All gas detectors require periodic calibration to compensate for sensor variations over time.
Calibration aligns the sensor signals to the instrument display. For example, if an instrument is exposed to 100 ppm CO, the instrument display should read 100 ppm. Calibration is performed by applying a known calibration gas to an instrument and dialing a potentiometer or pushing buttons to make the instrument read what it should. Calibration should only be performed by suitably trained individuals. Some instruments or sensors may require special blends of gases, a specific background gas, or absence of a particular background gas.