Replacing Bourdon Tube Controller Links - Fisher 4195 KB Series Instruction Manual

COURSE ZERO ADJUSTMENT
LINK 1
LINK 2
LINK 2 ADJUSTMENT
W5745 / IL
Figure 5–13. Bourdon Tube Controller Link
Locations and Adjustments
W5747 IL
Figure 5–14. Disconnecting Link 1 from the Bourdon Tube
6. Apply process pressure equal to the process scale
upper limit and check for leaks. Remove process pres-
sure.
7. Connect link 1 to the Bourdon tube.
8. With the process pressure at 0 percent, the pro-
cess pointer should indicate 0 percent on the process
scale. If not, loosen the two screws on link 1 and ad-
just the length of link 1 to position the process pointer
at 0 percent. Tighten the screws.
LINK 4 ADJUSTMENT
LINK 4
LINK 3 ADJUSTMENT
LINK 3
4195KA, KB, and KC Series
9. Perform the controller calibration procedures and, if
necessary, the appropriate remote set point calibration
procedure in section 3 or 4.

Replacing Bourdon Tube Controller Links

This section describes the separate replacement of
four links in the controller. Figure 5–13 shows the loca-
tion of each link. To clarify the location of each link,
the links are numbered as follows:
Link 1 connects the Bourdon tube and the pro-
cess pointer
Link 2 connects the process pointer and the flap-
per assembly (key 11)
Link 3 connects the set point indicator and the
set point beam assembly (key 23)
Link 4 (key 65) connects the flapper assembly
and the bellows bracket (key 31).
Replacing Bourdon Tube Controller Link 1
1. Remove the two screws (key 6), and lift off the pro-
portional band indicator cover (key 36).
2. Note the hole position of link 1 in the process point-
er. As shown in figure 5–14, disconnect the link from
the Bourdon tube and from the process pointer. Adjust
the length of the replacement link to the same length
as the link being replaced.
3. Attach the replacement link to the original holes in
the process pointer and the Bourdon tube. If you do
not know in which hole in the process pointer the link
was connected, place it in the middle hole. If during
the process indicator zero and span calibration, the
pointer will not travel the full scale even after full span
adjustment, move the link to the bottom hole (the hole
nearest the pointer pivot). If the process pointer has
too much travel, move the link to the top hole (the hole
furthest from the pointer pivot).
4. Move the set point Indicator, either manually or
with remote set point pressure, to the mid-scale mark
on the process scale and set the proportional band
between DIRECT and REVERSE.
5. The process pointer should be aligned with the
pointer subassembly as shown in figure 5–15. If not,
loosen the zero adjustment locking screw and adjust
the process pointer zero adjustment to align the pro-
cess pointer and pointer subassembly. Tighten the
zero adjustment locking screw.
6. Apply process pressure equal to the mid-scale val-
ue of the process scale span. The process pointer
should indicate mid-scale 3 percent of the process
scale span. If not, loosen the two screws in link 1 and
move the process pointer to the mid-scale mark on the
process scale. Tighten the screws.
5–17