Gemini 501-B User Manual
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Contents
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115.0 Inspection Protocol and Test Procedures5.1 General ObjectiveThe Gemini 501-B Analyzer was designed to perform on-site inspections of installed smoke detectors todetermine their sensitivities. Sensitivity is defined as the amount (concentration in mg/m3 or obscuration in%/ft) of smoke needed to trigger the alarm of the detector under test.Normally only a single test is needed for routine sensitivity inspection of detectors. To assure such anoutcome, choose a smoke concentration at the upper limit of the sensitivity range specified by themanufacturer (usually located on the back of the smoke detector). The detector should alarm since it isstatistically the highest concentration allowable by the manufacturer. However, if the above detector did notalarm, you have to do additional tests to determine the concentration that would trigger the detector.In cases where the detector has a history of nuisance (false) alarm, you may have to do two or more tests tofind the lowest concentration level below which the detector would not alarm.Figure 2 (page 12) contains an example in selecting the smoke concentration settings for sensitivity testsunder the NFPA 72 National Fire Alarm Code (1996) requirements. To get higher test precision than theroutine inspection requirement, use an increment of 0.2 %/ft instead of 0.5 %/ft. You may also want toestablish other test criteria by consulting with your state Fire Marshall and manufacturers to fit your ownneeds and resource. Record all data by using either the sample test report in APPENDIX C or your ownrecording method.5.2 Legal and Technical AuthoritiesSmoke detector inspection and sensitivity testing techniques are based ONLY on the following threerecognized authorities:The National Fire Protection Association (NFPA) publishes the NFPA 72 National Fire Alarm Code (1996). Itrecommends evaluation of smoke detector sensitivity within one year after installation and everyalternate year thereafter. The recommended test methods include the use of smoke aerosol andcalibrated sensitivity test instrument to verify the approved or manufacturer specified sensitivityrange.Underwriters Laboratories, through its UL-268 standard, considers detectors to be acceptable if its sensitivityare between 0.5 to 4.0 %/ft obscuration when exposed to the visible (gray) smoke in a UL smokechamber. This standard applies only if the manufacturer has not specified the sensitivity range.Authority Having Jurisdiction (AHJ). The Fire Marshal or Fire Chief at the state or local level is responsiblefor enforcing their published standards or codes. These standards generally follow some nationalstandards with or without modification to suit the local need. For example, the Boston FireDepartment requires detectors located in elevator waiting areas to meet a sensitivity of 3.0 %/ft orhigher. This is to avoid frequent false alarms from smoldering cigarettes that passengers leave priorto boarding the elevators. |
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