REFERENCE TABLES FOR THE PALLADIUM VS PLATINUM-15 PERCENT IRIDIUM THERMOCOUPLE
NATIONAL BUREAU OF STANDARDS GAITHERSBURG MD
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The purpose of the development of the palladium vs platinum-15 iridium PPI thermocouple was for measurement of temperatures up to 2300 F, and to obtain a high thermal sensitivity in this range. Comprehensive calibration tables have been prepared giving the thermal emf of the palladium versus platinum-15 iridium thermocouple system in the temperature range from -80 to 2550 F. These expanded tables are given in both degrees Celsius and Fahrenheit at intervals of one degree as the argument. Conversely, similar tables using electromotive force at intervals of 10 microvolts as the argument are presented. It is believed that these expanded calibration tables give thermal emf values better than 0.1 for the six thermocouples examined. Some other information includes a table of the observed temperature-emf relationship of the PPI negative element palladium vs platinum Pt 27, and of the positive element platinum-15 iridium vs platinum Pt 27. The method used in calibrating the thermocouples in the range 32 to 2550 F is described briefly.