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B-1
Appendix: Emissivity Values
B
Table B-1 provides guidelines for estimating the emissivity of various
common materials. Actual emissivity, especially of metals, can vary
greatly depending upon surface finish, oxidation, or the presence of
contaminants. Also, emissivity or infrared radiation for some materials
varies with wavelength and temperature. To determine the
exact
emissivities for most applications, follow the procedures in Appendix C.
Table B-1. Emissivity Table
MET
ALS
Material Emissivity (
ε
)
Aluminum – pure highly polished plate . . . . . . . . . . . . . . . . . . . . 0.04 to 0.06
Aluminum – heavily oxidized . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.20 to 0.31
Aluminum – commercial sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.09
Brass – dull plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.22
Brass – highly polished, 73.2% Cu, 26.7% Zn . . . . . . . . . . . . . . . . . . . . 0.03
Chromium – polished . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.08 to 0.36
Copper – polished . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.05
Copper – heated at 600°C (1110°F) . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.57
Gold – pure, highly polished or liquid . . . . . . . . . . . . . . . . . . . . 0.02 to 0.04
Iron and steel (excluding stainless) – polished iron . . . . . . . . . . . . 0.14 to 0.38
Iron and steel (excluding stainless) – polished cast iron . . . . . . . . . . . . . . 0.21
Iron and steel (excluding stainless) – polished wrought iron . . . . . . . . . . . 0.28
Iron and steel (excluding stainless) – oxidized dull wrought iron . . . . . . . . 0.94
Iron and steel (excluding stainless) – rusted iron plate . . . . . . . . . . . . . . . 0.69
Iron and steel (excluding stainless) – polished steel . . . . . . . . . . . . . . . . . 0.07
Iron and steel (excluding stainless) – polished steel oxidized at
600°C (1110°F) . . . . . . . . . . . . . . . 0.79
Iron and steel (excluding stainless) – rolled sheet steel . . . . . . . . . . . . . . . 0.66
Iron and steel (excluding stainless) – rough steel plate . . . . . . . . . 0.94 to 0.97
Lead – gray and oxidized . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.28
Mercury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
0.09 to 0.12
Molybdenum filament . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.10 to 0.20
Nickel – polished . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.07
Nickel – oxidized at 649 to1254°C (1200°F to 2290°F) . . . . . . . 0.59 to 0.86
Platinum – pure polished plate . . . . . . . . . . . . . . . . . . . . . . . . . . 0.05 to 0.10
Platinum – wire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.07 to 0.18
Silver – pure and polished . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.02 to 0.03
Stainless steel – polished . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.07
Stainless steel – Type 301 at 232 to 941°C (450°F to 1725°F) . . . 0.54 to 0.63
Tin – bright . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.06
Tungsten – filament . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.39
Zinc – polished commercial pure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.05
Zinc – galvanized sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.23