Chapter 07


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Chapter 07

  1. 1. Fire Alarm System Components and Functions Chapter 7
  2. 2. Learning Objectives <ul><li>Describe a fire alarm system </li></ul><ul><li>List four functions fire alarm systems provide </li></ul><ul><li>List and describe the three types of fire alarm signals </li></ul><ul><li>Discuss the functions of a fire alarm control panel and annunciation panel </li></ul>
  3. 3. Learning Objectives (continued) <ul><li>List and describe the different components that make up a fire alarm system </li></ul><ul><li>List and describe devices that interface with a fire alarm system to supervise the condition of fire protection systems </li></ul>
  4. 4. Introduction <ul><li>Surviving a structure fire depends on time </li></ul><ul><li>Fire alarm system: monitors initiating devices that activate notification appliances </li></ul><ul><ul><li>May provide operational control of other building systems </li></ul></ul><ul><ul><li>Capable of signaling other locations to notify staff </li></ul></ul><ul><ul><li>May perform other life safety functions, such as capturing elevators, releasing exit door locks </li></ul></ul>
  5. 5. Types of Fire Alarm Signals <ul><li>Not all information communicated by the alarm system indicates a fire </li></ul><ul><li>Signal at the panel may indicate system integrity problem or change in normal parameters </li></ul><ul><ul><li>May be mistaken for an alarm, causing fire department to be called </li></ul></ul><ul><li>Many different types of signals are generated by an alarm </li></ul><ul><ul><li>Indicates different levels of response </li></ul></ul>
  6. 6. Alarm Signals <ul><li>Alarm signal alerts occupants of a fire emergency </li></ul><ul><li>Occupants should immediately leave the building, call the fire department, etc. </li></ul><ul><li>Signals sound on operation of initiation device </li></ul><ul><ul><li>Pull station, smoke detector, water-flow switch </li></ul></ul><ul><li>Alarms may sound throughout building, or only on certain floors </li></ul><ul><li>Response should be immediate and urgent </li></ul>
  7. 7. Trouble Signals <ul><li>Trouble signal sounds when there is a problem with system integrity </li></ul><ul><ul><li>Power or component failure, device removal, communication or ground fault, break in wiring </li></ul></ul><ul><li>Typically sounds a constant tone, beep or buzz accompanied by visible light from control panel </li></ul><ul><li>Only maintenance personnel should receive notification </li></ul><ul><ul><li>Fire department response normally not necessary </li></ul></ul>
  8. 8. Supervisory Signals <ul><li>Sound when the normal (ready) status of other fire protection systems or devices (connected to or integrated with the fire alarm panel) has changed </li></ul><ul><li>Uses constant tone and visible light to indicate a condition requires attention </li></ul><ul><li>Responder must investigate </li></ul>
  9. 9. Supervisory Signals (continued) <ul><li>Fire alarm panel may electrically monitor: </li></ul><ul><ul><li>Sprinkler systems and fire pump status </li></ul></ul><ul><ul><li>Air and water temperature </li></ul></ul><ul><ul><li>Water level and pressure </li></ul></ul><ul><ul><li>Duct smoke detector operation </li></ul></ul>
  10. 10. Fire Alarm System Components <ul><li>All components require evaluation and testing for listing and approval </li></ul><ul><li>Some fire alarm system have few components; some have many interconnected components </li></ul><ul><li>Each component has a place and purpose in the system </li></ul><ul><li>Important to understand the components, how they relate, and how they operate </li></ul>
  11. 11. Fire Alarm Control Panel/Unit <ul><li>Point of interface between components, first responders, and alarm system </li></ul><ul><li>Monitors integrity of system circuits and devices </li></ul><ul><li>Processes manual and automatic input signals from initiating devices </li></ul><ul><li>Drives notification appliances </li></ul><ul><li>Provides interface to control or activate other systems in an emergency </li></ul><ul><li>Provides power to support all system devices </li></ul>
  12. 12. Power Sources <ul><li>Power supply component integral to the fire alarm control panel </li></ul><ul><ul><li>Only qualified service personnel need access to the power supply </li></ul></ul><ul><li>Two independent power sources required to operate the alarm system </li></ul><ul><ul><li>Power utility supplies main source of power </li></ul></ul><ul><ul><li>Rechargeable storage batteries provide backup </li></ul></ul><ul><li>Generators: four hours of battery capacity </li></ul><ul><ul><li>Multiple generators with one capable of auto startup </li></ul></ul>
  13. 13. Power Expander Panels <ul><li>When buildings are renovated, old control panels may not have necessary power capacity </li></ul><ul><li>Modern day notification systems use considerable current to operate </li></ul><ul><ul><li>Not always practical to place all power in one panel </li></ul></ul><ul><li>Power expander panels provide supplemental power to support devices </li></ul><ul><ul><li>Act in conjunction with main panel </li></ul></ul><ul><ul><li>Also must have primary and secondary power source </li></ul></ul>
  14. 14. Initiating Devices <ul><li>Initiating devices interface with the fire control panel </li></ul><ul><ul><li>Activation manual or automatic </li></ul></ul><ul><li>Manual activation requires a human to operate the device </li></ul><ul><li>Automatic activation is initiated by events associated with fire </li></ul><ul><ul><li>Exceptions: manual pull stations, valve tamper switches </li></ul></ul>
  15. 15. Manual Initiating Devices <ul><li>Manual pull station, manual station, or manual fire alarm box: main type of initiating device </li></ul><ul><li>Require a person to pull a handle to initiate alarm </li></ul><ul><li>May be the only type of fire protection system installed </li></ul><ul><li>Must be placed in unobstructed, obvious locations </li></ul><ul><ul><li>Normally within five feet of exit doors </li></ul></ul>
  16. 16. Manual Initiating Devices (continued) <ul><li>Operational characteristics: </li></ul><ul><ul><li>Non-coded or coded </li></ul></ul><ul><ul><li>General alarm </li></ul></ul><ul><ul><li>Pre-Signal </li></ul></ul><ul><ul><li>Break Glass or Non-Break Glass </li></ul></ul><ul><ul><li>Single-Action or Double-Action </li></ul></ul><ul><li>Once pulled, requires resetting </li></ul><ul><ul><li>May require special key, wrench, screwdriver </li></ul></ul>
  17. 17. Automatic Initiating Devices <ul><li>Heat detectors: sense temperature fluctuation </li></ul><ul><ul><li>Fixed temperature heat detectors operate when sensing element reaches predetermined temperature </li></ul></ul><ul><ul><ul><li>Spot type and line type </li></ul></ul></ul><ul><ul><li>Rate of rise detectors use electronic method to detect rate of temperature change </li></ul></ul><ul><ul><li>Rate compensation detector not dependent on rates of temperature change </li></ul></ul><ul><ul><li>Fixed temperature/rate of rise heat detectors combine characteristics in one unit </li></ul></ul>
  18. 18. Automatic Initiating Devices (continued) <ul><li>Types of smoke detectors </li></ul><ul><ul><li>Ionization smoke detection </li></ul></ul><ul><ul><li>Photoelectric light scattering smoke detection </li></ul></ul><ul><ul><li>Photoelectric light obscuration smoke detection </li></ul></ul><ul><ul><li>Air sampling smoke detection </li></ul></ul><ul><ul><li>Duct smoke detectors </li></ul></ul><ul><li>Alarm verification validates smoke condition before fire alarm signal sounds </li></ul>
  19. 19. Automatic Initiating Devices (continued) <ul><li>Radiant energy detector looks for light spectrum produced by flames, sparks, embers </li></ul><ul><li>Gas sensing detector detects gases and vapors associated with utilizing hydrocarbons </li></ul><ul><li>Water flow initiating device is a switch wired to the alarm system </li></ul><ul><li>Alarm pressure switch best suited for dry pipe </li></ul>
  20. 20. Figure 7-9 Operational characteristics of automatic fire detectors
  21. 21. Figure 7-10 Line type heat detector
  22. 22. Figure 7-11 Applications of line type heat detection devices include conveyers and cable trays
  23. 23. Figure 7-15 Principle of operation – light scattering photoelectric smoke detector
  24. 24. Figure 7-16 Principle of operation – light obscuration photoelectric smoke detector
  25. 25. Notification Appliances <ul><li>Produce audible and visible signals to prompt evacuation of occupants </li></ul><ul><li>Also may report system problems needing attention </li></ul><ul><li>Type of system and installation location depend on code requirements </li></ul><ul><li>May be simple or complex </li></ul><ul><li>May selectively report to a specific location </li></ul>
  26. 26. Public Mode/Private Mode Notification <ul><li>Public mode: general alarm sounded </li></ul><ul><ul><li>Required by most occupancy conditions </li></ul></ul><ul><ul><li>Installed to be heard throughout the building </li></ul></ul><ul><li>Private mode: alarm sounded at a reduced volume, controlled from a specific location </li></ul><ul><ul><li>Designed to avoid unnecessary movement of occupants </li></ul></ul><ul><ul><li>Appropriate for hospitals, prisons, nursing homes </li></ul></ul>
  27. 27. Coded, Non-Coded, and Textual Signals <ul><li>Alarm systems may provide responders with the location of the fire </li></ul><ul><li>Coded signals generate a predetermined number of visual or audible patterns </li></ul><ul><li>Non-coded signal provides a constant visual or audible signal </li></ul><ul><li>Textual signal may be a voice message over loud speakers, or a text message on the panel </li></ul>
  28. 28. Audible Appliances <ul><li>Audible devices must be at least 15 db above ambient sound level or 5 db above maximum level and last more than 60 seconds </li></ul><ul><li>Types of audible devices: </li></ul><ul><ul><li>Horns : most commonly installed; loud and piercing </li></ul></ul><ul><ul><li>Speakers : most versatile; reproduce many sounds </li></ul></ul><ul><ul><li>Bells : often used for supervisory signals </li></ul></ul><ul><ul><li>Chimes/Buzzers/Sirens/Piezos : used where normal audible devices would startle, or unnerve occupants </li></ul></ul>
  29. 29. Visible Appliances <ul><li>Flashing lights when alarm activates </li></ul><ul><li>Stem from conditions where people will not hear an audible alarm </li></ul><ul><ul><li>Loud ambient noise </li></ul></ul><ul><ul><li>Hearing impaired occupants </li></ul></ul><ul><li>Light intensity measured in candelas </li></ul><ul><li>Flash rate requirement avoids triggering seizures in people with photosensitive epilepsy </li></ul><ul><li>Strobe light standard appliance </li></ul>
  30. 30. Combination Appliances <ul><li>Common for audible and visible appliances to be combined </li></ul><ul><ul><li>Horn/strobe, speaker/strobe, bell/flashing lamp </li></ul></ul><ul><li>Advantages of combination systems: </li></ul><ul><ul><li>Provide needed audibility and light intensity </li></ul></ul><ul><ul><li>Provide visible signal when audible component cannot be heard </li></ul></ul><ul><ul><li>Identify and locate audible device that is sounding outside a cluster of buildings </li></ul></ul>
  31. 31. Annunciator Panels <ul><li>Typically located at or near the front door </li></ul><ul><li>May be additional annunciator panels in larger buildings </li></ul><ul><li>Provides information concerning the device and area where fire is located </li></ul><ul><li>Most provide basic information about the floor, zone, device, and signal </li></ul><ul><li>Graphic annunciator panel most informative </li></ul>
  32. 32. Other Components and Systems Associated with the Fire Alarm Systems <ul><li>Other components send signals to monitor fire protection systems </li></ul><ul><li>Monitor for normal status, system integrity, or alarm conditions </li></ul>
  33. 33. Electronic Valve Supervisory Devices <ul><li>One valve in the wrong position could render entire fire suppression system out of service </li></ul><ul><li>Tamper switches send a supervisory signal to indicate an off normal condition </li></ul><ul><li>Off normal signal sounds if valve off normal position one-fifth of the travel distance </li></ul><ul><li>Reset the switch and fire alarm system with valve in normal position </li></ul>
  34. 34. Other Types of Pressure Switches <ul><li>Pressure switch can generate a supervisory signal when installed on dry pipe, pre-action and pressure tank systems </li></ul><ul><ul><li>Detects drop in air pressure </li></ul></ul><ul><ul><li>Starts an air compressor to increase the pressure </li></ul></ul><ul><ul><li>Compressor turns off automatically when normal air pressure achieved </li></ul></ul><ul><ul><li>If low pressure continues or pressure exceeds maximum threshold, supervisory alarm is signaled </li></ul></ul>
  35. 35. Air and Water Temperature Sensors/Water Level Sensors <ul><li>Monitor temperature conditions </li></ul><ul><ul><li>In rooms housing fire protection and in water in storage tanks </li></ul></ul><ul><li>Early warning that water could freeze and render the system useless </li></ul><ul><li>Detect temperatures higher than necessary for installation conditions </li></ul><ul><li>Water level sensors monitor amount of water in storage tank </li></ul>
  36. 36. Summary <ul><li>Fire alarm systems: </li></ul><ul><ul><li>Notify occupants of fire conditions </li></ul></ul><ul><ul><li>Notify first responders </li></ul></ul><ul><ul><ul><li>Signals onsite and off-site locations </li></ul></ul></ul><ul><ul><li>Signal other building systems </li></ul></ul><ul><ul><li>Provide important information to first responders </li></ul></ul><ul><li>Three types of alarm signals: </li></ul><ul><ul><li>Alarm, supervisory, trouble </li></ul></ul><ul><li>Timing is critical to survival of structure fire </li></ul>