Notice!
Avoid sources of heat and air movement.
– Do not mount the D296/D297 detectors where hot or cold air can blow directly into the
beam path.
– Heating, ventilating, and air conditioning (HVAC) systems and ceiling fans can cause
smoke to blow away from the projected beam. Smoke must accumulate in the projected
beam to be detected.
– Heaters mounted close to the projected beam path can cause the beam to be distorted.
Notice!
Avoid sources of bright light.
– Sunlight: Avoid pointing the receiver directly at the rising or setting sun. If you are
installing the unit where sunlight cannot be avoided, mount the receiver slightly higher
than the transmitter and aim it down towards the transmitter . This reduces the problem
by causing the receiver to look below the horizon.
– Bright lights: Generally, bright lights are not a problem. Do not place exposed bulbs of
high-pressure sodium, mercury vapor, and metal halide close to the receiver . Bare
fluorescent lights might pose a problem in long hallways where a series of lights run
perpendicular to the beam.
Mounting
Because the D296/D297 detectors are line-of-sight devices that go into trouble on a sudden
and total loss of signal, ensure all obstacles are clear of the beam path at all times.
This requirement might cause the detectors to be impractical in factory applications where
overhead cranes and hoists are present and in warehouses where high forklifts might block
the beam. Also, consider this factor in occupied areas where there are normal ceiling heights.
The D296/D297 detectors depend on the measurement of the projected beam to sense
smoke. Shifts in the beam alignment from transmitter or receiver movement can cause trouble
or alarm conditions.
Therefore, you should:
– Always select a stable mounting surface. The walls and attached girders of steel-sided
buildings (especially walls facing the sun) might be very unstable throughout the day. In
this circumstance, a roof support girder might provide better support.
– Never mount the units on a suspended support such as a pipe or length of wood
supported at only one end.
– Never use mirrors to extend the beam around corners.
– Never mount the units behind clear glass or plastic covers other than those supplied by
Bosch Security Systems, Inc. with the detectors.
– When mounting in high ceiling areas such as atriums, consider several mounting levels to
account for stratification due to ceiling height or low energy fires.
See the following figure:
3.3.2
3.3.3
Projected-beam Smoke Detectors Document Introduction | en 7
Bosch Security System, Inc. Application Guide 2013.02 | 02 | F.01U.500.951
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