Chapter 2.ppt

Fire Detection and Suppression

Chapter 2Fire Detection and Signaling Systems

Fire Detection and Signaling Systems2-*Fire Detection and Signaling Systems

The early detection of a fire and the signaling of an appropriate alarm remain the most significant factors in preventing large losses from occurring.

Fire Detection and Signaling Systems

Fire Detection and Signaling Systems2-*Standards and CodesComponent tests by nationally recognized labsUnderwriters LaboratoriesFactory MutualCodesNFPA 70, National Electrical CodeNPFA 72, The National Fire Alarm CodeLocal codes and ordinances


Fire Detection and Signaling Systems2-*Basic System ComponentsSystem control unit (alarm panel)Brain of systemProcesses alarm signals from actuating devices and transmits them to the local or other alerting system


Fire Detection and Signaling Systems2-*Basic System Components (cont.)Power supplyPrimary power supplyPublic electric utilityEngine-driven generatorSecondary power supplyStorage battery and chargerEngine-driven generator and 4-hour storage batteryMultiple engine-driven generatorsTrouble signal power supply


Fire Detection and Signaling Systems2-*Basic System Components (cont.)Initiating devices: manual pull stations, heat detectors, smoke detectors, flame detectors, waterflow devices, tamper switches, and combination detectorsNotification appliances: bells, buzzers, horns, recorded voice messages, strobe lights, speakers, and other warning appliancesAuxiliary services


Fire Detection and Signaling Systems2-*Types of Fire Alarm SystemsSelection factorsLevel of life-safety hazardStructural features of the buildingLevel of hazard presented by the contents of the buildingAvailability of fire suppression resourcesState and local code requirements(Continued)


Fire Detection and Signaling Systems2-*Types of Fire Alarm Systems (cont.)Local systemNoncoded local alarmSimultaneous operation of all alarm-indicating devicesOnly practical in small occupancies with limited number of roomsMaster coded local alarmServes the premises as a local control unit and receives input from other fire alarm control unitsUsed in occupancies that use the alarm signals for other purposes(Continued)


Fire Detection and Signaling Systems2-*Types of Fire Alarm SystemsLocal system (cont.)Zoned/annunciated alarmIdentifies fire location quickly and accuratelyAlarm-initiating devices arranged in circuits or zonesInitiating device sounds alarm and lights corresponding lamp on control unitAnnunciator panel remote from control panelCoded signalsPresignal alarm(Continued)


Fire Detection and Signaling Systems2-*Types of Fire Alarm Systems (cont.)Auxiliary systemFacility that receives signals where personnel are always present to respondInitiation devicesLocal requirements and policiesTypes of auxiliary systemsLocal energy systemShunt systemParallel telephone system(Continued)


Fire Detection and Signaling Systems2-*Types of Fire Alarm Systems (cont.)Remote station systemConnected to dispatch center by means other than municipal fire alarm box systemLocal alarm capabilityMonitoring options(Continued)


Fire Detection and Signaling Systems2-*Types of Fire Alarm Systems (cont.)Proprietary systemUsed to protect large buildings or facilitiesSystems for individual buildings or areas wired into common receiving pointWide-ranging capabilities(Continued)


Fire Detection and Signaling Systems2-*Types of Fire Alarm Systems (cont.)Central station systemSimilar to proprietary system but receiving point is an outside, contracted central stationAlarm activation information received by central station employees, who initiate emergency response(Continued)


Fire Detection and Signaling Systems2-*Types of Fire Alarm Systems (cont.)Emergency voice/alarm communications systemSupplements other systemsCommunicates detailed information to occupants and fire fighting personnelOne-way/two-way


Fire Detection and Signaling Systems2-*Manual Alarm-Initiating DevicesGeneral requirementsMounting and distributionGenerally not required in fully sprinklered structuresOutmoded broken glass pull stationsCoded versus noncoded pull stationsSingle-action and double-action pull stations


Fire Detection and Signaling Systems2-*Automatic Alarm-Initiating DevicesContinuously monitor atmosphereFour basic typesHeat detectorsSmoke detectorsFire-gas detectorsFlame detectors


Fire Detection and Signaling Systems2-*Heat DetectorsFixed temperature heat detectorsFusible links/frangible bulbsContinuous line detectorBimetallic detectorRate-of-rise heat detectorPneumatic rate-of-rise spot detector (Fig. 2.34)Pneumatic rate-of-rise line detector (Fig. 2.35)Rate compensated detector (Fig. 2.36)Thermoelectric detector


Fire Detection and Signaling Systems2-*Smoke DetectorsPhotoelectric smoke detectorProjected beam (Fig. 2.37)Refractory photocell (Fig. 2.38)Ionization smoke detector (Fig. 2.39)Dual chamberAir-sampling smoke detectorsCloud chamber (Fig. 2.40)Second type (Fig. 2.41)(Continued)


Fire Detection and Signaling Systems2-*Smoke Detectors (cont.)LimitationsMay not provide early warning of a fire developing on another level of a buildingMay not detect fire developing on the other side of a closed doorMay not be effective when fire is caused by explosions resulting from careless housekeeping


Fire Detection and Signaling Systems2-*Flame DetectorsTypesUltraviolet (UV) Fig. (2.42a)Infrared (IR) Fig. (2.42b)Fast to respondFrequent false alarms


Fire Detection and Signaling Systems2-*Fire Gas DetectorsMonitors levels of gases released by combustionCarbon dioxideCarbon monoxideFaster than heat detectors but slower than smoke detectors


Fire Detection and Signaling Systems2-*Combination DetectorsVarious possible combinationsFixed rate/rate-of-rise detectorsHeat/smoke detectorsSmoke/fire gas detectorsOffer benefits of both systems and increase responsiveness to fire conditions


Fire Detection and Signaling Systems2-*Acceptance TestingShould be observe by representatives of building owner, fire department, system installer, and system manufacturer.All functions of the fire detection and signaling system should be operated:All alarm-indicating and alarm-initiating devicesRestorable heat detectorsResponse of outside entities responsible for monitoring the system


Fire Detection and Signaling Systems2-*General InspectionsFire department participationCheckpointsCondition of wiring and batteriesAll equipment free of foreign materialsAdequate clearance around system control units, recording instruments, and other devices


Fire Detection and Signaling Systems2-*Inspecting and Service Testing Initiating Devices (cont.)Manual alarm-initiating devicesAutomatic alarm-initiating devicesDetectors must not be damaged or painted.Replace or send the following detectors to a recognized testing laboratory for testing:Detectors on systems that are being restored to service after a period of disuseDetectors that are obviously corroded(Continued)


Fire Detection and Signaling Systems2-*Inspecting and Service Testing Initiating Devices (cont.)Automatic alarm-initiating devicesReplace or send the following detectors to a recognized testing laboratory for testing (cont.):Detectors that have been painted over, even if attempts were made to clean themDetectors that have been mechanically damaged or abusedDetectors on circuits that were subjected to current surges, overvoltages, or lightning strikes(Continued)


Fire Detection and Signaling Systems2-*Inspecting and Service Testing Initiating Devices (cont.)Automatic alarm-initiating devicesReplace or send the following detectors to a recognized testing laboratory for testing (cont.):Detectors subjected to foreign substances that might affect their operationDetectors subjected to either direct flame, excessive heat, or smoke damageTestingNonrestorableRestorable


Fire Detection and Signaling Systems2-*Inspecting System Control UnitsControl panel switches and functionsAuxiliary devicesReceiving signals


Fire Detection and Signaling Systems2-*System Testing TimetablesLocal systems: local guidelinesCentral station systems: monthlyAuxiliary systems: monthly (noncoded fire alarm boxes: monthly)Remote station and proprietary systems: authority having jurisdictionEmergency voice/alarm systems: quarterlyNOTE: In all cases, check the most current edition of NFPA 72, National Fire Alarm Code.


Fire Detection and Signaling Systems2-*Record KeepingMaintaining Files and RecordsDocuments:Inspection reports, forms, and lettersViolation noticesSummonsesPlans review comments, approvals, and drawingsFire reportsInvestigationsPermits and certificates issued(Continued)


Fire Detection and Signaling Systems2-*Record KeepingMaintaining Files and Records (cont.)Occupancies:Those that have been issued a permit, certificate, or licenseThose that contain automatic fire suppression or detection systemsThose that conduct hazardous operations or routinely house hazardous materialsDuration: life of structurePublic record(Continued)


Fire Detection and Signaling Systems2-*Record Keeping (cont.)Written recordsFile for each inspected propertyCataloging and storageElectronic records Two primary methods of entering data:Inspectors use laptop computers or handheld electronic data recording equipment during the inspection.Inspectors use written forms during the inspection and then enter the information upon returning to the office.(Continued)


Fire Detection and Signaling Systems2-*Record Keeping (cont.)Electronic records (cont.)Considerations in computer system managementHow will the information be filed?How can the information be retrieved?What portion of the information will be stored in a read-only format?What personnel will be given access to retrieve information from the system? What information can be released to the public?


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