UTC Fire and Security Det-Tronics R8471B Instructions Manual page 21

2. Controller calibration. This method of calibra-
tion typically requires two people, one person
at the controller and another at the sensor. All
adjustments are made automatically by the con-
troller.
The controller calibration procedure is typically
used when the system involves a sensor that gen-
erates an uncalibrated output signal (no transmit-
ter calibration is possible).
However, if the controller calibration procedure will
be used with a transmitter that can be calibrated,
the transmitter must be calibrated fi rst, followed
by the controller calibration. (The controller cali-
bration compensates for errors in sensor/transmit-
ter output. If the transmitter is calibrated following
a controller calibration, the controller must be
recalibrated.)
In most cases, the controller calibration procedure
can be used for all subsequent recalibrations, with no
need to repeat the transmitter calibration.
If the controller calibration method is used
for calibrating a new sensor in a system using
a transmitter that can be calibrated, the most
accurate calibration for the new sensor will be
achieved if a transmitter calibration is performed
initially (the controller must be placed into the
Sensor Replacement mode to set the controller
default calibration values), followed by a controller
calibration (24 hours later for maximum accuracy).
The controller calibration procedure can then be
used for all subsequent calibrations.
Setting Controller Default Values
(Required for Transmitter Calibration)
IMPORTANT
This procedure must be performed in addition to
transmitter calibration.
When calibration adjustments are made at the
transmitter, the controller must be set for the factory
default calibration values by momentarily entering the
Sensor Replacement mode.
1. Press and hold the RESET button for approxi-
mately 9 seconds until the digital display begins
fl ashing and the CAL LED is illuminated. Release
the RESET button.
2. Press the SET button. The FAULT LED comes on
and the digital display stops fl ashing. The con-
troller is now set for the factory default values.
2.1
NOTE
3. To exit the Sensor Replacement mode, press the
RESET button. The controller returns to the nor-
mal operating mode after a time delay.
The above procedure does not need to be performed
with each recalibration unless a controller calibration
(described below) is performed.
For information regarding calibration of the
transmitter, refer to the transmitter manual.
Controller Calibration Procedure
1. Be certain that the controller is properly pro-
grammed for the ppm concentration being used
for calibration. (See "Setpoint Adjustment" sec-
tion.) Reprogram the controller if required. Failure
to do so will greatly impair system response.
2. Be sure that only clean air (0 ppm) is present at
the sensor. (The microprocessor begins taking
Zero readings immediately upon entering the
Calibrate mode.) If the possibility of background
gases exists, purge the sensor with clean air to
assure accurate calibration.
3. Depress and hold the RESET button until the CAL
LED is illuminated and the digital display starts to
fl ash (approximately 9 seconds).
4. When the Zero calculations are complete (30 sec-
onds minimum), the digital display stops fl ashing
and reads "00."
5. Apply the calibration gas to the sensor. The digi-
tal display starts to fl ash, and the value indicated
on the display rises. The bar graph display also
indicates the level of gas at the sensor, but does
not fl ash.
6. When the microprocessor has completed the
Span adjustments (30 seconds minimum), the
digital display stops fl ashing.
7. Remove the calibration gas. When the gas level
falls below the lowest alarm setpoint, the control-
ler automatically exits the Calibrate mode. All
outputs and indicators return to normal operation.
If the operator fails to complete the calibration proce-
dure or if the sensitivity of the sensor has deteriorated
to the extent that calibration cannot be successfully
completed, a calibration fault ("F2X" status) will be
generated and the system will automatically revert
back to the former calibration settings (after 10 min-
utes or when the gas level drops below the lowest set-
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