Thorax

Experimental methodology for precise determination of density of RTILs as a function of temperature and pressure using vibrating tube densimeters

“…As it can be seen, Dq increases abruptly with the viscosity in region I, smoothly in region II, and it reaches a nearly constant value of 0.45 kg Á m À3 in region III. This behavior coincides with that commonly observed for other VTD [21,22,38,39]. Specifically, the results for this equipment follow the same behavior than those of the Anton Paar DSA48 [21] and DMA60/602 [39] but the maximum error is, in this case, lower (0.45 kg Á m À3 versus 0.7 kg Á m À3 ).…”

Tris(2-Ethylhexyl) trimellitate (TOTM) a potential reference fluid for high viscosity. Part II: Density measurements at temperatures from (293 to 373)K and pressures up to 68MPa

“…Several studies of this effect [11][12][13][14][15][16][17][18][19] have shown that the shape of the deviation is similar for all the studied vibrating-tube densimeters from Anton Paar. However, the reasons for this do not seem to be well understood.…”

“…The effect of viscosity on the density measurements made by U-tube densimeters has been extensively studied experimentally [11][12][13][14][15][16][17][18][19] and, recently, the increasing interest in high viscosity liquids has intensified the awareness in this effect [15][16][17][18]. However, to the knowledge of the authors, no theoretical study has been published.…”

“…Retsina et al [20] also note that an analytical treatment of the oscillation of a U-tube is not feasible. As a consequence of the complexity of a theoretical description of the liquid viscosity effect on U-tube density measurements, only empirical studies [11][12][13][14][15][16][17][18][19] about this phenomenon have been found in the literature. The viscosity effect on density measurements depends on the tube characteristics, which implies that the correction to the density readings has to be obtained for every particular instrument.…”

CHAPTER 3. Experimental Techniques 2: Vibrating Tube Densimetry

“…[20][21][22][23][24][25][26] The question is: what is the difference regarding the vibrating tube behaviour between a low viscosity sample and a high viscosity sample, both with the same density? A simple explanation of this problem was given by Stabinger 20 and can be understood by looking at Figure 3.6, where the behaviour of a segment of liquid mass in the tube for a low, medium, and high viscosity sample is shown.…”