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A medium and high vacuum primary standard, based on the static expansion method, has been set up at Centro Nacional de Metrología (CENAM), Mexico. This system has four volumes and covers a measuring range of 1 × 10-5 Pa to 1 × 103 Pa of absolute pressure. As part of its realization, a characterization was performed, which included volume calibrations, several tests and a bilateral key comparison. To determine the expansion ratios, two methods were applied: the gravimetric method and the method with a linearized spinning rotor gauge. The outgassing ratios for the whole system were also determined. A comparison was performed with Physikalisch-Technische Bundesanstalt (comparison SIM-Euromet.M.P-BK3). By means of this comparison, a link has been achieved with the Euromet comparison (Euromet.M.P-K1.b). As a result, it is concluded that the value obtained at CENAM is equivalent to the Euromet reference value, and therefore the design, construction and operation of CENAM's SEE-1 vacuum primary standard were successful. |
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TORRES-Guzmán J. C., SANTANDER L. A., Jousten K. (CENAM, PTB) Realization of the medium and high vacuum primary standard in CENAM, Mexico
The IMGC/CENAM-HG6 Mercury Manobarometer |
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A medium and high vacuum primary standard has newly been set up at the CENAM, Mexico. This vacuum standard is based on the static expansion method and covers a measuring range from 1 × 10-5 Pa to 1 × 103 Pa of absolute pressure. To validate its function and uncertainty budget, in 2002 a comparison was performed with a primary standard of the vacuum metrology section at PTB which had taken part in the key comparison CCM.P-K4. In this manner, the degree of equivalence of the pressure measurements performed with this standard with those of other national primary standards of the CCM.P-K4 could be found. In addition, a link could be achieved with the national standards of the Euromet comparison Euromet.M.P-K1.b, since the latter comparison was carried out with the same protocol and the same tranfer standards, having also PTB as common participant. Two spinning rotor gauges served as transfer standards and showed an excellent transport stability. The effective accommodation coefficients of the rotors had to be determined at eight target points, at and between 3 × 10-4 Pa and 0.9 Pa. The pressures generated by the PTB and the CENAM primary standards showed good agreement within their combined uncertainties. So, there is also equivalence of the CENAM medium and high vacuum primary standard with the other national primary standards of the CCM.P-K4. The CENAM primary standard is also equivalent with the reference value of the Euromet.M.P-K1.b. |
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JOUSTEN K., SANTANDER Romero L. A., TORRES Guzmán J. C.
The IMGC/CENAM-HG6 Mercury Manobarometer |
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MIDE, Metrología Integral y Desarrollo, S. A. de C. V. |
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“Respondemos por la calidad de tu medición” |
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Publicaciones Algunas de las publicaciones mas relevantes del personal de MIDE. |
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In an ordinary process of measurement it’s possible that the environmental changes of temperature induce errors of measurement which exceeds the accuracy specifications of load cells. The paper describes the effects of the environmental temperature on one type of high accuracy load cells, it indicates the degree of correlation between the variations of temperature and the mass readings of the cells, and furthermore it figures out the mathematical model of its behavior. |
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The Centro Nacional de Metrología (CENAM, Mexico) has established a national primary standard for barometric pressure based on a mercury column and a laser interferometer, the first in this range in Latin America. The original design of the manobarometer, the HG5, was made at the Istituto di Metrologia 'Gustavo Colonnetti' (CNR-IMGC, Italy) and it served to develop this new version, the IMGC/CENAM-HG6 mercury manobarometer which was constructed and assembled at CENAM. The special features of this new version and its main design characteristics are presented here, together with the differences from its predecessor. To verify its performance, an internal comparison in absolute mode (gas, N2) was carried out with a primary pressure balance, a piston-cylinder assembly with 50 mm diameter having direct traceability to SI base units and measuring range to 2.5 kPa to 175 kPa. The results of the comparison are presented and discussed. |
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El vocabulario internacional de metrología vigente, VIM 1993, cuya equivalencia en México está en la norma NMX-Z-055-1996-IMNC, incluye términos básicos ampliamente usados en el ámbito de la metrología como exactitud, error, repetibilidad y sesgo. En contraste con los documentos anteriores, la norma ISO 5725 parte 2 Exactitud (veracidad y precisión) de resultados y métodos de medición, actualmente en revisión como norma mexicana, introduce los términos de precisión y veracidad. El borrador de la nueva versión del vocabulario internacional de metrología, actualmente en revisión, intenta incorporar todos los términos anteriores. Por otro lado, la propia norma ISO 5725 parte 2 afirma que la exactitud es descrita por la veracidad y la precisión, lo cual es repetido en literatura especializada, dando lugar a un aparente conflicto con la definición de exactitud de medición dada por el VIM 1993 como la proximidad de concordancia entre el resultado de una medición y un valor verdadero del mensurando. En este trabajo se analizan las definiciones de los términos mencionados, se exponen las relaciones entre ellos y se proponen sus interpretaciones con objeto de ayudar a una mejor comunicación. |
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En un proceso de medición ordinario los cambios de temperatura ambiental inducen errores de medición que exceden las especificaciones de exactitud de las celdas de carga de alta exactitud. En este documento se presenta un método de compensación para disminuir los efectos de la temperatura ambiente sobre la respuesta de un tipo de celdas de carga de alta exactitud.
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Velasco M., Salas R., Luchsinger H. Analysis of the Sensitivity to the Environmental Temperature of High Accuracy Load Cells |
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Luis A. Santander Romero, Ignacio Hernández Gutiérrez y Rubén J. Lazos PRECISIONES SOBRE LA EXACTITUD Y OTROS TÉRMINOS RELACIONADOS
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TORRES-Guzmán J. C.,OLVERA-Arana P., ALASIA F., SARDI M., ZUÑIGA S., SANTANDER L. A.,ESPARZA A. (CENAM, IMGC) |
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Roberto Salas, M. Velasco |
