MANUFACTURE OF MINERAL INSULATED THERMOCOUPLE PROBES

摘要

A process for the manufacture of a mineral insulated thermocouple probe (1) of predetermined diameter comprises: (i) cutting a length of metal tube (2) to a predetermined length; (ii) sealing one end of the metal tube, for example by capacitance discharge welding; (iii) joining at least one pair of thermocouple wires (4 and 6) formed from dissimilar metals together to form a hot junction and positioning the wires together so that they are substantially parallel to each other with the hot junction at one end thereof; (iv) locating the thermocouple wires inside the tube (2) together with mineral insulant (8) so that the interior of the tube is substantially filled with the mineral insulant and the thermocouple wires, and the hot junction is located in the region of the sealed end of the tube; (v) reducing the diameter of the tube to form a thermocouple having a sheath of the predetermined diameter; and (vi) sealing the opposite end of the thermocouple (the cold junction). The process has the advantage of speed and relatively low scrap rate.