Actuator Earth Grounding; Three-Way Valve Applications Note; Manual Override - Emerson Fisher 785C Instruction Manual

Instruction Manual
D104483X012
Figure 3. Actuator Earth Grounding Interface
Three‐Way Valve Applications Note
In three-way valve applications where the actuator fully strokes at a frequency of once per minute or faster, and the
stroking speed is rapid (less than 0.5 seconds per stroke), there is a possibility that the stem can fracture at the plug if
the actuator cylinder pressure is greater than 5.5 bar (80 psig). This can cause loss of control of process fluid and
further damage to the actuator. Considerations should be given to the use of high-strength, fatigue-resistant stem
materials in these applications.
WARNING
To avoid loss of control of process fluid and subsequent personal injury or property damage caused by bursting of
pressure‐retaining parts, be sure the cylinder pressure does not exceed 5.5 bar (80 psig) in high cycle‐rate, fast stroking
speed, three‐way valve applications.

Manual Override

The actuator can be equipped with a manual override. The manual override can be executed with a Manual Handwheel
or a Manual Hydraulic Pump which can operate the actuator.
ACTUATOR EARTH
GROUND INTERFACE
785C Actuator
May 2022
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