Glass-break-detectors:security through advanced technologyHome > Security Systems > Glass Break Detectors Glass-break-detectors, devices intended to detect the breakage of protected glass, are necessary part of any security system intended to avoid intrusion, or at least to trigger an alarm if intrusion is attempted. In fact it must be admitted that glass is the most easily broken part of any residential or shop structure. Often by breaking glass, burglars may get access to the inside and reach by hand handles or locks, opening large frames that will let them in. Therefore it may be advisable to mount Glass-break-detectors with built in magnetic contact alarms, to signal unauthorized opening of doors or window frames. Otherwise, if the selected devices do not include contact sensors, one should consider separate mounting of suitable contact sensors and alarms in addition to glass break sensors to cover all events. Modern Glass-break-detectors based on acoustic technology, are aimed at listening to the characteristic sounds generated by breaking glass. Acoustic sensors can be depended on if they are placed within their operational range, measured in units of length (feet, meters), beyond which they are not effective. Special purpose Glass-break-detectors may be combined with Passive Infra Red (PIR) detectors, to signal brake-ins through shattered glass. Testers are provided by some manufacturers, to make sure that the glass breaking sound is well within the hearing range of the device even behind curtains. The devices are optimized to recognize the characteristic spectrum of frequencies involved in the breaking of glass, while ignoring all other noises, in order to minimize false alarms. In fact false alarms, that is triggering of the alarm also in the absence of threatening sounds, are serious inconveniences to be avoided, by powerful software capable of discriminating between innocent noise and shattering breaking. Shock sensors provide a different technology whereby the sensors feel the vibration waves produced in the event. These sensors are mounted directly on the glass or the frame of at least one square foot (0.3x0.3 m). They are claimed to provide a product practically immune to false alarms but may be insensitive to a bullet piercing a hole in the glass. The selection between acoustic and shock sensor Glass-break-detectors depends on the application. One acoustic sensor of suitable sensitivity may cover the many windows and doors of a large room. If however the shock sensor technology were selected, a device would be needed for each of the windows, because the triggering vibrations are not transmitted from frame to frame. Small noisy rooms are probably better protected with fewer false alarms by shock sensors. Not only windows but skylights may provide an inviting entry point for burglars. Glass skylights are best protected by acoustic sensors, while those covered by Plexiglas or any other rigid plastic plates should be equipped with shock sensors. Some of the devices send their signal by wireless transmission: in this case there is a maximum distance that should be respected to get adequate reception. Insulation windows may have two glasses separated by an air space. Only breaking of the innermost glass will trigger the alarm. If only the outside pane of glass is affected, there will be no alarm. One should be warned that normal Glass-break-detectors are unable to detect breakage of thick glass (more than 0.25 in or 6.4 mm) because much of the shock energy is absorbed. Special solutions may be needed. The same types of Glass-break-detectors can be used for protecting jewelry glass display cases and show cases A loud siren set off by the glass breaking event and a set of powerful blinking lights switched on at the same time are considered powerful deterrents, calling the attention of neighbors and occasional passers-by, and convincing any burglar to give up his/her plot. Click on Glass Break Detectors For any Questions, Comments or Feedback, please write us by e-mail. Use the Form reached by clicking on the Contact Us button in the NavBar, at top left of every page of this Website.
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