ASTM E220-07a PDF

SIGNIFICANCE AND USE For users or manufacturers of thermocouples, this test method provides a means of verifying the emf-temperature characteristics of the material prior to use. This test method can be used to calibrate a thermocouple for use as a reference, or it can be used to calibrate thermocouples representing a batch of purchased, assembled thermocouples. This test method can be used for the verification of the conformance of thermocouple materials to temperature tolerances for specifications such as the tables in Specification E 230 or other special specifications as required for commercial, military, or research applications. SCOPE 1.1 This test method describes the principles, apparatus, and procedure for calibrating thermocouples by comparison with a reference thermometer. Calibrations are covered over temperature ranges appropriate to the individual types of thermocouples within an overall range from approximately −195 to 1700 °C (−320 to 3100 °F). 1.2 In general, this test method is applicable to unused thermocouples. This test method does not apply to used thermocouples due to their potential material inhomogeneity—the effects of which cannot be identified or quantified by standard calibration techniques. Thermocouples with large-diameter thermoelements and sheathed thermocouples may require special care to control thermal conduction losses. 1.3 In this test method, all values of temperature are based on the International Temperature Scale of 1990. See Guide E 1594. 1.4 This standard may involve hazardous materials, operations and equipment. 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 requirements prior to use.