Replacing The Reset Restriction Valve (4195Kb Series) - Emerson Fisher KC Series Instruction Manual

Instruction Manual
Form 5207
April 2007
The following procedure (steps 21
through 32) adjusts the reset gain of
the controller to minimize steady-state
offset.
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
provide a means of applying regulated process
pressure.
22. Adjust the proportional band to 100 percent
DIRECT.
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 0.2 bar (3 psig) for a 0.2 to 1.0
bar (3 to 15 psig) output or 0.4 bar (6 psig) for a 0.4
to 2.0 bar (6 to 30 psig) output. Record the process
pressure reading.
When the reset valve is at 0.01, the
controller 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 1.0 bar (15 psig) for
a 0.2 to 1.0 bar (3 to 15 psig) output or 2.0 bar (30
psig) for a 0.4 to 2.0 bar (6 to 30 psig) 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).
29. If the reading recorded in step 26 is greater than
in step 25, adjust the reset gain screw (key 34)
one-half turn in (clockwise). If the reading recorded
in step 26 is less than in step 25, adjust the gain
screw (key 34) one-half turn out (counterclockwise).
30. Tighten the proportional bellows screw (key 35).
31. Repeat steps 25 through 30 until the difference
is less than ±1 percent of the process scale span.
4195KA, KB, KC, and KS Controllers
Note
Note
32. If ±1 percent of process scale span cannot be
achieved by adjusting the gain screw (key 34),
loosen the machine screw (key 35) attaching the
reset bellows and slide it to the left if the reading in
step 26 is greater than in step 25, or to the right if
the reading in step 26 is less than in step 25.
Tighten the screw and repeat steps 25 through 31.
33. Remove the supply pressure, the output
measurement device, and the regulated process
pressure source.
34. 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 of the case. Hold the controller assembly in
place while tightening the nine mounting screws.
35. Perform the controller calibration procedures
and, if necessary, the appropriate remote set point
calibration procedure in Section 3, 4, or 5.
36. Mount the controller as described in the
Installation section.
37. Connect the external piping to the controller.
Replacing the Reset Restriction Valve
(4195KB Series)
WARNING
Refer to the Maintenance WARNING
on page 6-1.
Refer to the 4195KB Series portion of figure 7-1 for
key number locations.
1. Remove the controller assembly from the case
by performing steps 1 through 3 of the case and
cover replacement procedure.
2. Remove the reset valve tubing assembly (key 42)
from the reset restriction valve (key 54).
3. Remove the reset tubing assembly (key 43) from
the reset restriction valve.
4. For controllers with anti-reset windup (suffix letter
F), remove the relief valve tubing assembly (key 44)
from the reset restriction valve.
5. Remove the screw (key 162) that fastens the
reset restriction valve to the frame.
6. Install the replacement reset restriction valve and
secure it with the screw removed in step 5.
7. Install the reset valve tubing assembly (key 42),
the reset tubing assembly (key 43), and for
controllers with anti-reset windup, the relief tubing
assembly (key 44). Tighten all connections.
6-17