Comparison of different methods for liquid level adjustment in tank prover calibration

The adjustment of the liquid level during the calibration of tank provers with fixed volume is normally done by overfill but it can be done in different ways. In this article four level adjustment techniques are compared: plate, pipette, ruler and overfill adjustment. The adjustment methods using plate and pipette presented good agreement with the tank’s nominal volume and lower uncertainty among the tested methods.Indisponível

Mathematica tools for uncertainty analysis

Some functions of the author´s Mathematica 9 package are presented. Links are given to the author´s interactive demonstrations. Mathematica supports 143 types of statistical distribution covering not only metrology but almost all statistical areas. The Supplement 1 to the ISO GUM mentions that analytical methods are ideal ones, but assume they are applicable only in simple cases, and recommends Monte Carlo method. In contrast, this paper presents Mathematica functions that can explore a multitude of methods in order to find analytical, numerical, or statistical results using (usually) one million random variates.Indisponível

Uncertainty and UncertaintyGUM mathematica functions

15 p. : il.Two functions from the authors Mathematica package are demonstrated. UncertaintyGUM is based on the Guide to the Expression of Uncertainty in Measurement (GUM) [1]. The more powerful Uncertainty use the propagation of distributions to find analytically, numerically, or statistically the expectation ± standard deviation for expression of random variables with prescribed statistical distributions. These two functions gives the same results for the linear expression c1*x1+c2*x2+c3*x3 with normal or multinormal statistical distributions of variables x1, x2, and x3. The approximate results of UncertaintyGUM and exact one of Uncertainty, for the nonlinear expressions Sin[x] and x^n of the normally distributed random variable x, are compared in three interactive demonstrations. This paper is a Mathematica notebook transformed to the new CDF (Computable Document Format) supported by the free CDF Player distributed by the Wolfram Research [3]

Transient liquid temperature at thermometer surface caused by its heating effect

4 f. : il.The calibration of solid volume using hydrostatic method needs the liquid temperature to be measured with high accuracy - resolution about 0.001 K. The solid has to be weighed in air and liquid to calculate the solid volume from the difference of buoyancy in the air and the liquid. During the calibration it is necessary to maintain the liquid motionless to avoid cause influence on the balance. In this condition it was noted that the semiconductor thermometer shows the raising of temperature, but if the liquid is moved around the thermometer the temperature goes down to the initial temperature. To explain the above observation and predict the temperature error T, a simple mathematical model is developed and programmed by using the new dynamic interactive computing, introduced by Wolfram Research with the release of Mathematica 6. When the model parameters are varied in predefined ranges, the temperature automatically is updated to always reflect the current values of the parameters. The paper demonstrates a new technology that could be applied in any other subject of ENCIT 2008

Medição de volume e de massa específica com um sistema de pesagem hidrostática de simples construção

5 p. : il.Foi montado um sistema simples de pesagem hidrostática para as medições de volume de um corpo sólido e de massa específica de sólidos e líquidos. A água pura foi usada como material de referência de massa específica para a medição de volume de um poliedro construído em vidro. Com o volume do sólido calibrado, mediu-se a massa específica de diferentes líquidos. Embora seja um sistema fácil montagem, apresentou capacidade de resolução melhor que o densímetro digital de resolução 0,00001 g/cm3

Implementation of double-timing pulse interpolation applied to compact piston provers

5 f. :il.This work presents an electronic circuit for double-timing pulse interpolation applied to compact piston provers (also referred as small volume provers). Compact provers are usually employed to prove meters with pulsed outputs. API and ISO standards [1,2]recommend a minimum of 10.000 pulses per run to obtain a resolution better than ± 0.01%. Since the volume of fluid displaced by a compact prover is relatively small, the number of pulses produced during a proving run is often considerably less than 10.000 pulses. Pulse interpolation techniques are commonly used to increase resolution and to diminish uncertainty during a proving run by estimating the fractional part of meter pulses within the time interval of the calibration. In this way, pulse interpolation techniques are essential to obtain accurate flow measurements and to allow the calibration of meters with compact provers. Our implementation uses a compact piston prover with an internal volume of 12 L and maximum flow capacity of 180 L/min. In order to implement the double-timing pulse interpolation method, we have used a Pentium D, 2.80 GHz installed with a 16-bit counter/timer board. Data acquisition and control software were written using VB .Net. An electronic circuitry was built to activate/deactivate counters gates, and to collect pulses. Some requirements and limitations of pulse interpolation techniques such as circuitry testing and pulse stability are also discussed in this work

Metrological evaluation of the interlaboratorial comparison of the ultrasonic flowmeter calibration

8 f. : il.This work deals with the metrological evaluation of the same ultra-sonic flowmeter, when calibrated in two different calibrating systems, belonging, respectively, to two accredited laboratories, both operating according to the manufacturer’s installation technical specification, and following the minimum requirements, as specified in international standards and recommendations. The research investigated the effect in calibration of the installation of a valve and a long curve upstream of the measurement straight section, as dimensioned according to the applicable standards. It was concluded that longer straight sections should be specified, so that the influence of the installation in the calibration could be neglected. The development of the present work was motivated by the growing utilization of ultrasonic flowmeters by the oil industry, and by the urgent need to contribute to the advance of the technology and the applicable standardization. In this aspect, this work contributes to (a) a better understanding of the measurement technology and of the calibration procedure of ultra-sonic liquid flowmeters, (b) the advance of the technology standardization, since it includes a critical analysis of the minimum requirements, as specified by the standards, and (c) improving the laboratory accreditation criteria for flow meter calibration, because the influence of the installation in the calibration was experimentally shown

Calibrations of tank prover with master flow meter and by weinhging methos using a mineral oil

2 f. : il.The calibrations of great tank provers are carried out by transferring water volume from other calibrated tank prover. In this article, we present the results of two different methods of calibrations of 0,5m3 tank prover in site by using the low viscosity mineral oil. In the first case the standard was a master flow meter and in the other case the weighing method was adopted. The results were very compatibles

First brazilian program for gas flow interlaboratory comparison on medium and high flow rates

6 p. : il.This article presents an evaluation of the first Interlalabory comparison program for medium and high gas flow measurement. Four important Brazilian laboratories, from São Paulo, Rio Grande do Norte, Rio de Janeiro and Minas Gerais had participated on the program