CO2 Gas Sensor Troubleshooting and FAQs

CO₂ Gas Sensor, order code CO2-BTA, $249
Specifications and User Guide

TROUBLESHOOTING
NOTE: There are two types of CO2 Gas Sensors. One model was sold up to ~1/2007. The new model was sold after 1/07 and replaces the old. There are specifications for both models in this TIL.

-Primary Test: Plug in the sensor, start up 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 older model sensor will max out at 5000 ppm the newer will max out at 10,000 ppm if set to the Low Range and 100,000 ppm if set to the High Range.

-Secondary Test: If the CO2 Gas Sensor is not giving reasonable readings in the Primary Test, try calibrating it. (If you recently blew into it for the Primary Test, wave it around to clear it first.) To calibrate, use a paper clip to press the "Cal" button on the sensor until the red LED begins to flash. You may have to repeat this two or three times for the CO2 value to adjust to around 380-400 ppm. Ideally, this is done in outside air which is around 380 ppm, but for a quick test of the sensor, it can be done in inside air. Just don't forget to recalibrate it in outside air before you want the most accurate values. Note: If the button feels like it's not depressing and the red light does not flash, the button may just be stuck under the edge of the plastic. Use the paper clip to free up the button and try calibrating again.

RELATED TIL ENTRIES
-TIL 1134: Tips for using the CO2-O2 Tee
-TIL 1020: What are the CO2 Gas Sensor power issues? Can I use two CO2 Gas Sensors at the same time?
-TIL 1927: Why does my new CO2 sensor ID as a Current sensor when used with a Go!Link?
-TIL 2318: Can I use a dishwasher to wash the Nalgene Gas Sampling Bottles that shipped with my O2 or CO2 Gas Sensor?
-TIL 2386: How can I insert a CO2 Gas Sensor or O2 Gas Sensor into my own container?
-TIL 2943: The calibration button on my CO2 Gas Sensor is unresponsive.
-TIL 2957: My CO2 Gas Sensor no longer Auto-IDs.

SPECIFICATIONS
- new order code: CO2-BTA
- old order code: CO2-DIN

- Measurement range: 0 - 5000 ppm CO2 (old model); 1-10,000 ppm and 0-100,000 ppm (new model)
OLD 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 impedence: 1 kΩ
- Input potential: 5 V (+/- 5 deg C)
- Gas sampling mode: diffusion
- Normal operating temperature range: 25 deg C (+/- 5 deg C)
- Storage temperature range: -40 to 65 deg C

NEW MODEL SPECS
-- Accuracy
+/- 100 ppm or +/- 10% of reading (low range)
+/- 100 ppm or +/- 20% of reading (high range)
Typical Resolution
-13-bit resolution (SensorDAQ): 1.5 ppm (low range); 15 ppm (high range)
-12-bit resolution (LabPro, LabQuest, Go! Link, ULI, or SBI): 3 ppm (low range); 30 ppm (high range)
-10-bit resolution (CBL 2): 12 ppm (low range); 120 ppm (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: 5V (+/- 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

CALIBRATION
- Calibrate? Usually no.
- If you do find that you need to calibrate your CO2 Gas Sensor, it can be calibrated using one known CO2 level. Note: This calibration method is different from the usual two-point calibration performed using other Vernier sensors. See the Specifications and User Guide for the CO2 Gas Sensor for detailed instructions on how to calibrate.

- If you wish to reset the CO2 Gas Sensor to its factory default calibration values (new model only), press and hold the Calibration button for approximately 5 seconds. The red light will change from flashing to steady. When the light turns off, the sensor will be back to its factory settings for that range.

RELATED VERNIER PRODUCTS
-250 mL Nalgene Bottle w/Lid, order code CO2-BTL, $3
-CO₂ to O₂ Tee, order code CO2-TEE, \Contact Us
BioChamber 250, order code BC-250, $6
BioChamber 2000, order code BC-2000, $19