Contents

Introduction

The Introduction page describes the technical basis of the database.  This page also contains links to appendices, tables, and references.

View Tables

In the View Tables page, select from a drop down menu to view a table of thermoelectric voltages (by type and temperature range), of the coefficients, or of the inverse coefficients.  Please note that one can select only ONE table at a time of thermoelectric voltages of each type by temperature range, of the coefficients, or of the inverse coefficients.  From this page one can also choose to View Thermocouple Types Definitions or proceed to the download page to Download Tables of Thermoelectric Voltages and Coefficients.

Tables of Thermocouples

The default units used in this version of the database for temperature and electromotive force are degrees Celsius (°C) and millivolts (mV), respectively.  Electromotive force is abbreviated as emf, or symbolically denoted as E .

All the thermocouples tables have the same format.  At the top and bottom of each table, there are two drop-down menus, each for the thermoelectric voltages and coefficients, and a link to the Download Tables of Thermoelectric Voltages and Coefficients.  Each table displays the thermoelectric voltages at a specific temperature range of a particular thermocouple type.  To view another table of the same or different thermocouple type, select the desired temperature range of that type from the temperature range drop-down menu at either the top or bottom of the current table.  Similarly, to view a table of coefficients of a particular thermocouple type, select the desired table for that particular type from the coefficients drop-down menu at either the top or bottom of the current table.

The drop-down menus are organized in such a way that the selected thermocouple type is always listed at the top.  The remaining thermocouple types are listed in alphabetical order.

To download the tables of thermoelectric voltages and/or coefficients, click Download Tables of Thermoelectric Voltages and Coefficients at either the top or bottom of the current table.

Tables of Coefficients

The default units used in this version of the database are degrees Celsius (°C) and millivolts (mV), respectively. Symbolically, emf is denoted as E .

All the coefficients tables have the same format.  At the top and bottom of each table, there are two drop-down menus, each for the thermoelectric voltages and coefficients, and a link to the Download Tables of Thermoelectric Voltages and Coefficients.  Each table displays the coefficients of a particular thermocouple type.  To view another table of coefficients of the same or different thermocouple type, select the desired coefficients table from the coefficients drop-down menu at either the top or bottom of the current table.  Similarly, to view a table of thermoelectric voltages of a particular thermocouple type, select the desired temperature range for that particular type from the temperature range drop-down menu at either the top or bottom of the current table.

To download the tables of thermoelectric voltages and/or coefficients, click Download Tables of Thermoelectric Voltages and Coefficients at either the top or bottom of the current table.

Download Tables

In the Download Tables page, click the link of the desired type to download the table of thermoelectric voltages and coefficients of that type.  To download a table containing BOTH thermoelectric voltages and coefficients of all types (B - T), click All Thermocouple Types.  To download a table of ONLY coefficients of all types (B - T), click Reference Function Coefficients Definitions.

Also, one can choose to view the Reference Function Coefficients Definitions, the Thermoelectric Voltage File Format, or the Coefficients File Format.

Version History

This page contains information on the version history of the database.

Disclaimer

This page contains the NIST disclaimer.

Contact Information

This page contains the contact information.

Terminology

Electromotive force, thermoelectric voltage - synonymous terms that describe the net value of electrochemical potential that is generated by a thermocouple with reference junctions at 0 °C and measuring junctions at the indicated temperature.  The electromotive force is abbreviated "emf" and is denoted by the symbol E.

International Temperature Scale of 1990 (ITS-90) - an internationally accepted definition of temperature, including the assignment of temperatures to various natural fixed-points, such as the freezing point of gold; specification of thermometer types; and specification of interpolation methods between fixed points.  The ITS-90 replaces earlier, obsolete scales that were adopted in 1927, 1948, and 1968.  The symbol t₉₀ or T₉₀ is used to designate temperature on the ITS-90.  Appendix A gives further information.

Inverse function - a mathematical function giving temperature as a function of voltage.  The thermocouple reference functions cannot be inverted exactly with a finite number of coefficients; consequently the inverse functions are only approximate, to within the errors stated in the tables of coefficients.

Inverse function coefficients, or inverse coefficients - the numerical parameters used in the inverse functions.  Polynomial coefficients are denoted d_i for the ith power of thermoelectric voltage.

Measurement junction - that junction of dissimilar metals in a thermoelectric circuit that is placed at the location of the unknown temperature that is to be determined.

Reference function - the mathematical function giving the thermoelectric voltage as a function of temperature.  This function defines the response of a specific letter-designated thermocouple type.

Reference function coefficients, or coefficients - the numerical parameters used in the reference functions. Polynomial coefficients are denoted c_i for the ith power of temperature.  For type K, there are additional coefficients a₀, a₁, and a₂.

Reference junctions - those junctions in a thermoelectric circuit that are maintained at a fixed, known temperature, which is often 0 °C.

Thermocouple - a pair of dissimilar electrical conductors joined at one end (the measuring junction).  When the other ends of the thermocouple are maintained at a known reference temperature, the thermoelectric voltage produced by the thermocouple is a repeatable function of the temperature of the measuring junction.

Thermoelectric voltage - see Electromotive Force.