Enabling international competitiveness at South African NMI

The challenge

The National Measurement Institute of South Africa (NMISA) required the ability to provide lower uncertainty calibrations of noble metal thermocouples to their customers in South African industry, for example, for heat treatment of components. They identified a need for cobalt-carbon (Co-C, 1324 °C) and palladium-carbon (Pd-C, 1492 °C) reference temperature cells and the equipment to operate them.

The best possible calibration uncertainties were required: high-performance reference cells were essential, as well as furnaces able to reliably reach the high temperatures required and remain uniform at their centre.

The solution

The National Physical Laboratory (NPL) manufactured and certified the temperature reference cells and then shipped the cells, bespoke high temperature furnaces and peripheral equipment to NMISA. The first cell, a Pd‑C cell, arrived in 2019, and the second, a Co‑C cell, arrived in 2023. We then installed and commissioned the equipment.   

In addition, we provided tailored training to the NMISA team on how to use the equipment. This included information on optimising the settings, and training on how to achieve the best measurement uncertainties with the equipment.

The impact

Using the NPL cells, NMISA were able to achieve a calibration uncertainty of ±0.44 °C, and ±0.67 °C, (k = 2) for calibrating thermocouples at 1324 °C, and 1492 °C, respectively, providing international competitiveness for both the National Laboratory and local industries.

NMISA would like to thank NPL for being very helpful whilst commissioning the Co-C fixed point cell. The furnace was commissioned to be used to improve our thermocouple measurement capability. NPL were very good at explaining all that needs to be clarified regarding the furnace being commissioned. NPL’s professionalism and eutectic fixed-point system know-how was commendable

 

NPL’s contact thermometry team operate world-leading, state-of-the-art calibration facilities for UKAS-accredited resistance thermometer and thermocouple calibrations. The temperature range covered is from -196 °C to +1800 °C. Ongoing research into developing new high-temperature reference cells is working to extending this range down to 4.2 K and up to +2200 °C.

Find out more about our calibration facilities and consultancy services