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Thermocouple

Vacker Nigeria supplies an electrical device we know as ‘Thermocouple’. It is a simple device that consists of two distinct conductors that on unison forms an electrical junction at various temperatures. It produces voltage that is dependent on temperature. We all know what temperature sensors are and thermocouple is one of its types. Modern thermocouples are self powered and have the potential of measuring a wide range of temperatures.

The scope of use of thermocouple includes field of science and industrial field too. In these fields it can be used for the measurement of temperature of diesel engines, gas turbine exhaust and many other processes involved in the industrial sector.

Apart from commercial and industrial purposes Vacker Nigeria supplies solution with thermocouples for residential and official purposes in major cities of Nigeria like: Lagos, Abuja, Kaduna, Port Harcourt, Aba, Ibadan and Kano. These days we commonly find thermocouple in the form of flame sensors some major appliances that are powered with gas.

Independent of other details, a thermocouple should measure range of temperature. There are numerous factors that determine the measurement and accuracy of the measurement.

Principle of operation

The first thermocouple came into being in 1821 it was discovered that when two or more distinct metals are connected end to end then a difference in temperature creates a magnetic field. The same was referred to as thermo-magnetism that was created due to thermo electric current. The voltage generated at the junction can be used for the measurement of very high or very low temperature. A thermopile uses multiple thermocouples for the generation of power.

Types

In modern practices, a combination of certain alloys is coming in regular practice in the field of industrial purpose. Selection of the alloys, however, depends upon various factors. Some of them are:

  • The cost associated with it.
  • How easily the alloy is available.
  • Melting points of the alloys.
  • Stability along with other chemical properties of the same.
  • Chemical inertness of thermocouple material.
  • Magnetism of the materials.

Various applications use various thermocouples depend upon the need of the applications. On the basis of the criticality required and the temperature range, different thermocouples are selected. Some of the commonly used thermocouples are:

Nickel alloy thermocouples

These thermocouples are made up of nickel alloys and are used for intermediate temperatures. There are various sub types: Type E, Type J, Type K, Type M, Type N and Type T.

Platinum/rhodium alloy thermocouples

These are the pure metal thermocouples. There are various sub types: Type B, Type R and Type S. These are used for high temperature ranges.

Tungsten/rhenium alloy thermocouples

These thermocouples are used for the measurement of extremely high temperature readings. The temperature ranges from 0°C to 2315°C. However the upper limit of the temperature range changes to 2760°C in inert atmosphere. Its sub types are: Type C, Type D and Type G.

Other commonly used thermocouples are as under:

  • Chromel – gold/iron alloy thermocouples
  • Type P (noble metal alloy)
  • Platinum/molybdenum alloy thermocouples
  • Iridium/rhodium alloy thermocouples
  • Pure noble metal thermocouples Au–Pt, Pt–Pd

Applications of thermocouples

Thermocouples can be used in following applications:

  • Steel industry
  • Gas appliance safety
  • Thermopile radiation sensors
  • Manufacturing
  • Power production
  • Process plants
  • Thermocouple as vacuum gauge