| 摘要 |
A sleeve heater for heating a body having an outside surface has a helicoidal heater element including a central resistive heating wire, an insulation mass surrounding it, and a dimensionally stable housing. The element forms an inside surface shaped to fit snugly around the outside surface of the body. A thermal insulating jacket externally surrounds the heater element. This jacket is rigid and tubular and normally is at least partially ceramic, typically of ceramic fibers. A foraminous tube surrounds the element and lies between the element and the thermal-insulating jacket. This tube is foraminous and can be a mesh or of perforated sheet metal, for instance a perforated stainless-steel sleeve. The sleeve is coated with the ceramic thermal insulation and is then slipped over the helicoidal heating element.
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