Thermocouple Specification Criteria

A Technical Selection Note at Smart Sensors Inc.’s Website

Smart Sensors’ Mineral Oxide insulated thermocouple cable with a cut away of the three most common junctions, (from left) ungrounded, exposed, and grounded.

Houston TX, USA — In a downloadable, free technical note on their website, Smart Sensors, Inc. provides a straightforward approach to specifying a thermocouple for a specific task. They state essentially that in specifying a thermocouple there are many parameters you could consider, however, most of the time if you keep their recommendations in mind on the key parameters your thermocouple “will keep its little millivolt heart pumping away forever or until the next maintenance shutdown whichever occurs first”.

The key parameters they say are: Operating Environment, Cost/Performance Ratio, Process Environment, Response Time, Longevity and Calibration. The note explains each.

The table in the technical note provides the details on each parameter for eight types of thermocouples as well as the properties of different junctions and sheath materials. It’s free online at: www.smartsensors.com/spectherm.pdf (NOTE: In PDF Format. Can be read using the free Adobe Acrobat Reader.)

For the most common thermocouple and RTD reference tables download them at Temperatures.com, or elsewhere.

Full printed copies of thermocouple tables, specifications and testing methods may be found in the following ASTM Standards: (All the ASTM Standards from the E20 -Committee on Temperature Measurement – are updated annually in print and DVD versions as the ASTM Volume 14.03 Temperature Measurement)

  • E230-03 – Standard Specification and Temperature-Electromotive Force (EMF) Tables for Standardized Thermocouples
  • E235-06 – Standard Specification for Thermocouples, Sheathed, Type K and Type N, for Nuclear or for Other High-Reliability Applications
  • E574-06 – Standard Specification for Duplex, Base Metal Thermocouple Wire With Glass Fiber or Silica Fiber Insulation
  • E585/E585M-09 – Standard Specification for Compacted Mineral-Insulated, Metal-Sheathed, Base Metal Thermocouple Cable
  • E601-07a – Standard Test Method for Measuring Electromotive Force (emf) Stability of Base-Metal Thermoelement Materials with Time in Air
  • E608/E608M-06 – Standard Specification for Mineral-Insulated, Metal-Sheathed Base Metal Thermocouples
  • E633-00(2005) – Standard Guide for Use of Thermocouples in Creep and Stress-Rupture Testing to 1800 °F (1000 °C) in Air
  • E696-07 – Standard Specification for Tungsten-Rhenium Alloy Thermocouple Wire
  • E780-06 – Standard Test Method for Measuring the Insulation Resistance of Mineral-Insulated, Metal-Sheathed Thermocouples and Thermocouple Cable at Room Temperature
  • E839-05 – Standard Test Methods for Sheathed Thermocouples and Sheathed Thermocouple Material
  • E1129/E1129M-08e1 – Standard Specification for Thermocouple Connectors
  • E1137/E1137M-08 – Standard Specification for Industrial Platinum Resistance Thermometers
  • E1159-98(2009) – Standard Specification for Thermocouple Materials, Platinum-Rhodium Alloys, and Platinum
  • E1350-07 – Standard Guide for Testing Sheathed Thermocouples, Thermocouples Assemblies, and Connecting Wires Prior to, and After Installation or Service
  • E1751/E1751M-09e1 – Standard Guide for Temperature Electromotive Force (emf) Tables for Non-Letter Designated Thermocouple Combinations
  • E2181/E2181M-06e1 – Standard Specification for Compacted Mineral-Insulated, Metal-Sheathed, Noble Metal Thermocouples and Thermocouple Cable

The reference page on the Smart Sensors website includes some other gems like:

NOTE: Some of the above are in PDF Format. They can be read using the free Adobe Acrobat Reader.

About Smart Sensors, Inc.

Its founders have almost a century of experience in the design production, sales, and application of thermocouples & RTDs. If they haven’t made it, sold it, or seen it before it probably has never been done.

Smart Sensors, Inc.
1920 Aldine Western
Houston TX 77038 USA

Tel: +1 281-272-5333
Fax : +1 281-272-5332
Email: Info@smartsensors.com
Web: www.smartsensors.com

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