testo 830-T4 Manual De Instrucciones página 14

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11.2 Emissivity
Materials have different emissivities, i.e. they emit different levels
of electromagnetic radiation. The emissivity of testo 830 is set
in the factory to 0.95. This is the ideal value for measuring non­
metals (paper, ceramics, plaster, wood, paints and varnishes),
plastics and food.
Bright metals and metal oxides are only suited to a limited extent
to infrared measurement on account of their low or nonuniform
emissivity.
► Apply emissivity enhancing layers such as varnish or emis­
sion adhesive tape (Item no. 0554 0051) to the object being
measured. If this is not possible, measure with the contact
thermometer.
Emissivity table of the most important materials (typical values)
Material (Temperature)
Aluminium, bright-rolled (170°C / 338°F)
Cotton (20°C / 68°F)
Concrete (25°C / 77°F)
Ice, smooth (0°C / 32°F)
Iron, polished (20°C / 68°F)
Iron with cast skin (100°C / 212°F)
Iron with rolled skin (20°C / 68°F)
Plaster (20°C / 68°F)
Glass (90°C / 194°F)
Rubber, hard (23°C / 73°F)
Rubber, soft grey (23°C / 73°F)
Wood (70°C / 158°F)
Cork (20°C / 68°F)
ε
Material (Temperature)
0.04 Heat sink, black anodised (50°C / 122°F) 0.98
0.77 Copper, lightly tarnished (20°C / 68°F) 0.04
0.93 Copper, oxidised (130°C / 266°F)
0.97 Plastics: PE, PP, PVC (20°C / 68°F)
0.24 Brass, oxidised (200°C / 392°F)
0.80 Paper (20°C / 68°F)
0.77 Porcelain (20°C / 68°F)
0.90 Black paint, matt (80°C / 176°F)
0.94 Steel, heat-treated surface
(200°C / 392°F)
0.94 Steel, oxidised (200°C / 392°F)
0.89 Clay, fired (70°C / 158°F)
0.94 Transformer paint (70°C / 158°F)
0.70 Brick, mortar, plaster (20°C / 68°F)
ε
0.76
0.94
0.61
0.97
0.92
0.97
0.52
0.79
0.91
0.94
0.93