LumaSense Technologies IS 320 - Manual (Page 16)

IS 320 • IGA 320 Manual General 16
same temperature. Different materials have different emissivities, ranging from 0% to 100%.
The emissivity of an object 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 (by entering a number between 10 and 100%). 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 [%]
Measuring
object
Emissivity [%]
IS 320
(0.8...
1.1 µm)
IGA 320
(1.45...
1.8 µm)
IS 320
(0.8...
1.1 µm)
IGA 320
(1.45...
1.8 µm)
“Black body
furnace“
100 100 Zinc 58 45 to 55
Steel heavily scaled 93 85 to 90 Nickel 22 15 to 20
Steel rolling skin 88 80 t 88 Gold, Silver, bright 2 2
Steel, molten 30 20 to 25 Porcelain glazed 60 60
Slag 85 80 to 85 Porcelain rough 80 to 90 80 to 90
Aluminum, bright 15 10 Graphite 80 to 92 80 to 90
Chromium, bright 28 to 32 25 to 30 Chamotte 45 to 60 45 to 60
Brass oxidized (tarnished) 65 to 75 60 to 70 Earthenware, glazed 86 to 90 80 to 90
Bronze, bright 3 3 Brick 85 to 90 80 to 90
Copper, oxidized 88 70 to 85 Soot 95 95
4.6 Transmittance
Due to the transmittance, measurements through windows slightly attenuate the measuring
signal. To ensure accurate measurements, the software can compensate for the transmission of
the window. 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 (software InfraWin).
4.8 Response Time/Exposure Time (t
90
)
Exposure time is the amount of time that the measured temperature has to
be present after an abrupt change before the output value of the pyrometer
is updated. The time it takes to reach 90% of the recorded temperature
difference is the response time. 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 t
90
is set to a lower value.
If the maximum value storage is selected, 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
...
10.00 s