Replacing The Proportional Or Reset Bellows - Fisher 4195 KB Series Instruction Manual

nearest the nozzle) until the output is within 2 psig
(0.14 bar) of supply pressure.
39. Loosen the two adjustment screws on link 4,
shown in figure 5–10, and connect the link to the bel-
lows bracket (key 31), allowing the link to find its free
length.
40. Tighten the two adjusting screws on link 4.
41. 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, repeat steps 39 and 40.
42. Adjust the proportional band to 40 percent RE-
VERSE or DIRECT depending on the desired control-
ler action.
43. Adjust the set point to the process scale lower
limit.
44. Tape the process pointer at the process scale
lower limit. The output pressure may be anywhere be-
tween 3 and 15 psig (0.2 to 1.0 bar) for a 3 to 15 psig
(0.2 to 1.0 bar) output signal range or between 6 and
30 psig (0.4 to 2.0 bar) for a 6 to 30 psig (0.4 to 2.0
bar) output signal range. If the output is not within the
specified range, adjust the flapper leveling screw near-
est the nozzle until the output is within the range spe-
cified. Record the controller output pressure.
45. Adjust the set point to the process scale upper
limit.
46. Remove the tape and move the process pointer
until the controller output equals the pressure recorded
in step 44. Note the process pressure indication.
47. The process pressure indication should be within
2 percent of the process scale upper limit.
If the process pressure indication in step 46 is greater
than the process scale upper limit by 2 percent, loosen
the shoe adjustment screws (key 30), shown in figure
5–3, and move the set point beam shoe (key 29)
slightly away from the center of the flapper assembly.
If the process pressure indication in step 46 is less
than the process scale upper limit by 2 percent, loosen
the shoe adjustment screws (key 30), shown in figure
5–3, and move the set point beam shoe (key 29)
slightly toward the center of the flapper assembly.
48. Repeat steps 43 through 47 until the error is less
than 2 percent of the process scale span at the pro-
cess scale upper limit.
49. Remove the tape from the process pointer and
reconnect link 1 to the input element. If the controller
has a capsular input element, be sure to reconnect link
1 in the same hole noted in step 21.
50. Position the controller assembly in the case and
start, but do not tighten the nine mounting screws.
Slide the controller assembly down to assure an O-
ring seal at the pressure connections along the bottom
4195KA, KB, and KC Series
RESET
BELLOWS
WASHER
(KEY 362)
TWO SCREWS
(KEY 35)
RESET
GAIN
BELLOWS
BRACKET
(KEY 31)
W4199 / IL
Figure 5–12. Bellows Assembly, Bellows Bracket,
and Bellows Beam Location
of the case. Hold the controller assembly in place
while tightening the nine mounting screws.
51. Perform the controller calibration procedures and,
if necessary, the appropriate remote set point calibra-
tion procedure in section 3 or 4.
52. Mount the controller as described in the Installa-
tion section.
53. Connect the external piping to the controller.
Replacing the Proportional or Reset
Bellows
Refer to figure 5–12, unless otherwise noted.
1. Remove the controller assembly from the case by
performing steps 1 through 3 of the case and cover
replacement procedure.
2. Remove the two screws (key 6) and lift off the pro-
portional band indicator cover (key 36).
3. Disconnect link 4 (key 65) from the bellows bracket
(key 31).
4. Remove the two machine screws (key 35) and
washer (key 362) from the bellows assemblies.
5. Remove the four machine screws (key 6) from the
bellows beam (key 49) and remove the bellows brack-
et (key 31).
6. Remove the proportional tubing assembly (key 40)
from the proportional bellows or remove the reset tub-
ing assembly (key 43) from the reset bellows, depend-
ing on which bellows is to be replaced.
FOUR SCREWS (KEY 6)
PROPORTIONAL
BELLOWS
LINK 4
(KEY 65)
5–13