Replacing Controller Parts; July - Emerson Fisher 4194HA Instruction Manual

Instruction Manual
D200156X012
Properly support the unit before trying to separate the controller and differential pressure unit.
4. To separate the controller and differential pressure unit, open the cover, locate link 1 (key 323, figure 6‐2) and
disconnect it from the drive arm (key 322).
5. Remove the pivot bracket (key 320) by removing the screws and washers (keys 329 and 332).
6. Loosen the locking screw (key 331) and slide the drive arm (key 322) off the extension shaft.
CAUTION
When removing the controller from the controller mounting plate (key 327), be careful not to bend the extension shaft
(key 321).
7. Remove four screws (key 336) from the controller mounting plate (key 328) and carefully slide the controller off the
extension shaft.
8. For controller maintenance — remove the controller mounting plate (key 328) by removing three screws (key 335)
to gain access to the back of the controller.
9. For differential pressure unit maintenance — loosen the set screw (key 333) and remove the extension shaft.
10. Remove four screws (key 334) from the mounting plate (key 327) to gain access to the differential pressure unit.
11. For maintenance of the differential pressure unit, refer to the instruction manual for the unit.
CAUTION
When reinstalling the differential pressure unit, carefully insert the extension shaft (key 321) into the controller to avoid
damage to controller parts.
When reassembling the pivot bracket, it must be carefully aligned so that it will not cause binding on the extension shaft
(key 331).
12. Follow this procedure in reverse to rejoin the controller and differential pressure unit. Before returning the unit to
process control, perform maintenance calibration and flapper alignment procedures.
Refer to the installation procedures when reinstalling the unit.

Replacing Controller Parts

WARNING
Refer to the Maintenance WARNING at the beginning of this section.
To avoid personal injury or property damage caused by the uncontrolled release of pressure, be sure any trapped pressure
is properly vented from the differential pressure unit. Vent any supply pressure from the controller before disassembly.
Note
Remove the controller and differential pressure unit to a maintenance area to perform the following procedures. Refer to the
installation procedures for process and supply tubing connections to disconnect when the differential pressure unit is removed
from the pipestand. Figure 2‐1 shows the location of the set screws connecting the differential pressure unit mounting bracket to
the pipestand.
4194HA, HB, HC Controllers

July 2018

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