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Instruction Manual
D200156X012
Section
55‐5‐
Maintenance
Inspection and Maintenance
Controller parts are subject to normal wear and must be inspected and replaced as necessary. Inspection and
maintenance frequency depends on the severity of service conditions. When inspection or repairs are require,
disassemble only those parts necessary to accomplish the job. Figure 5‐1 is a maintenance guide which summarizes
the information available in the maintenance procedures.
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 operations to avoid personal
injury.
D Provide some temporary means of control for the process before taking the controller out of service.
D Shut off the supply pressure to the controller.
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 11.
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 again process
media.
Note
Unless otherwise noted, key numbers refer to figure 6‐1. Figure 3‐1 shows the location of adjustments and major components. For
maintenance on the indicator assembly, refer to figure 6‐4.
Select the appropriate maintenance procedure and perform the numbered steps. Shut off the supply pressure and
process pressure before beginning maintenance.
The maintenance procedures section describes part replacement common to 4194HA, HB, and HC controllers. Other
portions of the maintenance procedures describe replacing the differential pressure unit, making process
zero‐and‐span and flapper alignments, and other calibration and maintenance procedures.
When maintenance procedures, including flapper alignment, have been completed, refer to the appropriate
prestartup procedure.
Troubleshooting
As an aid to troubleshooting, table 5‐1 lists some common operating faults, their probable cause, and suggested
procedures for correcting the fault.
4194HA, HB, HC Controllers
July 2018
37
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