CO2 concentration in the air of growing rooms is measured by sensors with a range from 0 to 5000 ppm (0 to 5%). The measurement error should not exceed 100 ppm.
These requirements correspond to the sensors which operation is based on the use of infrared rays. In a factory their calibration is made by specially prepared gas mixtures with a known CO2 concentration.
Mushroom growing farms do not have such equipment, so CO2 sensor is calibrated by outside air. Under the outside air means the air in a green area, far from the industrial sources of CO2 concentration (mushroom farms, barns, factories, motorways etc.).
In the open air CO2 concentration is nearly constant in every specific place, but its absolute value depends on the region. In rural areas, CO2 content in the fresh air is 350-450 ppm, in the industrial regions and big cities CO2 content reaches up to 600 ppm.
We recommend the mushroom growers to choose a convenient point for measuring CO2 concentration outdoors – a well ventilated green area a few kilometers from the mushroom farm.
Immediately, after receiving the CO2 sensor from the factory, it is necessary to measure CO2 level outside and write this value.
When using the sensor the mushroom grower should periodically measure CO2 concentration at the selected point. If CO2 sensor indications at this point deviated by more than 100 ppm from the original, it should be sent to the manufacturer for its calibration or be calibrated by outside air on your own.