Rivelazione e misurazione delle fughe Parte seconda

Questo numero del Giornale riporta la seconda parte di una serie di tre inserti su “Rivelazione e misurazione delle fughe”. • parte 2: risultati esemplificativi di taratura delle fughe di riferimento e le loro interpretazioni e generalizzazioni, la metodologia di ricerca delle perdite e la più significativa strumentazione in uso

EURAMET 1125. Evaluation of cross-float measurements with pressure balances

The calibration of a pressure balance involves determining the values of A0 and the pressure distortion coefficient that define the effective area Ae of the piston-cylinder assembly as a function of pressure. Various approaches are possible be to determine and estimate the uncertainties of these parameters, with results that may differ significantly. The purpose of EURAMET project 1125, led by LNE, is to verify numerically the performance of different methods used by the NMI’s by applying simulated data sets. Starting from simulated data prepared by LNE, INRIM calculated the values of the effective area values including the evaluation of their uncertainties by using a linear lest square method. Finally effective area at atmospheric pressure and reference temperature Ao and elastic distortion coefficient were also calculated. The report describes the calculation method and the results obtained

Gas flow measurements performed at INRIM Istituto Nazionale di Ricerca Metrologica - Torino- Italy

Primary standard flow meters are developed and maintained for the calibration of leak artefacts used in many applications in which the quantification of leakage is required. INRIM maintain a primary flowmeter based on constant pressure- changing volume in order to measure small gas flow of R134a referred to atmosphere (ambient pressure). In the framework of EURAMET project 1115 a comparison was organized by LNE. Other participants were PTB, INRIM, CMI. The laboratories have been performed measurements at two different R134a throughput levels 3.5 g/y and 1 g/y using a permeation leaks as transfer standards supplied by LNE

EURAMET 1047. EURAMET Key comparison of National Standards in the range from 1 Pa to 15kPa in gauge mode

In order to validate a new pressure balance based on the piston gauge principle with piston-cylinder unit having large effective area, INRIM decided to partecipate at EURAMET 1047 comparison in the pressure ranges from 1 Pa to 15 kPa. The non-rotating digital piston gauge DHI FPG 8601 serves as the transfer standard in the range (1 Pa - 15 kPa), both gauge and absolute. The transfer standard (of CMI property) and its staff visited INRIM laboratories in the week from 25 to 29 October for the bilateral comparison resulting in a star comparison. A CDG serves as a separator and zero indicator. INRIM participation to the comparison was limited in gauge mode. The present report describes the INRIM results by using DHI FPG 8601 digital piston gauge including the evaluation of the uncertaintie

Realization, characterization and measurements of standard leak artefacts

Predictability of gas flows through leak elements in various conditions (geometry of leak elements, gas species, pressure) from the results of only a few measurements in a specific configuration is an issue for the gas dynamics theory. This paper aims to provide results of leak flow rate measurements performed by national metrology institutes (NMIs) in the framework of the European project JRP IND12. Leak artefacts made of different materials with well defined geometry, were calibrated by means of primary standards with different gas species flowing to vacuum or atmospheric pressure. The numerous collected data are made available to allow the experts in gas dynamics to use this large database to improve the knowledge of gas flow in narrow ducts in terms of predictability for different gas species and find a simple model to describe the gas flow inside microchannels