Standard Specification for Mineral-Insulated, Metal-Sheathed Base Metal Thermocouples

Importancia y uso:

4.1 This specification describes the physical requirements of mineral-insulated, metal-sheathed base metal thermocouples and establishes suitable test criteria for their evaluation.

4.2 Standardized dimensional requirements and acceptable allowances for manufacturing variations, are given.

4.3 A set of standard tests to be applied to all thermocouples covered by this specification are described, in addition to optional tests from which applicable additional requirements may be selected.

4.4 Warning—Users should be aware that certain characteristics of thermocouples might change with time and use.

4.4.1 If a thermocouple's designed shipping, storage, installation, or operating temperature has been exceeded, the thermocouple’s moisture seal may have been compromised and may no longer prevent the deleterious intrusion of water vapor. Consequently, the thermocouple's condition established by test at the time of manufacture may not apply later after an extended period of use, and retesting may become necessary.

4.4.2 In addition, inhomogeneities can develop in thermoelements because of exposure to temperature, even in cases where the maximum exposure temperatures have been lower than the suggested upper temperature limits of Table 1. For this reason, calibration of thermocouples destined for delivery to a customer is not recommended (see S6.1).

4.4.3 Furthermore, 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 of known accuracy is recommended.

Subcomité:

E20.12

Referida por:

D0648-18, D8540-23, A0991_A0991M-22, E0780-17R21, D3012-19, D4693-07R21, E1350-18R23, D3012-19, D0746-24, D1525-17E01, E0344-23, D0746-24, E1684_E1684M-19, D0648-18, E1129_E1129M-19, E0230_E0230M-23A, E0585_E0585M-23, E2181_E2181M-24, D1525-17E01, E0839-23, E2846-20, D0648-18, D0648-18, D6984-18E01, D7320-18E01

Volúmen:

14.03

Número ICS:

17.200.20 (Temperature-measuring instruments)

Palabras clave:

base metal thermocouples; junction; metal-sheathed; moisture seal; sheathed thermocouples; termination; thermocouple; thermoelement ;