Siemens OOH740 - Setup; Structure of OOH740

Structure and function
Setup
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Building Technologies
A6V10305793_m_en_
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Fire Safety
2016-02-15
3.2 Setup
3.2.1 Structure of OOH740
The multi-sensor smoke detector ASA OOH740 is a multi-criteria fire detector and
has two optical and two thermal sensors.
Structure and function
Figure 8: Sensors of the OOH740
1 Heat sensors 4 Forward scatterer
2 Receiver 5 Labyrinth
3 Backward scatterer
The point detector's high-quality opto-electronic measuring chamber houses the
following components:
● Two optical transmitters
● One optical receiver
● Two thermal sensors
The transmitters illuminate the smoke particles from different angles. One sensor
acts as forward scatterer, the other as backward scatterer. The scattered light then
hits the receiver (photodiode) and generates a measurable electric signal.
The combination of a forward and backward scatterer facilitates an optimum
detection and the differentiation of light and dark particles, which leads to a
homogenous response behavior and optimizes the differentiation of wanted signals
and deceptive phenomena.
In addition, the heat sensors make it possible to detect fires without smoke
generation.