transmitter unit shall emit an infrared beam to the receiver unit. When
the signal at the receiver falls below a preset sensitivity, the detector
shall initiate an alarm. The receiver shall contain an LED which is
powered upon an alarm condition. Long-term changes to the received signal
caused by environmental variations shall be automatically compensated.
Detectors shall incorporate features to assure that they are operational; a
trouble signal shall be initiated if the beam is obstructed, the limits of
the compensation circuit are reached, or the housing cover is removed.
Detectors shall have multiple sensitivity settings in order to meet UL
listings for the different distances covered by the beam. In the event of
beam interference for more than three seconds a trouble alarm shall be
transmitted.
2.5.2.4
Duct Detectors
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NOTE: The requirements for Duct Detectors will be
coordinated with the HVAC requirements and Section
15951 DIRECT DIGITAL CONTROL FOR HVAC AND OTHER
LOCAL BUILDING SYSTEMS. All required duct detectors
will be shown on the contract drawings.
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Duct-mounted photoelectric smoke detectors shall be furnished and installed
where indicated and in accordance with NFPA 90A. Units shall consist of a
smoke detector as specified in paragraph Photoelectric Detectors, mounted
in a special housing fitted with duct sampling tubes. Detector circuitry
shall be mounted in a metallic enclosure exterior to the duct. Detectors
shall have a manual reset. Detectors shall be rated for air velocities
that include air flows between [2.5 and 20] [[_____] and [_____]] m/s [500
and 4000] [[_____] and [_____]] fpm. Detectors shall be powered from the
fire alarm panel. Sampling tubes shall run the full width of the duct.
The duct detector package shall conform to the requirements of NFPA 90A, UL
268A, and shall be UL listed for use in air-handling systems. The control
functions, operation, reset, and bypass shall be controlled from the fire
alarm control panel. Lights to indicate the operation and alarm condition;
and the test and reset buttons shall be visible and accessible with the
unit installed and the cover in place. Detectors mounted above 1.83 m 6
feet and those mounted below 1.83 m 6 feet that cannot be easily accessed
while standing on the floor, shall be provided with a remote detector
indicator panel containing test and reset switches. Remote lamps and
switches as well as the affected fan units shall be properly identified in
etched plastic placards. Detectors shall have auxiliary contacts to
provide control, interlock, and shutdown functions specified in Section
15951 DIRECT DIGITAL CONTROL FOR HVAC AND OTHER LOCAL BUILDING SYSTEMS.
The detectors shall be supplied by the fire alarm system manufacturer to
ensure complete system compatibility.
2.5.3
Combination Smoke and Heat Detectors
Combination smoke and heat detectors shall have an audible device
(self-contained) and be designed for detection of abnormal smoke densities
by the photoelectric principle and abnormal heat by a fixed temperature
sensor. Smoke detectors shall be provided with an LED light source.
Failure of the LED shall not cause an alarm condition and the sensitivity
shall be factory set at a nominal [3] [_____] percent and require no field
adjustments of any kind. Heat detector portion shall be fixed temperature
sensor rated at 57 degrees C 135 degrees F. The audible appliances shall
have a minimum sound output of at least [85] [_____] dBA at 3.05 m 10 feet.
SECTION 13850A
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