Coiled Heating Elements
By far the most commonly used heating element design comprising a round wire of resistance material FeCrAl or Ni Cr material.
The design involves proper selection of the wire, coil diameter, coil pitch and wattt loading of the element.
Based on the application and installation the coil can be of single shank( spiral) , double shank or multi shank, suitably connected with the terminal rod usually of the same alloy or a lower grade of alloy , for a better homogeneity and better temperature withstanding properties.
The coils could be supported in grooved refractory or on ceramic tubes. Greater consideration is given on the proper support, furnace atmospheres and contaminations, and most importantly the radiation properties of the element together with the watt loading.