Re: Window Foil

["Robert L Bass" <RobertLBass@xxxxxxxxxxx>]

"Beachcomber" <invalid@xxxxxxxxxxxx> wrote in message
news:476b566b.14191593@xxxxxxxxxxxxxxxxxxx
>
>>It depends on which detectors you're using.  Some detectors
>>(IntelliSense, for example) are designed to detect the high
>>frequency
>>cracking of the glass plus the low frequency pulse caused by
>>striking
>>the glass.  The low frequency sound depends on the glass being part
>>of the perimeter of the space, like the skin on a drum.  These are
>>tested by thumping the glass, which in turn triggers the tester to
>>emit a sound similar to glass shattering.
>>
>
> A questions for the pros about glass break detectors from an old
> foil
> installer (who did a lot of drug and liquor stores... back in the
> 70's).
>
> Do you have any personal knowledge of a case where there was an
> otherwise properly armed alarm system with glass break detectors
> where
> the GBD failed to go off when the intruder broke in?

Yes.  The detectors were made by IEI.  A unit mounted on the ceiling,
directly in front of a glass door completely failed in service with
no warning.  Fortunately, there was a PIR which detected the thief
the moment he entered.  Upon inspection it was found that a cap on
the glassbreak's circuit board had failed, leaking an oily substance.
There was no sign of lightning or other external cause for the
failure.

> It would seem to me that that would be the worst case scenario...

The only worse case would be if there was no backup.  Others here
have mentioned that they don't like to rely on glassbreak detectors
as the sole protection and this is one reason they're right.  I
prefer to use glassbreaks as an adjunct to door and window contacts
but always recommend at least basic motion detection as a backup.

> I know that some of the best of them would go off during a
> thunderstorm, but that could happen to the foil window systems too.

True, but properly applied foil was one of the least problematic
types of detection we used.  Most of our jobs were residential so I
mainly used foil on basement windows.  We did a fair number of
commercial jobs though and foil on glass entry doors was a nuisance.

> Will the so called "Swingers" always be with us...

Except for when he vacations on his rowboat, Jimbo will likely
continue swinging both ways.

--

Regards,
Robert L Bass

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