LumaSense Technologies IN 300/5 - Handbuch (Seite 19)

IMPAC pyrometers IN 300 · IN 300/5
19
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: 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. 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 ε (at 8 ... 14 µm) Measuring object ε (at 8 ... 14 µm)
"Black body furnace" 100% Brickwork
Human skin 98% Fire clay
Black dull varnish 95% Rubber
Carbon soot 95% Porcelain
Wood 80 ... 92% Ceramics
Paper 92 ... 95% Varnish
Asphalt 85% Plaster
Glass / quartz glass 72 ... 87% Oil paint
85 ... 95%
Textile 75 ... 95% Steel (oxidized) 60 ... 80%
Graphite 75 ... 92% Steel (smooth) 10 ... 30%
Cement 90% Aluminium (smooth) 2 ... 15%
Water 95% Aluminium (anodized) 96%
Measuring object
ε (at 5.14 µm)
Glass / quartz glass 97%
Potentiometer
for emissivity
adjustment
Locking screw
for rear cover
Rear cover