Tubular heaters, commonly called Calrods®, are comprised of resistance wire coiled inside a sheath. The wire is surrounded with Magnesium Oxide. Magnesium Oxide acts as both an electrical insulator and as a heat transfer material. Sheath materials depend on the heater’s intended application. Copper can be used for water. Stainless steel, carbon steel, Incoloy and Inconel are used for harsher environments.
Tubular heaters can be welded into a flange or screw plug; can be shaped into different configurations, and accessorized with fittings and leads. Tubulars can be placed in liquids, solids or gases. Tubulars can be used as infrared heaters. Sheath diameters come in varying sizes from 1/16 inch to 1/2 inch.
Common uses for tubular heaters include: molten salt tank heaters; infrared heaters; mold heating; air heating (duct heaters); liquid heating by over-the-side tank heaters or through-the-wall flanged immersion heaters or screw plug immersion heaters; heat sealing bars; aluminum extrusion die heaters.
Elements can be constructed in different ways for different applications. Some of the customization options are:
•Shape of element (bends)
•Cold ends or cold sections
•Terminations (threaded posts, lead wire, terminal box, bulkhead fittings)
•Fins (for heating air / gas flows)