a method for calibrating a smoke detector includes adjusting the sensitivity of the smoke detector to get a consistent predetermined response over the expected operating range . the sensitivity is generally consistent for all detectors and an independent offset value is determined for each detector . this offset value basically corresponds to the signal from the detector in a clean atmosphere . the sensitivity of the smoke detector is determined by measuring the response at different levels of obscuration and then appropriately adjusting the output of the light source of the detector . this process is repeated until the desired sensitivity is achieved . thereafter , the offset value is measured or calibrated and stored in the smoke detector for use in setting alarm values .