limiters de-energize the electric motor when the amount of turning force has reached a specified
value. The turning force normally is greatest when the valve reaches the fully open or fully
closed position. This feature can also prevent damage to the actuator or valve if the valve binds
in an intermediate position.
The important information in this chapter is summarized below.
Valve Actuator Summary
Pneumatic actuators utilize combined air and spring forces for quick accurate
responses for almost any size valve with valve position ranging from 0-100%.
Hydraulic actuators use fluid displacement to move a piston in a cylinder
positioning the valve as needed for 0-100% fluid flow. This type actuator is
incorporated when a large amount of force is necessary to operate the valve.
Solenoid actuators are used on small valves and employ an electromagnet to
move the stem which allows the valve to either be fully open or fully closed.
Equipped with limit switches and/or torque limiters, the electric motor actuator
has the capability of 0-100% control and has not only a motor but also a manual
handwheel, and a clutch and gearbox assembly.
end of text.
DOE - ANL-W, BNL, EG&G Idaho,
DOE - NE-73
EG&G Mound, EG&G Rocky Flats,
Project Number 6910-0019/2
LLNL, LANL, MMES, ORAU, REECo,
WHC, WINCO, WEMCO, and WSRC.