What does the “Sensor Gauge” on the channel module measure?
The “Sensor Gauge” measures the sensitivity of the sensor. This is the amount of milli-volts that the sensor outputs for each percent LEL of the gas being measured. Typically, as the sensor ages, wears, or becomes dirty the sensitivity will decrease (fewer milli-volts will be generated per percent LEL). A typical sensor will output approximately 3mV per LEL, but this varies from sensor to sensor and changes with the gas being measured. Because of this variance, the scale on the model 1220 is adjustable and is referenced to a calibrated sensitivity. During the first calibration, you may set the sensitivity gauge to full-scale by using the left and right arrows to adjust the gauge to 100 %. After setting the gauge to 100%, the present sensitivity becomes the reference for future gauge displays. With each subsequent calibration, the sensitivity gauge will adjust to show how much the sensitivity has dropped since the first calibration.
