Neue Magnetschwebewaagen für gravimetrische Messungen in der Verfahrenstechnik

Lösch, H. W.; Kleinrahm, Reiner; Wagner, Wolfgang

doi:10.1002/cite.330660808

Cited by 35 publications

(24 citation statements)

References 2 publications

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“…During the weighing of the calibration and tare weights, the permanent magnet and "lifting fork" remain in suspension, but both sinkers are on their rests. This is made possible by a relatively new type of magnetic suspension coupling which has two stable states [6] corresponding to the (lifting fork + p-magnet) and the (sinker + lifting fork + p-magnet).…”

Section: Force Transmission Error Analysismentioning

confidence: 99%

“…The magnetic suspension coupling used in the current version of this instrument was developed by Lösch [2], and further developments are described by Lösch et al [6]. The two sinkers have (nearly) the same mass, surface area, and surface material, but they are made of materials with different densities (e.g., a gold disk and a goldplated quartz-glass sphere) so that they have very different volumes.…”

Section: Two-sinker Densimetersmentioning

confidence: 99%

“…The two weighings of each object are averaged in this analysis, and the air density ρ air is calculated from the ambient temperature, pressure, and humidity measured in the balance chamber. Equations (6) and (7) are solved for α and β:…”

Section: Force Transmission Error Analysismentioning

confidence: 99%

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Force Transmission Errors in Magnetic Suspension Densimeters

2007

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Techniques to determine and compensate for the force transmission error (FTE), including the magnetic effects of the fluid being measured, in magnetic suspension densimeters are presented. For a two-sinker densimeter, the forces on the balance are expressed for each of the weighings comprising a density determination (i.e., the two sinkers plus balance calibration and tare weights). This yields a system of four equations, which are solved for the fluid density, a balance calibration factor, a coupling factor (related to the FTE), and a quantity related to the balance tare. For a single-sinker densimeter, an in situ weighing of the sinker in vacuum compensates for the FTE of the apparatus itself. A determination of the fluid-specific effect requires measurements with two different sinkers-analogous to the two-sinker analysis, but with the measurements spread out over time. The apparatus part of the FTE is generally less than ±20 ppm. Measurements on propane, helium, neon, nitrogen, argon, toluene, and air are analyzed for the fluid-specific effect; this effect is correlated with the magnetic susceptibility of the fluid together with an apparatus constant. With this analysis, the force transmission "error" becomes an effect that can be accounted for rather than a significant source of uncertainty in density measurements carried out with magnetic suspension densimeters.

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Section: Force Transmission Error Analysismentioning

confidence: 99%

Section: Two-sinker Densimetersmentioning

confidence: 99%

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Force Transmission Errors in Magnetic Suspension Densimeters

2007

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“…The key component of the weighing system is the magnetic suspension coupling. The principle of contactless weighing was developed by Clark [63], the first type of magnetic suspension coupling presented by Gast [64,65], and the technique developed further by Lösch [66] and Lösch et al [67,68]. This dual-sinker densimeter shown in Fig.…”

Section: Frontier Expansionmentioning

confidence: 99%