|
#69 Selecting Hi E or Lo E Based on
Emissivity Table
| Metals |
|
Emissivity Range |
|
IRt/c Selection |
| Aluminum |
|
|
|
|
|
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 and steel (excluding
stainless) |
|
|
|
|
|
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 |
|
0.69 |
|
Lo E |
|
steel, polished |
|
0.07 |
|
Lo E |
|
steel, oxidized at 1110 ºF (600
ºC) |
|
0.79 |
|
Lo E |
|
rolled sheet steel |
|
0.66 |
|
Lo E |
|
steel plate, rough |
|
0.94 - 0.97 |
|
Hi E |
| Lead, gray oxidized |
|
0.28 |
|
Lo E |
| Mercury |
|
0.09 - 0.12 |
|
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 |
|
Lo E |
| Tungsten filament,
aged |
|
0.03 - 0.35 |
|
Lo E |
| Zinc |
|
|
|
|
|
commercial pure,
polished |
|
0.05 |
|
Lo E |
|
galvanized sheet |
|
0.21 |
|
Lo 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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