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Instruction Manual
D200158X012
4194S Controllers
July 2018
21
Section 4
Maintenance
44-4-
Parts are subject to normal wear and must be inspected and replaced as necessary. The frequency of inspection and
parts replacement depends upon the severity of the service conditions. When inspection or repairs are required,
disassemble only those parts necessary to accomplish the job. Figure 4-1 is a maintenance guide. It summarizes the
information available in the maintenance procedures.
Select the appropriate maintenance procedure, and perform the numbered steps. Each procedure requires that supply
pressure and process pressure be shut off before beginning maintenance.
When maintenance procedures, including Maintenance Calibration and Flapper Alignment, have been completed,
refer to the appropriate prestartup portion in the controller operation procedure.
Note
Unless otherwise noted, key numbers refer to figure 5-1. Figures 3-1 and 3-2 show the location of adjustments and major
components. For maintenance on the indicator assembly, refer to figure 5-6.
WARNING
The following maintenance procedures require taking the controller out of service. To avoid personal injury and property
damage caused by uncontrolled process pressure, observe the following before performing any maintenance procedures:
D
Always wear protective clothing, gloves, and eyewear when performing any maintenance procedures to avoid personal
injury.
D
Personal injury or property damage may result from fire or explosion if natural gas is used as the supply medium and
preventive measures are not taken. Preventive measures may include, but are not limited to, one or more of the
following: Remote venting of the unit, re‐evaluating the hazardous area classification, ensuring adequate ventilation,
and the removal of any ignition sources. For information on remote venting of this controller, refer to page 10.
D
Provide temporary means of control for the process before taking the controller out of service.
D
Shut off the supply pressure to the controller.
D
Disconnect any operating lines providing supply air pressure, a process input signal, or other pressure source to the
controller.
D
Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.