Pneumatic actuators in control system, also known as terminal control element, it is positive path directly change the operation variable instrument, the executing agency response regulator to signal or artificial control signal, and the signal into displacement to actuating mechanism. Commonly used actuators have electric and pneumatic two kinds big, adjusting mechanism is commonly valve (valve, cut-off valve, gate valve, butterfly valve, etc.) and throttle damper.
1) direct connection: actuator general installation in adjusting mechanism (such as valve) upside, direct drive adjusting mechanism. This kind of actuators are: straight stroke electric actuators, electromagnetic valve coil control mechanism, electric valve electric device, pneumatic diaphragm actuator and pneumatic piston executing agency, etc.
2) indirect connection: actuator and adjusting mechanism apart installation, between them through the boom and connecting rod connections, boom for rotary motion, this kind of actuators have angular travel electric actuators, pneumatic long stroke actuators, etc.
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