Fire Alarms & Detection: Smoke Detector Sensitivity

In other than one- and two-family dwellings, system detectors or singleor
multiple-station smoke alarms should be subjected to a sensitivity test
within one year after they are installed. The test is intended to ensure
the sensing chamber remains calibrated within the sensitivity range
established by the manufacturer. If a detector is too sensitive, it will be
susceptible to nuisance alarms. If it is not sensitive enough, it may not
operate in the presence of smoke.
According to the National Fire Protection Association (NFPA) 72, National
Fire Alarm Code®, the sensitivity should be checked and calibrated every
alternate year after the first test. If, however, after the second required
calibration test, sensitivity tests show that the device has remained within
its listed and marked sensitivity range (or 4-percent obscuration light gray
smoke if not marked), the length of time between calibration tests may be
extended to 5 years.
For sensitivity tests, any of the following tests may be performed to ensure
that each detector is within its listed and marked sensitivity range:
1. Using a recognized, calibrated test method with smoke or listed
aerosol. This testing device provides a calibrated release
of artificial smoke. It tests detector performance and can be used to evaluate
the sensitivity.
2. Using the detector manufacturer’s calibrated sensitivity test
instrument.
3. Using listed control equipment (fire alarm control panels) that are
arranged to perform sensitivity tests.
4. Using a combination smoke detector/control unit where the detector causes a signal at the control unit when
its sensitivity is outside its listed sensitivity ranges.
5. Using any other calibrated sensitivity test methods approved by the code official.
Note that for the sensitivity tests, it is not required that smoke or aerosol be introduced into the detector.
However, when conducting a performance test—to ensure that the detector senses smoke and generates an
alarm—smoke or listed aerosol must enter the detection chamber. Performance tests and sensitivity tests are
intended to achieve different results: the first is to ensure the device works, the second is to verify it remains
within its listed range.

For additional information, refer to NFPA 72,2010, Chapter 14.4.2.2.14(g)