National Physical Laboratory

Thermocouple calibration - Supply of high temperature eutectic fixed points for calibration of thermocouples (1324 °C and 1492 °C)

Thermocouple calibration

Melting point cell

NPL is able to offer for sale the novel cobalt-carbon (Co-C, 1324 °C) and palladium carbon (Pd-C, 1492 °C) eutectic fixed points for thermocouple calibration with ultra-low uncertainties. The high temperature fixed point cells consist of a high purity graphite crucible containing an ingot of the eutectic alloy constructed from carbon and cobalt or palladium, each having a purity of 99.999% (99.95 % purity for palladium at present availability level).

The cells are supplied with an NPL certificate showing the melting temperature of the cell determined, traceable to ITS-90, by radiation thermometry:

  • Co-C fixed-point cell (1324 °C) uncertainty: ± 0.55 °C, k = 2
  • Pd-C fixed-point cell (1492 °C) uncertainty: ± 0.73 °C, k = 2

For proper implementation, the cells require a highly isothermal environment. If desired, NPL can supply a furnace with three control zones, alumina lining tube, and graphite insulation environment. The cells are approximately 120 mm in length with a diameter of 40 mm. The re-entrant well has a diameter of 7 mm.


Customer Services tel: +44 20 8943 6315

Last Updated: 11 Oct 2012
Created: 7 Sep 2009