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Prestartup Checks for 4194B and C
Series Controllers
Refer to figure 4-1 for adjustment locations and refer
to figure 5-21 for key number locations.
When performing the checks, open loop conditions
must exist. An open loop exists when the controller
output does not affect the input pressure or other con-
trol signal to the controller.
If the controller has the auto/manual sta-
tion (suffix letter E), be sure the control-
ler is in the automatic mode before per-
forming prestartup checks.
1. Provide a means of measuring the controller output
pressure by connecting the controller output to a pres-
sure gauge. Connect supply pressure to the supply
pressure regulator and be sure it is delivering the
proper supply pressure to the controller. Do not ex-
ceed the normal operating pressure in table 1-4.
2. For a controller with remote set point (suffix letter
M), connect regulated pressure of 3 to 15 psig (0.2 to
1.0 bar) or 6 to 30 psig (0.4 to 2.1 bar) to the remote
set point connection at the top of the controller case.
3. Remove the two machine screws (key 6) and lift off
the proportional band indicator cover (key 36).
4. Adjust the set point a minimum of 20 percent of
input span above the process pointer.
5. Turn the reset adjustment to 0.01 minutes per re-
peat.
6. Turn the rate adjustment to OFF (4194C Series).
7. Adjust the proportional band for 5 percent DIRECT.
8. If necessary, connect a pressure source to the pro-
cess connection and adjust the process pointer to the
last mark on the left side of the scale. If the last scale
mark is 0 psig, a pressure source is not required.
9. The controller output pressure should be 0 psig.
10. Rotate the proportional band to 5 percent RE-
VERSE.
11. The controller output should be within 2 psig (0.14
bar) of the supply pressure.
12. If the controller output is within tolerance, adjust
the proportional band to 400 percent in the desired
action. Secure the proportional band indicator cover
(key 36) with the machine screws (key 6), and go to
the startup procedure. If the controller output pressure
is not within tolerance, go to the 4194B and C Series
calibration procedure for recalibration.
Note
4194A, B, and C Series
Startup for 4194B and C Series
Controllers
Perform the prestartup checks and, if necessary, cali-
brate the controller prior to this procedure.
When performing the startup proce-
dures, keep in mind that the initial set-
tings are guidelines. They will vary de-
pending on the actual process being
controlled.
1. Be sure the supply pressure regulator is delivering
the proper supply pressure to the controller.
2. For controllers with:
Manual set point:
Move the set point indicator to the desired set point.
Remote set point:
a. See figure 2-5 for the location of the remote set
point connection. Connect an adjustable pressure
source to the remote set point connection.
b. Adjust the pressure source until the set point
indicator reaches the desired set point. Remember:
Increasing the remote set point pressure increases
the set point.
3. Set the reset adjustment to 0.05 minutes per re-
peat for fast processes. Set it to 0.5 minutes per re-
peat for slow processes. For controllers with rate, set
the rate adjustment to OFF.
4. Set the proportional band adjustment to 100 per-
cent for fast processes. For slow processes, calculate
the proportional band percentage from the equation
below:
Proportional
200
Band
Adjustment
For example:
200
2 Psig
30 Psig
5. If the controller is used in conjunction with a control
valve, return the control valve to service by slowly
opening the upstream and downstream manual control
valves in the pipeline. Close the manual bypoass
valve, if one is used.
6. Tune the various controller actions.
Tuning proportional action: Create a load upset by
momentarily changing the set point. Check for system
cycling. If the system does not cycle, lower the propor-
tional band setting (thus raising the gain) and disturb
Note
Allowable Overshoot
Pressure Span
13%
4–3
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