ennoLogic eT650D Manuel De L'utilisateur page 12

ennoLogic Dual Laser IR Thermometer - User Manual
DOWN button pressed will change the displayed
temperature set point at increasing increments.
Emissivity (EMS)
The emissivity ε is displayed in the top right corner of the
LCD display (e.g. ε=0.95). To change it, press the MODE
button until the mode indicator changes to EMS. Then use
the UP and DOWN buttons to select the desired emissivity
in 0.01 unit increments (range 0.10 to 1.00.)
Emissivity of a material is the ability of its surface to emit
thermal radiation. More accurately, it is the ratio of the
energy radiated from a material's surface to that radiated
from a perfect emitter (black body) at the same
temperature and under the same conditions. The
emissivity of a surface depends on the material and on the
nature of its surface. For instance, a polished metal surface
has a lower emissivity than an oxidized metal surface.
Since IR thermometers calculate the surface temperature of
an object by sensing its emitted thermal radiation it is
important to take emissivity into account. A polished metal
object will emit less thermal radiation than an object with a
flat black finish at the same temperature, and thus appear
colder. The temperature displayed by the IR thermometer
for the polished metal object would therefore be inaccurate,
unless the instruments emissivity setting is adjusted to
match the emissivity of the object.
Emissivity of a material surface is difficult to estimate since
it depends on its texture, color, and temperature. The table
provided here should only be used as a guideline. A good
default setting is ε=0.95, which is also used by IR
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