Calibration is the metrological control activity that must be carried out periodically on instruments for measuring physical or chemical quantities involved in an industrial process.
A set of operations applied to a measuring instrument or equipment, following a systematic procedure, the results of which, duly documented, make it possible to determine the errors (deviations) of this instrument with respect to the values indicated by a reference instrument (standard) of known uncertainty.

Its purpose is to determine whether an instrument is within the tolerances permissible by the industrial process. It is the famous “pass” or “it doesn’t happen”. If it is not within tolerance, the instrument should be uninstalled and removed from the control system. Without the calibration of an instrument or equipment, we could obtain erroneous data and consequently, spoil a production process or storage of raw material or finished product.