Comparative measurements on an electronic weighing instrument

Many times was heard the dilemma: “To measure or not to measure, that is the question”. But, when you measure, a question arises: how accurate/reliable are your measurements results so that the client should have the confidence that you measure in the right way? No matter how carefully you perform internal checks, systematic errors often can go unnoticed. For this reason, the simplest way to check the quality of your measurements is to participate in proficiency testing scheme (PTS) / interlaboratory comparison (ILC). Moreover, ISO/IEC 17025 requires “that laboratories have quality control procedures for monitoring the validity of tests and calibrations undertaken”. It is therefore important that you should regularly compare your measurement results with those of other laboratories so, to attend in intercomparisons. In this way, this paper describes and analyzes the comparative results and uncertainties associated obtained by a reference laboratory and other six participating laboratories, appearing with codes that have been assigned during the comparison. The proficiency test item consisted in a NAWI (non-automatic weighing instrument) having Max 6 kg and resolution of 10 mg. The measurements were performed at Mass laboratory of INM which was designated as Pilot (LP) and Reference Laboratory (LR). The determinations began in March 2015 and concluded in August 2015. The goal of interlaboratory comparison was to provide verification of each participating laboratory's measurement capability by obtaining a measurement that agrees with the LP/LR. The results are analyzed using En (normalized errors) values.