Replacing Pivot Assembly B (Key 115); Replacing The Drive Flexure - Emerson Fisher KC Series Instruction Manual

Instruction Manual
Form 5207
April 2007
3. Note where link A is connected. Disconnect link
A (key 116) from the lever arm on pivot assembly A
(key 114).
4. Disconnect the drive flexure (key 79) from the
adjustment arm of pivot assembly A. Be careful not
to bend or kink the drive flexure.
5. Remove the screw (key 122), washer (key 123),
and nut (key 124) that attach the guide flexure (key
119) to the top of the pivot assembly.
6. Remove the pivot screw and spring washer (keys
109 and 112) and the mounting screw (key 102)
attaching the pivot assembly to the mounting plate
(key 111). Lift out pivot assembly A.
7. Loosen the adjustment screw (key 118) on the
adjustment arm of the replacement pivot assembly,
and set the arm to the same length as the arm on
the pivot assembly being replaced. Tighten the
screw.
8. To replace the pivot assembly, first put the spring
washer (key 112) on the screw (key 109). Then,
insert the screw through the replacement pivot
assembly and into the mounting plate and tighten.
Install the mounting screw (key 102) and tighten.
9. Connect the guide flexure (key 119) to the top of
the replacement pivot assembly with the screw (key
122), washer (key 123), and nut (key 124) as it was
before. The guide flexure should be straight and
horizontal as shown in figure 6-23. If not, loosen the
screws (key 122) and retighten to eliminate any
bowing. Loosen the screws (key 139) and raise or
lower the pedestal assembly (key 105) to get the link
horizontal. Retighten the screws (key 139) and
ensure the diaphragm assembly extension (key 134)
is centered in the upper travel stop (key 83) hole.
10. Apply remote set point pressure equal to 50
percent of the remote set point input range.
See figure 6-20. The adjustment arm of
the remote set point pivot assembly A
turns on a bushing at each end of the
shaft supporting the adjustment arm.
In the next step, position the shaft so
both bushings ''float'' inside the
bearings and do not rest against the
end of either bearing.
11. Connect the drive flexure (key 79) to the arm on
the replacement pivot assembly, making sure it
stays straight and vertical. Adjust the length of the
pivot arm, if necessary, until the flexure is vertical.
4195KA, KB, KC, and KS Controllers
Note
Before tightening the drive flexure screws, hold the
pivot assembly shaft in the middle of the bushing
end play. Be sure neither bushing is resting against
the inside end of either bearing. Tighten the drive
flexure screws to hold pivot assembly A in this
position. Do not bend or twist the flexure when
tightening the screws.
12. Decrease the remote set point pressure to 0 bar
(0 psig).
13. Connect the end of link A (key 116) to the pivot
lever arm in the same holes noted in step 3.
14. Replace the tie bar (key 106).
15. Perform the remote set point maintenance
calibration procedure. Perform the appropriate
process indicator zero and span calibration and
flapper alignment procedures in Section 3, 4, or 5.

Replacing Pivot Assembly B (Key 115)

1. Decrease the remote set point pressure to 0 bar
(0 psig).
2. Note the holes where links A and B are
connected. Disconnect links A and B (keys 116 and
126) from the arms of pivot assembly B (key 115).
3. Remove the two screws (key 102) that attach
pivot assembly B to the mounting plate (key 111).
Remove the pivot assembly.
4. Loosen the linearity adjustment screw on the
replacement pivot assembly and set it in the same
position as the adjustment on the original pivot
assembly. Tighten the screw.
5. Set the replacement pivot assembly on the
mounting plate, and attach it with the two machine
screws.
6. Attach links A and B (keys 116 and 126) to the
arms of the replacement pivot assembly in the same
holes noted in step 2.
7. Perform the remote set point maintenance
calibration procedure. Perform the appropriate
process indicator zero and span calibration and
flapper alignment procedures in Section 3, 4, or 5.

Replacing the Drive Flexure

1. Using an Allen wrench, remove the cap screws
(key 12) and washers (key 13) to disconnect the
drive flexure (key 79) from the drive bracket (key
121) and from the adjustment arm of pivot assembly
A. Remove the drive flexure.
2. Set the remote set point pressure to 50 percent
of the remote set point input range.
6-37