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TECHNICAL SUPPORT
Emissivity
 What
is Emissivity?
Physics
of Emissivity
Affects
of Emissivity
Emissivity
Examples
Increasing
Emissivity
Calculating
Emissivity
Emissivity
Table
Emissivity
Testing
 support@optotherm.com
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 Emissivity Table
Emissivity
is a measure of a materials radiating efficiency. An emissivity
of 1.00 implies that the material is 100% efficient at radiating energy.
An emissivity of 0.20 implies that the material radiates only 20% of
that which it is capable of radiating.
Tables of
emissivity values are only approximated values for real materials. A
range of emissivity values is usually given for many materials whose emissivity
can be affected by surface roughness or finish. Additionally, thin
sheets of material such as plastics may be semi-transparent in the
infrared and therefore have reduced emissivity.
To optimize the
surface temperature measurement of a material:
-
Avoid
reflections by shielding the material from surrounding high
temperature objects.
-
For
semi-transparent materials such as plastic film, assure that the
background is uniform and lower in temperature than the material.
-
Conduct the
measurement perpendicular to the materials surface whenever the
emissivity is less than approximately 0.90. In all cases, do not
exceed angles greater than 30 degrees from perpendicular.
Note: Applicable for
material
temperatures from 0 to 250°C
Alumel
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Unoxidized |
0.10 0.25 |
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Oxidized |
0.60 |
Aluminum
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Polished |
0.10 0.05 |
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Oxidized |
0.10 0.40 |
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Rough |
0.10 0.30 |
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Anodized |
0.60 0.95 |
Brass
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Polished |
0.05 |
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Oxidized |
0.50 - 0.60 |
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Burnished |
0.30 |
Carbon
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Unoxidized |
0.40 0.90 |
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Filament |
0.50 |
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Soot |
0.50 - 0.95 |
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Coke |
0.95 1.00 |
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Graphite |
0.70 0.80 |
Clay
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Fired |
0.95 |
Chromel
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Oxidized |
0.60 0.85 |
Columbium
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Polished |
0.20 |
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Oxidized |
0.70 |
Copper
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Polished |
0.10 |
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Oxidized |
0.20 - 0.80 |
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Electrical
terminal blocks |
0.60 |
Glass
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Convex D |
0.80 |
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Nonex |
0.80 |
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Plate |
0.90 0.95 |
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Fused quartz |
0.75 |
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Pyrex, lead
and soda |
0.95 |
Granite
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Polished |
0.85 |
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Rough |
0.90 |
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Natural |
0.95 |
Inconel
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Polished |
0.15 |
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Oxidized |
0.70 0.95 |
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Sandblasted |
0.30 0.66 |
Iron
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Polished |
0.20 |
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Oxidized |
0.50 - 0.95 |
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Rusted |
0.50 0.70 |
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Wrought, dull |
0.90 |
Lacquer
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Colored on Al |
0.75 0.90 |
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Colored |
0.95 |
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Clear on Al |
0.10 |
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Clear on Cu |
0.65 |
Lead
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Polished |
0.05 0.10 |
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Oxidized |
0.30 0.65 |
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Rough |
0.40 |
Molybdenum
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Polished |
0.05 |
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Oxidized |
0.20 - 0.80 |
Monel
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Oxidized |
0.45 0.85 |
Nichrome
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Clean |
0.65 |
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Oxidized |
0.60 0.85 |
Nickel
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Polished |
0.10 |
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Oxidized |
0.20 0.95 |
Oil
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Animal/vegetable |
0.95 1.00 |
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Mineral |
0.90 1.00 |
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0.001 thick |
0.25 |
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0.002 thick |
0.46 |
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0.005 thick |
0.70 |
Paint
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Aluminum paint |
0.50 |
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Bronze paint |
0.80 |
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Paint on metal |
0.60 0.90 |
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Paint on
plastic or wood |
0.80 0.95 |
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Gold enamel |
0.40 |
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Clear silicone |
0.65 0.80 |
Rubber
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Hard glossy |
0.95 |
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Soft rough |
0.85 |
Silica
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Powder |
0.35 0.60 |
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Glazed |
0.85 |
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Unglazed |
0.75 |
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Silicone Carbide |
0.80
0.95 |
Soil
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Dry |
0.90 0.95 |
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Wet |
0.95 1.00 |
Stainless
Steel
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Polished |
0.10 0.15 |
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Oxidized |
0.45 - 0.95 |
Steel
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Unoxidized |
0.10 |
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Oxidized |
0.70 - 0.95 |
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Cold Rolled |
0.70 0.90 |
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Ground sheet |
0.40 0.60 |
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Rough surface |
0.95 |
Tantalum
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Unoxidized |
0.20 |
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Oxidized |
0.60 |
Textiles
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Carpet |
0.85 1.00 |
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Close weave |
0.70 0.95 |
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Cotton |
0.80 |
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Leather |
0.95 1.00 |
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Silk |
0.80 |
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Died black |
0.98 |
Tin
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Unoxidized |
0.05 0.10 |
Tungsten
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Unoxidized |
0.05 |
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Filament |
0.30 |
Water
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Liquid |
0.90 0.95 |
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Ice |
0.95 1.00 |
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Snow |
0.80 1.00 |
Wood
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Planed |
0.80 0.95 |
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Sawdust |
0.75 |
Zinc
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Polished |
0.05 |
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Oxidized |
0.10 |
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Galvanized |
0.20 0.30 |
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