| 摘要 |
An electric heating device is disclosed which comprises a generally tubular sheath, an elongated coil of electrical resistance heating wire passing through a portion of the sheath, and a metal terminal at each end of the sheath. The interior of the sheath is filled with a granular heat conducting, electrically insulating material, and the sheath is sealed at at least one end with a thermoplastic material having a melting temperature in the range of the temperature of the terminal when the heating device is in heated condition. The thermoplastic material must be substantially permeable to gases while melted and substantially impermeable to gases while solid. The use of such a seal enables the heating element to consume oxygen in a normal manner while hot, but will prevent the entry of moisture into the element while the element is cool and the seal is in a solid condition.
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