Emerson Fisher 4194HA Instruction Manual page 60

4194HA, HB, HC Controllers
July 2018
16. Refer to steps 4 through 10 in the procedure for replacing link 4. If the controller is a proportional‐only (4194HA)
controller, go to step 28. If the controller has reset (4194HB) or rate/reset (4194HC), continue with step 17 and the
following note.
17. Disconnect link 1 from the drive arm.
Figure 5‐15. Bellows Assembly and Proportional Band Adjustment (Process Scale and Proportional Band Adjustment
Cover Removed)
RESET
BELLOWS
WASHER
(KEY 362)
TWO SCREWS
(KEY 35)
W4199
Note
The following procedure (steps 18 through 28) adjusts the reset gain of the controller to minimize steady‐state offset.
18. Adjust the proportional band to 100 percent in direct action.
19. Adjust the set point to 50 percent of the process scale range.
20. Adjust the reset valve (4194HB and HC controllers) to 0.01 minute per repeat. Adjust the rate valve (4194HC
controllers) to OFF.
21. Increase the process differential pressure to the differential pressure unit until the output pressure stabilizes at 0.2
bar (3 psig) for a 0.2 to 1.0 bar (3 to 15 psig) output signal range or 0.4 bar (6 psig) for a 0.4 to 2.0 bar (6 to 30 psig)
output signal range. Record the process differential pressure reading.
Note
When the reset valve is at 0.01, the controller is very sensitive to any process differential pressure change. Only small changes to
the process indicator may be necessary.
60
FOUR SCREWS (KEY6)
Instruction Manual
PROPORTIONAL
BELLOWS
BELLOWS
BRACKET
(KEY 31)
LOCKING NUT
ADJUSTABLE
SET POINT PIVOT
ASSEMBLY (KEY 17)
SCREW AND
WASHER
LINK 4
(KEYS 19 AND 20)
D200156X012