Velleman DVM8861 Bedienungsanleitung Seite 7

Surface temperature
When going from low temperature to high temperature measurements or vice
versa, the IR sensor of the thermometer needs a few minutes to adjust.
Distance and spot size
As the distance (D) from the object increases, the spot size (S) of the area
measured by the unit becomes larger. The focal point for each unit is 914mm
(36").
Emissivity
Emissivity describes the energy-emitting characteristics of materials. Most organic
or oxidized surfaces have an emissivity of ±0.95 (default setting). Measuring shiny
or polished surfaces will be inaccurate. Use some masking tape or paint to
compensate, allow sufficient time for the tape or paint to reach the surface
temperature.
Substance
Asphalt
Concrete
Cement
Sand
Earth
Water
Ice
Snow
Glass
Ceramic
Marble
Plaster
Mortar
Brick
Field of view
The target must be larger than the spot size to ensure correct measurement. This
means that for smaller targets, the thermometer must be held closer to the target.
For best accuracy, make sure the target is at least twice as large as the spot size.
V. 04 – 08/07/2014
D:S= 12:1
Emissivity
0.90 to 0.98
0.94
0.96
0.90
0.92 to 0.96
0.92 to 0.96
0.96 to 0.98
0.83
0.90 to 0.95
0.90 to 0.94
0.94
0.80 to 0.90
0.89 to 0.91
0.93 to 0.96
DVM8861
12.5mm @ 150mm
25mm @ 300mm
0.5in @ 6in.
D
Substance
Cloth (black)
Human skin
Leather
Charcoal (powder)
Lacquer
Lacquer (matt)
Rubber (black)
Plastic
Timber
Paper
Chromium oxides
Copper oxides
Iron oxides
Textiles
7
S
1in @ 12in.
Emissivity
0.98
0.98
0.95 to 1.00
0.96
0.80 to 0.95
0.97
0.94
0.85 to 0.95
0.90
0.70 to 0.94
0.81
0.78
0.78 to 0.82
0.90
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