Optimizing detection and avoiding false alarms
PGP922 detects shattering glass. Like all glass-break sensors, the detector might not consistently
detect cracks in glass, or bullets that break through or break out the glass. Glass-break sensors
should always be backed up by interior protection.
For best detection, avoid installing in:
•
Rooms with lined, insulating, or sound-deadening drapes.
•
Rooms with closed wooden window shutters inside.
For best false alarm immunity
:
•
False alarms are most likely to occur when installed on a 24-hour loop, in glass airlocks, and
glass vestibule areas. Similarly, when mounted above sinks, residential garages, and in other
small acoustic living rooms, false alarms can be generated. In rooms where multiple sounds
can reflect and eventually duplicate the glass break frequency pattern, use PowerG shock
detectors.
•
Avoid 24-hour loop applications. The PGP922 is recommended for perimeter loops and is
designed to function in an occupied area. In 24-hour loop applications, where the device is
armed all day and all night, the false alarm prevention technology will be pushed to its limit.
Some sounds can duplicate the glass break pattern the acoustic sensor detects.
Install the PGP922 on a perimeter loop which is armed whenever the door and window
contacts are armed.
•
Do not use where white noise, such as air compressor noise, is present. A blast of
compressed air may cause a false alarm.
•
Avoid rooms smaller than 3 x 3 m (10 x 10 ft) and rooms with multiple noise sources such as
small kitchens, glass booths noisy areas, garages, and small bathrooms.
•
Do not install in humid rooms. The PGP922 is not hermetically sealed. Excess moisture on the
electronic board can shorten the circuit and cause false alarms.
•
Install in rooms with moderate noise. The false alarm immunity is best in rooms with only
moderate noise. For 24-hour occupied area protection, use PowerG shock detectors.
•
The device should be located at least 1.2 m (4 ft) away from noise sources (televisions,
speakers, sinks, doors, and similar). The device must always be in direct line of sight of all
protected windows. It cannot consistently detect glass breaking around corners or in other
rooms. Front or back, up or down, orientation is not necessary.
Areas to avoid
:
•
Glass airlocks and glass vestibule areas
•
Noisy kitchens
•
Residential car garages
•
Small utility rooms
•
Stairwells
•
Small bathrooms
•
Humid rooms
For glass break protection in such applications, use shock sensors on the windows or window
frames.
Note:
PGP9922 shall be installed in accordance with the Standard for Installation and
Classification of Burglar and Holdup Alarm Systems, UL 681
PGP922 Glass Break Detector Installation Guide
2
D-308652 PGP922 Rev.0
