Industrial Thermocouples - Types, Working Principle & Global Suppliers


A thermocouple is a temperature sensor, which is used to gauge temperatures in machining, manufacturing and scientific applications. It can also be used for everyday appliances.

For instance, a thermocouple is used to check whether steel, other metals are heated properly for machining, or to measure when a container or location is cool, too warm.

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The American Society for Testing and Materials (ASTM) has defined the term Thermocouple as follows:

Thermocouple, n. - in thermometry, the sensor of a thermoelectric thermometer, consisting of electrically conducting circuit elements of two different thermoelectric characteristics joined at a junction. [Vol. 14.03, E 344 - 02 § 3.1 (2007).]

Thermocouples can be made using common materials such as nickel, iron; They are also made of rare and expensive materials such as rhodium and platinum.

Thermocouple pairings are distinguished by a capital letter heading and there are four different classifications. They are:

a) The Home Body Class - Consists of 'standard' or commonly used metals
b) The Upper Crust Class - Consists of all platinum combinations
c) The Rarified Class - Consists of refractory metals
d) The Exotic Class - Consists of  special combinations of rare metals used for specified applications

Best Buying Guide for Industrial Thermocouples

Industrial Thermocouples - Market Overview

According to a report, the Thermocouple Sensors Market is estimated at US$1.61 billion by 2018 at a CAGR of 6.63% over the period 2014-2020.

The rising trends of security and surveillance, the inclination of growth towards vehicle production, availability of a strong aftermarket are the major growth drivers of Thermocouples market.

Why Thermocouples play an important role in industrial applications?

Thermocouples play an important role in industrial applications because:

•    Small size, fast response
•    Simple  
•    It can be used for a very wide range of temperatures
•    Resists shocks and vibrations
•    Point sensing capacity

Types of Thermocouples:

Thermocouples are classified into different types namely Type-K, Type-J, Type-T, Type-E, Type-N, Type-S, Type-R, and Type-B. Every thermocouple has its own characteristics.

Below are the types of thermocouples, their individual composition and temperature range:

Thermocouples are generally color coded besides their numbering system. The color coding are distinguished based on the country and they differ from country to country.

Thermocouples: The Operating Principle

Generally, a thermocouple is made using two different wires, joined at one end, called 'junction end' or measuring end. The two wires used are called thermo-elements and they are distinguished as positive and negative.

The other end of the thermocouple is called 'tail end' or reference end. For instance, let the temperature of a furnace be about 500°C, and the tail end is held at a different temperature T1 i.e. at ambient temperature. The junction end is immersed in the environment whose temperature T2 has to be measured.

Figure: Schematic drawing of a thermocouple

Due to the temperature difference between junction end and tail end; a voltage difference can be measured between the two thermo elements at the tail end: so the thermocouple is a temperature-voltage transducer.

The temperature vs. voltage relationship is given by:


Emf is the Electro-Motive Force or Voltage produced by the thermocouple at the tail end

T1 and T2 are the temperatures of tail and junction ends respectively

S12 is called Seebeck coefficient of the thermocouple

S1 and S2 are the Seebeck coefficient of the two thermo elements

In addition, the Seebeck coefficient depends on the material the thermo element is made of. Looking at the above equation, it can be noticed that:

1.    a null voltage is measured if the two thermo elements are made of the same materials: different materials are needed to make a temperature sensing device,
2.    a null voltage is measured if no temperature difference exists between the tail end and the junction end: a temperature difference is needed to operate the thermocouple,
3.    the Seebeck coefficient is temperature dependent.

Applications of Thermocouples:

•    Thermocouples are widely used in science and industry
•    They can be used for gas turbine exhaust, kilns, diesel engines, and other industrial processes
•    These are used as the temperature sensors in thermostats in offices, homes, offices & businesses
•    Thermocouples are used in industries for monitoring temperatures of metals in iron, aluminum, and metal
•    They are in the food industry for cryogenic and Low-temperature applications
•    Thermocouples are used as a heat pump for performing thermoelectric cooling
•    These are used to test temperature in the chemical plants, petroleum plants
•    These are used in gas machines for detecting the pilot flame.

What you should consider in Industrial Thermometers before purchasing

Consider the following parameters before purchasing the industrial thermocouples:

•    Temperature range
•    Accuracy
•    Life expectancy
•    Cost
•    Operating environment
•    Thermocouple protection
•    Accuracy required
•    Thermocouple wire size
•    Abrasion and vibration resistance

Key Players | Global Suppliers and Manufacturers of Industrial Thermocouples

Some of the prominent players operating in the global industrial thermocouples market are:

1) Pyrosales Pty Ltd

Pyrosales is a leading manufacturer of temperature instruments. We custom design and engineer our products to suit your requirements. We service a wide range of industries and applications including metals processing, steel, petrochemical, copper and much more.

Pyrosales Pty Ltd has been assessed and approved by QAS International Ltd to the ISO 9001 : 2008 Certificate Number A1066AUS quality management systems, standards and guidelines.

2) Manfred Jünemann Mess & Regeltechnik GmbH

Established in the year 1978 in Bad Salzuflen, Germany, Manfred JÜNEMANN Mess- und Regeltechnik GmbH is a leading producer of instruments for precision, pressure and temperature measurement for applications used in industrial installations that have been renowned for their quality, over the years.

The business had begun with mechanical pressure gauges and then gradually expanded to entire field of electrical and mechanical pressure and temperature measurements.

The company is well-oriented towards its proven guide principles which are the basis for an established and long-term successful company at Jünemann GmbH.

3) Durex Industries

Founded in 1980, Durex Industries has positioned itself as a leader in the design and manufacture of high quality electric industrial heaters, temperature sensors, temperature controls and process systems.

Over the years, we have grown to meet each new challenge in the market through innovative product development, continuous process improvements, and a commitment to high quality standards.

Our design and manufacturing capabilities are diverse and flexible to satisfy all of your requirements. Plus, our engineering experience supports you with product solutions from concept through production, and state-of-the-art design software allows our staff to provide dynamic visual enhancements of prototype designs prior to manufacturing.


We’ve been a leader in manufacturing quality thermocouple, and RTD assemblies since 1972. Thermo Sensors Corporation provides the chemical, petrochemical, refining, food, pharmaceutical, power, environmental and other industries with sensors of standard and special designs. We’re dedicated to a quality control program that sets us apart in the industry. You can always look to us for a great product!