Calibration of thermocouples for low temperature applications

In this communication, concept of enhancement of instrument accuracy in providing measuring values is been discussed. One way to increase instrument accuracy is through calibration technique. K-type thermocouple wire as got advantage of low cost of operation but with decreased accuracy. To overcome this disadvantage, Oil bath, a standard instrument for maintaining constant temperature is considered as reference and calibration of K-type thermocouples is carried out. This study led to the observation that variation in the values of oil temperature and thermocouples varies linearly with respect to each other at every particular temperature, thus utilizing mathematical procedure of linear regression analysis appeared suitable to find out the error in thermocouple readings. Linear regression method provides close approximations (at least within a given range of interest) to relationships which would otherwise be difficult to describe in mathematical terms. This study concluded that similar procedure can be adopted for calibration of other doubtful electrical and electronic instruments, thus increasing their accuracy.