How to Choose Valve Actuator   

   Actuator and valve body after assembly and debugging, together constitute the control valve. Used to drive the valve to act, while the mechanical position of the valve and the opening degree fed back to the automation system. The automation control unit is there.

  According to the access, there are three main categories:
     1.The electric actuator (AC220V AC380V DC24V access, and other models)
     2.The pneumatic actuator (access to gas as a power source)
     3.The electro-hydraulic actuator (access to hydraulic devices to drive a larger torque of the valve, usually used for large valves)

   According to the different valve structure and process conditions, different actuators are chosen to meet the control needs. After determining the valve construction and torque, as well as the process environment, the following key elements need to be identified to determine the final actuator model and function:
    1.The valve drive torque (rotary stroke part of the rotation and multi-turn), or thrust (straight stroke push and pull) in accordance with the valve rated drive torque to increase 30% torque used to ensure that under normal circumstances, or long-term operation of the valve body ,it  have the sufficient moment to actuate the valve movement.
    2. The scene can provide the drive energy. In the case of both power and air supply, the electric actuator is first. The reason is: Electric drive energy-saving (no action when the zero power consumption) wiring simple (without supporting the gas pipeline, gas source switch, oil and water filters and other cumbersome gas processing accessories, while reducing investment and operating costs)
    3.Valve action form: straight stroke or angular travel.
    4.Action (switch or adjust)
    5. Control signal (switch, 4-20mA, 0-10V and other signals)
    6.Feedback signal (passive contact, 4-20mA, 0-10V and other signals)
    7. It is necessary or not to configure over-torque protection device used to avoid the case of stuck valve stem to twiste off the stem.
     8.The actuator and the valve body connection (according to the ambient temperature to choose whether to increase the bracket or the layout of the heat sink)
     9.For example the low temperature ≤-40 ℃ operating conditions, the need to configure the dehumidifier.
     10.It is need or not to configure the hand wheel. 

   
   Electric actuator selection process
     1.Confirm the straight stroke or angle travel
     2.Confirm the valve action
     3.Confirm the torque
     4.Confirm the power
     5.Confirm the signal
     6.Confirm the ambient temperature
     7.Confirm the need for over-torque protection

   Pneumatic Actuator Selection Procedure
     1.Confirm the straight stroke or angle travel
     2.Confirm the role of single-and double-acting: a single role can be achieved after the gas source is interrupted, according to the preset air or gas off mode to open or close the valve, only one direction to use the gas source, the other direction using spring thrust drive . The dual-acting switch requires the use of air in both directions.
     3.Confirm the torque
     4. Confirm the valve action
     5. Confirm the control signal
     6. Confirm the feedback signal
     7.Confirm the air source attachment and positioner
     8.Confirm the ambient temperature

   Electro - hydraulic actuator selection process
     1.Confirm the straight stroke or angle travel
     2.Confirm the valve action
     3.Confirm the torque
     4.Confirm the power
     5.Confirm the signal
     6.Confirm the hydraulic accessories
     7.Confirm the ambient temperature
     8.Confirm the need for over-torque protection

   Electric actuator selection example:
     Valve technology parameters: V-type ball valve DN50 torque 70NM
     Site AC220V power supply ambient temperature at room temperature
     Control requirements: 4-20mA control with feedback 4-20mA signal
     The final selection: 100NM rotary actuator, AC220V power supply, with control module (support 4-20mA signal control and feedback)