1.1 This guide describes the essential features of freezing-point cells and auxiliary apparatus, and the techniques required to realize freezing points in the temperature range from 29 to 1085 °C.

1.2 Detailed design and construction are not addressed in this guide.

1.3 This guide is intended to describe good practice and establish uniform procedures for the realization of freezing points.

1.4 This guide emphasizes principles. The emphasis on principles is intended to aid the user in evaluating cells, in improving technique for using cells, and in establishing procedures for specific applications.

1.5 For the purposes of this guide, the use of freezing-point cells for the accurate calibration of thermometers is restricted to immersion-type thermometers that, when inserted into the reentrant well of the cell, (1) indicate the temperature only of the isothermal region of the well, and (2) do not significantly alter the temperature of the isothermal region of the well by heat transfer.