Fisher 585C Double-Acting Piston Actuator Sizes 25 to 130

Fisher 585C piston actuator: double-acting power for sliding-stem control valves

The 585C is a linear, double-acting pneumatic piston actuator for sliding-stem control valves. Instrument air is supplied to both sides of the piston, which gives stiff, accurate movement for throttling duty and fast on-off operation. The family runs from size 25 to size 130 and covers a wide range of thrust and travel requirements. With a standard air supply the size 130 can produce up to 111,000 N (25,000 lbf), so it is the choice for large globe valves, high-pressure valves and severe-service trims where a diaphragm actuator would be too large or too soft.

585C technical specifications

How the 585C works

A positioner or switching valve loads one side of the piston while exhausting the other. In throttling duty a Fisher 3610J or 3620J positioner, or a FIELDVUE DVC6200 digital valve controller, meters supply air to both cylinder chambers so that piston position follows the control signal. Double-acting action means the actuator thrust is available in both directions with no spring to fight, which suits high-friction packing and large unbalanced forces. On the small sizes 25 and 50 a spring is built in to provide a fail position. On larger sizes, fail-safe action is obtained with the Fisher 377 trip valve and a volume tank, which can drive the actuator up, down or lock it in last position when supply fails.

Where the 585C fits: valves, positioners and accessories

The 585C mounts on Fisher sliding-stem bodies such as the ED, EW, HP and GX families and on other bodies with the correct yoke boss, with standard sizes tied to yoke boss and valve stem diameters listed in the bulletin. Compatible instrumentation includes the DVC6200 and DVC6200f, the 3600 series positioner, and the 4200 position transmitter for sizes 25 and 50. Mechanical options are a top-mounted handwheel on sizes 25 and 50, an integral side-mounted handwheel on sizes 60-130, a cylinder bypass valve, limit switches and electrical stem position switches. For comparison, lighter duties are covered by the 657 and 667 diaphragm actuators.

585C selection and ordering checklist

• Valve body and stem diameter, which fixes the yoke boss and compatible actuator size.
• Required thrust: seating force plus packing friction plus unbalance, against supply pressure.
• Travel required, up to 203 mm.
• Available instrument air pressure; check the minimum recommended 1.4 or 2.4 bar.
• Fail action: spring return (sizes 25, 50), trip system for the rest, or lock in last position.
• Instrument: positioner or DVC6200, switching valve and tubing.
• Ambient range: standard, fluorocarbon or low ambient fluorosilicone construction.
• Handwheel, limit switches, bypass valve and air connection sizes.

Installation, stroking speed and maintenance

Stroking speed depends on actuator size, spring, travel and supply pressure, and the manufacturer recommends consulting an application engineer where speed is critical. Use adequately sized tubing and, where needed, volume boosters. Keep the supply clean and dry, since aluminum cylinders and piston O-rings dislike moisture and particulates. Routine maintenance covers stem O-ring and seal bushing replacement, piston O-ring changes and inspection of the stem connector. Parts kits are matched to actuator size.

Typical 585C applications in Oman and the GCC

Typical Gulf installations are large gas-processing and pipeline control valves, compressor anti-surge and recycle valves, high-pressure let-down valves, feedwater and steam control in power plants and desalination plants, and valves where a robust fail-closed or fail-open action through a trip system is required. High summer ambient heat and sun exposure favour inspecting the O-rings and paint annually.

585C size overview

Information to send with a 585C enquiry

• Valve model, size and stem diameter, or actuator size if known.
• Supply pressure and required fail action.
• Instrument and accessory list.
• Ambient temperature and any low-temperature requirement.
• Quantity and destination.

Site conditions in Oman for the 585C

Valves and their accessories in Oman work in demanding conditions: high ambient temperatures, direct sun on outdoor pipe racks, dust, and corrosive coastal air at many oil, gas and water sites. When you specify the 585C, confirm the pressure and temperature ratings, body and trim materials and any sour-service or hazardous-area requirements against the actual line data, and check that seals and soft parts suit the process medium and the full temperature range.

For reliable operation, plan access for maintenance, define which spare parts are kept on site, and record the configuration of each installed 585C. Sending the complete process data sheet with your RFQ allows the selection to be checked before the order is placed.

Documents and quotation for the 585C

A manufacturer product bulletin for the 585C is attached on this page. Seven Star LLC is an independent supplier in Muscat.

Send the 585C size and valve details and we will confirm availability and quote.