How to choose an automatic actuator?
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What are the advantages and disadvantages of pneumatic actuators and electric actuators? How should one consider when making a choice? Why are pneumatic actuators used more often than electric actuators?
The chemical industry mostly uses pneumatic actuators, while the power industry tends to use electric actuators； It is mainly based on considerations related to safety and explosion prevention ；
Pneumatic actuators generally require a dedicated instrument air supply; those available in the factory that do not have safety and explosion-proof requirements allow for flexible selection； Pneumatic actuators are usually equipped with pneumatic positioners, 24 volts ； Electric actuators are available in 220 and 380 volt versions ； Pneumatic actuators feature fast operation, high torque output, and simple wiring ； The electric drive operates slowly, the wiring is relatively complex, and the output torque is stable ；
An actuator is a regulating device that converts control signals into corresponding actions in order to control the position of the throttling element within a valve or other mechanisms. Pneumatic actuators are mainly divided into three types: diaphragm actuators, piston actuators, and rolling diaphragm actuators. Electric actuators are also mainly divided into three types: linear actuators, rotary actuators, and multi-turn actuators. In terms of structure, electric actuators are more complex than starting actuators. Pneumatic actuators use gas as a power source, while electric actuators use electricity as a power source. For fine adjustment, based on experience and the structure of the actuator, pneumatic systems are preferable. It has fewer mechanical components, and the transmission clearance is relatively small; therefore, position adjustment is relatively precise. In electric versions, due to the presence of many mechanical transmission components, if the precision of machining these mechanical parts is not properly controlled, the accuracy of position control will not meet the required standards. Furthermore, the power supply for electric actuators is usually 220V AC or 380V AC; in applications with high explosion-proof requirements, additional costs are incurred. A control valve can be formed by combining a pneumatic actuator with an electrical valve positioner; it usually operates on 24V DC, and can be designed in an explosion-proof or intrinsically safe configuration. The cost is relatively low. In environments with a high amount of dust, the failure rate of pneumatic systems is relatively low. In terms of adjustment and maintenance, pneumatic adjustment is more convenient. Without leakage and with relatively good gas quality, it can operate reliably after adjustment. If adjustments are made frequently, it is necessary to regularly check whether the sector plate in the valve positioner is worn. Electric types are suitable for use in applications requiring high torque and where the valve is separated from the actuator. For many specific issues, please refer to relevant materials and the actual conditions on site to determine the appropriate approach.
When a pneumatic actuator is in operation, it only requires an air supply that meets its specific operating conditions; as a result, it is more reliable and safe； Electric actuators require an external power supply to function, which makes them costly. In explosion-proof areas, there are strict requirements regarding the selection of electric actuators.