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The authors’ objective is to manage sulfur content in gasoline over a multi-product pipeline using data derived from a correlation study. Sulfur content is analyzed by ultraviolet fluorescence or monochromatic wavelength dispersive X-ray fluorescence spectrometry in three different sampling points by three laboratories. At the same time, this study evaluates the homogeneity between laboratories/methods and if the analytical results of data vary in different sampling points of the pipeline. By means of two-way analysis of variance with interaction, the results show that there are variations along the multi-product pipeline besides differences between methods and laboratories.

This paper discusses metrologically the best practice regarding the calibration curves applied to H2S mass fractions determination in natural gas by gas chromatography with sulfur chemiluminescence...

This paper presents a method for measuring flow rates in pipelines based on the flow induced vibration principle using water as fluid, eliminating the need for interrupting the flow and opening of the pipeline for installation of traditional water flow meters. Experimental measurements are carried out in an accredited laboratory for calibration of rate flow meters and a metrological validation, followed by an uncertainty evaluation, are presented. Data analysis is accompanied by a method of optimization that minimizes adjustment errors of measurement using regression by parts and by the selection of the optimum period to estimate more accurately the flow rate. The results meet the specifications of Brazilian Metrology Institute.

The low-quality of automotive fuels may lead to the generation of pollutants harmful to both environmental and human health. The quality evaluation of automotive fuels requires a multiparameter conformity assessment, which may lead to an increased total risk of false conformity decisions even if all parameters comply with the acceptance limits. Thus, the aim of this work was to propose the establishment of multivariate acceptance limits in order to ensure a reduced total risk of false conformity decisions applied to automotive fuels analysis. Particular and total (consumers’ and/or producers’) risks were estimated using frequentist (specific) and Bayesian (global) approaches. Multivariate acceptance limits were estimated using Monte Carlo method, adopting an appropriate multivariate coverage factor (k’) defined using MS Excel Solver function. The definition of multivariate acceptance limits ensures a total risk below the maximum admissible risk (typically 5%) and was successfully employed in the conformity assessment of automotive fuels (diesel and gasoline). The employment of the multivariate acceptance limits may be useful in the conformity assessment of several multiparameter products.

The economic impact that results from the reliability of measurements associated with natural gas (flow rate and fluid properties) and caveats related to custody transfer contracts demands vigilant control of the net balance in the delivery systems. The methodology for data reconciliation has proved to be an effective tool to reduce uncertainties associated with measurements used in the calculations of the net balance in distribution networks such as gas pipelines. The intrinsic nature of the calculation algorithm, founded on the redundancy of measurements, qualifies the technique for increasing confidence in the measurement, thus reducing the individual uncertainty associated with each physical magnitude capable of affecting the measurement. This Brazilian gas pipeline study discusses the adequacy of the data reconciliation technique. The proposed technique proves to be very effective as it generates lower uncertainties than those obtained by traditional techniques: the level of 1% associated with the accountability of the unaccounted for gas was reduced to less than 0.3% when the data reconciliation methodology was used.

This work presents a contactless ammeter prototype based on GMR magnetometers, able to measure direct and alternating electrical currents. Two techniques nonlinear curve fitting and artificial neural networks, were used to solve the inverse problem, which is, given the output voltages of the GMR sensors, to estimate the electric current flowing through the conductor - nonlinear curve fitting and artificial neural networks. The performance of both techniques was compared based on the standard uncertainty of the data calculated by each one. The results obtained with the neural networks are significantly better.

The composition and physicochemical parameters of natural gas can vary in space and time depending upon the gas source and blending. The key parameters of natural gas are important to know for transportation and efficient consumption. Thus, a natural gas quality measurement is required for technical and economic reasons. The data reconciliation technique has the objective of using measurement redundancies to obtain the best estimate of the conventional true value and, consequently, to minimize its uncertainty. This work discusses this subject in analytical applications related to the natural gas industry. This methodology shows to be more suitable than the traditional ones when it is applied to a characterization study, a dispute between supplier and customer, an operation diagnosis in industrial unit, and an among day homogeneity study.

In Brazil, National Metrology Institute, INMETRO, elaborated an N° 64 Ordinance, on April 11th 2003 [1], based on OIML [2]. This document approves the Metrological Technical Regulation, establishing the metrological and technical requirements applicable to measurement systems supplied with flow meters used in the measurement of oil, its derivatives liquid, alcohol anhydrous and hydrous alcohol fuel. For custody transfer purposes, liquefied petroleum gas (LPG) volumes are generally stated at a fixed base temperature and saturation pressure. As most volume transfers occur at temperatures and pressures other than standard conditions, these volumes are adjusted to standard conditions through the use of correction factors. The measurement uncertainty of these custody transfer systems must be controlled. Based in norms ASTM, IP, ISO and API – MPMS, the mathematical model for the calculation of the volume, it basically depends on quantities as: K factor, density, pulse number, turbine meter factor, temperature and pressure corrections. This work develops a methodology to calculate the LPG mass uncertainty that is completely different form the other liquid oil derivatives. This work details this calculation showing the complex temperature and pressure algorithms, including the equilibrium bubble point pressure. Based on this methodology, it is noticed that the pressure uncertainty contribution is not less than 43% overall the process and the expanded uncertainty is less than 1%, as required by INMETRO.Copyright © 2010 by ASME

In many cases, the declaration of compliance of a result of measurement is not clear. This is observed when there is a partial superposition of the expanded uncertainty of a quantity with its limit of specification. In these cases, a judgment is required based in pre-established criteria between the client and the supplier. The consequences of an inadequate decision may be disastrous. Either the supplier will have financial losses or it will lose credibility with its client. This work demonstrates how to calculate the probability, for an appropriate confidence level, that the uncertainty associated with the measurement is within the limits that were established in a contract, declaring the compliance or non-compliance relative to the specification, and study two methodologies for helping the claimer to take the decision of compliance or non-compliance, using as example the heat capacity of natural gas, calculated from its gas chromatography. This approach encourages the client/supplier relationship. This occurs because the results are reported to both parts with a probability of compliance instead of a single value. The first methodology is based on the increase in the size of the sample. The second proposal is based in the calibration of the chromatograph against certificate reference materials with more exact and precise uncertainty values.Copyright © 2004 by ASME