Description - Fisher 685 Instruction Manual

685 Piston Actuator
May 2013
Table 1. Specifications
(1)
Operating Pressure
Minimum: 2.7 bar (40psig)
Maximum Allowable: 10.3 bar (150 psig)
Consult your Emerson Process Management sales
office for supply pressures under 40 psi
(2)
Travel
51 mm (2 inch) through 606 mm (23-7/8 inch)
See table 2
Thrust Capabilities
See table 3
Piston Diameter and Area
Available in 51 mm (2 inch) increments between 305
mm (12 inch) and 660 mm (26 inch)
See table 2
Operative Temperature Limits
Standard: ­40 to 93_C (­40 to 200_F)
Low Temperature: ­54 to 93_C (­65 to 200_F)
High Temperature: ­29 to 204_C (­20 to 400_F)
1. The pressure/temperature limits in this bulletin and any other applicable standard or code should not be exceeded.
2. Consult factory for larger travels or cylinder diameters. The Fisher 585C family of actuators are available for smaller travels or cylinder diameters.
3. Consult factory for applications requiring low or high temperature requirements.

Description

The Fisher 685 is a double acting piston actuator (figure 1) that provides accurate, high thrust output for short to long
travel applications. This actuator is designed for use with a variety of medium to large Fisher sliding-stem control
valves including the easy­e™ and FB.
The 685 family is available in several configurations to cover a wide range of application requirements. Typical travels
range from 8-7/8 through 23-7/8 inches in cylinder diameters from 12 through 18 inches and 2 through 23-7/8 inches
in cylinder diameters from 20 through 26 inches. Thrust capabilities extend to 79,000 lbf and above with special
constructions.
The 685 can be used with the FIELDVUE™ DVC6200 digital valve controller for throttling applications, or with
switching valves for on­off control. This actuator can also be fitted with volume boosters for fast stroking
requirements. Constructions are also available with side-mounted manual handwheels to extend or retract the piston
rod.
2
(2)
(3)
(3)
Yoke Boss and Valve Stem Diameter
5H yoke boss with 32 mm (1-1/4 inch) stem
7 inch yoke boss with 51 mm (2 inch) stem
Pressure Connections
Standard: 3/4 NPT
Optional: 1 and 1­1/4 NPT
Instrument Mounting
Mounting kits are available for use with the FIELDVUE
DVC6200 series positioner
Construction Materials
PART
Yoke
Piston
Cylinder 12 to 22 inch Cylinder: 1026 DOM with
Tie Bolt
Piston Rod
Weights
See table 4
Instruction Manual
D103626X012
MATERIAL
ASTM A36
ASTM A36
chrome-plated bore
24 to 26 inch Cylinder: ASTM A516
Grade 70 with Xylan coated bore
ASTM A311 1045, Class B
ASTM A311 1045