Installation and Calibration of the DXC220 (CO2) in an Incubator

General information

The DXC220 is an USB sensor for carbon dioxide (CO2) in very demanding, even hostile environments. This instrument covers the range of 0 to 20% in CO2 concentration.

These units are calibrated in Dracal Technologies' factory, at a certified CO2 concentration level of 5%, at ambient temperature and relative humidity levels. These calibration conditions have been determined to cover a wide range of applications. However, when the conditions of use are different from the above calibration conditions, such as in an incubator situation, it is necessary to recalibrate the instrument to ensure an optimal degree of accuracy. But why?

Why do I need to calibrate my DXC220 for incubator use?

All Dracal Technologies sensors incorporate electronics that are sensitive to their environment. While this sensitivity allows for a level of accuracy that meets the highest scientific standards, it also implies that in order to obtain the most accurate measurements possible, the instrument needs to be calibrated in its final operating environment. This is the particular case of the DXC220 used in incubator conditions.

Since the relative humidity and temperature in an incubator situation are considerably higher than the factory calibration conditions, the CO2 levels returned are affected by these extreme operating conditions. As the CO2 reading mechanism of the DXC220 is based on a light wave absorption rate measurement principle, the high relative humidity level has a particularly important impact on the CO2 reading.

Also, as Dracal Technologies applies a calibration at a concentration level of 5% CO2, this means that the accuracy of the DXC220 when received by the user is optimal around this specific concentration level. If the user's use-case is at another concentration level (e.g. closer to 0%, or 10%), it is strongly recommended to calibrate the sensor at CO2 levels similar to the final use case in order to improve its accuracy.

This is why all our CO2 sensors (DXC120 and DXC220) provide a free one-point calibration mechanism for their CO2 reading channel.

Installation and calibration of the DXC220 in an incubator

1. Installation

In the case of calibration with a certified gas cylinder, remove the black cap that blocks the direct gas inlet to the instrument, by pushing on the blue ring that holds it. Insert one end of the orange tube that came with the instrument. Attach the other end of the orange tube to your gas cylinder.

Spray your instrument properly with disinfectant solution to avoid contamination of your culture elements.

Place your instrument in an upright position in your incubator. If you have a version that also has an external temperature and relative humidity sensor, it is important to place the probe so that its head points downward to avoid dripping in case of condensation.

Most incubators have an opening for the passage of wires inside the incubator. Take advantage of this opening to let the USB wire out.

The instrument has holes for attachment. A simple nylon cable tie is enough to install the instrument in its final position.

2. Quick verification

Check out our video tutorials where each tab of the software is presented in less than 3 minutes.

Plug in your sensor and, using DracalView, quickly validate your readings by displaying graphically via the Graph View tab the CO2 GAS PPM channel (filtered). You can also display any other channel of your choice. If you don't know which one to choose, simply display them all. Keep the graphical recording task running and make sure that it is configured to display historical data over a one week period.

It is also recommended that you run a logging task for all DXC220 channels in the Logging tab to ensure easy and secure redundancy of your valuable data.

3. Allow 7 days for adaptation

Let your instrument plugged in and powered for 7 days, under its final conditions of use, to let it adapt to its environment. Use Graph View to evaluate the stability of the readings.

4. Calibrate

Once the temperature, relative humidity and CO2 readings have stabilized, calibrate your instrument. If you are calibrating from a certified gas cylinder, open your cylinder and allow the reference gas to flow into the instrument at a rate of .4 LPM. Look closely at the graph of the CO2 channel reading to determine when it has stabilized.

Important Note: Stay close to your instrument. For best results, it is recommended to calibrate the instrument as soon as possible after the readings stabilize, in order to limit changes in the internal conditions of temperature and relative humidity of your instrument. Indeed, the gas you are injecting is cooler and less humid than your operating conditions, and it is important to limit the impact of these different conditions on your instrument. So be prepared to calibrate as soon as the opportunity arises.

Click on the "Calibrate" button to the right of the CO2 GAS PPM (instant) channel to open the calibration window. Enter, in ppm, the reference CO2 level, i.e. the one that should be returned at the precise moment of calibration. In particular, if you are calibrating from a certified gas cylinder, simply enter the concentration of the gas in question.

This operation is irreversible, but can be performed an unlimited number of times. The calibration applied in this way takes into account the internal temperature parameters in order to ensure temperature compensation and to provide better accuracy for different temperature conditions.

5. Complete the calibration

For those calibrating with a gas cylinder, be sure to close the cylinder. You can also quickly remove the orange tube from your instrument (by pushing the blue ring) and reinsert the black cap that was initially removed.

6. Visualize, measure and integrate

Your instrument is now calibrated and ready to use. Using the DracalView software, you can instantly view and log your data. It is also possible to easily redirect your data into your own software with our dracal-usb-get command line tool, which is automatically downloaded when installing DracalView.

Conclusion

Once calibrated, your DXC220 allows you to measure CO2, temperature, and relative humidity levels 7 days a week, 24 hours a day, at temperatures up to 70°C and relative humidity up to nearly 100% (as long as condensation conditions are not reached).

If you have any other questions regarding the installation and calibration of your DXC220, please contact us and we will be happy to provide you with all the necessary support to allow you to move forward with your project as quickly as possible.