testo 830-T1 Manual De Instrucciones página 14

14
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 emission
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) 0.04
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)
11.3 Measurement spot, Distance
A specific spot is determined depending on the distance from the
measuring instrument to the object being measured.
Measurement optics (Ratio Distance : Measurement spot)
testo 830-T1
Ø 16 mm
Ø 66 mm
500 mm
1000 mm
ε
Material (Temperature)
Heat sink, black anodised (50°C/ 122°F) 0.98
0.77 Copper, lightly tarnished (20°C/ 68°F)
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)
Ø 116 mm
2000 mm
5000 mm
Ø 216 mm
laser
ε
0.04
0.76
0.94
0.61
0.97
0.92
0.97
0.52
0.79
0.91
0.94
0.93
Ø 516 mm