Extech Instruments CO240 User Manual

6 CO240-en-US_v1.9 10/22
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.
Battery Safety Reminders
o Please dispose of batteries responsibly; observe all relevant regulations.
o Never dispose of batteries in a fire; batteries may explode or leak.
o Never mix battery types; install new batteries of the same type.
Troubleshooting / Error Message Displays
Erratic Readings Replace the batteries or use the AC/DC adaptor and check again.
ER1 Display CO
2,
Temperature or Humidity sensor failure or a sensor communication
error. Send for service if display persists.
ER2 Display Out-of-range condition for CO
2,
Temperature or Relative Humidity.
Detected reading exceeds CO
2,
Temperature or Humidity range
specification. This error is normal when clearing the maximum and
minimum readings in the MAX/MIN mode.
“9999” Display Reading exceeds the CO
2
maximum measurement range or the battery
power is weak.

Extech Instruments CO240 Specifications

Display and Measurement

display	Dual multifunction LCD
CO2 measure range	0 to 9, 999 ppm
CO2 accuracy	± (75 ppm + 5% of reading) 0 to 2, 000 ppm

Operating Environment

operating temperature	0 to 50°C (32 to 122°F); 0.1° resolution
operating relative humidity	0 to 95% RH (avoid condensation)
relative humidity accuracy	± 5% of rdg at 25°C (77°F) otherwise ±7% RH

Temperature Ranges

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); 0.1° resolution
temperature accuracy	± 1°C (1.8 °F)

Storage Conditions

storage temperature	‐20 to 50°C (‐4 to 122°F)
storage humidity	0 to 95% RH (avoid condensation)
dimensions	211 x 60 x 40 mm (8.3 x 2.4 x 1.6")

Power and Weight

power	AAA batteries x 6 pcs or AC adaptor
weight	181.4 g (6.4 oz.)