ABSTRACT
This chapter shows the principal construction of an element equipped with coils. One or more resistance coils or sinuated ribbons are situated on the surface of a ceramic fiber plate and fastened to it by cement, by staples or by partly embedding the coil or the corrugated ribbon into the ceramic fiber. In a vertical quartz tube element the bottom wire turn has to be mechanically well supported to avoid distortion of the coil. Rectangular elements of ceramic having parallel and half-open grooves for the resistance coil may be used for different radiation purposes. A broiler equipped with elements of this kind may be fitted out with a metallic grid under the element to prevent people from touching the live element. The wire temperature of vertical tube elements should not substantially exceed 1000°C, since the insulating properties of the oxide on the wire surface decrease with increasing temperature.
