Author:Site Editor Publish Time: 2018-10-16 Origin:Site
A trunnion mounted ball valve has additional mechanical anchoring of the ball at the top and the bottom, suitable for larger and higher pressure valves (say, above 10 cm and 40 bars).
A floating ball valve is one where the ball is not held in place by a trunnion. In normal operation, this will cause the ball to float downstream slightly. This causes the seating mechanism to compress under the ball pressing against it. Furthermore, in some types, in the event of some force causing the seat mechanism to dissipate (such as extreme heat from fire outside the valve), the ball will float all the way to metal body which is designed to seal against the ball providing a somewhat fire safe design.
Manually operated ball valve can be closed quickly and thus there is a danger of water hammer. Some ball valves are equipped with an actuator that may be pneumatically, hydraulically or motor operated. These valves can be used either for on/off or flow control. A pneumatic flow control valve is also equipped with a positioner which transforms the control signal into actuator position and valve opening accordingly.
Three- and four-way have an L- or T-shaped hole through the middle. The different combinations of flow are shown in the figure. It is easy to see that a T valve can connect any pair of ports, or all three, together, but the 45 degree position which might disconnect all three leaves no margin for error. The L valve can connect the center port to either side port, or disconnect all three, but it cannot connect the side ports together.
Multi-port ball valves with 4 ways, or more, are also commercially available, the inlet way often being orthogonal to the plane of the outlets. For special applications, such as driving air-powered motors from forward to reverse, the operation is performed by rotating a single lever four-way valve. The 4-way ball valve has two L-shaped ports in the ball that do not interconnect, sometimes referred to as a "×" port.
The above is an overview of the trunnion mounted ball valve. We are a manufacturer of trunnion tomunted ball valve and ball valve related products. If you are interested, you can consult us on the official website.