Temperature sensors remain accurate for a while without recalibration as long as the application conditions are within the operating range and the sensors are not damaged.For gas detectors, this depends on the sensor technology and application. Electrochemical gas sensors require field recalibration every 6 months. Metal oxide semiconductor sensors should be recalibrated every 12 months. Catalytic (pellistor) sensors should be recalibrated every 3...6 months. The optical sensor may be calibrated every five years if used under moderate conditions without strong temperature fluctuations. PID sensors need to be recalibrated monthly or more frequently depending on operating conditions. PID sensors acquire frequent calibration and maintenance, please see directions on the Calibration and maintenance section in the user manual.