In order to improve the metrological characteristics of the primary force standard machines, as well as to understand the causes of anomalies and to optimise calibration methods, it is important to measure the value and the effect of the parasitic components which could influence the final value and uncertainty of the applied vertical loads.
The paper describes the measurements performed on the 150 kN CENAM (Mexico) primary force standard deadweight machine in order to evaluate the value and the direction of the parasitic components (two side forces F_X and F_Y; two bending moments F_L and F_M, and the twisting moment F_N) generated by the standard machine The influence of the parasitic components on the Force Standard Machine accuracy and the values of dynamic components during the load application transient are studied as well. This evaluation was carried out in the framework of a scientific agreement between the Istituto Nazionale di Ricerca Metrologica (INRiM, Italy) and the Centro Nacional de Metrologia (CENAM, Mexico).

The National Measurement Institute of Australia (NMIA) and the Istituto Nazionale di Ricerca Metrologia of Italy together with the University of Cassino (INRIM/UNICAS) have participated in a research project to characterise a INRIM 100 MPa free deformation piston and cylinder assembly using two different numerical procedures based on a finite element method (FEM). The pressure distortion coefficient, ? and the piston fall rates, v were calculated from the clearance profile between the piston and cylinder obtained from dimensional measurement data. Comparison of the numerical results obtained by the two groups showed a relative difference of 2 × 10^-4 in λ and 2.5 × 10^-2 in v. The numerical results were also compared to the experimental results with a relative difference of 1.9 % in λ and 16 % at 100 MPa in v. This paper presents the numerical model used for the calculations of the pressure distortion coefficient and the piston fall rates with a sensitivity analysis of the model for the estimation of the uncertainty values of these two parameters.

To improve the consistency of 3-dimensional data describing the geometry of pressure-measuring piston-cylinder assemblies, a new approach, based on the leastsquares method, is proposed. It allows the results of diameter-, straightness- and roundness measurements to be linked with each other, with only minimum discrepancies between them. When processing the dimensional data, it is possible thanks to this new approach to weight them differently - according to their measurement uncertainties. The new approach was applied to three gas-operated piston-cylinder assemblies with nominal effective areas of 10 cm² and 5 cm² which are used at PTB as primary gas pressure standards for the range up to 2 MPa. The dimensional measurements were carried out by means of different instruments and the results were analysed. The discrepancies in the dimensional data sets obtained within the scope of the new approach are typically smaller than 16 nm, which agrees with the uncertainties claimed for each kind of dimensional measurement. The effective areas of the three piston-cylinder assemblies were calculated using the Dadson theory and then adjusted taking into account the results of both cross-float measurements carried out between them and pressure measurements carried out against a primary mercury manometer. Finally, relative standard uncertainties smaller than 2·10^-6 could be obtained.

This article is about a special type of pressure sensors usually labelled tactile sensors. After a short overview on the subject, two application examples, one in the medical domain developed by the authors for heart rate variability using an electretsbased pressure sensor, are presented.

Devices measuring pressure, temperature and humidity simultaneously are known as PTU devices. There are hardly any commercial calibration systems for the PTU devices available for low temperatures (< 0 °C). To obtain more comprehensive data on the performance of PTU devices, a new calibration system is developed at MIKES. In this PTU Apparatus, pressure, temperature and humidity can be controlled simultaneously so that all combinations over the ranges are possible. The nominal ranges of the system are the following: absolute pressure 500 hPa … 1200 hPa, temperature -52 °C … +80 °C and relative humidity 10 % … 95 %. The estimated uncertainties (k = 2) of the pressure, temperature and humidity are 10 Pa, 0,1 °C to 0,3 °C and 1 %RH to 3 %RH, respectively. The construction and operation as well as the results of operational tests of the PTU Apparatus are reported in this paper.