Hi-Watt Density Cartridge Heaters

Application and Selection Information

Hi-Watt Density Cartridge Heaters Maximum Allowable Watt Density

How to Order FIREBRAND®

  1. When ordering, specify:
    1. Overall length (1/4" cold section on each end is minimum and standard; longer cold sections ay be specified).
    2. Heated length
    3. Nominal diameter
    4. Lead length
    5. Voltage and wattage.
    Generally, diameter and length are determined by the space available and your requirements for even heat distribution. The standard lead consists of 2" bendable nickel pins with 8" flexible nickels leads insulated with silicone impregnated fiber glass.

  2. Determine: Watt Density = Total Wattage / (Diameter x Pi x Heated Length)
    Example: a 3/8" diameter firebrand 3"long overall (with the standard 1/4" cold end), rated at 300 watts
    .371 x 3.14 x 2-1/2" = 2.91 heated area of sheath
    300 / 2.91 = 103 watts per square inch

  3. Determine: fit = maximum inside diameter of hole equals the minimum outside diameter of the sheath
    Example: a 3/8" FIREBRAND in a .375±.001 reamed hole would have a .007 fit .376-.369=.007

  4. Check the operating temperature of your part against the watt density and fit indicated on the chart above. If you are within limits you can expect operating life in excess of one year(8700 hours)

  5. If you are outside the limits, you can:
    1. Decrease the watt density
      1. increasing the diameter
      2. increasing heated length
      3. increasing the number of units used
      4. reducing the wattage, allowing for longer heat-up time
    2. Use a tighter fit, center-less grinding the FIBERBRAND if necessary
    3. Ask our design engineering department for an estimated operating life and alternate recommendations.
Nominal Diameter 1/4" 3/8" 1/2" 5/8" 3/4"
Actual Diameter (±.002) .246" .371" .496" .621" .746"
Maximum Volts 240 240 240 480 480
Maximum Amps 4.4 6.7 9.7 23 23
Maximum Watts(120 V)
Maximum Watts(240 V) 		525
1020		 800
1600		 1160
2320		 2760
5520		 2760
5520
Minimum Watts(120 V)
1" long
2" long 		 
100
40		  
65
25		  
40
20		  
35
15		  
30
10