Menu
Close
Close
Temperature and humidity measurements

High temperature fixed-point blackbody sources

Range: 1153 °C to 2748 °C

Blackbody sources at temperatures above ITS-90

NPL can supply, due to our extensive research, high temperature fixed points (HTFPs) which are based on the melting temperature of a metal-carbon alloy. These have proven stability and reproducibility, which allows phase transition temperatures to be assigned with very low uncertainty.

In addition to maintaining a set of standard HTFPs suitable for use in the calibration of radiation thermometers, we can supply the cells for use in a suitable high temperature furnace.

The HTFPs consist of a blackbody cavity within a graphite crucible containing the eutectic material. The aperture diameter of the blackbody is nominally 3 mm. The estimated effective emissivity of the cavity has been calculated to be 0.9996. The standard design fixed point crucible is 24 mm diameter by 44 mm long.

These HTFPs are typically used to determine the radiation thermometer signal at the certified temperature, using the assigned temperature of the melting plateau.

HTFPs available from NPL: 

  • Iron, Fe-C (1153 °C) 
  • Cobalt, Co-C (1324 °C) 
  • Palladium, Pd-C (1492 °C) 
  • Platinum, Pt-C (1738 °C) 
  • Ruthenium, Ru-C (1954 °C) 
  • Iridium, Ir-C (2290 °C) 
  • Rhenium, Re-C (2474 °C) 
  • Tungsten carbide, WC-C (2748 °C)

Typical cell calibration uncertainties (k = 2) are 0.05 % of the temperature (i.e. 1.25 °C at 2500 °C). The calibration is traceable to national standards.

The HTFPs consist of a blackbody cavity within a graphite crucible containing the eutectic material. The aperture diameter of the blackbody is nominally 3 mm. The estimated effective emissivity of the cavity has been calculated to be 0.9996. The standard design fixed point crucible is 24 mm diameter by 44 mm long.

Other designs are possible by arrangement. Peripheral apparatus (such as a suitable furnace) for the operation of the blackbody sources can also be provided. 

Contact us

Work with us

Our research and measurement solutions support innovation and product development. We work with companies to deliver business advantage and commercial success.
Contact our Customer Services team on +44 20 8943 7070