Isotech Ultra Pure-Metal Freezing Point Cells are designed specifically to realize the liquid-solid equilibrium temperatures of certain high-purity metal elements, for calibration of thermometers at the ITS-90 Fixed Points.

When you purchase an Isotech Sealed Freeze Cell, you are not just purchasing a kilo of metal inside a graphite crucible sealed within a quartz shell, you are getting the fruits of more than 35 years of experience and learning, of not only how to make such an artifact without introducing contamination, but an Internationally-accepted embodiment of an ITS-90 fixed point.

These Isotech temperature calibration standards have been further developed and refined from cells designed and manufactured by Henry Sostmann, with the first international inter-comparison results being published in 1972.

In 2007, we combined 17 years' experience producing the best Metal Clad Slim Cells with our experience of producing the most accurate Fixed-Points sealed in quartz glass, to introduce Metal Clad Optimal Cells for the Primary Laboratory. These cells can be readily shipped between labs for inter-comparisons, overcoming the difficulty of transporting quartz cells due to increased airport security restrictions.

Isotech’s accredited laboratory has the smallest uncertainties, and can issue UKAS certificates with uncertainties as low as ±0.07mK at 0.01°C to ±2mK at 961.78°C, k=2.