Replacing The Reset Restriction Valve (4194Hb Controllers); Replacing The Rate/Reset Valve Assembly (4194Hc Controllers) - Emerson Fisher 4194HA Instruction Manual

Instruction Manual
D200156X012
22. Increase the process differential pressure very slowly until the output pressure stabilizes at 1.0 bar (15 psig) for a 0.2
to 1.0 bar (3 to 15 psig) output signal range or 2.0 bar (30 psig) for a 0.4 to 2.0 bar (6 to 30 psig) output signal
range. Record the process differential pressure reading.
23. If the difference between the recorded process differential pressure in step 21 and the process differential pressure
in step 22 is larger than ±1 percent of the process differential pressure span, proceed with step 24. If the difference
is less than ±1 percent, remove process differential pressure from the differential pressure unit/controller and go to
step 28.
24. Loosen the proportional bellows screw (key 35, figure 5‐15).
25. Adjust the gain screw (key 34) one‐half turn in — if the reading recorded in step 22 is greater than in step 21. Adjust
the gain screw (key 34) one‐half turn out — if the reading in step 22 is less than in step 21.
26. Tighten the proportional bellows screw (key 35).
27. Repeat steps 21 through 26 until the difference is less than ±1 percent of the process differential pressure span.
28. If ±1 percent of process scale span cannot be achieved by adjusting the gain screw (key 34), loosen the screw
(key 35) attaching the reset bellows and slide it to the left if the reading in step 22 is greater than in step 21, or to
the right if the reading in step 22 is less than in step 21. Repeat steps 22 through 27.
29. Reconnect link 1 and install the controller assembly in the case and cover.
30. Refer to the process pointer zero‐and‐span adjustment and flapper alignment procedure in the Maintenance
section.

Replacing the Reset Restriction Valve (4194HB Controllers)

Note
Before starting the following procedure, remove the controller from the case. Perform steps 1 through 7 of the Replacing the
Differential Pressure Unit procedure. Then, perform steps 1 and 2 of the Replacing the Case and Cover procedure.
Refer to the 4194HB controller portion of figure 6‐1 for key number locations.
1. Perform the procedures required in the Note above.
2. After removing the controller from the case and cover, 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. Remove the relief tubing assembly (key 44) from the reset restriction valve (option F only).
5. Remove the screw (key 162) holding the reset restriction valve to the frame (key 3).
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), the relief tubing assembly
(key 44, option F only) and tighten.
8. Set the reset restriction valve to 0.01 minute per repeat.
9. Apply the proper supply pressure to the controller, drive the controller output to within 0.14 bar (2 psig) of the
supply pressure by capping the nozzle and check the tubing connections for leaks.
10. Install the controller assembly in the case and cover.

Replacing the Rate/Reset Valve Assembly (4194HC Controllers)

Note
Read this entire procedure before removing any parts. Refer to the 4194HC portion of figure 6‐1 for key number locations.
4194HA, HB, HC Controllers
July 2018
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