CPC G01K 7/06 (2013.01) [F27B 5/18 (2013.01)] | 11 Claims |
1. In a cold wall vacuum furnace hot zone with a heating element diameter of 36 inches or less and operating at temperatures of 649″C or less for heat treating metal parts, a control thermocouple assembly for measuring the temperature in the hot zone comprising:
continuous sheath having an elongated longitudinal axis and a measuring tip located along said elongated longitudinal axis at a distal end of said sheath;
said sheath having an outside diameter of no more than 3/16 inch and being made from a ceramic material;
said sheath having an inner single bore ceramic tube comprised of a series of stacked tubes having air gaps therebetween located one on top of another within said sheath,
said sheath containing a first thermocouple wire therein and the series of stacked tubes having a single bore containing a second thermocouple wire therein, said first and second thermocouple wires being separated from each other within said sheath, and being joined together at the longitudinal tip of said sheath to form a thermocouple junction therebetween; and
a reflection shield being operatively connected to an outer face of the furnace hot zone and located in proximity to said thermocouple assembly sheath.
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