Performance evaluation and metrological characteristics of a deadweight force standard machine with substitute load control system

A new dead weight force standard machine covering the range from 5 kN to 500 kN direct weights has been designed and constructed at the National Institute for Standards (NIS)Egypt, by Gassmann Theiss Messtechnik GmbH (GTM). The machine capacity can be duplicated to 1000 kN by means of a substitute force generator. The machine has been verified through a comprehensive Inter-laboratory Comparison Programme run over a period of two years at the Physikalisch-Technische Bundesanstalt (PTB) of Germany and NIS of Egypt. A well-selected set of high precision force transfer standards was used in the comparison calibration protocol. Rounds of measurements were carded out on deadweight machines at both the PTB and NIS. This paper presents the protocol followed to evaluate the metrological characteristics of the new machine as well as the Inter-laboratory Comparison scheme used in the verification process. The results prove that the machine achieve an uncertainty better than 2.10(-5) for calibration of force transducer by pure deadweights. Using the substitute force generator mechanism to double the machine capacity resulted in an uncertainty figure better than 1.10(-4).