When performing sensitivity testing on a smoke detector, what constitutes a failure, and what actions must be taken?

When performing sensitivity testing on a smoke detector, a failure occurs when the detector's response falls outside the manufacturer's specified sensitivity range or the limits defined by applicable codes and standards, such as NFPA 72. Sensitivity testing involves using calibrated aerosol generators or other testing devices to introduce a known concentration of smoke or aerosol into the detector's sensing chamber. The detector's response, typically measured in terms of obscuration per foot or percentage obscuration, is then compared to the acceptable range. A detector fails the test if it does not alarm within the specified sensitivity range, alarms outside the acceptable range (either too sensitive or not sensitive enough), or fails to alarm at all within the testing parameters. For example, if a detector is supposed to alarm between 2% and 4% obscuration per foot, and it alarms at 1% or 5%, or does not alarm even at 6%, it has failed the sensitivity test. When a smoke detector fails sensitivity testing, several actions must be taken. Firstly, the detector should be cleaned according to the manufacturer's instructions to remove any accumulated dust or debris that may be affecting its performance. Secondly, if cleaning does not resolve the issue, the detector must be adjusted or recalibrated, if the detector allows for field calibration. Thirdly, if adjustment or recalibration is not possible or does not correct the problem, the smoke detector must be replaced with a new or properly re-certified detector. Lastly, all test results, cleaning attempts, adjustments, and replacements must be documented in the system's inspection and testing records. Failing to address a failed sensitivity test compromises the detector's ability to reliably detect smoke, potentially delaying or preventing alarm activation during a fire.