Thermoelectric Instability of Some Noble Metal Thermocouples at High Temperatures

Abstract

NOTICE: When government or other drawings, specifications or other data are used for any purpose other than in connection with a definitely related government procurement operation, the U. S. Government thereby incurs no responsibility, nor any obligation whatsoever; and the fact that the Government may have formulated, furnished, or in any way supplied the said drawings, specifications, or other data is not to be regarded by implication or otherwise as in any manner licensing the holder or any other person or corporation, or conveying any rights or permission to manufacture, use or sell any patented invention that may in any way be related thereto.

Measurements of the thermal conductivity and electrical resistivity of platinum from 373 to 1373 degrees K

“…For the parameter values appropriate to our experiment, the term in # o I 2 and the term in ft 0 /k 0 in the denominator of the right-hand side of (4-16) are small compared to unity and, as shown in Appendix E, (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16) reduces to the form ftp 1281…”

“…Ko(rra/21 ) J (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) where u^is the maximum temperature rise the neck would have if there were no heat losses, i.e., if = 0.…”

Research Techniques for High Pressure and High Temperature

“…Sheathed thermocouples made by at least some manufacturers drift excessively, possibly due to the use of impure ceramic between the sheath and the thermocouple wires (Walker et al, 1962). The National Bureau of Standards will calibrate platinum versus platinum-rhodium thermocouples to an accuracy of to.5 C up to 1100 C with the error increasing to tl.7 C at 1450 C, and these uncertainties place a limit on the accuracy of the temperature measurement.…”

High Temperature Sensors for Gas Turbines

“…This type of error is caused by changes in composition of the thermocouple wires in the portion of their length that is in a temperature gradient. The calibration error is the sum of the uncertainty in the initial calibration plus changes with time caused by vaporization, contamination, and diffusion (2). It is therefore necessary to test for calibration drift in the service environment; calibrations conducted under other conditions may not reflect the true change that has occurred in service (3).…”