15
4 Parameter Descriptions / Settings
4.1 Emissivity (ε)
For a correct measurement, it is necessary to adjust the emissivity ε. This emissivity is the
relationship between the emission of a real object and the emission of a black body radiation
source (this is an object which absorbs all incoming rays and has an emissivity of 100%) at the
same temperature. Different materials have different emissivities ranging between 0% and
100% (settings at the pyrometer between 0.2 ... 1, equivalent to 20 … 100%). Additionally, the
emissivity is dependent on the surface condition of the material, the spectral range of the
pyrometer, and the measuring temperature. The emissivity setting of the pyrometer has to be
adjusted accordingly. Typical emissivity values of various common materials for the two spectral
ranges of the instruments are listed in the emissivity table below. The tolerance of the emissivity
values for each material is mainly dependent on the surface conditions. Rougher surfaces have
higher emissivities.
Note: The pyrometer is set ex works to an emissivity of 100%.
To adjust the emissivity factor to your own
purpose, you have to remove the rear cover
by unscrew the locking screw. Be sure to
remove the cover carefully. In the tube there
is a scale that can be turned with a small
screwdriver. Adjust the emissivity factor to
your desire. After that, push the cable
carefully back in the tube, put the cover on
the tube and tighten the locking screw for
the cover.
The following table may give brief information of the correct setting of the emissivity. For exact
measurement we recommend a comparison measurement with a contact thermometer (e.g.
TASTOTHERM MP 2000 with a suited probe).
4.1.1 Emissivity table
Measuring object