The activities carried out deal with mass and related topics, such as volume and density of solids, properties of liquids and fluid mechanics, including air speed. Further activities concern advanced mechanical design and mathematical and statistical tools for metrology, with special focus on the uncertainty of measurement.
INRIM keeps the Italian standards of mass, the copy no. 62 of the International Prototype Kilogram, and density, a 1 kg silicon sphere. Several reference mass standards were recalibrated, including the national 500 kg standard, made of 25 pieces of 20 kg each.
Accurate density measurements were performed within a collaboration with the Istituto Nazionale di Fisica Nucleare, section of Florence (Italy), for the MAGIA (Accurate Measurement of G by Atom Interferometry) experiment. In this experiment, the measurement of the Newtonian gravitational constant is obtained by measuring the perturbation to the acceleration of free-falling cold atoms, due to cylinders of sintered tungsten of known mass and density. Since density distribution is fundamental for the experiment, to evaluate the density homogeneity of these cylinders, measurements were performed on 15 parallelepipeds of about 500 g each, obtained from sample cylinders. The test was carried out on two cylinders made with different sintering processes. The density was determined by hydrostatic weighing using bi-distilled water as reference liquid. The cylinder with the best homogeneity showed a relative variation in density of 6.6 ×10-4. As expected, because of porous regions due to the sintering process, a density reduction was observed moving towards the centre of the cylinder.
The 15 parallelepipeds obtained from a sample cylinder.
INRIM has been involved in some international programmes concerning: viscosity, participating in the CCM.V-K2 "CCM Key Comparison on viscosity at 20 °C, 100 °C and 150 °C"; density, coordinating the regional key comparison EUROMET Project 702 "Comparison of the calibrations of high resolution hydrometers for liquid density determinations" in which 11 national metrological institutes are involved; still density, collaborating with the Portuguese IPQ in the EUROMET project 858 as a continuation of the 46/IPQ/2005 contract. In addition to the dissemination activity in favour of domestic industry, INRIM supported a project to design a new facility for measuring fluids in the ranges from 500 kg/m3 to 3000 kg/m3 and for testing on-line densimeters. The new apparatus is completely automatised; the test parameters and all acquired data are shown in real-time.
Screenshot of the control panel of the unit for measuring the density and testing on-line densimeters.
The data of the EUROMET Project 852, the comparison of air flow measurements, carried out in 2005 between Italy and Switzerland by means of a G25 rotary piston gas meter, were analyzed and the results were published. INRIM participated also in the subsequent intercomparison (EUROMET 806), still in progress, which aims to provide experimental support to the CMC claimed by a number of EUROMET members in the range of low flowrates of both nitrogen and air (0.1 L/min to 25 L/min).
Within a Working Group of Comitato Italiano Gas a standard on how to establish traceability chains and carry out uncertainty calculations for volume and flowrate measurements of important fluids such as combustible gases has been drafted. This work, started in 2004, is expected to cover in 2008 an important metrological subject not dealt with so far by any written standard, at both national and international level.
Metrological support to SIT Laboratories, dissemination of units and consultancy to industries were supplied in the fields of both liquid and gas volume or flowrate measurements.
A high-to-low pressure regulator based on piezo technology was developed in the framework of a contract with Alcatel Alenia Space (AAS-I, Italia). Together with a micro-thruster also built by INRIM the previous year, the regulator completes the supply line of a micro-propulsion system proposed by AAS-I for the attitude control of scientific satellites (GAIA and LISA Pathfinder). The titanium all-welded body and the accurate design of the internal components enabled to meet ESA strict requirements of upstream pressure resistance (burst without rupture up to 1200 bar), whole mass (<150 g) and maximum leakage (internal <10-7 SCCS and external <10-8 SCCS of He at 300 bar).
Under a further contract with AAS-I, the design of a piezo-pump and the construction of the first prototype of a release piezo-valve for the caging-system of the LISA-Pathfinder ESA program was also carried out.
Within a project led by the Istituto di Scienza e Tecnologia dei Materiali Ceramici (CNR), a study in the automotive field was initiated, focused on the development of piezo-injectors for GPL and CH4. The first results obtained with plate piezo-benders appear encouraging and an operating prototype is expected by the end of 2007.
A possible shape of a 4-way piezo injector.
Low-speed test rigs were developed in view of the EUROMET 514 comparison, a long-standing project which is expected to reach INRIM laboratories in 2007. Moreover, a draft protocol was prepared for a future comparison in the field of high speeds within EUROMET, for which INRIM is the candidate pilot.
In the field of SIT activities, the procedures of a laboratory which required certification for airspeed measurements were analyzed; the certification is still ongoing and is expected to be completed by the end of 2007.
Dissemination of airspeed units was continued; consultancy was provided to industries in the field of airspeed measurements. Research went on in the field of studies on airspeed measurements (specifically, hot wire and ultrasonic anemometers) through dedicated experiments. Activities continued in the field of study of flow within micropropulsors, in cooperation with the Flowrate Group and AAS-I. This activity is partially financed by Regione Piemonte in the framework of the Applied Research Grant 2004. Also, again in cooperation with the Flowrate Group, a research project aimed at the investigation of the flow within flow meters of the "Sonic Nozzle" type, started. Finally, some preliminary experiments on aeroacoustic measurements were performed. This activity might open important development perspectives, as some industries show interest in it.
All activities were conducted in cooperation with the relevant department of the Politecnico di Torino.
Several contributions were published in JCR journals.
A special issue of Metrologia (W. Bich and M. G. Cox editors) was devoted to the specific topic in August. This issue gained a wide interest.
(Courtesy of Metrologia).