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Electric Heaters
Heat Loss Factors
and Graphs
Continued
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2600 2400 2200 2000 1800 1600 1400 1200 1000
800 600 400 200
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1. Based upon combined natural convection and radiation losses into 70°F environment.
2. Insulation characteristics k = 0.67 @ 200°F
k = 0.83 @ 1000°F.
3. For molded ceramic fiber products and packed or tightly packed insulation, losses will be lower than values shown.
For 2 or 3 inches Insulation multiply by 0.84 For 4 or 5 inches Insulation multiply by 0.81 For 6 inches Insulation multiply by 0.79
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0 01 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 11
Losses—W/in2
Ref. 13
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1.2 1.3 1.4 1.5 1.6 1.7 1.8
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1400
1300 1200 1100 1000 of 900 800 700 600 500
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910 11 12 13 14 15 16 17 18 19 20
Losses—W/in2
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For losses of molten metal surfaces, use the curve e=0.40.
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500 600 700 800
Losses W/ft2
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