LumaSense Technologies IGA 320/23-LO - Manual (Page 20)

IGA 320/23-LO Operating Manual Settings / parameter descriptions 20
4.5 Emissivity
For a correct measurement, it is necessary to adjust the emissivity. This 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%). As such, the emissivity is also
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 spectral range of the
instrument 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 2.3 µm)
Measuring object
Emissivity [%]
(at 2.3 µm)
“Black body furnace“ 100 Steel, molten 20 to 30
Extruded Aluminum 13 Nickel 15 to 20
Brass 18 Titanium, non-oxidized 50
Brass oxidized (tarnished) 65 to 70 Titanium, oxidized 75 to 80
Copper 5 Molybdenum 10
Copper, oxidized 70 to 80 Molybdenum, oxidized 75 to 80
Inconel 30 Black Carbon 95
Inconel, oxidized 85 Graphite 80 to 90
Oxidized Iron 85 to 90 Stoneware, glazed 60
Steel rolling scale 80 to 88 Porcelain rough 80 to 90
4.6 Transmittance
Measurements through windows slightly attenuates the measuring signal (due to the
transmittance). To obtain correct measuring results, the transmission of the window must be
compensated. Alternatively, the emissivity can be adapted.
4.7 EmiAutoFind
If the true temperature of the measured object is known, you can calculate the emissivity of the
measured object using the Emi: AutoFind function.
4.8 Response time / exposure time (t90)
The exposure time is the time 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 “min” position, the device operates using its
time constant.
The dynamic exposure time adjustment prolongs the exposure time at the
lower range limit, also if t
90
is set to a lower value.
If the maximum value storage is selected and the measuring object has a low emissivity and the
measuring temperature is at the beginning of the range, a higher exposure time must be chosen
to prevent measurement errors. Longer exposure times can be used for the measurement of
objects which have rapidly fluctuating temperatures to achieve constant temperature reading.
Settings:
min
0.01 s
0.05 s
0.25 s
1 s
3 s
10 s