Bilateral comparisons of hydrometer calibrations between the IMGC-LNE and the IMGC-MIKES

Lorefice, Salvatore; Heinonen, Martti; Madec, Tanguy

doi:10.1088/0026-1394/37/2/6

Cited by 9 publications

(7 citation statements)

References 8 publications

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“…In metrology, it is mandatory to validate either a new measurement method or a modification with an already validated method [ 20 , 21 ]. In order to validate the methodology proposed in this work based on the aligning mark immersion hydrometer scale under calibration with the vision system and the algorithm of digital image processing [ 22 ], two international comparisons in the calibration immersion of hydrometers were carried out.…”

Section: Resultsmentioning

confidence: 99%

Alignment of the Measurement Scale Mark during Immersion Hydrometer Calibration Using an Image Processing System

Peña-Perez¹,

Pedraza-Ortega

Ramos-Arreguín

et al. 2013

Sensors

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The present work presents an improved method to align the measurement scale mark in an immersion hydrometer calibration system of CENAM, the National Metrology Institute (NMI) of Mexico, The proposed method uses a vision system to align the scale mark of the hydrometer to the surface of the liquid where it is immersed by implementing image processing algorithms. This approach reduces the variability in the apparent mass determination during the hydrostatic weighing in the calibration process, therefore decreasing the relative uncertainty of calibration.

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Section: Resultsmentioning

confidence: 99%

Alignment of the Measurement Scale Mark during Immersion Hydrometer Calibration Using an Image Processing System

Peña-Perez¹,

Pedraza-Ortega

Ramos-Arreguín

et al. 2013

Sensors

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“…The effect should be considered especially if the hydrometer body is near the liquid surface. This is also the most probable explanation for the discrepancies observed in the results of the comparison between findings from MIKES and the Istituto di Metrologia 'G Colonnetti' (IMGC) in 1998-1999 [5] because the measurements at were carried out in a jacketed glass tube with a slightly raised liquid level.…”

Section: Discussionmentioning

confidence: 99%

“…We studied the effect induced by a vertical temperature gradient experimentally. Measurements were carried out using the MIKES hydrometer calibration system [4,5] and a hydrometer with a scale covering the range 1.950-2.000 g cm −3 , i.e. 1950-2000 kg m −3 .…”

Section: Measurementsmentioning

confidence: 99%

The effect of density gradients on hydrometers

Heinonen¹,

Sillanpää²

2003

Meas. Sci. Technol.

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Hydrometers are simple but effective instruments for measuring the density of liquids. In this work, we studied the effect of non-uniform density of liquid on a hydrometer reading. The effect induced by vertical temperature gradients was investigated theoretically and experimentally. A method for compensating for the effect mathematically was developed and tested with experimental data obtained with the MIKES hydrometer calibration system. In the tests, the method was found reliable. However, the reliability depends on the available information on the hydrometer dimensions and density gradients.

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“…In those situations where the range of the hydrometer to be calibrated is lower than the density of the reference liquid, additional weights are added to the hydrometer to cause it to sink. This is the most accurate method and it is in use at most NMIs (National Metrology Institutes), including the INRiM [18][19][20]. Full details of this method are given in the next section.…”

Section: Hydrostatic Weighingmentioning

confidence: 99%

Calibration of hydrometers

Lorefice

Malengo

2006

Meas. Sci. Technol.

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After a brief description of the different methods employed in periodic calibration of hydrometers used in most cases to measure the density of liquids in the range between 500 kg m−3 and 2000 kg m−3, particular emphasis is given to the multipoint procedure based on hydrostatic weighing, known as well as Cuckow's method. The features of the calibration apparatus and the procedure used at the INRiM (formerly IMGC-CNR) density laboratory have been considered to assess all relevant contributions involved in the calibration of different kinds of hydrometers. The uncertainty is strongly dependent on the kind of hydrometer; in particular, the results highlight the importance of the density of the reference buoyant liquid, the temperature of calibration and the skill of operator in the reading of the scale in the whole assessment of the uncertainty. It is also interesting to realize that for high-resolution hydrometers (division of 0.1 kg m−3), the uncertainty contribution of the density of the reference liquid is the main source of the total uncertainty, but its importance falls under about 50% for hydrometers with a division of 0.5 kg m−3 and becomes somewhat negligible for hydrometers with a division of 1 kg m−3, for which the reading uncertainty is the predominant part of the total uncertainty. At present the best INRiM result is obtained with commercially available hydrometers having a scale division of 0.1 kg m−3, for which the relative uncertainty is about 12 × 10−6.

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Bilateral comparisons of hydrometer calibrations between the IMGC-LNE and the IMGC-MIKES

Cited by 9 publications

References 8 publications

Alignment of the Measurement Scale Mark during Immersion Hydrometer Calibration Using an Image Processing System

Alignment of the Measurement Scale Mark during Immersion Hydrometer Calibration Using an Image Processing System

The effect of density gradients on hydrometers

Calibration of hydrometers

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