Single Action Rack and Pinion

Rubber lined butterfly valves are a type of valve which can be used for isolating or regulating flow.

The closing mechanism is the disc which sits in the center of the valve body. The disc is connected to a handle or actuator via the shaft which passes from the disc through the top of the valve body.

Unlike a ball valve, the disc of the butterfly valve is always present in the flow, which will induce the pressure drop.

Compared with the ball valve, a butterfly valve can be shut off quickly but requires less support due to its lighter weight.

Rubber lined butterfly valves operate in a quarter turn, meaning that rotating the closed disc 90°will fully open the valve, and vice versa. They can also be opened incrementally in order to throttle flow.

This can be accomplished manually, but throttling flow will be more precise when an actuator is used cooperatively.

Actuators can be customized to allow incremental flow, by using positioners in the case of pneumatic and hydraulic actuators, or by using modulating boards in the case of electric actuators.