CO250-EU V1.2 6/09
6
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 to Extech for
a standard calibration.
CAUTION:
Do not calibrate the meter in an atmosphere of unknown CO
2
concentration.
1.
Place the meter in the 400ppm calibration chamber. Turn the
meter on and hold down the
CAL/Esc
and
MODE/
▲ buttons
simultaneously to enter CO
2
calibration mode. 400ppm and
“CAL” will blink on the LCD while performing calibration.
2.
Wait about 5 minutes until the blinking stops. The calibration
is then completed and the meter automatically returns to the
normal mode.
NOTE:
Ensure the batteries are fresh prior to calibration to prevent an interruption or failed
calibration.
RH CALIBRATION
The meter is calibrated to a standard 33% and 75% salt solution bottle.
CAUTION: Do not calibrate the humidity without the default calibration salt. Otherwise,
permanent damage could occur. Contact the Extech for calibration salts or services.
33% calibration
1.
Plug the sensor probe into 33% salt bottle.
2.
In the normal mode, Press and Hold the
CAL/Esc
and
DP/WBT/▼
buttons to enter the 33% calibration. “CAL” and
calibrating value (32.7% if at 25°C) will blink on the LCD with
current temperature at the left.
3.
The meter is now calibrating, and will finish in about 60 minutes
when “CAL” and humidity stop blinking.
75% calibration
1.
After the 33% calibration, plug the sensor probe into a 75%
salt bottle.
2.
Press the
M
N
/AV
button to enter 75% calibration.
3.
“CAL” and calibrating value (75.2% if at 25°C) will blinking on
the LCD with current temperature at the left.
4.
The meter is now calibrating. Wait about 60 minutes until the blinking stops, then
calibration is completed and the meter will return to normal mode.
NOTE: Single point calibrations are allowed. To calibrate 33% only, press
CAL/Esc
and
exit when 33% calibration is completed. To calibrate 75% only, press
MODE/
▲
within the 5 minutes while initializing 33% calibration.
PC CONNECTION
The meter is equipped with an RS-232 PC interface jack (3.5mm phono) for connection to
a PC. The supplied cable and Windows
TM
compatible software allows the user to store
readings in a text file and display real-time measurements in a series of selectable formats.
For more information or specific operating instructions, refer to the User Guide included
with the software.
