We received the CO2 within a couple of days (from Hong Kong to Belgium) The sensor works as a charm, the data seems to be correct. At the moment, we read the data via the arduino serial output. The LCD screen was not yet showing data as we may have used the wrong LiquidCrystal_I2C library. But since we're not yet using the screen, we have all we want. Thanks. A small aircraft will do measurements in the atmosphere. (as a high school science project)
I needed a easy to use Co2 meter that wasn't expensive for testing air quality in some buildings. The K30 sensor have been a good choice. It have been very easy to interface with an Arduino, although I used the serial connection instead of the reccomended SPI interface. The sensor gives a correct reading only 4 seconds after the Powerup.