Saturday 21 September 2013

High thrust piston actuators for improved process control and increased productivity

Emerson Process Management has introduced the Fisher® 685 double acting piston actuator that provides high thrust output for short to long travel applications. The accurate and reliable operation of the actuator improves process control and increases availability - contributing to increased productivity and efficiency.

Designed for use with both medium and large Fisher sliding-stem control valves, including the easy-e™ and FB series, the 685 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.

The actuators 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 actuator response to control signals giving better process control. This enables fast operating times of less than 2 seconds in critical applications such as compressor anti-surge.

Low friction piston seals and either chrome plated or Xylan coated cylinder bores, reduce sliding friction and wear - minimising deadband, reducing maintenance costs and extending operational life.

These low maintenance actuators can be specified with durable corrosion resistant paint and are suitable for operation over a wide temperature range. Standard constructions offer a temperature range of -40°C to +93°C, however higher or lower temperatures are possible. Special constructions extend this range from -54°C to +204°C making these actuators ideal for the extreme conditions found in many oil and gas onshore plants and offshore platforms.

The 685 can be used with the FIELDVUE™ DVC6200 digital valve controller for throttling applications, or with switching valves for on/off control. This actuator can also be fitted with volume boosters for fast stroking requirements.

The 685 is part of a broad range of Fisher piston actuators that provide accurate throttling or on-off operation for sliding-stem control valves.

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