A close relationship exists between actuators and valves. They are mechanical components of many types. Pneumatic actuators for control valves are the most common. In addition to those, hydraulic actuators, electric actuators, and manual actuators are widely used. It is most commonly specified to use pneumatic actuators with springs and diaphragms because of their simplicity and dependability. With pneumatic piston-driven actuators, large stem forces can be produced under challenging operating conditions. Directly on rotary-shaft control valves can be mounted adapters with springs and diaphragms and pneumatic pistons.
Actuators are divided into a variety of types based on their designs and characteristics, so distinguishing between them is essential. Air is used to operate diaphragm-based actuators from a controller, positioner, or another source. These siłowniki are easy to use, reliable, and inexpensive.
When pneumatically operated, a piston actuator uses high-pressure plant air up to 150 psi, eliminating the need for an external pressure regulator. Actuators of this kind provide maximum thrust output and rapid stroking speeds.
Unlike other types of actuators, electro-hydraulic actuators require only an electrical signal from the controller and a power supply for the motor. Electro-hydraulic siłowniki are a good solution for locations where pneumatic pressure is not available, but where precise control of valve plug position is needed.
Another type is the manual actuator which is manually operated. It can be useful when automatic control isn’t necessary but the ease of use and manual control still need to be maintained. They are commonly used during the maintenance or shutdown of an automatic system to activate the bypass valve of a three-valve bypass loop.
For rotating shaft valves, rack and pinion design is a compact and cost-effective solution. As a result of their backlash, they are often used in on-off applications or when process variability is not a concern. In traditional electric actuators, gear reductions and electric motors are used to operate valves. These mechanisms for continuous control have been adapted through adaptation with varying degrees of success.