I am frequently asked by gas detector users how often they should replace the gas detector sensor.
In fact, there is no fixed maintenance schedule for the sensors of portable gas detectors. You shouldn't think of changing the sensor as changing the gas in your car, it's similar to filling up the gas tank. When the sensor does not have sufficient sensitivity to achieve a successful calibration, it can be considered that the fuel tank is not full and should be replaced. As long as there is "oil in the tank", the sensor will work fine.
Industrial Scientific has a standard way of confirming the status of the sensors to determine how much fuel is left in the tank. It's called retained value. The retained value is a measure of the sensor's sensitivity, obtained when the detector is calibrated. After the detector is calibrated, the retained values for each sensor are displayed and stored in the instrument's calibration record. When the remaining value of the sensor is less than or equal to 50% of the calibration gas concentration, the sensor will fail to calibrate and should be replaced. When the remaining value is between 50% and 70% of the standard gas concentration, it indicates that the sensitivity of the sensor is at the edge, and it is time to consider replacing the sensor.
So the bottom line should be this. As long as your sensor's sensitivity or retention values can be successfully calibrated, they will work fine. The sensor does not need to be replaced until the sensor calibration fails and cannot be used. Keep an eye on the retention value so you don't run into an empty tank.
