frequency is allowed at the project site.
**************************************************************************
2.2.1
Balanced Magnetic Switch (BMS)
The BMS shall detect 6 mm 1/4 inch of separating relative movement between
the magnet and the switch housing. Upon detecting such movement, it shall
transmit an alarm signal to the alarm annunciation system.
2.2.1.1
BMS Subassemblies
The BMS shall consist of a switch assembly and an actuating magnetic
assembly. The switch mechanism shall be of the balanced magnetic type.
Each switch shall be provided with an overcurrent protective device, rated
to limit current to 80 percent of the switch capacity. Switches shall be
rated for a minimum lifetime of one million operations. The housings of
surface mounted switches and magnets shall be made of nonferrous metal and
shall be weatherproof. The housings of recess mounted switches and magnets
shall be made of nonferrous metal or plastic.
2.2.1.2
Remote Test
A remote test capability shall be provided. The remote test shall be
initiated when commanded by the alarm annunciation system. The remote test
shall activate the sensor's switch mechanism causing an alarm signal to be
transmitted to the alarm annunciation system. The remote test shall
simulate the movement of the actuating magnet relative to the switch
subassembly.
2.2.2
Glass Break Sensor, Piezoelectric
The glass break sensor shall detect high frequency vibrations generated by
the breaking of glass while ignoring all other mechanical vibrations. An
alarm signal shall be transmitted upon detecting such frequencies to the
alarm annunciation system.
2.2.2.1
Sensor Element
The sensor element shall consist of piezoelectric crystals. The sensor
element housing shall be designed to be mounted directly to the glass
surface being protected. Only the adhesive recommended by the manufacturer
of the sensor shall be used to mount detectors to glass. The detection
pattern of a sensor element shall be circular with at least a 1.5 m 5 foot
radius on a continuous pane of glass. A factory installed hookup cable of
not less than 1.8 m 6 feet shall be included with each sensor. The sensor
element shall not exceed 2600 square mm 4 square inches. The sensor
element shall be equipped with a light emitting diode (LED) activation
indicator. The activation indicator shall light when the sensor responds
to the high frequencies associated with breaking glass. The LED shall be
held on until it is turned off manually at the sensor signal processor or
by command from the alarm annunciation system.
2.2.2.2
Sensor Signal Processor
The sensor signal processor shall process the signals from the sensor
elements and provide the alarm signal to the alarm annunciation system.
The sensitivity of the sensor shall be adjustable by controls within the
sensor signal processor. The controls shall not be accessible when the
sensor signal processor housing is in place. The sensor signal processor
SECTION 13721A
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