Pyrometer- Handbook - Contika

2-colour pyrometers are used for difficult measuring tasks.
• high temperatures
• blocked views or interference in the atmosphere (for
example, smoke, suspended matter)
• the object is smaller than the spot size (down to 10% of
the spot size)
• changing, low, or unknown emissivity (for example,
molten metal).
In order to measure both signals various constructions are
used:
1. Sandwich detector
2. Two separate detectors with different filters
3. One detector with a rotating filter wheel
The disadvantage of a pyrometer with a rotating filter
wheel is that the signals do not arrive simultaneously. The
calculation of the ratio in the pyrometer increases the
sensitivity toward changing signals in one of the two
detectors. If there are quickly changing temperatures or
moving objects a 2-colour pyrometer with rotating filter
may record an inaccurate temperature.
To measure temperatures of bright flames (the most
common type of flame) flame pyrometers have been found
to work well. The radiation coming to the pyrometer stems
from glowing soot or other burning particles. In this case,
the soot factor “n” must be set on the pyrometer in order to
record the correct measurement.
Pyrometer Handbook
bright flames
flame
pyrometers
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