Thermoplastic end seal for electric heating elements

An electric heating device comprising:

• a generally tubular sheath;
• an elongated coil of electrical resistance heating wire passing through a portion of said sheath and spaced therefrom;
• an elongated first metal terminal arranged at one end of said sheath, one end of said first terminal being electrically connected to one end of said wire at the interior of said sheath and spaced therefrom, the other end of said first terminal being disposed at the exterior of said sheath;
• an elongated second metal terminal arranged at the other end of said sheath, one end of said second terminal being electrically connected to the other end of said wire at the interior of said sheath and spaced therefrom, the other end of said second terminal being disposed at the exterior of said sheath;
• a mass of granular, heat conducting, electrically insulating material disposed within said sheath and embedding said wire and said terminals and retaining said wire and said terminals in spaced relation with said sheath;
• a seal disposed at least one end of said sheath between said terminal and said sheath, said seal formed of a thermoplastic material having a melting temperature in the range of the temperature of the terminal when the heating device is in heated condition, said thermoplastic material being substantially permeable to gases while melted, and substantially impermeable to gases while solid.