7 CO200-EU-EN-V1.1-11/11
Calibration
CO
2
CALIBRATION
The meter is calibrated to a standard 400ppm CO
2
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 CO
2
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.
