Chromalox Big Red Book

Technical

Technical Information Heat Loss Factors & Graphs Graph G-126S — Heat Losses from Surfaces of Insulated Walls of Ovens, Pipes, Tanks, Etc.

Graph G-125S — Heat Losses from Uninsulated Metal Surfaces Combined Losses from Convection & Radiation

2400 2200 2000 1800 1600 1400 1200 1000

Curves based on combined natural convection and radiation losses at 70°F Insulation k= 0.67 @ 200°F

2 " T h i c k I n s u l a t i o n

110 100

1 " T h i c k I n s u l a t i o n

6 " T h i c k I n s u l a t i o n 4 " T h i c k I n s u l a t i o n 3 " T h i c k I n s u l a t i o n

90 80 70 60 50 40 30 20 10

A-Oxidized Steel (e = 0.80)

B-Oxidized Steel (e = 0.80)

C-Oxidized Steel (e = 0.80) A-Oxidized Aluminum (e = 0.22)

B-Oxidized Aluminum (e = 0.22)

C-Oxidized Aluminum (e = 0.22)

800 600 400 200 0 Watts Per Square Foot Per Hour

5 0 Watts Per Square Foot Per Hour 0

2 F.P.S. 40% Relative Humidity 1 F.P.S. 40% Relative Humidity Graph G-114S — Heat Losses from Water Surfaces 1600 1500 1400 1300 1200 1100 1000 Curves Based on 70°F Ambient Note — The above graph is difficult to read for surface temperatures below 250°F. To estimate heat losses for surface temperatures below 250°F, and the air is still, use the following formula: 0.6 W x ft 2 x ∆ T °F Where: ∆ T is the temperature difference in °F between the heated surface and the ambient. Curve A shows heat loss from vertical surfaces of tanks, pipes, etc. and the top of a flat horizontal surface. Curve B shows the combined heat loss from both the top and bottom surfaces of flat horizontal surfaces. Curve C shows heat losses from only the bottom surface of flat horizontal surfaces. All Curves based on still air (1 fps) @ 70°F, e = emissivity. 2 F.P.S. 60% Relative Humidity 1 F.P.S. 60% Relative Humidity 200 300 400 500 600 700 800 900 1000 Surface Temperature (°F)

200 400 600 800 1000 1200 1400 1600

Temperature Difference (°F)

Graph G-127S — Heat Losses from Oil or Paraffin Surfaces

1000 900 800 700 600 500 400 300 200 100 0 Watts Per Square Foot Per Hour 0 100 Curves Based on 70°F Ambient

200

300

400

500

600

Temperature of Oil or Paraffin (°F)

Graph G-128S — Heat Losses from Molten Metal Sur- faces (Lead, Babbit, Tin, Type Metal, Solder, Etc.) Curves Based on 70°F Ambient

1400 1300 1200 1100 1000

900 800 700 600 500 400 300 200 100 0 Watts Per Square Foot of Water Surface Per Hour 80 100 120

900 800 700 600 500 400 300 200 100 0 Watts Per Square Foot Per Hour 300 400

140 160

180

200 210

500

600

700

800

900

Temperature of Water (°F)

Temperature (°F)

I-10