Abstract:

ESDU 06018 is one of a series of Data Items concerned with temperature measurement and provides background information and practical guidance on designing temperature measuring systems using thermocouples. The nominal temperature range covered is -272 to 2000 degrees C but the comments will apply, in general terms, to all thermocouple systems. It is aimed at the user who wishes to design and install a practical thermocouple system using improved techniques that will allow temperatures to be measured within known tolerances. ESDU 06018 considers the selection, preparation, and installation of thermocouples, the use of compensating or extension cables, and methods of referencing to a known temperature. The requirements for reliable systems operating to commercial tolerances are also described. Various factors that might impair the accuracy and stability of thermocouples are identified together with methods of reducing their effect. A check list for the design of a thermocouple system is given and a flowchart procedure for selecting appropriate thermocouple materials is provided. The employment of the techniques described will ensure that the temperature of the measuring junction is within known tolerances.