Home Technical Information Thermocouples 4. Selection of the types of element

Technical Information

4. Selection of the types of element

Platinum-Rhodium-Platinum (Pt-RhPt) Type S, Type R

  • Temperature range 0 - 1300°C
  • small temperature voltage coefficient
  • very exact and reproducibly
  • constant against oxidation and corrosion even at higher temperatures

Nickel-Chrome-Nickel (NiCr-Ni) Type K

  • Temperature range 0 - 1000°C
  • small temperature voltage coefficient
  • relatively exact and constant sufficient linearity of the voltage curve starting
  • from 600 degrees of scaling by oxidation

Iron Copper-Nickel (Fe-CuNi) Type J

  • Temperature range 0 - 700°C
  • high temperature voltage coefficient
  • iron strongly susceptible to corrosion
  • no time constance of the thermoelectric characteristics

General requirements at thermocouples are:

  • High temperature voltage coefficient
  • linear potential gradient
  • time constancy of the thermoelectric characteristics
  • mechanical and chemical resistance
  • corrosion resistance
  • applicable in a broad temperature range
  • favourable dynamic performance

The types U and L are standardized according to DIN 43710 and if possible should only still be used for installation in old facilities.

The thermovoltages of the wire pairings specified according to ITS 90 are evident in mV/°C from the tables of the DIN EN 60584-1.