Engineering Data | Dalton Electric Heating Co., Inc.

The following reference information can assist you in the selection of Watt-Flex heaters for new process heating designs.

Heating Metal Parts

The required wattage for a metal-heating application is equal to the sum of watts required for material heat up plus watt loss during heat-up, plus a 20% safety margin added for contingencies.

To calculate the heater capacity needed to produce a required level of heat, find the thermal values in the Physical Properties of Materials Table below and plug them into the following equations:

Calculation of Required Wattage

To calculate the heater capacity needed to produce a required level of heat, find the thermal values in the Physical Properties of Materials Table below and plug them into the following equation:

  • WATTS FOR MATERIAL HEAT-UP =
    $${{Weight of Material (lbs.) * Specific Heat * Temperature Rise (F) } \over 3.412 * Heat up Time (hours)}$$
  • WATTS HEAT LASS DURING HEAT-UP =
    $${Watt Loss per sq. in. * [Area (sq.in)}$$
  • Total Watts Required = (A + B)*1.2
    (20% safety factor for contingencies)
  • **Consult graph for applicable wattage loss rates

Physical Properties of Materials Table

Substance

Specific Heat

Heat of Fusion

Lowest 

melting point

Density 

Thermal 

conductivity

Thermal 

Expansion

 

Btu/lboF

 Btu/lboF

 oF

 lb/ft3

  lb/in3

 Btu/hr/
ft2/oF/ft

 inches per inch 

  per oF x 10-6

Aluminum 1100

.24

169

1190

169

.098

128

13.1

Aluminum 2024

.24

167

935

173 

.100

112

12.9

Aluminum 3003

.24

167

1190

170 

.099 

112

12.9 

Antimony

.052

69

1166

423 

.245 

10.9

4.7 - 6.0 

Brass

.10

1700±

525 

.304 

56

11.1 

Carbon

.204 

 -

6700

.080 

13.8

.3 -> 2.4 

Copper

.10 

91 

1981

550 

.318

224

9.2 

Glass

.20

 -

2200±

165 

.096 

.45 

Graphite

.20

 -

 

130 

.075

.104

Incoloy800

.12

 -

2475

501 

.290

8.1

7.9

Inconel 600

.11

 -

2470

525 

.304

9.1

7.4 

Invar

.13

 -

2600

508 

.294

6.1

0.6 

Iron, Cast

.13

 -

2300±

450 

.260

33

6.5 

Iron, wrought

.12

 -

2800±

480 

.278 

36

6.5 

Lead, solid

.031

10 

621

710 

.411

20

16.3

Lead, melted

.04

 -

665 

.385

 -

 -

Magnesium

.232

160

1202

109 

.063 

91

14

Monel 400

.11

 -

2370 

551 

.319 

14

7.7

Nickel 200

.11

133 

2615

554 

.321

39

7.4

Nichrome
(80% Ni, 20% Cr)

.11

2550 

524 

.303

8.7

7.3 

 Solder
(50%Pb, 50%Sn)

.04

17 

415

580

.336 

26

13.1 

Steel, mild carbon 

.12

2550±

490 

.284 

38

6.7

Steel,stainless 304 

.11

2550

488 

.282

8.8

9.6

Steel,stainless 430 

.11

 -

2650

475 

.275

12.5

6.0

Tin, solid 

.056

25 

450

455 

.263 

36

13

Tin, melted 

.064

-

 -

437 

.253

18

 -

Type Metal
(85% Pb, 15% Sb)

.040

15 

500

670 

.388 

 -

 Zinc

.095

51

787

445 

.258

65

9.4 - 22

Heating Liquids

Consideration should be given to the following factors when heating liquids with Watt-flex Cartridge Heaters:

  • Locate heater wells in an unrestricted space in the main body of the liquid.
  • The heated section of the well should be covered by liquids at all times.
  • In metal-melting applications, explosions can result unless pressure is vented during melting phase of heat-up.
  • Certain watt-density limits exist in immersion applications. Please consult the factory for technical assistance.

For a consultation on any heating application, call our heating engineers at 978-356-9844.