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7 CO200-EU-EN v1.2 08/13
Calibration
CO2 CALIBRATION
The meter is calibrated to a standard 400ppm CO2 concentration at the factory
NOTE: When the accuracy becomes a concern or after a year of use, return the meter to Extech for
a standard calibration.
CAUTION: Do not calibrate the meter in an atmosphere of unknown CO
2 concentration.
ABC (Automatic Baseline Calibration)
ABC (Automatic Baseline Calibration) establishes a baseline calibration to eliminate the zero drift of
the infrared sensor. The ABC function is always “ON” when the meter is turned on. ABC is designed
to calibrate the meter at the minimum CO
2 reading detected during 7.5 days continuous monitoring
(power on). It assumes that the area being tested receives fresh air with a CO
2 level of
approximately 400ppm at some period of time during the seven days. It is not suitable to use
desktop CO
2 in closed areas with consistently high CO2 levels 24 hours a day.
Manual Calibration
Manual calibration is suggested to be done outdoors on a sunny day with good ventilation and fresh
air where the CO
2 level is approximately 400 ppm. Do not calibrate on a rainy day because high
humidity will affect the CO
2 level in air.
Do not calibrate in places crowded with people or close to where high CO
2 concentrations may exist
such as ventilating outlets or fireplaces.
Place the meter in the calibration site. Turn on the meter and hold down the SET, ▲ and
MIN/MAX▼ buttons simultaneously more than 1 second to enter CO
2 calibration mode. “400ppm”
and “CO
2” will blink while the calibration is in process.
The calibration will take about 30 minutes. When the calibration is complete, the blinking stops and
the meter returns to normal operation. To abort the calibration, press the RESET button for more
than 1 second.
Note: Keep away from any animal, human or plant which might affect the CO
2 concentration during
the calibration.