Emissivity; Emissivity Table - LumaSense Technologies IN 300 Betriebsanleitung

IMPAC pyrometers IN 300 · IN 300/5
6

Emissivity

For a correct measurement it is necessary to adjust the emissivity ε. This emissivity is the relation-
ship 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 tempera-
ture. Different materials have different emissivities ranging between 0% and 100% (settings at the
pyrometer between 40 and 100%). Additionally the emissivity is depending on the surface condi-
tion 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 emissiv-
ity table below. The tolerance of the emissivity values for each material is mainly dependent on the
surface conditions. Rough surfaces have higher emissivities.
Note:
To adjust the emissivity factor to your own purpose,
you have to remove the rear cover by unscrew the
locking screw. 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 a first 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).
6.1

Emissivity table

Measuring object
"Black body furnace"
Human skin
Black dull varnish
Carbon soot
Wood
Paper
Asphalt
Glass / quartz glass
Textile
Graphite
Cement
Water
Measuring object
Glass / quartz glass
The pyrometer is set ex works to an emissivity of 100%.
ε (at 8 ... 14 µm)
100%
98%
95%
95%
80 ... 92%
92 ... 95%
85%
72 ... 87%
75 ... 95%
75 ... 92%
90%
95%
ε (at 5.14 µm)
97%
Locking screw
for rear cover
Potentiometer
for emissivity
adjustment
Rear cover
Measuring object
Brickwork
Fire clay
Rubber
Porcelain
Ceramics
Varnish
Plaster
Oil paint
Steel (oxidized)
Steel (smooth)
Aluminium (smooth)
Aluminium (anodized)
ε (at 8 ... 14 µm)
85 ... 95%
60 ... 80%
10 ... 30%
2 ... 15%
96%
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