What is the butterfly valve actuation method?

Butterfly valve can be operated manually by handles and gears or automatically by electric, pneumatic or hydraulic actuators. These devices allow precise rotation of the disc to positions ranging from fully open to fully closed. A brief understanding of the different types of actuation methods are below.


Manual actuation
Manual actuated butterfly valves are inexpensive and easy to operate. The two common methods are a discussed below:
 
Hand Lever: Is common for small butterfly valves and is capable of being locked into a position of open, partially open, or closed. 

 
Gear: These are designed for slightly larger butterfly valves and utilize a gearbox to increase torque at the expense of decreased speed of opening/closing. Gear operated valves are also self-locking (cannot be back driven) and can be equipped with position indicators.


Automatic actuation
Power operated actuators are a reliable method of controlling valves from a remote location. These actuators also make rapid operation of larger valves possible. Actuators can be designed to fail-open (stay open in case of actuator failure) fail-close (stay closed in case of actuator failure) and often come with a manual actuation method in case of failure (as seen in Figure 7). The three types of automatic actuators are listed below, but more a more thorough understanding read our actuator article. 
 
Electric: Use an electric motor to turn the valve stem.

Pneumatic: Requires compressed air to move a piston or diaphragm to open/close the valve.
 
 
Hydraulic: Requires a hydraulic pressure to move a piston or diaphragm to open/close the valve.