Stepping actuator operated choke
Generally, linear stepping actuators use in choke valve. Linear stepping actuators produce linear movement as a series of discrete linear steps. Each increment of the excitation pulse sequence moves the actuator forward by a fixed linear displacement. The displacement can be accurately controlled by applying a measured number of steps.
There are two types of stepping actuator generally use for choke:
Stepping actuator - hydraulic
The actuator is coupled into a hydraulic system. Via a series of hydraulic controls and two-directional solenoid valves, oil is fed into one of two cylinders, which act upon a mechanical rat chat/gear wheel. The rotation of gear wheel is selected by giving an electrical pulse to one of the two solenoid valves. Linear motion is achieved via a drive nut, which is connected to the gear wheel. The drive nut will be connecting to valve stem.
Stepping actuator - pneumatic
The actuator is coupled into a pneumatic system. Via a series of pneumatic controls and two-directional solenoid valves air is fed into one of two cylinders, which act upon a mechanical rat chat/gear wheel. The rotation of gear wheel is selected by giving an electrical pulse to one of the two solenoid valves. Linear motion is achieved via a drive nut, which is connected to the gear wheel. The drive nut will be connecting to valve stem.
Options available with an actuator as per customer requirement
- Electronic actuator position controller - 24 VDC, 4-20 mA command & feedback signal.
- Position controller with HART or Foundation Fieldbus.
- Position indication - rotary potentiometer or alternatively limit switches.
- Electrical enclosure - copper-free aluminum or Stainless Steel.
- De-Clutch able hand wheel for manual operation.
- Electronic position transmitter and controller with communication protocols - analog, HART and Foundation Fieldbus with diagnosis features for configuration.
- Fail conditions on the loss of signal failure and supply source failure - fail last.
- Actuator operation from wellhead/production gas.
- Instruments used with stepping actuated chokes are certified for all hazardous area locations around the globe.