Fisher 4195 KB Series Instruction Manual page 47

4195KA, KB, and KC Series
7. Remove the four machine screws (key 71) from the
bellows beam and remove the bellows beam from the
frame.
CAUTION
When removing and replacing the pro-
portional or reset bellows, keep in mind
that the bellows has left-hand threads.
Overtightening could damage the
threads.
Both bellows need not be removed if
only one requires replacement.
8. Unscrew the bellows assembly (key 48). If the bel-
lows assembly cannot be removed by hand, thread a
machine screw (key 35) into the bellows until tight;
then loosen the bellows assembly by applying clock-
wise torque to the machine screw.
9. Before installing the replacement bellows, coat the
threads with a suitable lubricant, such as key 310 or
equivalent. Screw in the replacement bellows until it is
finger tight against the frame (key 3).
10. Reinstall the bellows beam (key 49) and tighten
the machine screws (key 71).
11. Position the bellows bracket (key 31) over the bel-
lows. Insert a machine screw (key 35) through the bel-
lows bracket (key 31) and into the proportional bel-
lows. Do not tighten.
12. Place the washer (key 362) on the second ma-
chine screw (key 35) and start the screw through the
bellows bracket (key 31) into the reset bellows. Do not
tighten.
13. Compress the bellows and start the four machine
screws (key 6) through the bellows bracket (key 31)
into the bellows beam (key 49), but do not tighten.
14. Be sure that the bellows bracket is aligned such
that it does not rub on the frame at any point and tight-
en the screws (keys 6 and 35).
15. Install the proportional or reset tubing assembly
on the bellows base.
16. For a 4195KB or KC Series controller, set the re-
set adjustment for 0.01 minutes per repeat. For a
4195KC Series controller, set the rate adjustment to
OFF.
17. Apply the correct supply pressure with the nozzle
capped and check for leaks. Remove the supply pres-
sure.
18. Reconnect link 4 (key 65) to the bellows bracket.
Be sure that the link does not contact the frame. If it
5–14
Note
does, loosen the four screws (key 6) that attach the
bellows bracket to the bellows beam and reposition
the bellows bracket to provide clearance. Be sure the
bellows bracket does not rub on the frame; then, tight-
en the screws.
19. Lift link 4 out of the hole in the bellows bracket
(key 31) and ensure it drops back into the hole under
its own weight. If not, perform steps 35 through 41 of
the Flapper Assembly and Flapper Flexure Pivot As-
sembly replacement procedures.
20. If the controller is a proportional-only (4195KA
Series), go to step 33. If the controller has reset
(4195KB or KC Series), continue with step 21.
The following procedure (steps 21
through 32) adjusts the reset gain of the
controller to minimize steady-state off-
set.
21. Apply the correct supply pressure (refer to table
1–6) to the controller and provide an accurate means
of measuring the controller output pressure. Also pro-
vide a means of applying regulated process pressure.
22. Adjust the proportional band to 100 percent DI-
RECT.
23. Adjust the set point to the mid-scale mark on the
process scale.
24. Adjust the reset adjustment to 0.01 minutes per
repeat. For a 4195KC Series controller, set the rate
adjustment to OFF.
25. Increase the process pressure until the output
pressure stabilizes at 3 psig (0.2 bar) for a 3 to 15 psig
(0.2 to 1.0 bar) output or 6 psig (0.4 bar) for a 6 to 30
psig (0.4 to 2.0 bar) output. Record the process pres-
sure reading.
When the reset valve is at 0.01, the con-
troller is very sensitive to any process
pressure change. Only small process
pressure changes may be necessary.
26. Very slowly increase the process pressure until
the output pressure stabilizes at 15 psig (1.0 bar) for a
3 to 15 psig (0.2 to 1.0 bar) output or 30 psig (2.0 bar)
for a 6 to 30 psig (0.4 to 2.0 bar) output. Record the
process pressure reading.
27. If the difference between the recorded process
pressure in step 25 and the process pressure in step
26 is larger than 1 percent of the process scale span,
proceed with step 28. If the difference is less than 1
percent, go to step 33.
28. Loosen the proportional bellows screw (key 35).
Note
Note