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Measures against condensation
If the PBA-1191 or the reflector is mounted on cool outside walls or in rooms in which there is high
humidity and a rapid increase in temperature (e.g. sunshine on a non-insulated roof), use the detector
heating unit PBH-1191. If condensation on the front cover causes troubles or false alarms, or for short
distances, use the reflector PBR-1191 with built-in heating.
Installation locations
When installation locations are rigid and vibration-free, large temperature fluctuations (e.g., between
day and night) have only a slight influence on steel girders and do not greatly affect the building struc-
ture. However, if the installation location is not rigid, the closely bundled infrared beam can drift from
the receiver and cause an alarm or trouble signal. Unstable installation locations include:
•
the walls of rooms constructed of steel which expand and contract due to the
temperature coefficient of steel
•
masonry walls upon which a steel roof has been constructed
•
non-bonded wooden beam construction
In the cases listed above the PBA-1191 must be mounted on the rigid structural element, while the
reflector can be mounted on the unstable wall.
Deflection of the IR beam caused by heat on the steel roof
Possible solution: mounting the PB-1191 on the stable surface
PBR-1191
INCORRECT
Figure 24
PBA-1191
CORRECT
Figure 25
and mounting the reflector on the unstable wall
PB-1191 Beam Detector Manual
PBA-1191
PBR-1191
17
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