PureAire Monitoring Systems, Inc.
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6: Maintenance & Sensor Verification
Only qualified personnel should perform maintenance and sensor verification
6.1 Sensor Calibration, CO
2
PureAire incorporates the use of an NDIR (NonDispersive InfraRed) CO
2
sensor in the CO
2
Monitor.
The sensor is factory calibrated and will always provide an accurate reading that is the difference
between a baseline setting and the actual CO
2
measurement. As typical with most NDIR sensors, long
term drift can affect the baseline setting. To compensate for this drift, an automatic background
calibration function is built into the sensor and is enabled by default from the factory. This calibration
feature assumes that during a 24 hour period, the monitored CO
2
levels return to normal ambient
conditions, such as in an office environment or spaces that are unoccupied during the evening.
If the monitor is constantly exposed to elevated levels of CO
2
, for example, in an agricultural
growing room, the auto calibration feature should be inhibited, “turned off” and a manual
calibration preformed approximately every six months. S
ee Section 5.5.11 to turn off the autocal
feature.
CAUTION: DO NOT ADJUST the CO
2
sensor unless you are certain that the CO
2
level has
returned to normal ambient conditions, such as in an outdoor environment or spaces that are
unoccupied. If using calibrated CO
2
span gas, ensure that the gas is not being diluted with room
air.
To perform a manual adjustment of the CO
2
sensor to ambient 400PPM, use the following procedure.
Use the joystick to enter the password, then push the joystick to the right and navigate to the “Sensor
Adjustment” menu. The display will scroll
Push the joystick right once and the display will scroll:
Push the joystick right once and the display will display:
…Set CO2 sensor span..
1.00
600PPM
…Sensor adjustment..
