The Isotech fluidized calibration bath outperforms dangerous salt baths in all respects: wider temperature range, less hazardous and better uncertainties. The fluidized bath is the result of 20 years research and development into flow patterns, powder technology, and filtration. Recent developments have enabled the baths facilities to be extended even further: it is now eminently suitable for liquid-in-glass thermometer calibration. To achieve this, the filter and exhaust system were re-designed to cope with the increased level of powder needed for Liquid-In-Glass thermometer calibration.

The result is a temperature calibration system to National Standards. The performance is only matched by heat pipe technology. The profiles are so small that the bath has been used by National Laboratories for fixed points of indium through aluminium, with great success. In comparison mode 2, sigma uncertainties of ±0.020°C at 300°C, and ±0.035°C at 660°C can be obtained.

This is the only product capable of covering a very wide temperature range without a change of thermal media. Like most fluidized baths, the 875 thermocouple calibration bath consists of a container of aluminum oxide powder with a porous base plate. Sufficient air is passed through the base plate to motivate the powder into a fluid-like state so that it will flow, display buoyancy effects, and have good heat transfer characteristics.

A disadvantage of many fluidized-bed baths is that good temperature stability and uniformity cannot be achieved in the fluidized medium itself. They are obtained by using large metal blocks, or by inhibiting the fluidizing action in the powder around the work piece - either locally, or by completely collapsing the bed at the required temperature. This is not the case with the 875 temperature calibration system. A full evaluation report is available upon request.