Simultaneous calibration of large number of thermocouples

The objective of the paper is to analyze major error sources in the process of simultaneous calibration of large number of thermocouples (TC). The main reason for occurrence of additional error sources when large numbers of thermocouples are simultaneously calibrated is due to additional inhomogeneity effects and specifics of a particular measuring set-up. The need for such calibrations is due to the fact that often large number of relatively low cost but traceably calibrated TC are needed for monitoring purposes, measurements of temperature profiles in applications such as evaluation of temperature and humidity chambers, wind channels, tunnel furnaces in steel plants etc. The fact is that the overall uncertainty attributed to each particular TC during simultaneous calibration exceeds the uncertainty assigned to TC during a calibration process of a single TC. Nevertheless, in most cases the proposed solution is highly acceptable, especially in the area of testing, due to significant decrease of calibration costs but still meeting testing requirements. This is due to the implementation of the requirements of new standard ISO/IEC 17025 for the uncertainty specifications and traceability in testing reports