Watlow Heater Catalog

Strip/Clamp-On Heaters

375 High-Temperature Strip Heaters Applications and Technical Data Calculating Watt Density Use the Maximum Allowable Watt Density graphs and formulas to ensure the allowable watt density for the heater does not exceed the specific application requirements. Watt density is calculated for one side of the heater only.

Formulas

Wattage Heated Area

Watt Density =

Heated Area (Offset Terminals) = [Overall Length (A) x 1.5 in.] - 6 in 2 = [Overall Length (A) x 38 mm] - 38.7 cm 2 Heated Area (Parallel Terminals) = [Overall Length (A) x 1.5 in.] - 4.7 in 2 = [Overall Length (A) x 38 mm] - 30.3 cm 2 Heated Area (One-on-One Terminals) = [Overall Length (A) x 1.5 in.] - 6 in 2 = [Overall Length (A) x 38 mm] - 38.7 cm 2 600 Part Temperature — °C 500 375 Strip < 24 in. (610 mm) O.A.L.; ba clamped operating in 70°F (21°C) ambient air 375 Strip < 24 i . (610 mm) O.A.L.; bar clamped operating in insulated or enclosed environments 6 8 10 12

Watt Density — W/cm 2

2

4

1200

1000

800

400

600

300

Maximum Allowable Watt Density Clamped

Units 24 in. (610 mm) and longer Consult Factory

400

200

100

200

Part Temperature — °F

20

40

60

80

100

Watt Density — W/in 2

Maximum Allowable Watt Density in Air

6 10 Watt Density — W/cm 2 8

2

4

1200

Sheath Temperature — °C

600

Sheath Temperature (Aluminized Steel)

1000

500

800

400

70°F (21°C) ambient operating in still air

600

300

Sheath Temperature (SS)

400

200

100

200

Sheath Temperature — °F

20

40

60

80

100

Watt Density — W/in 2

467