The Isotech Model ITL-M-17725 Cryostat is a self-contained, mechanically-refrigerated system with a main well to house one cell, and two auxiliary wells for pre-chilling thermometers. The cryostat temperature is steplessly adjustable from -36°C to 42°C with scale-divisions of 0.1°C (interpolation possible), and 24 hour stability better than ±0.05°C measured by an SPRT in the well of a Mercury Cell inside the cryostat.

The cryostat has several unique features, providing outstanding convenience and safety. The refrigeration system has sufficient capacity to bring a cell to operating temperature in about one hour. At operating temperature, the cooling rate is about 1 Kelvin/minute, and the heating rate is about 2 Kelvin/minute.

This permits rapid changes to be imposed on the temperature of the cell environment to avoid excessive demands on the (low) heat-of-fusion energy of the mercury within the cell.

In addition, all temperature control is accomplished through refrigerant flow, providing inherently fail-safe operation. Indicators provided on the cryostat are "POWER ON" and "COOLING".

The Isotech cryostat machine provides convenient conditions for operating mercury fixed-point cells both in heating and in cooling mode. Laboratories everywhere use this Isotech cryostat machine to realise the triple point of mercury.