| #69 Selecting Hi E or Lo E Based on Emissivity Table |
|
| Metals |
Emissivity Range |
IRt/c Selection |
|
highly polished plate, pure |
0.04 - 0.06 |
Lo E |
|
oxidized at 1110 ºF (600 ºC) |
0.11 - 0.19 |
Lo E |
|
commercial sheet |
0.09 |
Lo E |
| Brass |
highly polished plate, pure |
0.1 |
Lo E |
oxidized at 1110 ºF (600 ºC) |
0.61 - 0.59 |
Lo E |
| Chromium, polished |
0.08 - 0.36 |
Lo E |
|
|
| Copper |
polished |
0.05 |
Lo E |
heated at 1110 ºF (600 ºC) |
0.57 |
Lo E |
| Gold, pure, highly polished |
0.02 - 0.03 |
Lo E |
iron, polished |
0.14 - 0.38 |
Lo E |
cast iron, polished |
0.21 |
Lo E |
cast iron, oxidized at 1100 ºF (600 ºC) |
0.64 - 0.78 |
Lo E |
wrought iron, polished |
0.28 |
Lo E |
wrought iron, dull oxidized |
0.94 |
Hi E |
iron plate, rusted |
0.07 |
Lo E |
steel, polished |
0.79 |
Lo E |
steel, oxidized at 1110 ºF (600 ºC) |
0.66 |
Lo E |
rolled sheet steel |
0.94 - 0.97 |
Lo E |
steel plate, rough |
0.28 |
Lo E |
Lead, gray oxidized |
0.09 - 0.12 |
Hi E |
Mercury |
0.10 - 0.20 |
Lo E |
Molybdenum filament |
0.10 - 0.20 |
Lo E |
| Nickel |
polished |
0.07 |
Lo E |
plate, oxidized at 1110 ºF (600 ºC) |
0.37 - 0.48 |
Lo E |
|
|
| Platinum |
polished plate, pure |
0.05 - 0.10 |
Lo E |
wire |
0.07 - 0.18 |
Lo E |
Silver, pure, polished |
0.02 - 0.03 |
Lo E |
| Stainless steel |
polished |
0.07 |
Lo E |
type 310, oxidized from furnace service |
0.90 - 0.97 |
Hi E |
Tin, bright |
0.06 |
Hi E |
Tungsten filament, aged |
0.03 - 0.35 |
Hi E |
| Zinc |
commercial pure, polished |
0.05 |
Hi E |
galvanized sheet |
0.21 |
Hi E |
| Nonmetals Emissivity |
Material |
Range |
IRt/c Selection |
|
|
Asbestos |
0.93 - 0.94 |
Hi E |
| Brick |
red, rough |
0.93 |
Hi E |
fire clay |
0.75 |
Hi E |
| Carbon |
filament |
0.53 |
Hi E |
lampblack, rough deposit |
0.78 - 0.84 |
Hi E |
Glass (Pyrex, lead, soda) |
0.85 - 0.95 |
Hi E |
Marble, light gray, polished |
0.93 |
Hi E |
| Paints, lacquers, and varnishes |
white enamel |
0.91 |
Hi E |
flat black lacquer |
0.96 - 0.98 |
Hi E |
aluminum paints |
0.27 - 0.67 |
Lo E |
oil paints, 16 colors |
0.92 - 0.96 |
Hi E |
Porcelain, glazed |
0.92 |
Hi E |
Quartz, opaque |
0.68 - 0.92 |
Hi E |
Water |
0.95 - 0.96 |
Hi E |
Wood, oak, planed |
0.90 |
Hi E |
|
| Note: |
| Lower emissivity surfaces require more stable conditions than high emissivity surfaces for accurate temperature control. These tables include approximate values, which can vary significantly with surface condition. For best results, install an IRt/c and test. Emissivity data from Heat, Mass, and Momentum Transfer by Rohsenow and Choi (Prentice-Hall, 1961). |
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