National Physical Laboratory

New temperature sensors and services

NPL's ultra-stable Platinum/Palladium (Pt/Pd) thermocouples and UKAS-accredited high temperature calibration services are now available through Isothermal Technology Ltd(Isotech), a UK temperature instrumentation and calibration company.

Thermocouple temperature sensor

Thermocouples are a type of temperature sensor used widely in science and industry. They consist of two wires made from different metals, joined at one end. When the wires are in a temperature gradient, a voltage develops which is a function of the difference in temperature between the joined end and the open end of the sensor. These wires are made of different metals depending on the range of temperatures that need to be measured, and the accuracy required.

Temperature measurements above 1000 °C can be subject to large uncertainties and can be difficult to verify. However, thanks to the use of pure metals, rather than alloys, Pt/Pd thermocouples are able to measure these higher temperatures, up to around 1500 °C, with unprecedented accuracy and stability (very low drift / de-calibration). NPL's thermocouples contain a novel mechanism that reduces the mechanical stresses caused by the differential expansion of the platinum and palladium wires with increasing temperature. This gives the NPL model superior robustness compared to conventional platinum/platinum rhodium thermocouples. These thermocouples are supplied with an NPL calibration with an uncertainty of ± 0.2 °C, from 0 °C to 1100 °C, rising linearly to ± 0.55 °C at 1330 °C (using the Co-C fixed point at 1324 °C) or ± 0.7 °C at 1500 °C (using the Pd-C fixed point at 1492 °C).

Isotech has a global reach and will also market NPL's existing thermocouple calibration services (including calibration of Platinum-Rhodium thermocouples), which use metal-carbon eutectic fixed point cells and are the first in the world to be ISO 17025 (UKAS) accredited. These services will help ensure better temperature measurements in industry, leading to reduced energy use and associated benefits to industrial efficiency and the environment.

More on metal carbon eutectic high temperature fixed points

More on NPL's Products & Services in Temperature

Isotech catalogue for Solutions for Primary & Secondary Laboratories

For further details, please contact Leon Rogers

Last Updated: 25 Oct 2012
Created: 24 Oct 2012