Some type of actuator is necessary to allow for the positioning of a valve.
Actuators vary from simple manual handwheels to relatively complex electrical
and hydraulic manipulators.
DESCRIBE the construction and principle of operation for the
following types of valve actuators:
Valve actuators are selected based upon a number of factors including torque necessary to operate
the valve and the need for automatic actuation. Types of actuators include manual handwheel,
manual lever, electrical motor, pneumatic, solenoid, hydraulic piston, and self-actuated. All
actuators except manual handwheel and lever are adaptable to automatic actuation.
Manual, Fixed, and Hammer Actuators
Manual actuators are capable of
Figure 30 Fixed Handwheel
placing the valve in any position but
do not permit automatic operation.
The most common type mechanical
actuator is the handwheel.
type includes handwheels fixed to
the stem, hammer handwheels, and
handwheels connected to the stem
Handwheels Fixed to Stem
handwheels fixed to the stem
advantage of the wheel.
these valves are exposed to high operating temperatures, valve binding makes operation difficult.