Emerson Process Management has introduced the Fisher® 685 double acting piston actuator that provides high thrust output for short to long travel applications. Designed for use with both medium and large Fisher sliding-stem control valves, the actuator is suitable for general, severe, and critical service applications. The range includes piston diameters from 305 to 660mm and travel from 25 to 610mm as standard, with special constructions available up to 1118mm piston diameter. The actuator has a high thrust capability, with a maximum of 351.4 kN (79,000 lbf) available at 10.3 barg supply pressure. They feature ¾" NPT supply connections, with 1" or 1¼’’ NPT supply connections available on the larger size actuators. Larger air connections reduce the complexity of instrument piping and improve response to control signals giving better process control. This enables fast operating times of less than 2 seconds in critical applications such as compressor antisurge. Low friction piston seals and either chrome plated or Xylan coated cylinder bores, reduce sliding friction and wear – minimizing deadband, reducing maintenance costs and extending operational life. These actuators are suitable for operation over a wide temperature range, even the extreme conditions found in many oil and gas onshore plants and offshore platforms.
Emerson Process Management