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|  Low temperature isothermal furnace liners (IFLs) and heat pipe blackbody cavities (HPBCs) cover the temperature range of -50 to +250°C. Ammonia and water are the working fluids for the temperature ranges of -50 to +50°C and 50 to 250°C, respectively. Typically, these IFLs and HPBCs are manufactured in an annular geometry. The inner tube is where the calibration, testing or materials processing is performed. The space between the inner and outer tubes is where the heat pipe wick structure and the ammonia or water working fluid are contained. The outer tube surface is attached to a circulating coolant that is heated or cooled by a refrigerated bath. Smaller units can be designed and manufactured using thermoelectric coolers and resistance heating elements. For Ammonia IFLs and HPBCs, a dry nitrogen or argon purge gas is used to minimize condensation or freezing to the inner tube working space. The purge gas is routed though a small diameter tube wound in the shape of a spiral and attached to the circulating chiller fluid. Therefore, the purge gas is essentially at the same temperature as the working space when it reaches the working space, and will not adversely affect the thermal stability. Thermocouple wells and grounding straps or studs can be added for custom designs. For Water IFLs and HPBCs, a pressure relief rupture disk is installed on each unit to safely vent the internal pressure should the pipe be accidentally put into an over temperature condition. Ammonia IFLs and HPBCs are manufactured using stainless steel, and Water IFLs and HPBCs are manufactured using MonelŪ as the heat pipe material. ACT has extensive test data demonstrating the long term compatibility of these materials and working fluids. Life test heat pipes have been operated in excess of 30,000 hours at elevated temperatures with no sign of incompatibility or physical deformation.
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In many cases, the inner tube surface has a special coating to provide a stable, uniform, high emissivity surface useful for blackbody cavity calibration instruments. ACT manufactures both stand alone IFLs or HPBCs and custom designed turnkey systems including the IFL or HBPC, heating and cooling mechanisms, temperature and fluid controls, and safety measures. Custom features, such as thermocouple wells, grounding studs and mounting flanges, are easily accommodated and can be incorporated to achieve a significant increase in value. An example of a custom Ammonia HPBC turnkey system is shown in the picture below.
) Ammonia HPBC installed in an enclosure with controls, purge gas regulator, and selectable aperture plates (click for larger version) An example of a custom Water HPBC turnkey system is shown in the picture below.
) Water HPBCs installed in an enclosure with controls, temperature sensor wells, and selectable aperture plates (click for larger version) |
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 Ultra High Temperature Isothermal Furnace Liner Pressure Controlled Heat Pipe Furnace Contact and Visit ACT Information ISO 9001:2008 and AS 9100-B Certification ACT Brochures and Product Datasheets
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