Emerson Fisher 785C, Instruction Manual

Page: 1 / 72

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Fisher
™
785C Piston Actuators
Contents
Introduction 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scope of Manual 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Description 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Educational Services 3 . . . . . . . . . . . . . . . . . . . . . . . . .
Principle of Operation 3 . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Actuator Earth Grounding 9 . . . . . . . . . . . . . . . . . . . . .
Three‐Way Valve Applications Note 9 . . . . . . . . . . . . .
Manual Override 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Handwheel Operation 10 . . . . . . . . . . . . . . . . . . . . . . .
Manual Hydraulic Handpump Operation 12 . . . . . . . .
Actuator Mounting 22 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance 23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Actuator Removal 23 . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembling the Pneumatic Cylinder 24 . . . . . . . . .
Replacing the Pneumatic Cylinder Seals 25 . . . . . . . .
Assembling the Pneumatic Cylinder 27 . . . . . . . . . . .
Lubrication 28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembling the Handpump Hydraulic Cylinder 30
Handpump Hydraulic Cylinder Seals Replacement 30
Handpump Hydraulic Cylinder Reassembly
30 . . . . .
Other Maintenance Specifications 32 . . . . . . . . . . . . .
Troubleshooting 35 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Ordering 36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Kits 36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts List 47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assembly Drawings 50 . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1. Fisher 785C Single-Acting Spring Return
with Handpump
X1851
Introduction
Scope of Manual
This instruction manual includes installation, maintenance, and parts information for the Fisher 785C piston actuator.
Refer to separate instruction manuals for information regarding other equipment and accessories used with these
actuators.
Do not install, operate, or maintain 785C actuators without being fully trained and qualified in valve,
actuator, and accessory installation, operation, and maintenance.
To avoid personal injury or property
damage, it is important to carefully read, understand, and follow all the contents of this manual,
including all safety cautions and warnings.
If you have any questions about these instructions, contact
your Emerson sales office before proceeding.
Instruction Manual
D104483X012
785C Actuator
May 2022