The aerospace industry sets particularly strict and accurate standards for thermal processing, outlined in specifications such as AMS 2750 (current version: AMS 2750F) and the industry manual by NADCAP (National Aerospace and Defense Contractors Accreditation Program). Accurate measurement and calibration of the temperature sensors used, as well as all process monitoring and temperature-dependent system components, play a central role. The aim of this blog post is to give a brief description of the ice point references used and to highlight their importance in complying with guidelines.
In specialized industries, like the aerospace industry, which work with high-temperature processes for applications like hardening, annealing, and thermal shields for reentry vehicles, error-free temperature control is of immense importance. Any inaccuracy in temperature measurement can significantly impair the quality of the final product and potentially jeopardize safety. To meet these high standards, precise regulations and norms apply. Two crucial standards in this regard are the AMS 2750F specification and Nadcap's (National Aerospace and Defense Contractors Accreditation Program) industry manual. Both impose stringent requirements on the precision and calibration of pyrometers, thermocouples, and other temperature measurement and control devices used in furnaces and other heat treatment equipment.
The cold junction compensation is particularly crucial when using thermocouples for temperature measurement. Thermocouples generate an electric voltage using the Seebeck effect - a temperature difference along a junction of different metals - used for temperature measurement. However, the challenge is that each individual connection of two different metals also acts as a thermocouple and generates an additional, often undesired, thermoelectric signal. This is referred to as the cold junction error, which can falsify the thermocouple signal.
To effectively compensate for this source of error Ice Point References play a crucial role. They provide a constant temperature of 0°C (the freezing point of water), serving as a known reference point for calibrating thermocouples. This allows for accurate interpretation of the thermoelectric voltage in the actual measured temperature range and ensures that the signal is not falsified by the cold junction error. The accurate, reproducible temperature measurement of a thermocouple using an ice point reference is thus crucial, especially in industries where the accuracy of temperature measurements is of significant importance for the quality and safety of the final product.
For over 65 years, Kaye has been a global leader in the development and supply of thermocouple reference systems. From the first patented development of the Ice Point Reference in the 1960s to the patented Uniform Temperature References, Kaye leads in providing solutions for critical applications in aerospace and other industrial markets for accurate measurement of thermocouples. Kaye Ice Point References offer an optimal solution for cold junction compensation in thermocouple measurement circuits, especially in industrial applications. From fixed 0°C Ice Point References, which offer accuracy of 0.02°C without long-term drift, to our passive Uniform Temperature Reference, which find application in areas with high temperature gradients and vibrations, Kaye offers a solution. Kaye's expertise in thermocouple measurement and elimination of potential error sources offers maximum accuracy in terms of automatic referencing.
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