Emerson Fisher 685 Data Sheet
685 Piston Actuator
D103625X012
Fisherr 685 Piston Actuator
The 685 is a double-acting piston actuator 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™, FB, TBX, HP, EH,
and 461.
The 685 family is available in several configurations to
cover a wide range of application requirements.
Typical travels range from 25 to 610 mm (1 to 24
inches) and cylinder diameters range from 305 to 660
mm(12to26inches).Thrustcapabilitiesextendto
354 kN (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.
Product Bulletin
61.2:685
September 2014
Features
High Thrust Capability — Maximum thrusts of up to
354 kN (79,000 lbf) can be produced.
Broad Application Coverage — Standard
constructions offer travels of up to 610 mm (24
inches) and cylinder diameters of up to 660 mm (26
inches). Even larger constructions are available
upon request.
Low Friction — Low friction piston seals and either
chrome plated or fluoropolymer coated cylinder
bores reduce sliding friction and wear.
X0922
Wide Temperature Range — Standard constructions
offer a temperature range of -40 to 93_C(-40to
200_F), however higher or lower temperatures are
possible. Special constructions can operate as low
as -54_C(65_F)andashighas204_C(400_F).
Manual Override — An optional side-mounted
handwheel is capable of extending or retracting the
actuator manually and can be engaged at any
position from full open to full closed.
www.Fisher.com
Product Bulletin
61.2:685
September 2014
Table 1. Specifications
685 Piston Actuator
D103625X012
Operating Pressure
(1)
Minimum: 2.7 bar (40psig)
Maximum Allowable: 10.3 bar (150 psig)
Consult your Emerson Process Management sales
office for supply pressures under 2.7 bar (40 psig)
(2)
Travel
Construction Materials
PART MATERIAL
Yoke ASTM A36 (steel)
Piston ASTM A36 (steel)
Cylinder 305to559mm(12to22inch)
25 mm (1 inch) through 610 mm (24 inch)
See table 4
Thrust Capabilities
See table 5
Piston Diameter and Area
(2)
Upper/Lower Heads ASTM A36 (steel)
Tie Bolt ASTM A311 1045, Class B (steel)
Piston Rod S31603 (316L stainless steel)
Stem Connector ASTM A36 (steel)
Available in 51 mm (2 inch) increments between 305
mm (12 inch) and 660 mm (26 inch)
See table 4
For additional sizes, contact your Emerson Process
Weights
See tables 11 and 12
Management sales office.
Lifting Point Load Ratings
Operative Temperature Limits
See table 2
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)
Yoke Boss and Valve Stem Diameter
J 127mm(5Hinch)yokebosswith32mm(1-1/4
inch) stem
J 178 mm (7 inch) yoke boss with 51 mm
(2 inch) stem
(3)
(3)
Options
J Mechanical Handwheel, J Pneumatic fail mode
via Fisher 377 trip valve,
Fisher Optimized Digital Valve (ODV) Package
Dimensions
Seefigure3andtables7,8,9,and10
Pressure Connections
Standard: 3/4 NPT
Optional: 1and11/4 NPT
Seefigure2andtable6
Instrument Mounting
Mounting kits are available for use with the FIELDVUE
DVC6200 series positioner
1. The pressure/temperature limits in this bulletin and any other applicablestandard or code shouldnot be exceeded.
2. Consult factory for larger travels or cylinderdiameters. The Fisher 585Cfamily of actuators canbe used for smaller travelsor cylinder diameters.
3. Consult factoryfor applications requiringlow or high temperature requirements.
Certifications
J Pressure Equipment Directive (PED) 97/23/EC,
J ATEX Group II Category 2 Gas and Dust
,
J Systematic Safety Integrity, SIL 3, J GOST-R
(Russia),
J GOST-K (Kazakhstan)
cylinder: 1026 DOM (steel)with
chrome-plated bore
610to660mm(24to26inch)
cylinder: ASTM A516 Grade 70
(steel) with fluoropolymer
coated bore
J Volume Boosters, J
2
685 Piston Actuator
D103625X012
Product Bulletin
61.2:685
September 2014
Principle of Operation
685 piston actuators utilize a pneumatically controlled
piston that moves inside of a cylinder to generate
thrust. A seal contained on the circumference of the
piston provides a seal between the piston and the
cylinder, preventing supply pressure leakage.
From an equilibrium state, the actuator operates by
reacting to a force unbalance that is created by
increasing supply pressure on one side of the piston,
anddecreasingitontheother.Thismovesthepiston
up or down, and results in a repositioning of the
attached control valve. Travel can be adjusted using
travel limits within a valve positioner, which limit the
travel range of the actuator. The optional handwheel
manual override does not have the ability to act as a
hard travel stop.
An optional handwheel manual override is capable of
extending or retracting the actuator manually and can
be engaged at any position from full open to full close.
This override utilizes a worm gear assembly that is
attached to the stem connector and not attached to
the cylinder or piston rod. This enables the manual
override to reposition the control valve even if the
actuator cylinder or piston is removed for
maintenance.
Instrument Selection
An excellent selection of sensitive and accurate
instruments is available for 685 piston actuators.
TheseincludetheFIELDVUE DVC6200 digital valve
controller, as well trip valves and volume boosters.
DVC6200 Digital Valve Controller
FIELDVUE DVC6200 digital valve controllers are
communicating, microprocessorbased
currenttopneumatic instruments. In addition to the
traditional function of converting a current signal to a
pressure signal, DVC6200 digital valve controllers,
using HARTr or FOUNDATION™ fieldbus
communications protocol, give easy access to
information critical to process operation.
For additional information, refer to Fisher bulletin
62.1:DVC6200 (D103415X012) or 62.1:DVC6200f
(D103399X012), available at www.FIELDVUE.com or
from your Emerson Process Management sales office.
3
Product Bulletin
61.2:685
September 2014
Figure 1. Fisher 685 Piston Actuator
TIE RODS
685 Piston Actuator
D103625X012
PRESSURE CONNECTIONS
(TOP AND BOTTOM)
PISTON WEAR RING
PISTON QUAD SEAL
PISTON
MOUNTING BOSSES
X0923
CYLINDER
PISTON ROD
BEARING ASSEMBLY
BEARING RETAINING RING
VALVE STEM CONNECTOR
YOKE
Table 2. Lifting Point Load Ratings
ACTUATOR SIZE
12 to24
26 2 2860 6300
12 to24
26 2 6350 14000
LIFTING
ORIENTATION
Actuator Centerline
Horizontal
Actuator Centerline
Vertical
NUMBER OF LIFTING POINTS USED
2 1540 3400
2 3760 8300
MAXIMUM LOAD
kg lbs
Table 3. Handwheel Specification
ACTUATOR
SIZE
12 44482 10000 305 12 3.8 96 290 65
14 to 18 88964 20000 406 16 3.0 80 380 85
20 to 26 133447 30000 610 24 2.8 72 450 100
4
OUTPUT THRUST HANDWHEEL DIAMETER
N lbs mm Inch N lbs
TURNS PER
mm OF
TRAVEL
TURNS PER
INCH OF
TRAVEL
MAXIMUM RIM FORCE
REQUIRED
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