The higher the optical resolution (distance to spot size) is, the
more accurately can be measured at greater distances.
2.4. Emissivity
For an infrared temperature measurement, the different surface
conditions must be minded, as these have an influence on the
measurement result. The emission factor describes the
characteristics of the reflectivity of materials. The duller and
darker the object is, the more accurate the measurement will be.
A measurement of very shiny, reflective or transparent objects
distorts the measurement result. It is here recommended to
colour the targeting surface in dull- black or to attach a dull-black
tape on it, which you can use as measurement surface after the
temperature harmonized.
Most organic, painted or oxidized surfaces have an emissivity of
0.95, so this is set as default for the
PeakTech
®
4955.
You can set different emission factors before each measurement
in the "MEASURE SET "menu as listed in the following table:
Material
Condition
Temperature-Range
Emissivity-
factor (
ɛ
)
Aluminium
polished
50°C … 100°C
0.04 ... 0.06
Raw surface
20°C … 50°C
0.06 ... 0.07
oxidized
50°C ... 500°C
0.2 ... 0.3
Aluminium oxide,
Aluminium powder
normal Temperature
0.16
Brass
matt
20°C ... 350°C
0.22
oxidized at 600°C
200°C ... 600°C
0.59 ... 0.61
Polished
200°C
0.03
Wrought with
sandpaper
20°C
0.2
Bronze
polished
50°C
0.1
porous and raw
50°C ... 150°C
0.55
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