95-8533
5-6
18.2
4. Activate the reed switch. (The red LED
flashes for three seconds while the switch
is closed.)
5. The communication module records
the uncalibrated value in position one
of the calibration log and calibrates the
zero value. The calibrate LED stays on
steady.
6. Set the Zero Switch on the sensor to the
“normal” position. Apply clean air (20.9%
oxygen) to set the sensor analog span
value.
7. The calibrate LED flashes when the input
goes high.
8. Activate the reed switch. (The red LED
flashes for 3 seconds while the switch is
closed.)
9. The communication module records the
uncalibrated value in the first register of
the calibration log and calibrates the span
value.
10. The calibration is complete. The calibrate
LED turns off.
NOTE
Pressing the sensor replacement switch
aborts the calibration.
CALIBRATION ALGORITHM G
FOR DCUs WITH POINTWATCH
OR DUCTWATCH
Routine Calibration
1. Apply the zero gas.
2. Activate the reed switch for at least 4
seconds. (The red LED flashes for 3
seconds while the switch is activated.)
3. The calibrate LED flashes, indicating it is
ready for the zero input.
4. When a steady zero reading is obtained,
the communication module records the
uncalibrated value in the calibration log
and calibrates the zero value during this
time. The LED stays on steady.
5. Apply calibration gas. (The calibrate LED
flashes when the sensor detects gas.)
6. When the sensor input has been stable for
30 seconds, the communication module
records the uncalibrated value in the
calibration log and calibrates the span
value.
7. The calibrate LED stays on steady.
8. Remove the calibration gas.
9. The communication module waits until the
sensor input drops below 4% full scale.
10. The calibration is complete. (The calibrate
LED turns off.)
NOTE
Calibration is aborted if not complete
within 12 minutes. If not completed, the
detector will revert back to the previous
calibration values. The red LED will ash
and the calibration will be logged as
aborted.
Sensor Replacement
WARNING
The hazardous area must be
de-classied prior to removing a junction
box cover with power applied.
1. Remove power from the DCU and
PointWatch/DuctWatch unit. Replace
the PointWatch unit. Apply power. Press
the Sensor Replacement Switch on the
communication module for approximately
1 second.
NOTE
Allow at least 10 minutes for the sensor
to warm up.
NOTE
Pressing the Sensor Replacement
Switch prevents the communication
module from generating a fault signal
when the input drops to zero.
NOTE
The calibration will not be aborted if the
calibration procedure is not completed
within 12 minutes
.
2. Apply zero gas.
3. The calibrate LED flashes, indicating that it
is ready for the zero input.
4. Continue from step 4 of the PointWatch/
DuctWatch routine calibration procedure
described above.
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