A different strategy to control or throttle the flow of fluid is to use a rotary element in the flow path.
Rotary valve relies on the rotation of a shaft to actuate a trim.
Vane type of actuator used with such type of rotary valve because of vane rotates valve disc.
When air pressure applied to air supply port it pushes the vane and rotates disc for example of a butterfly valve or ball valve.
Air on the other side of the vane is bleed off through another air supply port. Same applicable in reverse.
Below is a schematic of different type of rotary valve which doesn't require to move up-down it operates by rotating handle.
Have a look at cut view of the plug valve in the below figure.
Internal view of the ball valve as its shape is like a ball and contain a hole inside it can allow or block the flow of the fluid.
One important advantage of the rotary valve over the sliding stem valve is that it provides obstruction less path for flowing fluid.
In my next article, I will explain each type of valve in detail.