Evaluation of different types of comparisons to a common set of reference values of a CIPM key comparison is essential to satisfy the concept of the CIPM Mutual Recognition Arrangement (CIPM MRA), where the DoEs of any participant who... more
Evaluation of different types of comparisons to a common set of reference values of a CIPM key comparison is essential to satisfy the concept of the CIPM Mutual Recognition Arrangement (CIPM MRA), where the DoEs of any participant who took part in comparisons should be within the Calibration and Measurement Capability (CMC) section of the CIPM MRA Key Comparison Data Base. The subject of this supplementary report is therefore to present the equivalence of each National Metrological Institute (NMI) participant in the CCM.D-K4 'Hydrometer' key comparison, which was performed in the density range 600 kg/m3 to 2000 kg/m3 at the temperature of 20 °C, and the linkage of the European and Inter-American NMI results performed in the RMO.M.D-K4 comparisons as well as those of the supplementary SIM.M.D-S2 to the common set of KCRVs of the CCM.D-K4 'Hydrometer'. The linking procedure has been obtained by numerical simulation, based on the Monte Carlo method, in which the differe...
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−This article reports the calibration procedure for a commercial Solartron 7835 densimeter which is currently used as “reference” instrument in an automatic apparatus for the calibration of on-line densimeters. Three different materials... more
−This article reports the calibration procedure for a commercial Solartron 7835 densimeter which is currently used as “reference” instrument in an automatic apparatus for the calibration of on-line densimeters. Three different materials (fluids), whose densities are known at the usual working condition of pressure and temperature, are used for characterizing the reference densimeter. The procedure applied at the INRIM to produce accurate parameter estimates in the densimeter calibrations is described in this papers. It is based on the application of the weighted least square method (WLS), considering together with the uncertainties of the dependent and independent variables also those of the model. The model analysis performed by a Chi-square test and the expected uncertainty computed over the calibration range have shown to be fully consistent with the experimental data.
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SIGLEITItal
The improvement of modern oscillation-type density meters requires density reference liquids with low uncertainty and very accurate procedures that take into account the physical properties of the fluids. INRIM adopted a procedure... more
The improvement of modern oscillation-type density meters requires density reference liquids with low uncertainty and very accurate procedures that take into account the physical properties of the fluids. INRIM adopted a procedure concerning the substitution method in determining the densities by vibrating tube densimeter of deuterated water, n-pentadecane and the oil EF 170 having a viscosity of approximately 170 mm²/s, liquids provided by the pilot laboratory BEV as transfer standards in the EURAMET project 1240. In the present paper are shown as an example about the validity of the used procedure through the results of the density determinations at 20 °C of the deuterated water and of the viscous oil, being the differences of the physical properties of the two liquids significant enough
ABSTRACT This paper describes the metrological research and dissemination work carried out in the viscosity field at the Istituto di Metrologia “G. Colonnetti” (IMGC) of the National Research Council of Italy, which is responsible for... more
ABSTRACT This paper describes the metrological research and dissemination work carried out in the viscosity field at the Istituto di Metrologia “G. Colonnetti” (IMGC) of the National Research Council of Italy, which is responsible for national standards of mechanical and temperature units. Emphasis is given to the viscosity standard, to the latest research work concerning certain liquids to be used as reference viscosity standards, and to international activities.
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Hydrometers are instruments usually made of glass that are widely used for different levels of precision to measure density, specific gravity, alcoholic strength, sugar concentration, milk density, etc., of a liquid.
Abstract- Density measurements are frequently associated to specific requirements in order to evaluate the quality of a process or to determine mass and/or volume of the material. Hydrostatic weighing is the usual method to get directly... more
Abstract- Density measurements are frequently associated to specific requirements in order to evaluate the quality of a process or to determine mass and/or volume of the material. Hydrostatic weighing is the usual method to get directly the traceability to the SI system of the density as well as of the solid volume. INRIM (the former CNR- IMGC) supplied to IPQ a hydrostatic apparatus with a measuring cell, devoted to measure the density of liquids and the volume (density) of small solid bodies, with technical support and assistance in the density field. Since 2005 the partnership between the two Institutes has been developed within the EUROMET project 858 “Hydrostatic weighing – exchange of experiences”. This paper deals with the activity concerning the main technical and metrological characteristics of the supplied measuring cell and also shows the preliminary results for testing it. For this purpose a comparison was carried out between the two laboratories. Each one determined the...
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Density measurements are frequently associated to specific requirements in order to evaluate the quality of a process or to determine mass and/or volume of the material. Hydrostatic weighing is the usual method to get directly the... more
Density measurements are frequently associated to specific requirements in order to evaluate the quality of a process or to determine mass and/or volume of the material. Hydrostatic weighing is the usual method to get directly the traceability to the SI system of the density as well as of the solid volume. INRIM (the former CNR IMGC) supplied to IPQ a hydrostatic apparatus with a measuring cell, devoted to measure the density of liquids and the volume (density) of small solid bodies, with technical support and assistance in the density field. Since 2005 the partnership between the two Institutes has been developed within the EUROMET project 858 “Hydrostatic weighing – exchange of experiences”. This paper deals with the activity concerning the main technical and metrological characteristics of the supplied measuring cell and also shows the preliminary results for testing it. For this purpose a comparison was carried out between the two laboratories. Each one determined the volume and...
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Hydrometers are simple but effective instruments for measuring the density of liquids. In this work, we present the new hydrostatic weighing system developed at the INRiM, formerly IMGC – CNR, for the calibration of hydrometers in the... more
Hydrometers are simple but effective instruments for measuring the density of liquids. In this work, we present the new hydrostatic weighing system developed at the INRiM, formerly IMGC – CNR, for the calibration of hydrometers in the range 500 kg.m-3 to 2000 kg.m-3. The apparatus which uses a method to automatically align specific scale-marks for the calibration of hydrometers, makes easy the whole calibration procedure and allows to reduce the former uncertainty declared by laboratory. It consists of a vision system, a stepping motor, and software to control the system. The vision system, composed of a CCD camera and a frame grabber, is used to acquire images. The overall performance of the apparatus is illustrated by the assessment of the uncertainty for some usual kinds of hydrometers sent to the Institute for calibration.
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Density measurements are frequently associated to specific requirements in order to evaluate the quality of a process or to determine mass and/or volume of the material. Certified reference liquids can be used to assure metrological... more
Density measurements are frequently associated to specific requirements in order to evaluate the quality of a process or to determine mass and/or volume of the material. Certified reference liquids can be used to assure metrological traceability of density measurements to the International System of Units (SI) with uncertainty lower than 0.005 %. This paper presents the new approach of the Italian Istituto Nazionale di Ricerca Metrologica (INRIM) to set density standards. The procedure involved accurate density determinations of some liquid samples, to be used as references, on which in addition analysis by means of gas-chromatography coupled with mass spectrometry (GC-MS) was performed to support homogeneity and short-term stability. In this exercise GC-MS analyses on two chlorinated liquids (namely tetrachloroethylene and trichloroethylene) were carried out before and after density measurements. The results obtained with the two different techniques were encouraging. Samples that ...
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At the SIM meeting in Buenos Aires, from 30 May to 1 June 2012, it was decided a RMO key comparison on pH measurement coordinated by INMETRO would be performed, named SIM.QM-K91, in order to investigate the degrees of equivalence of... more
At the SIM meeting in Buenos Aires, from 30 May to 1 June 2012, it was decided a RMO key comparison on pH measurement coordinated by INMETRO would be performed, named SIM.QM-K91, in order to investigate the degrees of equivalence of measurement procedures for the pH determination of a phthalate buffer solution (nominal pH around 4.01 at 25 °C). Phthalate buffer is widely used to calibrate pH electrodes in the acid range. A buffer solution of 0.05 mol kg-1 potassium hydrogen phthalate, KHC8H4O4, is one of the primary pH reference buffer solutions recommended by IUPAC. It was only allowed to participate in this comparison by using a differential cell or a glass electrode, instead of primary cells, if the highest metrological standard in the institute or if the CMCs are based on the type of cell to be used. The results obtained by INMETRO and NIST (who also participated in CCQM-K91 comparison) were used to link the results from the other institutes to the key comparison reference value...
This report describes the third CCM key comparison in capillary viscometry at twelve National Metrology Institutes (NMIs), which was carried out between October 2012 and February 2013. Seven NMIs, which do not maintain an independent... more
This report describes the third CCM key comparison in capillary viscometry at twelve National Metrology Institutes (NMIs), which was carried out between October 2012 and February 2013. Seven NMIs, which do not maintain an independent viscosity scale, also took part in this comparison. Three samples of Newtonian liquids with nominal kinematic viscosities of 6 mm²/s at 15 °C and 5 mm²/s at 20 °C, 2000 mm²/s at 20 °C and 500 mm²/s at 40 °C, and 160000 mm²/s at 20 °C and 25000 mm²/s at 40 °C prepared by NMIJ were provided to each of the NMIs. For each of these liquids at two temperatures, total number of 98 measurements was carried out and from the results of viscosity measurements, the key comparison reference values (KCRVs) for six data sets were determined. The degrees of equivalences was evaluated by difference from the KCRV and, with a few exceptions, these differences were almost equal to or less than expanded uncertainties, showing a good equivalencies of capabilities at the part...
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n-Undecane (C11H24) density and speed-of-sound measurements in liquid phase have been reported along five isotherms at temperatures between (278 and 318) K. The density results have been obtained at pressure up to 60 MPa by means of a... more
n-Undecane (C11H24) density and speed-of-sound measurements in liquid phase have been reported along five isotherms at temperatures between (278 and 318) K. The density results have been obtained at pressure up to 60 MPa by means of a vibrating tube DMA 512 while speed-of-sound measurements for pressures up to 100 MPa. The speed-of-sound values have been measured by means of a double-path pulse-echo technique at three different operating frequencies. It has been chosen to repeat the measure- ments at different frequency values because of the observed discrepancies in the fly-time determination. A particular emphasis has been done to analyze these discrepancies, not directly explicable by traditional diffraction corrections. Indeed we have deduced that the source of differences is ascribable to a combi- nation of sample speed-of-sound, of the signal frequency and to the geometrical configuration of the experiment, that affect the determination of the fly-time of the ultrasonic burst.
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A key comparison was performed in order to compare national measurement systems to determine volume of liquids, particularly at fixed volumes of 20 L and 100 mL. The participants were CENAM (Mexico), NIST (United States of America),... more
A key comparison was performed in order to compare national measurement systems to determine volume of liquids, particularly at fixed volumes of 20 L and 100 mL. The participants were CENAM (Mexico), NIST (United States of America), NRC/MC (Canada), SP (Sweden), PTB (Germany), INRIM (former IMGC, Italy), NMIA (Australia) and INMETRO (Brazil). CENAM acted as pilot laboratory. The measurements were
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The results of the SIM.M.D-S2 bilateral comparison between INRIM-Italy and INMETRO-Brazil are summarized in this report. The aims of this comparison were to check the stated uncertainty levels and the degrees of equivalence between the... more
The results of the SIM.M.D-S2 bilateral comparison between INRIM-Italy and INMETRO-Brazil are summarized in this report. The aims of this comparison were to check the stated uncertainty levels and the degrees of equivalence between the two institutes on the calibration of hydrometers for liquid density in the range of 800 kg m-3 to 1000 kg m-3 at 20 ºC, by
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In this work, accurate density measurements of subcooled water (freshly double-distilled water) were performed along eight constant-mass curves in the temperature range of (243 to 283) K and in the pressure range of (140 to 400) MPa, by a... more
In this work, accurate density measurements of subcooled water (freshly double-distilled water) were performed along eight constant-mass curves in the temperature range of (243 to 283) K and in the pressure range of (140 to 400) MPa, by a pseudo-isochoric method. The experimental apparatus mainly consisted of a high pressure vessel, especially designed for this experiment, of known volume as a function of temperature and pressure, used to perform measurements in the T-p range under study. The density of subcooled water was obtained by measuring the equilibrium pressure at different temperatures, keeping the mass constant. All terms contributing to the uncertainty of subcooled water density measurements were considered; the estimated relative uncertainty, in the investigated temperature and pressure range, is about 0.07%. The experimental results were compared with the literature densities. In particular, the trend of density versus temperature for a constant mass of sample observed ...
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Density measurements are frequently associated to specific requirements in order to evaluate the quality of a process or to determine mass and/or volume of the material. Hydrostatic weighing is the usual method to get directly the... more
Density measurements are frequently associated to specific requirements in order to evaluate the quality of a process or to determine mass and/or volume of the material. Hydrostatic weighing is the usual method to get directly the traceability to the SI system of the density as well as of the solid volume. INRIM (the former CNR - IMGC) supplied to IPQ a hydrostatic apparatus with a measuring cell, devoted to measure the density of liquids and the volume (density) of small solid bodies, with technical support and assistance in the density field. Since 2005 the partnership between the two Institutes has been developed within the EUROMET project 858 "Hydrostatic weighing - exchange of experiences". This paper deals with the activity concerning the main technical and metrological characteristics of the supplied measuring cell and also shows the preliminary results for testing it. For this purpose a comparison was carried out between the two laboratories. Each one determined th...
A novel pycnometer and a cryogenics apparatus were designed and manufactured in support of the EMRP – ENG 03 “Metrology for LNG” to provide accurate density measurements of Liquid Natural Gas and synthetic natural gas mixtures in the... more
A novel pycnometer and a cryogenics apparatus were designed and manufactured in support of the EMRP – ENG 03 “Metrology for LNG” to provide accurate density measurements of Liquid Natural Gas and synthetic natural gas mixtures in the liquid region. Densities of two Synthetic Natural Gas Mixtures have been determined in the temperature range 100 K and 111 K with pressures up to 6 bar (0,6 MPa). An unexpected change in composition of the samples affected the liquid density. Such effect could be due to adsorption in the Titanium surface of gas molecules and to evaporation of the mixture light components.
Density measurements are frequently associated to specific requirements in order to evaluate the quality of a process or to determine mass and/or volume of the material. Certified reference liquids can be used to assure metrological... more
Density measurements are frequently associated to specific requirements in order to evaluate the quality of a process or to determine mass and/or volume of the material. Certified reference liquids can be used to assure metrological traceability of density measurements to the International System of Units (SI) with uncertainty lower than 0.005 %. This paper presents the new approach of the Italian Istituto Nazionale di Ricerca Metrologica (INRIM) to set density standards. The procedure involved accurate density determinations of some liquid samples, to be used as references, on which in addition analysis by means of gas-chromatography coupled with mass spectrometry (GC-MS) was performed to support homogeneity and short-term stability. In this exercise GC-MS analyses on two chlorinated liquids (namely tetrachloroethylene and trichloroethylene) were carried out before and after density measurements. The results obtained with the two different techniques were encouraging. Samples that ...
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ABSTRACT After a description of the thermal disturbance anemometry principle, its practical operation conditions are discussed as regards use in applied superconductivity for measuring the flow rate of liquid and supercritical... more
ABSTRACT After a description of the thermal disturbance anemometry principle, its practical operation conditions are discussed as regards use in applied superconductivity for measuring the flow rate of liquid and supercritical helium.Thermodynamic and experimental considerations are then discussed in order to evaluate the amount of energy to be released by the heat-pulse generator in three different helium states. In the last section of the paper, the behaviour of different types of semiconductors used as thermal sensors is reported, particularly as regards their sensitivity to small temperature changes and their response time around 4 K. The first results show that a commercial silicon diode (BAS21 from Philips) has good characteristics, being rugged and cheap, with a typical sensitivity of −500 mV/K in the close vicinity of 4.2 K.
The results of the SIM.M.D-S2 bilateral comparison between INRIM-Italy and INMETRO-Brazil are summarized in this report. The aims of this comparison were to check the stated uncertainty levels and the degrees of equivalence between the... more
The results of the SIM.M.D-S2 bilateral comparison between INRIM-Italy and INMETRO-Brazil are summarized in this report. The aims of this comparison were to check the stated uncertainty levels and the degrees of equivalence between the two institutes on the calibration of hydrometers for liquid density in the range of 800 kg m-3 to 1000 kg m-3 at 20 ºC, by
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ABSTRACT
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Hydrometers are instruments usually made of glass which are widely used for different levels of precision to measure liquid density and related quantities to control different products and processes. This bilateral comparison on the... more
Hydrometers are instruments usually made of glass which are widely used for different levels of precision to measure liquid density and related quantities to control different products and processes. This bilateral comparison on the calibration of hydrometers shows that results reported by CENAM-Mexico and INRIM-Italy are consistent within the claimed uncertainty in the range of 800 kg/m3 to 1200 kg/m3.
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A key comparison was performed in order to compare national measurement systems to determine volume of liquids, particularly at fixed volumes of 20 L and 100 mL. The participants were CENAM (Mexico), NIST (United States of America),... more
A key comparison was performed in order to compare national measurement systems to determine volume of liquids, particularly at fixed volumes of 20 L and 100 mL. The participants were CENAM (Mexico), NIST (United States of America), NRC/MC (Canada), SP (Sweden), PTB (Germany), INRIM (former IMGC, Italy), NMIA (Australia) and INMETRO (Brazil). CENAM acted as pilot laboratory. The measurements were