5.2 Warm-up period
The measuring chamber of the sensor is being heated up until 50°C
(122°F) have been reached. This will take approximately 3 minutes at an
ambient temperature of 20°C (68°F). The actually prevailing temperature
inside the measuring chamber will be displayed in °C. A progress bar
shows the percentage of completion.
After 50°C (122°F) have been reached, warming up is being continued a
certain time period (‘stabilizing’) in order to make sure that the whole
unit has adopted the desired operating temperature.
As soon as the unit finished heating, zero adjustment starts.
5.3 Zero adjustment
Repetitive zero adjustment will compensate possible changes in the sen-
sor equipment (e.g. aging of infrared source) and this way eliminate zero
drift. Ambient air is being drawn in through the installed activated carbon
filter (
fig. 1, item 2
) or as may be the case through an external zero gas
inlet (see below) and measured in the sensor. Since in a properly serviced
zero filter the activated carbon will adsorb the measurable substance(s),
the concentration of substance(s) in the sensor equals zero.
To provide error-free zero adjustment, the activated carbon filter
must be changed regularly. Spent activated carbon filters will lead to
incorrect test results or to error indication
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