Contamination Measurement - Bosch NOM 100 LSN Product Information

Product Information Optical Smoke Detector NOM/NOM K 100 LSN

6.2. Contamination measurement

Contamination is measured using a different method. A second light source
(infrared LED) sends a light flash to the opposite interior wall.
If the detector is not contaminated, the light beam is absorbed almost completely
by the black interior wall. The presence of small volumes of smoke does not lead to
any substantial change.
The evaluation of this limited volume of light is used to monitor proper detector function.
If the detector is contaminated, the accumulated dirt particles cause the light beam
to be reflected.
Bundled by the convex lens, more scattered light reaches the photo cell. Evaluation
takes place irrespective of the scattered light value determined (see also "Detector
Fault").
Photo diode
Light source for
contamination
measurement
Measurement when
detector is not
contaminated
No reflection
of light beam
Seite 12 von 30
PI − 34.62c
Measurement when
detector is
contaminated
Reflection of the
light beam to
the smoke particles
BDL−F .01U.002.709
A5.en / 29.12.2004
ST−FIR/ PRM1 / deh