I have bought a MQ135 gas sensor. I have read online from multiple sources that a calibration/warm-up period of between 12-24hrs is required for the sensor to give its most accurate readings. I currently have it attached to one of my UNO's just spitting out Analog readings to the Serial monitor and seems (just after an hour!) to have settled at a reading of 50 which it has stayed at now for a period of around 20 minutes. My questions surrounding this process really are:
- What is the point in doing this process if when a project that uses this sensor is powered off for some number of hours? Will you have to let it warm-up/calibrate again before having faith in the readings?
- How do I actually identify PPM for a gas such as C02? Is there some form of constant that I should be comparing the reading obtained to or something similar?