testo 835 Manual De Instrucciones página 24

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12.2 Emissivity
Materials have various emission levels, i.e. they emit various amounts of
electromagnetic radiation. The emissivity of the instrument has a default setting of
0.95. This is ideal for the measurement of non-metals (paper, ceramic, gypsum,
wood, paints and varnishes), plastics and foodstuffs.
Because of their low or non-uniform emission level, blank metals and metal oxides
are only of limited use for IR measurement.
Coatings that increase the emission level, e.g. paint or emission adhesive (art. no.
0554 0051) must be applied to the measurement object. If this is not possible:
measure using a contact thermometer.
Emissivity table for important materials (typical values)
Material (Temperature)
Cotton (20°C / 68°F)
0.77
Concrete (25°C / 77°F)
0.93
Ice, smooth (0°C / 32°F)
0.97
Iron, polished (20°C / 68°F)
0.24
Iron with cast skin (100°C / 212°F)
0.80
Iron with rolled skin (20°C / 68°F)
0.77
Plaster (20°C / 68°F)
0.90
Glass (90°C / 194°F)
12.3 Measuring range, distance
Depending on the distance of the measuring instrument from the measurement
object, a specific measuring range is recorded.
Measuring lens (ratio of distance : measuring range)
In italics = laser
Not in italics = measuring range
13. Information on contact measurement
Observe the minimum penetration depth for immersion/penetration probes: 10x
probe diameter
e
Material (Temperature)
Heat sink, black anodised (50°C /
122°F) 0.98
Copper, oxidised (130°C / 266°F)
0.76
Plastics: PE, PP, PVC (20°C / 68°F)
0.94
Brass, oxidised (200°C / 392°F)
0.61
Paper (20°C / 68°F)
0.97
Porcelain (20°C / 68°F)
0.92
Black paint, matt (80°C / 176°F)
0.97
Steel, heat-treated surface (200°C/
e