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Instruction Manual
D200158X012
4194S Controllers
July 2018
36
12. Apply the correct supply pressure, and check for leaks. Remove the supply pressure.
If the length of link 4 (key 65) was not changed, proceed with step 14.
13. If the length of link 4 (key 65) was changed during this procedure, refer to the replacement procedures for the
flapper flexure pivot assembly. Perform steps 36 through 38 of the procedure.
through 12 to straighten the bellows bracket (key 31).
15. Refer to the Flapper Alignment procedures.
16. Remove the supply pressure, the output measurement device, and the regulated differential process pressure
source.
17. Rotate the proportional band knob to the desired controller action. Replace the proportional band indication cover
(key 36), and tighten the two screws (key 6).
18. Install the controller assembly in the case. Slide the controller frame down to assure an O‐ring seal at the pressure
connections. Hold the frame in place.
19. Install and tighten the nine screws that hold the controller assembly in the case.
Links
This section describes the separate replacement of five links in the controller. To clarify the location of each link (see
figure 4-12), the links are numbered as follows: link number 1 connects short pivot assembly and the process pointer;
link number 2 connects the process pointer and the input feedback beam assembly (key 11); link number 3 connects
the set point adjustment and the set point beam assembly (key 23); link number 4 (key 65) connects the input
feedback assembly and the bellows bracket (key 31). Link number 5 (key 88, figure 5-2) connects the short pivot
assembly and the long pivot assembly. Figure 4-12 shows the location of each link.
Link Number 1
1. Remove the two screws (key 6) and lift off the proportional band indicator cover (key 36).
pointer assembly. Remove the link.
4. Adjust the set point manually or with remote set point pressure to 100 percent of the scale range, and set the
proportional band between DIRECT and REVERSE.
zero adjustment locking screw. Then adjust the fine zero adjustment to align the process pointer and pointer
subassembly.
6. With a regulated air supply, adjust process differential pressure to 50 percent of process scale range. The process
pointer should be at the 50
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1.0 percent position on the scale. If not, loosen the screw (coarse zero adjustment
7. Refer to the Maintenance Calibration and Flapper Alignment procedures.
8. Install the proportional band indicator cover (key 36) and tighten the two screws (key 6).