Electric actuator manufacturer AUMA has launched explosion-proof variable speed valve actuators for use in potentially hazardous environment. The new SAVEx actuators for open-close duty and SARVEx multi-turn actuators for modulating duty, combined with intelligent ACVEx actuator controls, provide full control of the motor speed at any time.
In oil and gas applications, variable speed offers significant advantages for challenging valve control tasks, since it allows the optimum operating speed to be selected for each change of valve position. High positioning accuracy and optimised setpoint control considerably increase the effectiveness of pressure control valves in gas pipelines, for example. On multiport valves, variable speed actuators aid rapid and accurate switch-over between ports.
Mechanical stresses on valve, actuator and pipeline are minimized by reducing the operating speed close to the end positions, allowing the moving element of the valve to make gentle contact with the seat. Pressure surges and cavitation effects in the pipeline can be avoided by using speed profiles.
When working in modulating duty, the actuator speed can be set to reduce progressively as the valve position approaches the setpoint, giving a significant increase in positioning accuracy.
Actuator speed can also be controlled by an external signal – either 4–20 mA analog or 0–100 % digital – to take full advantage of additional control variables or algorithms. A further option is speed synchronisation between two actuators.
AUMA’s new explosion-proof SAVEx and SARVEx actuators complement the weatherproof SAV and SARV type range. They are available in six sizes covering torques up to 1,000 Nm. Speed ranges include 6–60 rpm, 12–108 rpm and 24–216 rpm.