ASTM E780-92(1998) PDF

1.1 This test method covers the techniques and requirements for measuring the electrical insulation resistance at room temperature between the thermoelements and between each of the thermoelements and the metal sheath of compacted ceramic-insulated, sheathed thermocouple material. It may be used to measure the insulation resistance of bulk lengths of sheathed thermocouple material environmentally sealed at the time of manufacture. It may also be used for testing sheathed thermocouples with a Type U junction. This test method cannot be used for sheathed thermocouples with a Type G junction unless the junction is removed, prior to testing.

1.2 This test method applies to the testing of sheathed thermocouple materials that are suitable for use in air. It is also applicable for sheathed thermocouple materials whose sheath or thermoelements are composed of refractory metals and are tested in a dry and nonreactive environment.

1.3 This test method may be used for sheathed thermocouple material having an outside diameter of 1.0 mm or larger.

1.4 Since the insulation resistance at room temperature of sheathed thermocouple materials may change during shipment, storage and use, the results obtained by this test method may not be the same as insulation resistance values determined at some later time.

1.5 This standard does not purport to address all of the safety problems, 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.