J. Setina, J. Tesar, Z. Krajicek
Generation of absolute pressure with a pressure balance is commonly done by enclosing the space above weights with a bell jar and evacuating it with a vacuum pump. Residual pressure in a bell jar is usually of the order of few tens of Pa to few Pa, depending on the effective pumping speed. Its value is added to a calculated pressure of the gravitational force of the piston and weights to obtain the generated absolute pressure. By connecting to the absolute pressure balance a precise and stable pressure gauge with sufficient resolution it is easy to observe that small changes of residual...
Cultivating Metrological Knowledge
· TC16
· 2007
· Download
J. C. Torres-Guzmán, L. H. Paraguassú, P. R. G. Couto, I. L. Bezerra
This comparison constitutes the second part of the first vacuum comparison among National Metrology Institutes (NMI) within the Interamerican Metrology System (SIM). Each laboratory used its national standards for the compared range. The Centro Nacional de Metrología (CENAM, Mexico) used a reference standard (comparison system type) and the Instituto Nacional de Metrologia, Normalização e Qualidade Industrial (INMETRO, Brazil) used a similar reference standard (comparison system type). The comparison started in December 2004 and finished in March 2005. The objective of the comparison was to...
Cultivating Metrological Knowledge
· TC16
· 2007
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A. Navarro-Nateras, J. C. Torres-Guzman, P. Olvera-Arana
The pressure and vacuum group of the Force and Pressure Division, at the Centro Nacional de Metrologia (CENAM, Mexico) has developed two measurement systems for calibration, one for leaks and another for holes in dynamic pressure. The leaks calibration system is based on the method of pressure increment at constant volume (and constant temperature) within the measurement range starting at 1 x 10-6 Pa·m³·s -1 up to 5 Pa·m3·s -1 with volumes of 0.5 L or 1 L (according to the leak range to be calibrated), with an operation pressure from 1 x 10 -5 Pa up to 130 kPa, using helium, nitrogen or air...
Cultivating Metrological Knowledge
· TC16
· 2007
· Download
J. Galvan-Mancilla, J. C. Torres-Guzman, D. Ramirez-Ahedo
A torque proficiency test among accredited laboratories in Mexico was performed starting in January 2007. The main objectives of this exercise were to estimate the level of agreement for the dissemination of the quantity among laboratories and to evaluate the compatibility, including the uncertainty associated to its measurements, of the laboratories results with the set references values. The Centro Nacional de Metrologia, CENAM (Mexico) was the pilot laboratory and responsible for the coordination of this program. The maximum torque measurement for this proficiency test was 800 N·m. The...
Cultivating Metrological Knowledge
· TC3
· 2007
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D. Ramirez-Ahedo, J. C. Torres-Guzman, F. Martinez-Juarez
The torque laboratory at the Centro Nacional de Metrología in Mexico (CENAM) started operations in 1997 with the design, built up and set up of a torque transfer standard machine for 2 kN·m (TTSM-2kN·m). Since that time, a total of five torque standards have been developed at CENAM. Two of them realize the quantity via the primary method (dead weights applied in a lever arm of a well known length) in the measuring ranges of 2 kN·m and 1 kN·m. The other three transfer standard machines are in the ranges from 20 N·m and 2 kN·m, and the last one is a TTS machine which is in the set up stage,...
Cultivating Metrological Knowledge
· TC3
· 2007
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S. Martínez-Sanchez, F. M. C. Laguna-Aguilar, J. C. Torres-Guzman
The Universidades Tecnológicas (Technological Universities) in Mexico have as a mission to offer a high quality education model which has been in operation for more than 50 years in countries where it has proven to be a success. In 1998, the Centro Nacional de Metrología (CENAM) collaborated with the Technological Universities by means of an indepth technical training in Metrology. The objective was to disseminate the metrological knowledge among the academic members and stimulate them to establish secondary calibration laboratories in their institutions.
Cultivating Metrological Knowledge
· TC3
· 2007
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C. Ferrero
The increasing demand, in particular in Italy, for calibration and certification work and for the accreditation of new calibration centres, is due to a number of concomitant factors: The need for industry to operate in accordance with EN 45000, ISO 9000 and ISO17025 as regards quality; the Italian law 273/91 establishing the National Calibration System, which comprises the Primary Metrological Institutes and the SIT centres). INRiM provides for traceability to the standards of mechanical, thermal and electrical quantities all over the country, so as to allow high-quality measurements and...
Cultivating Metrological Knowledge
· TC3
· 2007
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G. D’Agostino, A. Germak, C. Origlia, D. Quagliotti, G. Barbato
The knowledge of the acceleration g due to gravity plays an important role in force metrology in calibration of mechanical standards and, recently, in mass metrology in realizing new mass standards based on electrical references for the redefinition of kilogram. Moreover gravimetric surveys are carried on for applications in Geophysics and Geodesy. Over the past thirty years the development of transportable ballistic absolute gravimeters has dramatically pushed up the ability to measure the g value. The application of new technological advances and the deep study of the physical phenomena...
Cultivating Metrological Knowledge
· TC3
· 2007
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Antonio Cruz Serra, Leo Van Biesen
IMEKO is a non-governmental federation of 36 national Member Organisations. The Member Organisations are scientific/technical societies or committees. They include representatives of metrological institutions, higher education institutions, industry and users of instruments. This communication will deal shortly with the objectives of the Confederation, will inform on its structure, will highlight IMEKO imeko_proceedings and will present an overview on the activities of the 23 Technical Committees.
Cultivating Metrological Knowledge
· TC3
· 2007
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Richard Davis
The International System of Units (SI) still relies on an artifact standard to define the unit of mass, the kilogram. The unit of electrical current, the ampere, is defined in terms of a force in newtons, which in turn is traceable to the kilogram. It has long been appreciated that the mass of any artifact, such as the international prototype of the kilogram, will certainly vary with respect to a so-called "fundamental" constant of mass, such as the mass of an atom of carbon-12. Until recently, however, there was no highly accurate experimental method that might link the mass of a...
Cultivating Metrological Knowledge
· TC3
· 2007
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