Handheld carbon dioxide and relative humidity meter

 

CO2 Meter Model CO250 by Extech Instruments

 

Measures indoor CO2 levels, air temperature, dew point, wet bulb temperature, and relative humidity (RH).

 

Specifications are as follows:

  • CO2: range of 0-5000 ppm, 1ppm resolution, +/-(5%rdg+50ppm) accuracy
  • Temperature: -10 to 60°C (14 to 140F), 0.1° resolution, +/- 0.6°C accuracy
  • Humidity: 0.0 to 99.9%, 0.1% resolution, accuracy of +/-3% between 10 to 90%
  • Wet bulb: -5 to 60°C, 0.1° resolution
  • Dew point: -20 to 60°C, 0.1° resolution
  • Wet bulb and dew point are calculated from RH and temperature.

IMPORTANT:

  • Meter is calibrated to a standard 400 ppm CO2 concentration, and 33% and 75% salt solution for RH at the factory.  Do not calibrate otherwise permanent damage could occur.  Contact RGH staff if accuracy of the equipment is questionable.

MATERIALS:

  • Extech CO250
  • Paper towel
  • 2% v/v detergent

METHODS:

  1. Turn the meter on by pressing the SET button. 
  2. Press DP/WBT to toggle between air temperature (AIR), dewpoint (DP), wet bulb temperature (WBT) and desired unit on display.
  3. Press M(N/X)/AV to measure minimum (MIN), maximum (MAX), 15 mins weighted average (STEL) and 8 hours weighted average (TWA).
  4. CO2 reading is readily measured and updated every 30 secs.  RH reading is updated every 30 mins.  DO NOT hold the meter close to your mouth when measuring environmental CO2.
  5. Press HOLD to freeze the current reading on display. 
  6. Press HOLD once more to unfreeze.
  7. Press SET to turn off instrument.
  8. Clean the meter using a damp paper towel and 1% v/v detergent.  Do not use solvents or abrasives.
  9. Remove battery and store.

Optional: Use Extech CO250 with a PC using RS-232 PC interface jack (3.5mm phono) and 407752 Software from http://www.extech.com/software/downloads.  USB-C to RS232 Serial DB9 adapter cable is also provided.

 

Here is a tutorial video:

 

For further and/or more detailed instructions, refer to User’s Guide which can be found either online or with the meter storage itself.  Also read Extech CO250 Datasheet.

You do not need to book this equipment. You may request for Environmental sensor use/other equipment training at Bookitlab Reservations page if you are using the equipment for the first time.

Created by Andrew Yu, Simmi Vasta and Vera Velasco, 20211112

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