Lancaster, Pennsylvania – August 23, 2010 – Advanced Cooling Technologies, Inc. (ACT) has been manufacturing and supplying ultra high temperature heat pipes for precision contact thermometry calibration at the melting point of copper (˜ 1083 °C).
In the past, contact thermometry calibration work typically stopped short of the copper point. The highest practical temperature point had been the silver point (˜ 962 °C). Some of the issues with working between the silver and copper points were materials related. For example, high temperature standard platinum resistance thermometers (HTSPRTs) have shown stability and repeatability issues at copper point temperatures. Over the past few years, significant progress has been made toward improving HTSPRTs’ stability and repeatability at the higher temperatures. Another limitation had been the life expectancy of the Inconel/Sodium heat pipes that are often used to provide the high precision, isothermal environment for freeze point cells and blackbody cavities. Typical life expectancies of an Inconel/Sodium heat pipe at the copper point temperature are on the order of 1,000 hours.
The heat pipe life expectancy is limited by the creep strength of the Inconel envelope material. As the heat pipe operating temperature increases from 1,000°C to 1,100°C, the strength of the envelope decreases. Simultaneously, the internal vapor pressure of the sodium is rapidly increasing above 1,000°C. This results in physical deformation of the heat pipe, potentially trapping and damaging the freeze point cell, and can ultimately result in envelope failure.
ACT developed the Ultra High Temperature (UHT) heat pipe in 2004 in response to customer feedback requesting longer life expectancy up to 1,100°C so that work at the copper point could be performed safely and efficiently. ACT shipped the first UHT heat pipe in 2005 and has provided several early adopters with units over the past few years. To date, there have been no failures reported or unfavorable feedbacks from the field.
ACT’s UHT heat pipes use Haynes 230® as the envelope material. Haynes 230® is a high temperature, high strength material that was developed for extreme applications like high temperature furnace muffles, heat treat fixtures, and jet engine components.
ACT manufactures heat pipes for many of the equipment manufacturers that supply primary calibration laboratories around the world. ACT also designs, develops and manufactures turnkey systems for researchers that have unique requirements and one-of-a-kind applications that cannot be met by off-the-shelf equipment. Please contact ACT if you are working in the copper point temperature range and are interested in ACT’s UHT heat pipes.