CEM DT-982, Руководство пользователя

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6.10-Temperature Measurement
6.11-Emissivity Adjustment
All objects radiate infrared energy. The quantity of energy radiated is base on the actual surface temperature
and the surface emissivity of the object. The Thermal Imager senses the infrared energy from the surface
of the object and uses this data to calculate an estimated temperature value. Many common objects and
materials such as painted metal, wood, water, skin, and cloth are very good at radiating energy and it is easy
to get relatively accurate measurements. For surfaces that are good at radiating energy (high emissivity),
the emissivity factor is >=0.90. This simplification does not work on shiny surfaces or unpainted metals
as they have an emissivity of <0.6. These materials are not good at radiating energy and are classified as
low emissivity. To more accurately measure materials with a low emissivity, an emissivity correction is
necessary. Adjustment to the emissivity setting will usually allow the Thermal Imager to calculate a more
accurate estimate of the actual temperature. More information please see Emissivity Adjustment to get the
most accurate temperature measurements.
The correct emissivity value is important to make the most accurate temperature measurement. Emissivity
of a surface can have a large effect on the apparent temperatures that the Thermal Imager observes.
Understanding the emissivity of the surface, but may not always, allow you to obtain more accurate temperature
measurements.
Surfaces with an emissivity of <0.60 make reliable and consistent determination of actual temperature
problematic. The lower the emissivity, the more potential error is associated with the Imager’s temperature
measurement calculations. This is also true even when adjustments to the emissivity and reflected background
adjustments are performed properly.
Emissivity is set directly as a value or from a list of emissivity values for some common materials. The
global emissivity displays in LCD Screen as E=x.xx.
The following table gives typical emissivity of important materials.
Note
Material
Water
Stainless steel
Aluminum plate
Asphalt
Concrete
Cast iron
Rubber
Wood
Brick
Tape
Brass plate
Human skin
PVC plastic
Polycarbonate
Oxidized copper
Rust
Paint
Soil
Emissivity
0.96
0.14
0.09
0.96
0.97
0.81
0.95
0.85
0.75
0.96
0.06
0.98
0.93
0.80
0.78
0.80
0.90
0.93
Thermal Imager User Manual
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