Intermediate Checks: Ensure Confidence in Validity of Measurement Results

According to the definition, calibration refers to the procedures with which comparison is carried out between the results of a measuring instrument or a measuring system and the corresponding values in the measurement standard. It includes evaluation of measurement uncertainty and providing measurement traceability to SI units. Calibration is carried out in a periodic time cycle referred as a calibration interval, which is expected to ensure the reliability of the equipment performance. In order to confirm the equipment performance and maintain confidence in the measurement carried out, intermediate checks in between calibrations shall be performed as per documented procedure. Intermediate checks are the best monitoring system in between the calibration interval for identifying any drift or change in the performance of the equipment. The ISO/IEC 17,025:2017 (1) standard requirement is that ‘when intermediate checks are necessary to maintain confidence in the performance of the equipment these checks shall be carried out’ and ‘when’ mentioned in the requirement is the selection of periodicity for performing intermediate checks based on the significance of applications. Discovering an equipment which is out of calibration (beyond tolerance limits) has a high potential value which would result in reducing the risks like financial risk, consumer risk etc. The sooner the equipment is identified as out of tolerance, the lesser the risks associated with the measurements. The purpose of this paper is to provide the details about the importance of the intermediate checks, plan and perform intermediate checks, analyze the results and maintain the records. It is hoped that the intermediate checks on measuring and test equipment will be given more importance and carried out for the equipment which requires calibration to minimize the risks involved in performing measurements.