LumaSense Technologies IS 12-S - Manual (Page 25)

IS 12 / IGA 12 Manual Settings / parameter descriptions 25
5 Parameter descriptions / Settings
5.1 Emissivity
For a correct measurement, it is necessary to adjust the emissivity. The emissivity is the
relationship between the emission of a real object and the emission of a blackbody 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 10 and 100%, the set value is indicated on the display). 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 below. The tolerance of the emissivity values for each material is mainly
dependent on the surface conditions. Rough surfaces have higher emissivities.
Measuring object
Emissivity [%]
(at 0.7 to 1.1 µm) (at 1.45 to 1.8 µm)
“Black body furnace“ 100 100
Steel heavily scaled 93 85 to 90
Steel rolling skin 88 80 to 88
Steel, molten 30 20 to 25
Slag 85 80 to 85
Aluminum, bright 15 10
Chromium, bright 28 to 32 25 to 30
Brass oxidized (tarnished) 65 to 75 60 to 70
Bronze, bright 3 3
Copper, oxidized 88 70 to 85
Zinc 58 45 to 55
Nickel 22 15 to 20
Gold, Silver, bright 2 2
Porcelain glazed 60 60
Porcelain rough 80 to 90 80 to 90
Graphite 80 to 92 80 to 90
Fireclay 45 to 60 45 to 60
Stoneware, glazed 86 to 90 80 to 90
Brick 85 to 90 80 to 90
Soot 95 95
5.2 Exposure Time (t
90
)
The exposure time is the time interval when the measured temperature has
to be present after an abrupt change so that the output value of the
pyrometer reaches a given measurement value. The time taken is to reach
90% of the recorded temperature difference. In the “0.00” position, the
device operates using its time constant. The dynamic exposition time
adjustment prolongs the exposure time at the lower range limit.
Settings:
0.00 s
0.01 s
0.05 s
.
.
.
10.00 s