Rolling-ball Viscometer Research Articles

An assessment of a rolling-ball viscometer for studying non-Newtonian fluids

This paper assesses the potential value of a rolling-ball viscometry method for studying opaque non-Newtonian fluids under ambient conditions. In the apparatus described an ultrasonic technique is used to monitor continuously the rolling velocity of a ball in an inclined tube filled with fluid. A relationship to enable the approximate calculation of the equivalent shear rate imposed by the rolling ball is proposed. The computed drag forces on the ball have been used to quantify the rheological characteristics of typical Bingham and power-law fluids. Experimental results produced for bentonite dispersions (Bingham-plastic fluids) and Polyox solutions (power-law fluids), obtained from the rolling-ball rheometer, have been compared with those obtained from a Bohlin VOR Rheometer. The self-consistency between the corresponding data sets is good, confirming the applicability of the rolling-ball method for studying rheologically complex fluids and the accuracy of the first-order estimate of the equivalent shear rate. The intrinsic simplicity of the construction of the rolling-ball viscometer provides the basis for the construction of a robust and accurate device for studying the rheology of fluids at high pressures and temperatures.

High pressure rolling-ball viscometer of a corrosion-resistant type

A high pressure rolling-ball viscometer was designed for use with corrosive solutions such as electrolytes, using a glass inner cell with a glass cylinder and its piston. The viscosities of water and 2.55-m sodium chloride aqueous solution were measured up to 375 MPa at 25 °C with an error of less than ±1%.

Dynamic Viscosity of Supercritical Ethene

AbstractThe viscosity of ethene was determined using a self‐constructed rolling ball viscometer up to pressures of 200 MPa at four temperatures ranging from 293 to 413 K. The recommended empirical equations of Reichenberg and Jossi, Stiel and Thodos predict the measured values only below 100 MPa with sufficient accuracy. The correlation of the residual viscosity with the density leads to a single curve for all temperatures and up to the greatest observed density σ = 2.7 σ. Since an exponential expression is given, the viscosity range can be extended to higher temperatures provided the density is known. The applicability of Dymond's correction of the Enskog dense fluid theory to the measured values is discussed.

A High Pressure Rolling-Ball Viscometer up to 1 GPa

A rolling-ball viscometer has been developed for use under high pressures up to 1 GPa. It is proven that the calibration coefficient of the viscometer depends on its inclination angle and that this dependence varies with the diameter ratio of the ball and tube. In order to permit a simultaneous measurement of the density, the viscometer was improved, allowing for the attachment of a potentiometric displacement sensor. The precision of the density measurement is estimated to be ±0.22%. The viscosity data of a pressure-transmitting liquid, di-(2-ethyl-hexyl) sebacate (Univis P12), is presented in the range of pressures up to 800 MPa at temperatures from 6 to 60°C. The accuracy of a viscosity measurement is estimated to be ±0.95%.

A rolling ball viscometer for high pressure use

A rolling ball viscometer has been developed for use at high pressures up to 1 GPa. It is proved that the calibration coefficient of the viscometer depends on its inclination angle and this dependence varies with the diameter ratio of the ball and tube. Improvement is made in order to allow simultaneous measurement of the density by assembling a potentiometric displacement meter. The precision of the density measurement is estimated to be ±0.22%. The viscosity data of di-(2-ethyl-hexyl) sebacate (Univis P12) is presented in the range of pressures up to 800 MPa at temperatures from 6 to 60°C. The accuracy of the viscosity measurement is estimated to be ±0.95%.

Viscosity of binary gaseous mixtures of fluorocarbons.

Viscosity of eight binary gaseous mixtures consisting of fluorocarbon refrigerants, namelyR290 mixtures: R290 + R22, R290 + R115, R290 + R502R22 mixtures: R22 + R12, R22 + R13, R22 + R13B1, R22 + R14, R22 + R152ahave been measured at temperatures from 298 to 348 K at atmospheric pressure. The measurements were performed by a rolling-ball viscometer, which was calibrated using nitrogen as a standard gas. The uncertainty of the viscosity data obtained is estimated to be within ± 1.0%. The visocisty of all gaseous mixtures investigated changes almost linearly with composition at constant temperature. The experimental data could be expressed by the empirical Sutherland equation with mean deviation of 0.36 %. It was found that the Chapman-Enskog theory reproduced the experimental data with mean deviations within 1 % except for R290 + R502 mixtures.

Study of Drag Reduction Due to Aqueous Sodium Polyacrylate by the Rolling Ball Method

A new apparatus was constructed by modifying the rolling ball viscometer in order to study drag reduction due to polymer solutions. Using this apparatus, dilute aqueous solutions of sodium polyacrylate (200 ppm) containing various amounts of KNO3 were examined at 25°C in the region of the Reynolds number where drag reduction begins to appear. The drag coefficient and Reynolds number were calculated using the equations proposed by Hubbard and Brown. It was found that drag reduction is markedly affected by the concentration of added KNO3 and that the maximum effect appears at 5.00×10−3 moll−1 of KNO3. This finding may be favorably explained by Kohn’s energy storage theory.

Calibration of rolling ball viscometer in the intermediate reynolds number region

AbstractThe applicability of proposed correlations for the calibration of a rolling ball viscometer in the intermediate Reynolds number region (0.3 < Re 1000) has been studied. The constants for the equation correlating ball roll time with viscosity have been derived and compared with their experimental values. The dependency of these constants on temperature and on the dimensions of the viscometer has also been described which may help in the optimal design of a rolling ball viscometer.

Collaborative Evaluation of Rolling Ball Viscometer for Measuring Somatic Cells in Abnormal Milk

The Ruakura rolling ball viscometer was evaluated in 3 laboratories along with currently approved instrumental methods for measuring somatic cells in milk and the Wisconsin mastitis test. Replacement of the Teepol reagent with Wisconsin mastitis test reagent in the rolling ball viscometer was also evaluated. Both repeatability and reproducibility were satisfactory for all methods evaluated. The instrumental methods each gave higher readings than the other 3 methods. Use of Wisconsin mastitis test reagent in the rolling ball viscometer improved both repeatability and reproducibility. Additional work on standardization is suggested to match rolling ball viscometer readings with those of the instrumental methods.

On the factors governing the pressure dependence of the viscosity of moderately concentrated polymer solutions

AbstractViscosity measurements were carried out as a function of pressure and temperature with solutions of polystyrene in eight (endothermal) θ‐solvents at the respective critical composition by means of a Searle‐type apparatus. A rolling‐ball viscometer was used for the investigation of the pure solvents. In all cases the viscosity coefficient increases in a more or less exponential manner when the pressure is raised. For θ‐conditions, the volumes of activation of the solutions exceed that of the pure solvent by typically 10–15%. The exact amount of this extra efffect stemming from the presence of the polymer and its variation with temperature can be qualitatively correlated with the heats of mixing. The ratio of the viscosity of the solution at 1000 and 1 bar, respectively, can be varied for a given solvent power (θ‐temperature) by the choice of the solvent from ca. 2 (cyclopentane) to 4 (trans‐decalin). Within a given system, the maximum effects that can be realized by a change of the solvent power via the variation of temperature ranges from ca. 3 to 6 (tert‐butylacetate).

Methods to Detect Abnormal Milk – A Review

Screening and confirmatory methods for detecting abnormal milk, mastitic milk, or milk of high somatic cell count are reviewed. Those procedures reviewed in some detail include the Catalase Test. Brabant Mastitis Reaction, pH and chlorine analysis, Ruakura Rolling Ball Viscometer method. California Mastitis Test (CMT), Wisconsin Mastitis Test (WMT), Optical Somatic Cell Count (OSCC). Direct Microscopic Somatic Cell Count (DMSCC), and Electronic Somatic Cell count (ESCC). Other detection methods are tabulated.

The pressure effect on the thermodynamic properties of polystyrene—trans-decalin solution

The viscosity of a solution of polystyrene in trans-decalin was measured over pressure and temperature ranges from atmospheric pressure to 400 kg/cm 2 and 20° to 40°C. The viscosity measurements at elevated pressure were made by the use of a rolling-ball type viscometer, and the validity of this method was confirmed by comparing with the calibrated Ubbelohde viscometer at atmospheric pressure. Values of the interaction parameter, χ, were obtained from the coil expansion coefficients on the assumption of the fifth-power rule of the Flory theory for the expansion of the polymer molecules in the solution. χ 1 increases with increasing pressure. The pressure coefficient of the theta-temperature calculated from the pressure and the temperature derivatives of χ 1 is in good agreement with the result of Schulz et al. The values of χ 1 were compared with those calculated from the new Flory theory and the Patterson theory for polymer solutions. At lower pressure these theories predict the behaviour of χ 1 well, but at higher pressure the prediction becomes inaccurate.

Composition dependence of viscosity of n-hexane-benzene binary mixtures at elevated temperatures

Viscosities of n-hexane and benzene liquid mixtures of different composition levels at temperatures of 363.15, 383.15, 403.15, 423.15, 443.15, and 463.15 K and the corresponding vapor pressures using a rolling ball viscometer have been measured. Six different equations were tested for the prediction of viscosity at these particular conditions and the McAllister equation was found to fit the experimental data better than the others.

Viscosity of organic liquids at elevated temperatures and the corresponding vapour pressures

AbstractThis work involved the measurement of the viscosities of pure organic liquids at temperatures ranging from 353.15 K to 463.15 K and at the corresponding vapour pressures. A rolling ball viscometer was used where considerable emphasis was given to achieve simplicity and rapidity in obtaining results, without sacrificing the accuracy.Considering the forces affecting the motion of the ball inside the viscometer tube, an equation for the calibration of the viscometer at the same working temperature was derived. The constants of this equation were determined using benzene as the reference liquid, and the dependency of the constants on the temperature was also established. Comparing the derived equation with published ones demonstrated its adequacy in both the streamline and transition flow conditions.The liquids studied were toluene, methanol and n‐hexane. In some cases, the results compared reasonably well with published data while in others, deviations of up to 15% were found.Nine equations were tested with the experimental results for the prediction of the viscosity of these liquids. It was found that the 3‐constant Agrawal and Thodos empirical equation gave the least average deviation.

Viscosity of binary gaseous mixtures at moderate pressures - N2+He, N2+CClF3 (R13) and N2+CHClF2 (R22) systems.

The viscosities of three binary gaseous mixtures N2 + He, N2+CClF3 (R13) and N2+CHCIF2 (R22), have been measured at 25°, 50° and 75°C over a range of pressures from the atmospheric to about 8 bar. The measurements were performed by a rolling-ball viscometer in the laminar flow region on a relative basis. The calibration curves were prepared using N2 and H2 at the experimental conditions. The uncertainty in the viscosity should be smaller than 0.5 percent. The viscosity of the nonpolar gas system, N2+He, increases with pressure throughout the experimental temperatures in the same manner as nonpolar pure gases. However, the mixtures containing one polar gas, N2+CClF3 and N2+CHC1F2, behave anomalously at the lowest temperature, 25°C, where the viscosity decreases slightly with increasing pressure. The experimental viscosity values were used to evaluate three expressions presented by Bird-Hirschfelder-Curtiss, Wilke and Brokaw for the estimation of the viscosity of gas mixtures.

Density and viscosity of aqueous hydrogen sulfide solutions at pressures to 20 atm

The physical properties of aqueous hydrogen sulfide solutions under pressure are of practical importance in the large-scale concentration of deuterium by counter-current extraction of natural water with H/sub 2/S gas, the so-called GS process for heavy water production. In addition, information on these properties may be valuable in pollution abatement design. By virtue of the close chemical relationship between hydrogen sulfide and water, some scientific interest also is attached to the behavior of the solutions. The density and viscosity of water saturated with hydrogen sulfide at temperatures in the range 20/sup 0/ to 40/sup 0/C and pressures up to 20 atm are measured. The density float method and a rolling-ball viscometer, modified to permit pre-equilibration of liquid with gas at pressure, are used. (23 refs.)

On the use of the rolling-ball viscometer for the measurement of rheological parameters of power law fluids

An attempt has been made to determine the flow curve of fluids obeying the power law rheological model on a rolling ball viscometer. The theoretical analysis is based on the hydrodynamical model developed byLewis in 1956 for the purpose of rolling ball viscometer calibration and extended in 1964 byTurian andBird for the two-parametric power law model. The shear rate variation has been accomplished on varying the tube angle of inclination. Experiments performed on an adapted, commercialHoeppler viscometer with aqueous solutions of carboxymethylcellulose and polyacrylamide reproduced the flow curves obtained simultaneously on rotational and capillary instruments with reasonable accuracy.

A VISCOMETRIC METHOD FOR THE ESTIMATION OF MILK CELL COUNT

The use of a rolling ball viscometer to estimate the cell count of milk treated with California Mastitis Reagent is described. The method compares favorably with the direct microscopic count and requires relatively simple apparatus and unskilled operators. A correlation coefficient for mean count and log viscometer time of 0.93 with a coefficient of variation of 8.1% were obtained. The repeatability of viscometer readings was 0.97.

Viscosity of sea water at moderate temperatures and pressures

Results of observations of experiments with a rolling ball viscometer to determine the viscosity of 19.374‰ chlorinity IAPO standard sea water for the pressure range of 0 to 1406 kg/cm2 (gage) and temperatures from 0° to 30°C are given. Experimental results are compared with sea-water data reported in the literature and with previously reported data on the relative viscosity of pure water and show that: (1) the relative viscosity of sea water is always greater than that of pure water at comparable temperature and pressures; (2) the pressure of minimum relative viscosity of pure water decreases with the addition of an electrolyte; and (3) the activation energies of viscous flow of sea water decrease in a uniform manner with increasing pressure and temperature.

Rolling-ball viscometer for measuring viscosity of fluids at high pressures and moderate temperatures

Rolling-ball viscometer for measuring viscosity of fluids at high pressures and moderate temperatures