Long-range beam smoke detectors
System overview | en
5
Bosch Security Systems, Inc.
Installation manual
2017.03 | 7.0 | F.01U.068.899
2
System overview
2.1
Description
The D296 (24 VDC) and D297 (12 VDC) Long‑range beam smoke detectors have a separate
transmitter and receiver. Internal aim adjustment provides coverage flexibility without
brackets. Automatic signal synchronization and range adjustment reduce installation costs.
Selectable sensitivity and alarm response time provide installation flexibility.
Use the D296/D297 detectors:
–
Where there are high ceilings such as in atriums and aircraft hangers. Mount the
detectors on walls for easy access.
–
In dusty environments such as warehouses, factories, and barns. These detectors have
built-in compensation to prevent alarms caused by dust.
–
Where there are expansive ceilings. One set of D296/D297 detectors can replace up to 24
spot‑type detectors. This saves on service and installation costs, especially in areas such
as large offices or department stores.
–
On ornamental ceilings where spot‑type detectors are a distraction.
–
Where there is limited access to the ceiling such as in factories and warehouses.
Available accessories:
–
Included: a D344‑RL Remote indicator plate, a D1005 Test cable, and a set of four plastic
sensitivity test filters.
–
A D344‑RT Remote test/indicator plate (not supplied) is required for remote alarm
testing.
–
A D308 Field test kit (not supplied) is needed for field testing.
2.2
Operation
The detectors have separate transmitters and receivers . The transmitter projects an infrared
(IR) beam across the protected area to a receiver containing a photosensitive cell that
monitors the signal strength of the light beam.
The D296/D297 detectors work on the principle of obscuring light. The detector’s
photosensitive element in the receiver sees light produced by the transmitter in a normal
condition. The receiver is calibrated to a preset sensitivity level based on a percentage of total
obscuration . Beam length and the desired response time determine this sensitivity level. The
installer can choose from eight sensitivity settings based on the length of the beam used in a
particular application.
The transmitter and receiver can be independently powered, greatly reducing wiring runs and
installation cost. Since battery backup is required for fire alarm systems, battery backup is
required for the transmitter whether it is powered from the control panel or is independently
powered.
Unlike spot‑type photoelectric smoke detectors , beam-type smoke detectors are generally
less sensitive to the color of smoke. A beam‑type smoke detector might be suited to
applications inappropriate for spot‑type detectors, such as applications where the anticipated
fire would produce black smoke. Beam‑type smoke detectors require visible smoke and might
not be as sensitive as ion detectors in some applications.
Beam‑type smoke detectors are sensitive to the cumulative obscuration presented by a smoke
field. A combination of smoke density and the linear distance of the smoke field create this
obscuration across the projected light beam . Cumulative obscuration is a measure of the
percentage of light blockage.
Summary of Contents for D296 Series
Page 1: ...Long range beam smoke detectors D296 D297 en Installation manual ...
Page 2: ......
Page 31: ......
