Pneumatic actuator operated choke
The most commonly applied actuator to choke is the pneumatically driven actuator because the power source - compressed air - is relatively cheap as compared to a human resource or electric or hydraulic power source. From a maintenance point of view, pneumatic actuated chokes are more easily service and calibrated than other types. Pneumatic actuators can generate substantial thrust to handle a majority of applications, including high-pressure and high-pressure-drop situations. Pneumatic actuators also bleed compressed air to atmosphere, which is environmentally safe, when compared to hydraulics. The main disadvantage of pneumatic actuators is that some response and stiffness are lost because of the compressibility of air/gases. Pneumatic actuators are available in two main forms; piston actuator and diaphragm actuator. They are available in single acting and double acting features. Instruments like smart positioner, air filter regulator, solenoid valves, limit switch, volume booster, and trip valve can be mount on actuator.
Key features
- Quick disconnect - permits removal of the actuator without depressurizing the valve. This greatly reduces downtime and lost production.
- Rising stem - provides visual indication of valve position.
- External safety relief device - protects the actuator from over pressurization.
- Compact design - permits easy maintenance in restricted areas.
- Manual override - top-mounted and side-mounted hand wheel.
- Electro-Pneumatic positioners with communication protocols - analog, HART and Foundation Fieldbus with diagnosis features for configuration.
- Fail conditions on the loss of signal failure and supply air/gas failure - fail close, fail open and fail last.
- Pneumatic actuator operation from wellhead/production gas.
- Instruments used with pneumatic actuated chokes are certified for all Hazardous Area locations around the globe.
