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UT320T User Manual
UT320T User Manual
7. Infrared Measurement
7.1 D: S (Distance to Spot Ratio)
As the distance (D) between the thermometer and the measured target increases,
the light spot diameter (S) of the measured area also increases. The relationship
between measurement distance and light spot diameter is shown in the figure below.
7.2 Field of View
When measuring, make sure that the measured target is larger than the light spot
diameter (S). The smaller the target, the closer the test distance should be (refer
to D: S for the detailed light spot diameter). It is recommended that the measured
target be larger than twice the light spot diameter of the thermometer.
7.3 Emissivity
Emissivity represents the ability of the measured object to emit infrared energy.
Infrared measurement is to measure the infrared energy to determine the temperature.
Objects of different materials have different emissivity. The emissivity of most organic
materials, painted or oxidized surfaces is about 0.95. The user can use masking
tapes or flat paints to cover the metal surface, and then wait for a period of time to
make the surface temperatures of the tapes/flat paints and the covered object the
same. At this point, the surface temperature of the tapes/flat paints is equal to the
metal surface temperature.
The following table shows the total emissivity ε of some metals and non-metals.
Light spot diameter (S)
Distance of measured target (D)
The light spot diameter represents
95% of the energy in the circle
Aluminum
Oxide
A3003 Alloy
Oxide
Crude
Brass
Polishing
Oxide
Cuprum
Oxide
Electrical terminal board
Hastelloy
Alloy
Inconel
Oxide
Abrasive blasting
Electropolishing
Ferrum
Oxide
Rusting
Ferrum (casting)
Oxide
Non-Oxide
Casting
Ferrum (forging)
Passivating
Plumbum
Crude
Oxide
Molybdenum
Oxide
Nickel
Oxide
Platinum
Black
Measured surface
Metals
Emissivity
