10. Apply the calibration gas and wait for the output to
stabilize.
11. With 50% LFL calibration gas applied to the sensor,
adjust R3 for a reading of 1.2 vdc (12 ma) on the
meter.
12. Place the calibrate switch on the transmitter board
in the “normal” position. The red LED blinks at a 1
Hz rate.
13. Activate the reed switch. The red LED blinks at a 2
Hz rate for 3 seconds while the reed switch is
activated.
14. The communication module records the
uncalibrated value in the first register of the
calibration log and calibrates the span value. The
calibrate LED goes on steady.
15. Remove the calibration gas and place the cover
back on the DCU enclosure.
16. The communication module waits until the analog
value drops below 4% full scale. The calibration is
complete. The calibrate LED turns off.
Pressing the sensor replacement switch aborts the
calibration and starts over.
Sensor Replacement — Toxic Gas
NOTE
When replacing a sensor, compare part numbers
to be sure that the correct replacement sensor is
being used.
WARNING
The hazardous area must be de-classified prior to
removing a junction box cover with power applied.
1.
Remove the cover from the DCU enclosure.
2.
Press the sensor replacement switch on the
communication module for about 1 second. The
calibrate LED on the communication module blinks
at a 1 Hz rate, indicating that it is ready for the zero
input.
NOTE
Pressing the sensor replacement switch prevents
the communication module from generating a fault
signal when the input drops to zero due to
removing the sensor. In addition, the calibration
will not be aborted if the calibration procedure is
not completed within 12 minutes.
3.
Replace the sensor.
4.
Wait at least 5 minutes for the sensor output to
stabilize.
5.
Activate the reed switch. The red LED blinks at a 2
Hz rate for 3 seconds while the reed switch is
activated. The communication module records the
uncalibrated value in position one of the calibration
log and calibrates the zero value. The calibrate
LED goes on steady.
6.
Apply the calibration gas. The calibrate LED blinks
at a 1 Hz rate when the input increases.
7.
Activate the reed switch. The red LED blinks at a 2
Hz rate for 3 seconds while the reed switch is
activated.
8.
The communication module records the
uncalibrated value in the first register of the
calibration log and calibrates the span value. The
calibrate LED goes on steady.
9.
Remove the calibration gas and place the cover
back on the DCU enclosure.
10. The communication module waits until the analog
value drops below 4% full scale. The calibration is
complete. The calibrate LED turns off.
Pressing the sensor replacement switch aborts the
calibration and starts over.
CALIBRATION ALGORITHM D
FOR UNIVERSAL DCUs WITH O
2
SENSOR
Normal Calibration
1.
Apply clean air (20.9% oxygen).
2.
Activate the reed switch for at least 4 seconds. The
red LED blinks at a 2 Hz rate for 3 seconds while
the reed switch is closed.
3.
The calibrate LED blinks at a 1 Hz rate, indicating
that calibration has begun.
4.
The communication module waits 3 seconds.
5.
The communication module records the
uncalibrated value in the calibration log and
calibrates the span value.
6.
The calibrate LED goes on steady.
IX-5
95-8470
