| 摘要 |
1,265,752. Thermometers. WESTON INSTRUMENTS Inc. April 25, 1969 [April 30, 1968], No. 21201/69. Heading G1D. A thermometer comprises a sealed housing 4, 20 supporting a temperature scale 31, a bi-metallic temperature sensitive element 6 coupled to a pointer 36 and oxygen getting material 14 which becomes active as the temperature nears the maximum temperature measurable by the thermometer. The material 14 is in the form of a thin tantalum ribbon and the element 6 comprises a pair of iron base alloy members, one member containing nickel and chromium whilst the other contains chromium. One end of the element 6 is welded to a plug 5 and the other end is welded to a shaft 9 which passes through guides 10-12. A ring 27 presses a transparent cover plate 25 against a gasket 26 to seal the housing 20. The scale 31, marked with the temperature range 200-1200‹ C. on its lower surface, is held in position by a ring 30 and a plane mirror 37 fixed to the housing 20 by lugs 38 enables the scale to be read. On assembly the thermometer is filled with an inert gas such as argon and heated to 1500‹ C. for a sufficient time to anneal the element 6. During this time the tantulum removes any oxygen in the housing to prevent the oxygen affecting the characteristics of the bi-metallic element. To assist calibration of the thermometer the scale may be rotated by rotating the ring 30, the ring then being locked by a screw 35. In a modification, the mirror 37 is dispensed with and the scale is mounted in the housing. |
