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List of Alloys & profiles

List of Alloys & profiles

Designing a Tape Element

The method is similar to that used in designing a round wire element.

Where:

bTape width (mm)
tTape thickness (mm)

Example:

1.  To calculate the tape size and length required for a 600w/220v mica-wound element in a band heater, operating at a maximum temperature of 800°C, the total resistance of the element at operating temperature (Rt) will be:

Designing a Tape Element - Alloy Wire International 1

2.  Using RW80 tape, the Temperature Resistance Factor (F) at 800°C is 1.051.  Thus, the total resistance of the element at 20°C (R) will be:

Designing a Tape Element - Alloy Wire International 2

3.  Knowing the dimensions of the mica-board, the length of the tape that may be wound round it may be estimated.  Thus, the resistance required per metre of tape will be:

For example a length of tape of 7 metres –

Designing a Tape Element - Alloy Wire International 3

4.  A tape size of 1.1mm x 0.09mm has a resistance per metre of 11.10 ohms/m (see stock sizes) which is near to 10.97 ohms/m.

5.  To verify the actual tape length (L)

Designing a Tape Element - Alloy Wire International 4

A change in tape length may mean adding or subtracting turns (altering the pitch of the tape) to achieve the total resistance value required.

6.  To verify the surface area loading (S):

Designing a Tape Element - Alloy Wire International 5

If your calculated surface area loading is too high or low (see table) you should re-calculate changing one or more of the following:

– The tape length and size