Instruction Manual
D103292X012
C1 Controllers and Transmitters
March 2017
23
c. With falling input pressure, the output should switch from full supply pressure back to zero when the lower
switching point is reached.
Reverse-acting controllers produce the opposite response.
7. Vary the process pressure and observe the switching points. Widen or narrow the differential gap by rotating the
proportional band adjustment knob, then repeat the above steps.
If the output is within the limits stated, refer to the startup procedures in this section. If the output pressure cannot
be adjusted within the limits stated, refer to the maintenance procedures.
Startup: Differential Gap Controllers
Calibrate the controller prior to this procedure.
1. Be sure that the supply pressure regulator is delivering the proper supply pressure to the controller.
2. Adjust the proportional band setting for the proper differential gap (see figure 10).
3. If the controller is used in conjunction with a control valve, slowly open the upstream and downstream manual
shutoff valves, and close the bypass valves.
procedure.
Transmitter Operation
This section describes the adjustments and procedures for calibration and startup. Refer to figure 11 for the
adjustment locations. All adjustments must be made with the cover open. When the adjustments and calibration
procedures are complete, close and latch the cover.
To better understand the adjustments and overall operation of the transmitter, refer to the Principle of Operation
section in this manual for transmitters. Refer also to the schematic diagram in figure 13.
Adjustments
Adjustment: Zero
The pressure setting dial is marked ZERO ADJUSTMENT PRESSURE SETTING. Zero is in the center of the dial, and the
pressure values increase to the right and left of the center as shown in figure 11. To set the zero, rotate the pointer
around the pressure setting dial. Rotate the pointer clockwise to increase or counterclockwise to decrease the output
depending on transmitter action and desired setting.
For direct-acting transmitters, zero adjustment determines the process pressure at which the transmitter output
signal will be at its lower range limit.
The dial (key 6) graduations are approximate indications of the transmitter zero setting. When making adjustments,
do not rely solely on the dial setting. Monitor the process pressure and output pressure to be sure the desired settings
are attained.