Standard Test Methods for Sheathed Thermocouples and Sheathed Thermocouple Cable

Importancia y uso:

5.1 This standard provides a description of test methods used in other ASTM specifications to establish certain acceptable methods for characterizing thermocouple assemblies and thermocouple cable. These test methods define how those characteristics shall be determined.

5.2 The usefulness and purpose of the included tests are given for the category of tests.

5.3 Warning—Users should be aware that certain characteristics of thermocouples might change with time and use. If a thermocouple’s designed shipping, storage, installation, or operating temperature has been exceeded, that thermocouple’s moisture seal may have been compromised and may no longer adequately prevent the deleterious intrusion of water vapor. Consequently, the thermocouple’s condition established by test at the time of manufacture may not apply later. In addition, inhomogeneities can develop in thermoelements because of exposure to higher temperatures, even in cases where maximum exposure temperatures have been lower than the suggested upper use temperature limits specified in Table 1 of Specification E608/E608M. For this reason, calibration of thermocouples destined for delivery to a customer is not recommended. Because the emf indication of any thermocouple depends upon the condition of the thermoelements along their entire length, as well as the temperature profile pattern in the region of any inhomogeneity, the emf output of a used thermocouple will be unique to its installation. Because temperature profiles in calibration equipment are unlikely to duplicate those of the installation, removal of a used thermocouple to a separate apparatus for calibration is not recommended. Instead, in situ calibration by comparison to a similar thermocouple known to be good is often recommended.

Subcomité:

E20.14

Referida por:

E2877-12R19, E2488-22, E1350-18R23, E0235_E0235M-23, E0608_E0608M-13R19, E0344-23, E2877-12R19, E0585_E0585M-23, E2821-20, E2846-20, G0151-19, E0608_E0608M-13R19, G0151-19

Volúmen:

14.03

Número ICS:

17.200.20 (Temperature-measuring instruments)

Palabras clave:

high temperature insulation test; insulation resistance; sheath integrity; sheathed thermocouple; thermal cycle; thermal response time; thermocouple; thermocouple assembly properties; thermoelement; thermoelement properties ;