ASTM E2846-14
Standard Guide for Thermocouple Verification

Standard No.

ASTM E2846-14

Release Date

2014

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM E2846-20

Latest

ASTM E2846-20

Scope

5.1 These verification tests may be performed by users or calibrators of thermocouples. The methods are useful for both new and used thermocouples. They provide a means to assess the accuracy with which a thermocouple is capable of measuring temperature.

5.2 Results from these tests may be used to determine whether to use or discard a thermocouple. If the thermocouple is subsequently used, the test results may be included in the measurement uncertainty budget. In many circumstances, the results of in situ verifications may be used to recalibrate a used thermocouple. Laboratory measurements, on the other hand, may be used only to verify the original thermocouple calibration or to determine the uncertainty of temperature measurements with the tested thermocouple. Laboratory measurements generally do not suffice to determine the emf-versus-temperature response of a thermocouple found to be inhomogeneous.

1.1 This guide describes tests that may be applied to new or previously used thermocouples for the purpose of verification. Some of the tests perform a suitable verification by themselves, but many tests merely alert the user to serious problems if the thermocouple fails the test. Some of the tests examine inhomogeneity and others detect wire or measuring-junction breakage. For Style U mineral-insulated metal-sheathed (MIMS) thermocouples with ungrounded measuring junctions, this guide includes tests that examine the electrical isolation of the sheath as well as sheath deterioration.

1.2 The first set of tests involves measurement verifications designed to be performed while the thermocouple is in its usage environment. The second set is composed of electrical tests and visual inspections designed to evaluate the functionality of the thermocouple; these tests may be performed either in house or in a calibration laboratory. The third set is made up of homogeneity tests designed to be performed in a calibration laboratory. Some of the tests provide simple methods to identify some, but not all, defective thermocouples, and alone do not suffice to verify a used thermocouple. They may need to be complemented by other tests for a complete verification.

1.3 The reader of this guide should decide which of the described tests need to be performed. This decision is dependent on whether the reader uses thermocouples for temperature measurement or performs thermocouple calibrations in a laboratory. For users of thermocouples, it is recommended that appropriate tests from the first and second sets be performed initially, as they provide immediate on-site verification of the thermocouples. The appropriateness of a test is dependent upon the user’s temperature measurement uncertainty requirements. Some tests may have lower uncertainties in their verification measurements than others. If these tests do not clearly determine the suitability of the thermocouples, they should be sent to a calibration laboratory for performing appropriate tests from the third set, which give the most complete information on the thermocouple homogeneity. For those who perform thermocouple calibrations in a laboratory, it is recommended that appropriate tests from the second and third sets be performed prior to calibration. The appropriateness of a test is dependent on the calibration laboratory’s capability and convenience for performing the test, as well as the characterist......

ASTM E2846-14 Referenced Document

• ASTM E1350 Standard Guide for Testing Sheathed Thermocouples Prior to, During, and After Installation
• ASTM E2181/E2181M Standard Specification for Compacted Mineral-Insulated, Metal-Sheathed, Noble Metal Thermocouples and Thermocouple Cable
• ASTM E220 Standard Test Method for Calibration of Thermocouples By Comparison Techniques
• ASTM E344 Terminology Relating to Thermometry and Hydrometry
• ASTM E563 Standard Practice for Preparation and Use of an Ice-Point Bath as a Reference Temperature
• ASTM E585/E585M Standard Specification for Compacted Mineral-Insulated, Metal-Sheathed, Base Metal Thermocouple Cable
• ASTM E608/E608M Standard Specification for Mineral-Insulated, Metal-Sheathed Base Metal Thermocouples
• ASTM E780 Standard Test Method for Measuring the Insulation Resistance of Sheathed Thermocouple Material at Room Temperature
• ASTM E839 Standard Test Methods for Sheathed Thermocouples and Sheathed Thermocouple Material

ASTM E2846-14 history

• 2020 ASTM E2846-20 Standard Guide for Thermocouple Verification
• 2014 ASTM E2846-14 Standard Guide for Thermocouple Verification
• 2011 ASTM E2846-11 Standard Guide for Thermocouple Verification