotation of exactly 90 °, in contrast, for example, to globe valves.
Ball valves can be delivered with full bore or reduced bore. Ball valves with full bore have a ball which has the same internal diameter as the connected pipe. This allows low pressure losses.
There are ball valves with floating balls or with guided balls (Trunnion). Generally there are seals made of synthetic material (for example, PTFE, Nylon, PEEK, etc.) between ball and body which are suitable for temperature ranges from -196°C to 260°C. At higher operating temperatures metallic seals are used. In the construction principle of floating balls, the ball is pressed into the opposite seat by the fluid. In the construction principle of the guided ball (TRUNNION), the ball has bearings in the body. In this case the springs are pressing the seats against the ball.