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Heatpipes provide the ideal conditions for the creation and maintenance of freeze points from ITS-90.
1. The lab furnace core is a specially-designed, stress-free isothermal heat pipe, which provides a very low thermal gradient along the core working length. The lab furnace heater is of the parallel-tube design used at NIST.
2. The heat pipe is designed so that the inner wall is not subject to thermal expansion stresses from the outer wall before the heat pipe reaches conduction temperature. The working fluid within the laboratory tube furnace is permanently and safely sealed within the plasma-arc-welded enclosure.
3. Three temperature ranges are available with this parallel-furnace:
Low Temperature: 125°C to 250°C, 17702W, Water
High Temperature: 400°C to 1000°C, 17702P, Potassium
Very High Temperature: 500°C to 1090°C, 17702S, Sodium
Connections are provided for a water supply of 0.5 to 1 liter per minute to cool the top of the apparatus (not on 17702W). An ordinary garden hose may be used for water supply and waste connections. Use without cooling is not recommended above 700°C.
4. An advanced, proportional electronic system controls the temperature within the parallel-tube furnace. The control may be self-calibrated using Freeze Point Cells as references. Two entirely independent over-temperature safety circuits are provided. The active safety is a second (off-on) control circuit driven by a second thermocouple. The passive safety is a fusible link in the main power supply.
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Model
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Temperature
Range
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Heat Pipe
Type
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Cells
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17702W
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125°C to 250°C
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Water
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Indium and Tin
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17702P
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400°C to 1000°C
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Potassium
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Zinc, Aluminum,
Silver
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17702S
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500°C to 1100°C
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Sodium
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Aluminum,
Silver, Copper
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Literature
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Heat Pipe Metrology Furnace Product Datasheet
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Heat Pipe Metrology Furnace Manual
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