CO2 Gas Sensor (CO2-BTA)
Specifications and User Guide

Troubleshooting

Note: There are three types of CO2 Gas Sensors. One model was sold up to about January 2007, then replaced with another model from 2007 until May of 2023.  The newest model was introduced in June 2023. Specifications for all three models are in this article.

Primary Test: Plug in the sensor, start the data-collection program, and allow the sensor to warm up for at least 90 seconds. Blow directly on the shaft of the sensor. You should see an increase in CO2 levels. The pre-2007 model will max out at 5000 ppm. The post-2007 models will max out at approximately 10,000 ppm if set to the Low Range and 100,000 ppm if set to the High Range (although your breath will probably not reach 100,000 ppm).

Secondary Test: If the CO2 Gas Sensor is not giving reasonable readings in the Primary Test, try calibrating it. Note: If you recently blew into the sensor for the Primary Test, fan it with fresh air to clear it first.

Calibration

Calibration is usually not necessary, but if needed, it is best to calibrate outdoors in fresh air. To calibrate, use a paper clip to press and release the “Cal” button on the sensor. The red LED should begin to flash. If you hold it so long that it is a solid red, you have reset the factory calibration. If this happens, simply press and release again. You may have to repeat this two or three times for the CO2 value to adjust to around 400 ppm. Remember that the accuracy is +/- 100 ppm at this range, so it may not read exactly 400 ppm. While calibration is best performed in outside air, which is around 400 ppm in unpolluted air, it can be done in inside air for a quick test of the sensor.  Note: If the button feels like it’s not depressing and the red light does not flash, the button may be stuck under the edge of the plastic. Use the paper clip to free the button and try calibrating again.

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Specifications

New order code: CO2-BTA (2007 to present)
Former order code: CO2-DIN/CO2-BTA (prior to 2007)

Measurement range: 0-5000 ppm CO2 (old model); 1-10,000 ppm and 0-100,000 ppm (new model)

Pre-2007 Model Specs

Accuracy (at standard pressure, 1 atm):
+/- 100 ppm in the range of 0–1000 ppm
+/- 10% of reading in the range of 1000–5000 ppm
Typical resolution, old model: 20 ppm
Response time: 95% of full-scale reading in 120 seconds
Warm-up time (connected to powered interface): 90 seconds
Output signal range: 0–2.5 V
Output impedance: 1 kΩ
Input potential: 5 V (+/- 0.25 V)
Gas sampling mode: diffusion
Normal operating temperature range: 25 deg C (+/- 5 deg C)
Storage temperature range: −40 to 65 deg C

Post-2007 Model Specs

Accuracy
+/- 100 ppm or +/- 10% of reading (low range)
+/- 200 ppm or +/- 20% of reading (high range)
Response time: 95% of full scale reading in 120 seconds
Warm up time: 90 seconds
Pressure effect: 0.19% of reading/mm Hg from standard pressure
Output signal range: 0-4.0 V
Input potential: 5 V (+/- 0.25 V)
Gas sampling mode: diffusion
Normal operating temperature range: 25 deg C (+/- 5 deg C)
Operating humidity range: 5–95% (non-condensing)
Storage temperature: −40 to 65 deg C

Related Vernier Products

250 mL Nalgene Bottle w/Lid (CO2-BTL)
BioChamber 250 (BC-250)
BioChamber 2000 (BC-2000)