Long Term Uncertainty Investigations of 1 MN Force Calibration Machine at NPL, India (NPLI)

The present paper is an attempt to study the long term uncertainty of 1 MN hydraulic multiplication system (HMS) force calibration machine (FCM) at the National Physical Laboratory, India (NPLI), which is used for calibration of the force measuring instruments in the range of 100 kN - 1 MN. The 1 MN HMS FCM was installed at NPLI in 1993 and was built on the principle of hydraulic amplifications of dead weights. The best measurement capability (BMC) of the machine is ± 0.025% (k = 2) and it is traceable to national standards by means of precision force transfer standards (FTS). The present study discusses the uncertainty variations of the 1 MN HMS FCM over the years and describes the other parameters in detail, too. The 1 MN HMS FCM was calibrated in the years 2004, 2006, 2007, 2008, 2009 and 2010 and the results have been reported.