The Gemini R is a blackbody source with which radiation pyrometers, commonly referred to as IR sensors, can be calibrated. With a temperature range of 30 to 550°C, or 700°C, the temperature of the cavity can be set with 0.1°C resolution. The temperature of the furnace is set and indicated on a PID controller. An independent indicator is also provided for higher accuracy with a standard probe, which indicates the actual radiance temperature. Temperature variation over a 5-minute period, as viewed on the temperature controller, is ±0.2°C and a radiation thermometer directed into the cavity detects similar variations.

The Gemini R's cavity's size is 2.5" Ø x 6.3" deep (65mm x 160mm). Maximum temperature differences are ±1°C in the range of 100 to 500°C. The Gemini R is capable of accepting blackbody fixed points to achieve the highest level of a radiation measurement possible. Typical fixed-point uncertainties are ±0.25°C. Gallium, indium, tin and zinc cells are available.

The Isotech Hydra Model 798 has been developed to offer good immersion depth, 300mm at an affordable price. The temperature range of the 798H is 30 to 200°C. The M and L models include internal refrigeration and extend the minimum temperatures to –40°C and -80°C respectively, with a maximum operating temperature of 125°C. Liquids are circulated by a propeller which mixes and forces the liquid down the rear of the calibration volume. The liquid flows up the front calibration voulme into a collection tray where it returns for circulation.

This evaluation report describes the performance of this bath, the intent is to provide a guide to the performance that can be expected in the calibration laboratory. When comparing uncertainties and bath performance it is important to check that the specifications being compared are like for like, if in doubt please contact Isotech for advice. There is no agreed International standard for the expression of comparison bath performance and some other parties, without accredited labs of their own, have made claims which can lead to disappointment when a laboratory needs to measure the actual bath performance to establish calibration uncertainty.

Maximum Immersion Depth of 300mm

Liquid Capacity Approximately 5L

Stability, +/-0.01°C See Graphs

Outstanding Vertical Profile