- Essentially Gradient Free
- Heat pipe Operation from Indium to Copper
- Simple Use - no zone offsets to adjust
Heat Pipe Furnaces
Isotech metrology furnaces have more than 35 years of proven use and are widely used by the worlds’ leading NMIs. For the optimal use of fixed point cells the temperature uniformity should be less than 10mK over the length of the fixed point sample CCT/2000-13, “Optimal Realization of the Defining Points of the ITS-90...”
Isotech heat pipe furnaces offer essentially gradient free operation; heat pipes provide the ideal conditions for the creation and maintenance of ITS-90 fixed point cells. Unlike some other companies Isotech can provide heat pipe furnaces to suit Indium, Tin, Zinc, Aluminum, Silver and Copper fixed points.
Plateau length is determined by the difference in temperature between the heat pipe and cell - this can be adjusted to give a plateau of any length of up to tens of hours. Our controllers offer extra resolution and allow adjustment to 0.1°C right up to 1090°C. The Potassium and Sodium models have a cooling coil in the lid with connections to circulate tap water to keep the furnace lid cool protecting the SPRT and reducing heat load into the lab. A pre warming tube with a temperature approximately equal to that of the heat pipe made of a unique and gas-tight material, is provided to heat the SPRT prior to it being placed in a cell. The furnaces feature an adjustable independent and adjustable over temperature device to protect expensive cells and SPRTs as well as a second internal over temperature safety device.
In addition to the heat pipe furnaces described the Dual Furnaces incorporate a second furnace which, because of its unique design, will safely (and without contamination) pre and post-condition the thermometers. There is also a separate storage enclosure for up to four thermometers with adequate support for the thermometer head.
With the Dual Furnace the thermometers are removed from their storage enclosure and placed in the pre-conditioning furnace. The furnace is slowly heated to the Cell temperature. The thermometers are protected from contamination by a slow air flux around them. One by one the thermometers are transferred into the cell for 20 to 30 minutes for calibration and thence back to the conditioning furnace. When all the thermometers have been calibrated, the conditioning furnace is slowly cooled back to 400°C whence the thermometers can safely be removed into room temperature.