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Chapter 8

Chapter 8. Sensors The Eyes & Ears of the system. Alarms: The First Line of Defense. Perimeter Sensor Objective. To Detect an Event. An Open Door. A Broken Window. Entry Thru Wall, Roof or Floor. Entry Thru Outer Perimeter. Perimeter. The perimeter is the outer reaches of a system.

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Chapter 8

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  1. Chapter 8 Sensors The Eyes & Ears of the system Alarms: The First Line of Defense © 2001 National Burglar & Fire Alarm Association 8-1

  2. Perimeter Sensor Objective • To Detect an Event. • An Open Door. • A Broken Window. • Entry Thru Wall, Roof or Floor. • Entry Thru Outer Perimeter. © 2001 National Burglar & Fire Alarm Association 8-2

  3. Perimeter • The perimeter is the outer reaches of a system. • For a building system it is the walls, floor and ceiling. • For an outdoor system it is a fence or perhaps the outer edge of the sensors pattern. © 2001 National Burglar & Fire Alarm Association 8-3

  4. Magnet Magnet Magnetic Reed Switch Switch changes with magnet away from switch. Contacts are enclosed In hermetically sealed tube. © 2001 National Burglar & Fire Alarm Association 8-4

  5. Mechanical Switches • Simple & inexpensive. • Easily defeated. • Subject to corrosion. © 2001 National Burglar & Fire Alarm Association 8-5

  6. Door & Window Switch False Alarms • Doors & windows must be tight fitting & locked. • Door & window contacts must be free of paint & varnish. • Make sure there is no door or window warping. • Any broken contacts should be replaced immediately. © 2001 National Burglar & Fire Alarm Association 8-6

  7. Foil Patterns 18 ” Plate Glass Tempered Safety Re-inforced or Sun Film Coated Multi-pane © 2001 National Burglar & Fire Alarm Association 8-7

  8. Foil False Alarms • Foil contains lead & needs to be replaced every 3-5 years due to extreme summer weather. • It can be easily scratched or damaged. • Scratched or damaged foil can cause false alarms. © 2001 National Burglar & Fire Alarm Association 8-8

  9. Shock or Vibration Detectors • Vibration causes contacts to open. • Tension on contacts is adjustable. • Contact opening may be too fast. © 2001 National Burglar & Fire Alarm Association 8-9

  10. Mercury Devices Closed • Vibration of mercury sealed in tube causes an alarm. • Sensitivity adjusted by varying tube angle. Open © 2001 National Burglar & Fire Alarm Association 8-10

  11. Piezo Electric Devices • Small crystal vibrates to produce electricity when glass is broken • Can be self contained or be wired to a processor. © 2001 National Burglar & Fire Alarm Association 8-11

  12. Shock Sensors Impact • Use simple sensors connected to processors that decide when to initiate an alarm. At Rest © 2001 National Burglar & Fire Alarm Association 8-12

  13. Screens • Screen is laced with thin wire. • Alarm circuit is run through the wiring. © 2001 National Burglar & Fire Alarm Association 8-13

  14. Interior Sensors • Combination Motion Sensors • Ultrasonic Detectors • Microwave Detectors • Passive Infrared Detectors • Photoelectric Detectors • Audio Processors © 2001 National Burglar & Fire Alarm Association 8-14

  15. Motion or Space Detection What changes occur when people move? The detector must respond! © 2001 National Burglar & Fire Alarm Association 8-15

  16. Avoid False Alarms!! • What changes occur when there are no people present or moving? • Detector must NOT respond! © 2001 National Burglar & Fire Alarm Association 8-16

  17. Disguised Sensors Various types of sensors can be concealed or disguised as: 1. Duplex Electrical Outlets. 2. Thermostats. 3. Speaker Grills. 4. Smoke Detectors. 5. Light Fixtures. © 2001 National Burglar & Fire Alarm Association 8-17

  18. Trap Channel Spot Volumetric Motion Sensor Uses © 2001 National Burglar & Fire Alarm Association 8-18

  19. Older Motion Sensors • Ultrasonic • Listens to reflected sound, & responds to a change from movement. • Microwave • Monitors for a reduction in level of transmitted energy which may be caused by motion. • Photoelectric • Responds to an interruption the light beam sent between a transmitter & receiver. © 2001 National Burglar & Fire Alarm Association 8-19

  20. Passive Infrared Responds to changes of infrared energy levels within specific fields of view. © 2001 National Burglar & Fire Alarm Association 8-20

  21. Poor or No Catch Gradual Change Motion + 0 © 2001 National Burglar & Fire Alarm Association 8-21

  22. Good Catch Rapid Change Motion + 0 © 2001 National Burglar & Fire Alarm Association 8-22

  23. PIR Patterns Pet Alley Think! Pets climb, jump, & go places they shouldn’t. If a pet can cause a false alarm assume it will. © 2001 National Burglar & Fire Alarm Association 8-23

  24. Microwave PIR Dual Technology Sensors Overlapping patterns of the two technologies provide stability preventing false alarms in harsh environments. © 2001 National Burglar & Fire Alarm Association 8-24

  25. What Can Cause Motion Detector False Alarms? • helium balloons (especially mylar) • pets • bugs on the lens • curtains All interior equipment should be dusted, vacuumed around, etc for bugs & spiders. © 2001 National Burglar & Fire Alarm Association 8-25

  26. Glassbreak Sensors Audio discriminators listen for the sounds of forced entry; • Glass Breakage • Splintering Wood • Etc. © 2001 National Burglar & Fire Alarm Association 8-26

  27. Glass Break Sensor False Alarm Sources • Single technology glass break sensors can mistake the following for glass breaking: • Clinking glasses • Strong or heavy vibrations • Pots & pans hitting each other • Other sounds similar to the sound of glass breaking • USE DUAL TECHNOLOGY SENSORS! © 2001 National Burglar & Fire Alarm Association 8-27

  28. Pressure Mats Mounted under carpet in area likely to be walked upon. Pressure on the mat shorts the metal strips together. © 2001 National Burglar & Fire Alarm Association 8-28

  29. Stress Sensors Mount under joists in area to be covered. © 2001 National Burglar & Fire Alarm Association 8-29

  30. Mats & Stress Sensor False Alarm Sources Both are stable until furniture is rearranged around or on top of them © 2001 National Burglar & Fire Alarm Association 8-30

  31. Manual Devices • Foot rail. • Holdup button. • Money clip. • Portable duress sensor. • Touchpad Activated © 2001 National Burglar & Fire Alarm Association 8-31

  32. Manual DevicesFalse Alarm Sources • Improper user training • ”Single action" buttons • “Single action” money clips • Batteries in wireless buttons that are not replaced when the manufacturer recommends. © 2001 National Burglar & Fire Alarm Association 8-32

  33. Fire Alarm Sensors • Smoke Detectors. • Heat Detectors. • Flame Detectors. • Manual Pull Stations. © 2001 National Burglar & Fire Alarm Association 8-33

  34. Condition Monitoring • Alarms Can Be Used to Monitor: • Medical Emergencies. • Low or High Temperature. • Failure of Equipment. • Operation of Equipment. • (Generators, Sump Pumps , Etc..) • Water or Moisture • Power Failure © 2001 National Burglar & Fire Alarm Association 8-34

  35. Carbon Monoxide Gas Alarms • Indicates an unacceptable level of carbon monoxide gas is present in a room. • May indicate a failure in a furnace or improper ventilation in a room with a fireplace or wood stove. • Even limited exposure to high levels of carbon monoxide can be lethal to humans and animals. © 2001 National Burglar & Fire Alarm Association 8-35

  36. 1- Introduction 2- What is an Alarm System 3- What is A False Dispatch 4- Impact of False Dispatches 5- Causes of False Dispatches 6- Preventing False Dispatches 7- User Controls 8- Sensors 9- The Control 10- The Central Station 11- How Authorities Respond 12- What to expect for Alarm Co.s 13- The Alarm Ordinance 14- Sources of Information 15- Site Survey Alarms: The First Line of Defense Next Chapter 5 Minute Break 10 Minute Break 30 Minute Lunch 60 Minute Lunch © 2001 National Burglar & Fire Alarm Association 8-36

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