Temperature calibration document library

Industrial PRTs can have uncertainties of around 0.01 °C at 0 °C, with relatively low cost and are more rugged than Standard Platinum Resistance Thermometers. When lower uncertainties are needed Standard Platinum Resistance Thermometers can be used. Primary SPRTs are constructed in such a way that the platinum wire coil is free to expand and contract without strain. The flipside of the performance benefit is that the SPRTs are very fragile and require very careful handling. Primary SPRTs need the most care, whilst secondary or working SPRTs still need careful handling they are less prone to mechanical shock and can still be calibrated to low uncertainties, typically 0.001 °C at 0 °C and 0.006 °C at 660 °C.

This article presents data from a group of water triple point cells made from a still designed to produce pure, air free water of isotopic composition close to V-SMOW.

NTPL's experience in making the best measurements in ITS-90 Cells.

A brief history of the Water Triple Point Cell is given leading up to the ITS-90 definition, and an explanation of the main sources of error in a cell.

Revisting the Stimpson Ball Cell for an Optimal Water Triple Point.

A comprehensive study of Water Triple Point Cells.

Different methods to realize the triple point of water for the calibration of thermometers.

Fascinating review of the water triple point - from the Titanic to the isotopic content of water.

Looking at 100 Cells, includes sample Isotopic Analysis Certificates.

The paper investigates the properties of thirty four lots of 6N pure metal used to make cells conforming to ITS-90 from mercury through silver over a period of twenty years.