1.1 This test method provides comparison of emf stability of single-element base-metal thermocouple materials in air referenced to platinum at specified constant elevated temperatures.

1.2 Since the useful life of a thermocouple depends on the stability of the emf generated at given temperatures for a required time period, the method includes emf drift measurements with time. The emf is measured against platinum, which may be the platinum leg of the platinum-rhodium/platinum reference thermocouple used to indicate the temperature at the time of taking the emf readings, or an additional platinum reference.

1.3 The total life is included as added information, if required.

Note 1-Some thermoelements may show insignificant emf drift while undergoing relatively rapid oxidation. In these cases, failure of the thermoelement may be indicated only by open circuit.

Note 2-See ASTM STP 470B for recommended upper temperature limits in air.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.