USER GUIDE Carbon Dioxide Meter Model CO240
EXTECH INSTRUMENTS Introduction Thank you for selecting the Extech Instruments Model CO240. The CO240 measures Carbon Dioxide (CO2), Air Temperature, and Relative Humidity. It also calculates Dew Point Temperature and Wet Bulb Temperature. The user‐programmable high alarm feature alerts the user when CO2 level rises above the programmed limit and the data streaming feature allows readings to be captured in real time by PC (USB connection).
EXTECH INSTRUMENTS Meter Description 1. Sensors 2. LCD Screen 3. HOLD / Up Arrow Button 4. MODE / 5. SET Button 6. AC Adaptor jack 7. Tripod Mount 8. POWER ( ) Button 9. (Max/Min) / 1 Left Arrow Button 2 Right Arrow Button 3 4 5 10. UNIT Button 11. Down Arrow Button 12. USB PC interface port 6 Battery compartment on rear of meter. 8 9 10 11 12 7 3 CO240‐en‐GB_v1.
EXTECH INSTRUMENTS Operation Powering the meter Momentarily press the POWER button to power on the meter. Hold the POWER button for 2 seconds to turn off the meter. During measurement, if the alarm is sounding (audible beeper) press the POWER button momentarily to turn off the beeper. Press again to activate the beeper function. The alarm beeper is set to ON by default. The meter can be powered by 6 AAA batteries or AC Adaptor.
EXTECH INSTRUMENTS Automatic CO2 Baseline Calibration (ABC) The ABC algorithm continually tracks the sensor’s lowest reading over a fixed time interval and slowly corrects for any long‐term drift (as compared to the expected fresh air value of 400ppm). The ABC period is 15 days, during which the ABC function default is always on. CO2 Alarm Setting Press and hold the SET button for 2 seconds to enter the high CO2 alarm threshold.
EXTECH INSTRUMENTS Maintenance and Troubleshooting Battery Replacement When the battery icon appears on the LCD, the batteries must be replaced. In a downward motion, slide the rear battery compartment cover off of the meter housing. Remove the old batteries and replace with new batteries (all of the same type) observing correct polarity. This meter uses six (6) 1.5V AAA batteries. Please replace the battery compartment cover before attempting to use the meter.
EXTECH INSTRUMENTS Specifications Display CO2 measure range Dual multifunction LCD 0 to 9,999ppm CO2 accuracy ± (75ppm + 5% of reading) 0 to 2,000ppm Temperature range ‐10 to 50°C (14 to 122°F); 0.1° resolution Temperature Accuracy ± 1°C (1.8 °F) Relative humidity range 10 to 90%RH Relative Humidity Accuracy ± 5% of rdg at 25°C (77°F) otherwise ±7% RH Dew Point Temperature range ‐72.9 to 47°C (‐99.22 to 118°F); 0.1° resolution Wet Bulb Temperature range ‐11 to 48.2°C (12.2 to 118.8°F); 0.
