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Intro to basic fire alarm technology
This document provides an overview of basic fire alarm technology, including the components that make up a fire alarm control system. It describes the main controller as the "brains" that provides power and monitors inputs and outputs. It also discusses initiating devices like smoke detectors and manual pull stations that activate the system, as well as notification appliances like horns and strobes that provide outputs. The stages of a fire are outlined to explain what type of detection technology works best at each stage. Common detector types, manual call points, and notification devices are also defined.
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Intro to basic fire alarm technology
- 1. Intro to Basic FireAlarm Technology Silent Knight :: 7550 Meridian Circle :: Maple Grove, MN 55369 :: 800-328-0103 1
- 2. Basic Fire Let’s examinethe components that make a basic Fire Alarm Control System. 2
- 3. Main Controller • Thebrains of the system • Provides power to the system, monitors inputs and controls outputs through various circuits • Performs other functions as required by the appropriate code 3
- 4. Elements of aControl Panel Requires two Power Sources Primary (AC) Secondary (DC) 4
- 5. Elements of aControl Panel Inputs A fire alarm system can have a variety of input devices. Smoke Detector Manual Pull Station 5
- 6. Inputs • Initiating Device:A system component that originates transmission of a change of state condition, such as a smoke detector, manual fire alarm box, supervisory switch, etc... • Initiating Device Circuit (IDC): A circuit to which automatic or manual initiating devices are connected where the signal received does not identify the individual device operated 6
- 7. Elements of aControl Panel Outputs Horns Strobes 7
- 8. Outputs • Notification Appliance:A fire alarm system component such as a bell, horn, speaker, light, or text display that provides audible, tactile, or visible output, or any combination thereof. • Notification Appliance Circuit: A circuit or path directly connected to a notification appliance. 8
- 9. The Basic System MainController Inputs Primary (AC) Outputs Secondary (DC) 9
- 10. Basic Fire AlarmTechnology • Signal Initiation/Initiating Devices Need to understand stages of fire and what technology works best for each 10
- 11. The Stages ofa Fire • Stage One Incipient: Products of Combustion particles are produced (<0.3 microns). No visible smoke or detectable heat. May occur for milliseconds or days. • Use ionization detectors 11
- 12. The Stages ofa Fire • Stage Two Smoldering: Visible smoke particles are produced (>0.3 microns). Little visible flame or noticeable heat. • Use Photoelectric Detectors 12
- 13. The Stages ofa Fire • Stage Three Flame: Rapid combustion produces radiant energy in the visible, and invisible (IR, UV) spectrums. Heat begins to buildup at this stage • Use Spark or Flame Detectors 13
- 14. The Stages ofa Fire • Stage Four High Heat: Uncontrolled combustion is caused by the heating of nearby combustibles to their ignition point. • Use Heat Detectors Note! Major disadvantages of using thermal energy for fire identification are • Takes a while for a fire to be recognized • The toxic gases that are produced before an alarm point is reached 14
- 15. Types of Detectors •Photoelectric • • • Light Scattering Light Obscuration Ionization Duct Heat (Thermal) 15
- 16. Photoelectric Smoke Detectors: Light-Scattering Type •Uses a Light-Emitting Diode (LED) that sends a beam of light into a dark chambera photo diode sits on the other side of a partition within the chamber • Smoke particles entering the chamber deflect some of the light rays into the photo cell. The photo cell generates a current when exposed to light, and if the current reaches a certain level, the detector alarms. 16
- 17. Photoelectric Smoke Detectors: LightObscuration Type • In a projected Beam Detector, alarms are generated by diffusing the projected light beam by a specified percentage of obscuration. • Total beam blockage generally results in a trouble signal. 17
- 18. Ionization Smoke Detectors •Contain a small amount of radioactive material encapsulated in a metal chamber. Ionizing radiation develops a low, but steady electrical current. Smoke particles entering the chamber disrupt the current and trigger the detector's alarm. • Ion detectors react more quickly to fast flaming fires that give off little smoke. 18
- 19. Heat Detectors • FixedDetectors: Alarm when the sensing element reaches a certain set point. Two common models have 135 and 200-degrees F range. Fixed element is generally a non-restorable type, and when activated, must be replaced. • Rate-of-Rise Detectors: Respond when the rate of temperature increase is greater than an allowable limit (15 degrees in 60 secs.) (placement in a stable environment) (e.g.. ovens, heating vents, etc.). The Rate-of-Rise element is restorable when conditions return to normal. • Rate Compensation will respond regardless of the rate of temperature rise. 19
- 20. Duct Detectors • Photoelectricdetector mounted in housing outside the ductwork that has probes that extend into the duct to sample the air inside the duct. • Primarily used as a smoke control device to control the flow of air in ductwork. 20
- 21. Initiating Devices Manual FireAlarm Stations • Manually-operated device used to initiate an alarm signal Single Action Stations require a single operation to activate it. Generally a pulling down action. Dual Action Stations require two distinct operations. A set-up and an activating action. 21
- 22. Notification Appliances Types •Audible - Horns, Bells, Sounders, Sirens, Chimes, Speakers • Visual - Strobes • Physical - Bed shakers • Olfactory - Smell 22
- 23. Audible Devices • Bells:Used if they are only for fire, or have a distinctive sound from other bell signaling devices. Often used as an external gong to indicate the flow of water in the sprinkler system. • Horns: Loud and distinctive output. Often used in highnoise environments, such as manufacturing plants. 23
- 24. Audible Devices • Sounders:Electronic or mechanical audible devices, which are capable of producing a variety of tones. Often, the tone is selectable during installation of the device. • Chimes: Soft-toned appliances used where loud noises could be disruptive to other operations. Generally used where qualified personnel are continuously in attendance. 24
- 25. Audible Devices • Sirens:Extremely loud devices generally limited in use to outdoor or heavy industrial areas. • Speakers: Audible devices used in conjunction with voice evacuation messages. Life-Safety speakers are not generally associated with Muzak systems. 25
- 26. Visual Signaling Appliances Visual signalingappliances are used in high-noise environments, in areas occupied by hearingimpaired individuals, or in areas where audible devices may not be desired. 26
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- 29. Types of FireAlarm Control Panels • Conventional (hard wired) Fixed Programmable • Addressable (multiplexed) • Intelligent (analog data transfer) 29
- 30. Conventional “Hard Wired” System •Simplest type of control unit. • Generally, a single circuit board contains power supply, control, initiating and notification circuitry. • Some models use auxiliary circuit boards to perform special functions. • Input/output devices connect to dedicated circuits. • Designated outputs occur when initiating signals are received. • Limited special functions and capabilities. 30
- 31. Conventional “Programmable” System • Basic“Designed System” • Components selected by the designer to meet the direct needs of the customer. • Initiating circuits are programmable for fire, waterflow, supervisory service, etc. • Output circuits are programmable for code selection and silenceability. • On some systems, input-to-output CIRCUIT (not device) mapping. 31
- 32. Addressable System • Eachdevice (detector, pull station…) has a unique number assigned to it called the address for reporting alarms and troubles. • Employs a Signaling Line Circuit (SLC) Loop along which all addressable input and output devices are connected to the fire alarm control panel. • Addressable devices transmit an electronic message back to the Control Unit representing their state (Normal, Alarm, Trouble) when polled by the Control Unit. 32
- 33. Analog System • Alwaysan Addressable System. • Processes detailed, analog data from detectors about smoke levels. • Can provide sensitivity data for each detector. • Employs Drift Compensation (self calibration) in its detectors. 33
- 34. Terminology • • • • • • • • • • • • FACP - FireAlarm Control Panel. FACU - Fire Alarm Control Unit. FCC - Federal Communications Commission UL - Underwriters Laboratories NFPA - National Fire Protection Agency. AHJ, LAHJ - Authority Having Jurisdiction, Local AHJ ADAAG - Americans with Disabilities Act Accessibility Guidelines. PoC - Products of Combustion LED - Light Emitting Diode IDC - Initiating Device Circuit NAC - Notification Appliance Circuit ELR, EOL - End of Line Resistor 34
- 35. Terminology • • • • • • • • • • • • NEC - NationalElectrical Code (NFPA 70) NEMA - National Electrical Manufacturing Association EIA - Electronics Industry Association Cd - Candela dB, dBA - Decibels FWR - Full Wave Rectified ANSI - American National Standards Institute PIV - Post Indicator Valve OS&Y - Outside Stem and Yoke Valves SFPE - Society for Fire Protection Engineers Shall - Indicates a mandatory requirement Should - Indicates a recommendation or advisement 35
- 36. References • • • • • • • NFPA 70 -National Electrical Code NFPA 72 - National Fire Alarm Code NFPA 101 - Life Safety Code National Electrical Code Handbook, NFPA Life Safety Code Handbook, NFPA Fire Protection Handbook, NFPA Fire Alarm Signaling Systems, NFPA 36
- 37. Basic Fire Alarm Technology Pleasevisit www.farenhyt.com for fire alarm system solutions for your facility Silent Knight :: 7550 Meridian Circle :: Maple Grove, MN 55369 :: 800-328-0103 37
Editor's Notes
- #4 Nicknames for the main controller. Main Board, Main Controller, Motherboard, Central Processing Unit (CPU) Also includes a user interface (keypad) and locked enclosure.
- #8 A fire alarm system can have a variety of output devices
- #10 This is it for a basic system. Anything else that might be needed is considered "SUPPLEMENTARY"
- #18 Smoke obscures a normal linear path of light. Complete and solid blockage from say a ladder will generate a trouble. Beam detection may provide more cost effective solutions to point detection over long distances, especially when the buildings are relatively tall, or where excessive height excludes the use of point detection. Applications include large production facilities, warehouses, ceiling voids, above false ceilings, open areas of shopping malls, churches, aircraft hangers.
- #21 Sometimes these devices are considered to be supervisory in nature rather than alarm. Why? Does an HVAC system run all the time? Remember that smoke inside the duct will be diluted, inducing a delay in response time for detection of an alarm.
- #23 Notification Appliances are made for four of the five senses - hear, see, touch, smell (but not taste).
- #25 Chimes - Used for PRIVATE MODE applications
- #26 The DC siren shown (Federal Signal) gives off 127 dB at 100 ft!
- #30 The history of fire alarm development - basic "no frills" panel through programmability, addressability and now intelligence.
- #34 A system that is said to be INTELLIGENT or ANALOG has capabilities like those listed here. Top-of-the-line systems can make decisions about alarm conditions by using data from one or more input devices.
- #35 This presentation includes a large number of acronyms and abbreviations. Let’s introduce some of the more common ones now.