Display Backlighting; Measuring Principle - Dräger CMS Notice D'utilisation

Measuring principle

7.12

Display backlighting

The display backlighting can be activated
with the sliding switch in positions 1 – 3.
For example, during measurements in dark
surroundings.
1. Briefly press side button: the display is
backlit for approx. 5 seconds.
2. Press and hold side button for 2 seconds:
The display is backlit until the analyzer is
switched off.
The higher energy consumption reduces
the analyzer duty period.
8 Measuring principle
Dräger CMS is designed for quantitative measurement of hazardous gases or vapours in
ambient air.
The measuring principle is based on the chemical reaction between the gas in question and a
gas-specific reagent system. The reagent system is encapsulated in a glass capillary and
precisely defined. After opening the glass capillary, the air sample to be investigated is drawn
through the reagent system with constant flow.
The hazardous gas or vapour under test reacts with the reagent system.
This chemical reaction is detected optoelectronically.
The complete reaction basically takes place within a very much shorter period of time at higher
concentrations than at lower concentrations. The measuring time for higher concentrations of
hazardous gas is consequently shorter than for lower concentrations. The measurement
parameters required for the measurement and specific to the reagent system used (e.g. flow,
maximum measuring time, etc.) are saved in a barcode printed on the chip. They are read by
the analyzer before starting measurement and used for evaluation purposes.
The measured gas result is evaluated automatically and displayed directly on the LC display of
the analyzer as a concentration.
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Optoelectronics
Gas flow F
Glass capillary
0
1
2
3
Reagent-
system
CMS
0
1
2
3
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Dräger CMS Analyzer