BJC cartridge heaters are manufactured +0.00mm – 0.10mm for any given diameter. This sizing is maintained so that all units are a slide fit into a standard reamed hole. Thermal action will expand the element to ensure a close fit for maximum heat transfer.
In most applications cartridge elements are inserted into reamed holes and dissipate their heat by direct contact thus allowing loadings up to 6.2 watts/cm2 of surface area of the cartridge (40W/in2 )
In applications where they are not in direct contact such as defrosting and air heating in switch gear cubicles, etc., then the maximum watt density must not exceed 3.1 watts/cm2 of surface area (20W/in2 ).
All sizes feature flexible nickel wire leads with double glass insulation. Standard lead length is 250mm but longer leads can be supplied on application.