Kapton® Heater Wattage and Watt Density Information
Determine Required Wattage
Every process has a unique wattage requirement to heat that particular load up to temperature or to maintain a particular temperature.
If the required heater wattage is not known, estimate the required wattage using the thermodynamic formulas listed in chapter 16, Engineering. A safety factor of 25% additional wattage is recommended to compensate for unknown variables.
Example
To raise the temperature of an aluminum plate 6″ × 12″ × 0.5″ (3.53 lb.) 200°F (from 70° to 270°F) in 0.5 hours:
| Watts = |
3.53 lbs. × (0.24 btu/lb.°F) × 200°F
3.412 btu/watt hr. × 0.5 hrs. | 99 watts |
Add safety margin: 99 W + 25% = 124 watts
Determine the Heater Size and Watt Density
A flexible heater should use the maximum space available for mounting and heating the process. Factors that affect heater size include the mounting method and watt density.
| Watt Density = |
Heater Wattage
Area of Heater |
As a general rule, the following can be applied for Kapton® heaters:
- Low Heat-Up:2.5 w/in2
- Average Heat-Up:5 w/in2
- High Heat-Up:7.5 w/in2 and greater
Continuing the aluminum plate example, determine what size the heater should be:
- Kapton® Heater:5″ × 10″ = 50 in2
- Watt Density= 135 watts ÷ 50 in2 = 2.7 watts/in2
Since the watt density falls between 2.5 and 5 w/in2, the heater selected should work satisfactorily.
Suggested Maximum Watt Density by Heater Type and Mounting Method
| Kapton® – Foil Element | ||
|---|---|---|
| Watt Density w/in2 | Acrylic PSA | Acrylic PSA with
3 mil Aluminum Foil |
| 5 | 212 to 189°F | 302 to 275°F |
| (100 to 87°C) | (150 to 135°C) | |
| 10 | 189 to 163°F | 275 to 257°F |
| (87 to 73°C) | (135 to 125°C) | |
| 15 | 163 to 131°F | 257 to 230°F |
| (73 to 55°C) | (125 to 110°C) | |
Note: Use an appropriate Temperature Controller for the application.
View Tempco Temperature Control Products.
See Also:
- Heat Requirement Calculations
(Catalog PDF, Section 16) - Wattage Estimation Tables
(Catalog PDF, Section 16)
