Showing papers on "Viscometer published in 2019"

Experimental evaluation of dynamic viscosity of ZnO–MWCNTs/engine oil hybrid nanolubricant based on changes in temperature and concentration

Abstract: In this work, an experimental investigation on the effects of temperature and concentration of nanoparticles on the viscosity of ZnO–MWCNTs/engine oil (SAE 10W40) hybrid nanolubricant is presented The experiments were repeated at volume fractions of 005%, 01%, 02%, 04%, 06%, and 08%, temperature range of 5–55 °C, and shear rates from 6665 to 13,330 s−1 The viscosity of hybrid nanolubricant was measured using the Brookfield digital viscometer (CAP2000) We found that the nanofluid has a Newtonian behavior at all volume fractions and temperatures Also, by increasing the volume fraction of nanoparticles and nanotubes at a constant temperature the nanofluid viscosity is increased Nanofluid viscosity decreases with increasing the temperature at a constant volume fraction

Functionalized BODIPYs as Fluorescent Molecular Rotors for Viscosity Detection.

Abstract: Abnormal changes of intracellular microviscosity are associated with a series of pathologies and diseases. Therefore, monitoring viscosity at cellular and subcellular levels is important for pathological research. Fluorescent molecular rotors (FMRs) have recently been developed to detect viscosity through a linear correlation between fluorescence intensity or lifetime and viscosity. Recently, 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (boron dipyrrins or BODIPY) derivatives have been widely used to build FMRs for viscosity probes due to their high rotational ability of the rotor and potentially high brightness. In this minireview, functionalized BODIPYs as FMRs for viscosity detection were collected, analyzed and summarized.

Experimental investigation of effective parameters on MWCNT–TiO2/SAE50 hybrid nanofluid viscosity

Abstract: In the present study, rheological behavior of multi-walled carbon nanotube (MWCNT) (30%)–TiO2 (70%)/SAE50 hybrid nanofluid is investigated. Samples of nanofluid with nanoparticle concentrations of 0% up to 1% were prepared, and their dynamic viscosity was measured at temperatures between 25 and 50 °C and various shear rates using Brookfield viscometer. The relation between shear stress and shear rate of MWCNT–TiO2/SAE50 nanofluid showed its non-Newtonian behavior at all concentrations. In order to predict the viscosity, a comparison was done between the efficiency of different proposed empirical correlations in this prediction. Three empirical correlations were proposed, and two different independent variables were considered for each one. In all three cases, conformity of obtained results for viscosity was compared with experimentally obtained viscosities. Results revealed much better accuracy of proposed empirical correlations containing temperature as an independent variable compared with the other correlations not containing independent variable of temperature. Accuracy and efficiency of predicting correlations for relative viscosity was compared with efficiency of absolute viscosity prediction correlations and results indicated relatively equal accuracy of results and prediction values. Furthermore, viscosity changes of MWCNT (30%)–TiO2 (70%)/SAE50 nanofluid were compared with other studies in order to prove its better performance.

Experimental determination of thermal conductivity and viscosity of different nanofluids and its effect on a hybrid solar collector

Abstract: In this research, three different volume concentrations (ϕ = 0.05, 0.1 and 0.2%) of Al2O3/water, CuO/water and Al2O3–CuO/water (50:50) nanofluids are prepared by adopting a two-step nanofluid preparation method. Al2O3 and CuO nanoparticles with the average diameter of 50 nm and 27 nm were dispersed in distilled water. The thermal conductivity and viscosity of prepared nanofluids are measured for different temperatures by using KD2 Pro thermal property analyzed and Brookfield viscometer, respectively. The effects of nanofluids on the thermal, electrical and overall efficiency of photovoltaic thermal (PVT) solar collector are also studied. The experimental results revealed that the thermal conductivity and viscosity increase with the increase in percentage volume concentration and viscosity decreases with the increase in temperature. Furthermore, the obtained maximum thermal and electrical efficiencies of a PVT solar collector for 0.2% volume concentration of hybrid nanofluids are 82% and 15%, respectively, at peak solar radiation. The highest overall efficiency of a PVT collector with .2% volume concentration of hybrid nanofluid was 97% at peak solar radiation. Results recommend that nanofluids can be used as a heat transfer in PVT solar collector.

A physiometer for simultaneous measurement of whole blood viscosity and its determinants: hematocrit and red blood cell deformability

Abstract: In this study, a microfluidic-based physiometer capable of measuring whole blood viscosity, hematocrit, and red blood cell (RBC) deformability on a chip is introduced. The physiometer consists of two major parts: a hydrodynamic component for whole blood viscosity measurement and an electronic component for hematocrit and RBC deformability measurement. In the hydrodynamic component, the whole blood is infused with phosphate buffered saline as a reference fluid for estimation of the whole blood viscosity. At a given flow rate, ten sets of whole blood viscosity readings are successfully obtained over a wide range of shear rates; this is achieved via a series of geometrically optimized microchannel arrays. In the electronic component, analysis of the whole blood impedance spectrum under flowing conditions reveals the electrical characteristics of the blood: the cytoplasm resistance (Rcytoplsm), plasma resistance (Rplasma), and RBC membrane capacitance (constant phase element). The hematocrit is estimated from Rcytoplsm and Rplasma, while the RBC deformation index is determined from the membrane capacitance change of the RBC. Each unique function is experimentally demonstrated and compared to the corresponding gold standard method. The whole blood viscosity measured using the physiometer is 0.8 ± 1.4% in normalized difference compared to that using a rotational cone-and-plate viscometer. For the hematocrit measurement, the coefficient of variation for the physiometer ranges from 0.3 to 1.2% which is lower than the one obtained from centrifugation. In the deformability measurement, there is a strong linear correlation (R2 = 0.97) between the deformation index acquired by image processing and the change in the membrane capacitance acquired by using the physiometer. The effects of the hematocrit and RBC deformability on the whole blood viscosity are also demonstrated. For simultaneous and reliable measurement on a chip, a physiometer equipped with a temperature-control system is prepared. Lab-made software enables the measurement of the three target indices and the temperature control in an automated manner. By using this system, the temperature is controlled to 36.9 ± 0.2 °C which greatly matches with the target temperature (37.0 °C) and it is varied from 25 °C to 43 °C. The developed physiometer is potentially applicable for a comprehensive analysis of biophysical indices in whole blood.

Investigation of structure and rheological behavior of a new epoxy polymer pentaglycidyl ether pentabisphenol A of phosphorus and of its composite with natural phosphate

Abstract: Novel pentafunctional epoxy resin, mainly based on pentaglycidyl ether pentabisphenol A of phosphorus (PGEPBAP) has been synthesized and characterized through different spectroscopic methods (FTIR, 1H NMR, 13C NMR and 31P NMR) Moreover, the analysis of the viscosity of (PGEPBAP/Methanol) system was determined by using viscosimeter VB-1423 of the Ubbelohde type Furthermore, the analysis of the rheological properties of the matrix PGEPBAP and their (PGEPBAP/MDA/PN) elaborated composite was performed according the RHM01-RD HAAKE rheometer In addition, the morphology of different (PGEPBAP/MDA/PN) prepared composite was determined by using the polarizing optical microscope

Apparent Viscosity Prediction of Water-Based Muds Using Empirical Correlation and an Artificial Neural Network

Abstract: Apparent viscosity is of one of the main rheological properties of drilling fluid. Monitoring apparent viscosity during drilling operations is very important to prevent various drilling problems and improve well cleaning efficiency. Apparent viscosity can be measured in the laboratory using rheometer or viscometer devices. However, this laboratory measurement is a time-consuming operation. Thus, in this paper, we have developed a new empirical correlation and a new artificial neural network model to predict the apparent viscosity of drilling fluid as a function of two simple and fast measurements of drilling mud (i.e., March funnel viscosity and mud density). 142 experimental measurements for different drilling mud samples have been used to develop the new correlation. The calculated apparent viscosity from the developed correlation and neural network model has been compared with the measured apparent viscosity from the laboratory. The results show that the developed correlation and neural network model predict the apparent viscosity with very good accuracy. The new correlation and neural network models predict the apparent viscosity with a correlation coefficient (R) of 98.8% and 98.1% and an average absolute error (AAE) of 8.6% and 10.9%, respectively, compared to the R of 89.2% and AAE of 20.3% if the literature correlations are used. Thus, we conclude that the newly developed correlation and artificial neural network (ANN) models are preferable to predict the apparent viscosity of drilling fluid.

Enhanced stability and high temperature-tolerance of CO2 foam based on a long-chain viscoelastic surfactant for CO2 foam flooding

Abstract: CO2 switchable foams have gained increasing attention recently for their smart properties. However, their performance at high temperature and high pressure has been less documented. In this study, a long-chain viscoelastic surfactant, N1-(3-aminopropyl)-N3-octadecylpropane-1,3-diamine bicarbonate (ODPTA) has been studied as a CO2 foam agent for its application in CO2 flooding in complex and harsh reservoir conditions, and the foam performance under static and dynamic conditions was tested up to 160 °C and 10.5 MPa using a visualized foam-meter and in sand-pack flooding experiments. The viscosity of the ODPTA and conventional surfactant solutions saturated with dissolved CO2 was measured using a long coiled-tube viscometer at HTHP, and its effect on the high temperature-tolerance of CO2 foams has been analyzed. The experimental results show that CO2 foam generated using ODPTA is much more stable than the conventional surfactants (such as SDS and alkylphenol ethoxylates) and has high temperature-tolerance up to 160 °C, and has also exhibited excellent mobility control in CO2 flooding experiments. The viscosity of the ODPTA–CO2 bulk phase can be maintained as high as 12 mPa s under 160 °C and 10.5 MPa, which is much higher than that of the conventional surfactant solutions (similar to water). ODPTA's good foam performance with extremely high temperature-tolerance can be attributed to its high bulk phase viscosity in the brine water saturated with CO2.

Viscosimetric and rheological properties of epoxy resin TGEUBA and their composite (TGEUBA/MDA/TGEMDA+TSP)

Abstract: The objective of our work is to study the viscosimetric and the rheological behaviors of new epoxy resin namely: Tetraglycidyl ether urea of bisphenol A (TGEUBA) and its composite. Furthermore, we determined the viscosity of (TGEUBA/Methanol) system using the viscosimeter VB-1423 Ubbelohd capillary type. Besides, the viscosity of epoxy resin TGEUBA crosslinked by methylene dianiline (TGEUBA/MDA) and the rheological properties of different composite (TGEUBA/MDA/TGEMDA + TSP) formulated by two charges such as tetraglycidyl ether of methylene dianiline (TGEMDA) and trisodium phosphate (TSP) at various percentages (0%, 10% and 15%) were determined using the RHM01-RD HAAKE rheometer.

Effect of Composition, Temperature, and Pressure on the Viscosities and Densities of Three Diesel Fuels

Abstract: In this work, a Rolling-Ball Viscometer/Densimeter is used to measure high-pressure, hightemperature (HPHT) density and viscosity data from 298.2 to 532.6 K and pressures up to 300.0 MPa for three different diesel fuels. The densities and viscosities have combined expanded uncertainties of 0.6% and 2.5%, respectively, with a coverage factor, k = 2. Two of the diesels, Highly Paraffinic (HPF) and Highly Aromatic (HAR), contain a larger paraffinic and aromatic content relative to the others, and are standard engine test fuels. The third is a Ultra-Low Sulfur Diesel (ULSD) that resembles an unfinished commercial diesel. Detailed compositional information is also reported for each diesel that provides a basis for interpreting the impact of composition on density and viscosity at high pressures. Both density and viscosity data are correlated to Tait-type equations with uncertainties of 0.6% and 4.0%, respectively. The Tait equations provide a facile means to compare observed differences in the density-pressure and viscosity-pressure profiles of the three different diesels. Density data are modeled with the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state (EoS) with pure component parameters calculated representing diesel as a single, pseudo-component only requiring average molecular weight (Mave) and hydrogen to carbon ratio (RH/C) as inputs. Viscosity data are modeled reasonably well using entropy scaling coupled with the PC-SAFT EoS and information on the diesel Mave and RH/C. The HPHT viscosity data are also modeled reasonably well with Free Volume Theory (FVT) with model parameters correlated to Mave and RH/C.

eCapillary: a disposable microfluidic extensional viscometer for weakly elastic polymeric fluids

Abstract: We report a disposable microfluidic extensional viscometer based on an optimized hyperbolic contraction–expansion geometry. This “eCapillary” device works by measuring pressure drop as a function of flow rate while accounting for viscous contribution to the pressure drop. The viscometer operates by applying a constant pressure and using an image-based approach to measure the flow rate. The device is fabricated entirely out of polydimethylsiloxane with no embedded sensors, making it disposable. We tested our approach using weakly elastic polymer solutions whose relaxation times were characterized by dripping-on-substrate rheology. Flow visualization was used to determine the onset of inertioelastic instabilities in the eCapillary device, thereby establishing the operating limits for extensional rheological measurements. Holography-based velocimetry analysis showed that extensional strain rate is uniform in a narrow section of the contraction throat necessitating correction for the shear contribution to the measured pressure drop. We observed the onset of extensional thickening to occur at Deborah number ≈ 1 and found that the apparent extensional viscosities are 2–4 orders of magnitude higher than the shear viscosities. Finally, we compared our data with those from other microfluidic extensional viscometers reported in the literature and found good agreement.

Microfluidics-based device for the measurement of blood viscosity and its modeling based on shear rate, temperature, and heparin concentration

Abstract: Blood viscosity measurements are crucial for the diagnosis and understanding of a range of hematological and cardiovascular diseases. Such measurements are heavily used in monitoring patients during and after surgeries, which necessitates the development of a highly accurate viscometer that uses a minimal amount of blood. In this work, we have designed and implemented a microfluidic device that was used to measure fluid viscosity with a high accuracy using less than 10 μl of blood. The device was further used to construct a blood viscosity model based on temperature, shear rate, and anti-coagulant concentration. The model has an R-squared value of 0.950. Finally, blood protein content was changed to simulate diseased conditions and blood viscosity was measured using the device and estimated using the model constructed in this work. Simulated diseased conditions were clearly detected when comparing estimated viscosity values using the model and the measured values using the device, proving the applicability of the setup in the detection of rheological anomalies and in disease diagnosis.

Curve fitting on experimental data of a new hybrid nano-antifreeze viscosity: Presenting new correlations for non-Newtonian nanofluid

Abstract: In this paper, the rheological behavior of a mixture of water and ethylene glycol containing a combination of multi-walled carbon nanotubes and aluminum oxide in a temperature range of 25 to 50 °C was investigated experimentally. Homogeneous and stable samples with different concentrations were made by suspending carbon nanotubes and aluminum dioxide in a 50–50 mixture of water and ethylene glycol using a two-step method. The viscosity of nanofluid samples at different shear rates was measured by the DV-I PRIME Brookfield digital viscometer, which uses a rotating cylinder method. The results showed that, despite the Newtonian behavior of the base fluid, all nanofluid samples showed a non-Newtonian behavior. It was also observed that non-Newtonian behavior of nanofluid follows the Power law model. Thus, using the curve fitting, the consistency index and the power law index were obtained. Moreover, mathematical correlations were proposed as a function of temperature and volume fraction for obtaining consistency index and the power-law index. Comparisons showed the accuracy of proposed correlations.

Experimental Investigation of Thermal Conductivity and Viscosity of SiO₂/Multiwalled Carbon Nanotube Hybrid Nanofluids.

Abstract: In this study, the thermal conductivity and viscosity of SiO₂/multiwalled carbon nanotube (MWCNTs) hybrid nanofluids are investigated. The volume fraction of the nanofluids varied in the range of 0.5% to 2%, while the SiO₂ to MWCNTs volume proportion is either 95-5 or 90-10. The nanofluids are synthesized using a wet chemical method and a two-step technique is used to disperse nanoparticles in glycerol (base fluid). The thermal conductivities and viscosities of the nanofluids are measured using a modified transient hot-wire method and falling ball viscometer, respectively. The colloidal stability of the dispersion was investigated visually. Effective application of an ultrasonic disruptor and a suitable surfactant (gum arabic) enhance the dispersion behavior. When the effects of temperature and volume fraction on the thermal conductivity and viscosity of SiO₂/multiwalled carbon nanotube (MWCNTs) hybrid nanofluids are studied, the results showed that the thermal conductivity of nanofluids increased with an increase in the volume fraction and temperature. Further, their viscosities increased with an increase in the volume fraction but decreased when the temperature increased. The thermal conductivity and viscosity of the hybrid nanofluids increased by 16.7% and 105.4%, respectively, at a volume fraction of 2% and volume proportion of 90-10. The experimental results are compared with those predicted by classical theoretical models. Two correlations for thermal conductivity and viscosity of hybrid nanofluids are proposed on the basis of the experimental results.

The viscosity at the glass transition of a liquid lubricant

Abstract: In the classical study of elastohydrodynamic lubrication (EHL) which does not employ real, measurable viscosity in analysis, the possibility of a glass transition has not been considered in many years. Indeed, the two rheological assumptions of classical EHL, the Newtonian inlet and the equivalence of a traction curve to a flow curve, would not have persisted so long had the pressure dependence of the viscosity been accurately stated. With the recent appearance of viscosity obtained from viscometers in EHL analysis, the possibility of a glass transition in the contact should be reexamined, especially for the fragile traction fluids. This article employs published data for a synthetic cycloaliphatic hydrocarbon to estimate the glass transition viscosity so that, when using real viscosities in EHL simulations, the state of the liquid may be assessed. Far into the glassy state the liquid should be treated as an elastic solid with a yield stress.

Rheological characterization of cactus pear mucilage for application in nutraceutical food products

Abstract: Mucilage could exert therapeutic, nutritional and functional advantages if applied as a functional ingredient in innovative nutraceutical food products. Mucilage has unique flow behaviour that should be fully understood in order to predict its behaviour during processing, packaging, preparation and consumption. Extraction and drying of mucilage from mature cladodes from four cultivars, harvested in winter (July 2014), involved a patented procedure of slicing, microwave cooking, macerating, centrifuging at 8000 rpm for 15 min, and freeze-drying at -60°C for 72 h. The viscosity of 5% reconstituted freeze-dried mucilage was determined using the line-spread test (cm) and a rotational RV Brookfield viscometer (cP) at 50 rpm after 60 s. Flow behaviour was determined by controlling the rate of spindle rotation (5, 10, 20, 50 and 100 rpm), time intervals (15, 30, 60, 90 and 120 s), temperature (5, 10, 20, 40, 60 and 80°C), pH ( >11, 9-10, 8-9, 7-8, 5-6, 4-5, 3-4 and 1-2), and ionic strength (NaCl, CaCl2, FeCl3 at 0.1, 1, 10, 100 and 1000 mM) of reconstituted mucilage. The four cultivars had viscosities between 26.0 and 29.8 cm (not significantly different) using the line-spread test and 150 and 328 cP using the viscometer. In the controlled-rate and time-interval tests, mucilage showed non-Newtonian, pseudoplastic tendencies but no rheopectic or thixotropic behaviour. Mucilage exhibited dynamic yield (0.38-0.74% torque), indicating the force needed for it to start moving. Viscosity increased at lower temperatures (200-418 cP) and decreased at higher temperatures (50-120 cP). In alkaline regions (pH >11-8), viscosities of native mucilage increased (360-2400 cP), and they decreased (60-600 cP) in acidic (pH 6-1) regions. Monovalent ions had little, divalent more, and trivalent the most influence on native mucilage viscosity. The properties of the innovative products, environmental conditions and handling could have adverse effects on the consistencies of mucilage-containing food products.

Liquid and Vapor Viscosities of Binary Refrigerant Mixtures Containing R1234yf or R1234ze(E)

Abstract: Liquid and vapor viscosities are reported for the binary refrigerant mixtures (R125 + R152a), (R125 + R1234ze(E)), (R143a + R1234ze(E)), (R143a + R1234yf), and (R1234ze(E) + R1234yf). The measurements were made with a vibrating wire viscometer and span temperatures from (252 to 403) K and pressures from (0.9 to 4.0) MPa. The performance of the vibrating-wire apparatus was validated by measuring the viscosity of pure R152a in both the vapor and liquid regions. These measurements and previously published data were used to tune binary interaction parameters in the extended corresponding states equation model for viscosity implemented in the NIST software REFPROP 9.1. After tuning, deviations between the model and reported viscosities were reduced from between (−4 and 8)% to within ±2%.

In situ Viscometry of Primitive Lunar Magmas at High Pressure and High Temperature

Abstract: Understanding the dynamics of the magmatic evolution of the interior of the Moon requires accurate knowledge of the viscosity () of lunar magmas at high pressure (P) and high temperature (T) conditions. Although the viscosities of terrestrial magmas are relatively well documented, and their relation to magma composition well studied, the viscosities of lunar titano-silicate melts are not well known. Here, we present an experimentally measured viscosity dataset for three end member compositions, characterized by a wide range of titanium contents, at lunar-relevant pressure-temperature range of 1.1 – 2.4 GPa and 1830 - 2090 K. In-situ viscometry using the falling sphere technique shows that the viscosity of lunar melts varies between  0.13 and 0.87 Pa-s depending on temperature, pressure and composition. Viscosity decreases with increasing temperature with activation energies for viscous flow of Ea = 201 kJ/mol and Ea = 106 kJ/mol for low-titanium (Ti) and high-Ti melts, respectively. Pressure is found to mildly increase the viscosity of these intermediate polymerized melts by a factor of  1.5 between 1.1 and 2.4 GPa. Viscosities of low-Ti and high-Ti magmas at their respective melting temperatures are very close. However at identical P-T conditions ( 1.3 GPa,  1840 K) low-Ti magmas are about a factor of three more viscous than high-Ti magmas, reflecting structural effects of Si and Ti on melt viscosity. Measured viscosities differ significantly from empirical models based on measurements of the viscosity of terrestrial basalts, with largest deviations observed for the most Ti-rich and Si-poor composition. Viscosity coefficients for these primitive lunar melts are found to be lower than those of common terrestrial basalts, giving them a high mobility throughout the lunar mantle and onto the surface of the Moon despite their Fe and Ti-rich compositions.

Development of a Paper-Based Viscometer for Blood Plasma Using Colorimetric Analysis.

Abstract: The viscosity of biofluids can be used to acquire meaningful medical information on the conditions of a patient but has seldom been utilized in clinical practices owing to cumbersome measurement procedures and the need for large sample volumes. We present a colorimetric method to measure the viscosity of blood plasma using a paper-based viscometer developed in this study specifically for clinical diagnosis. The proposed analytical device consists of multilayered papers with fluid-loading, -mixing, and -measuring regions, and it can be fabricated readily in a simple manner using three-layered paper channels and tape. Moreover, the colorimetric analysis enables viscosity estimations by analyzing a single optical image. To validate the device performance, we measured the viscosities of fluids such as glycerin aqueous solutions, bovine-serum-albumin solution, dimethyl sulfoxide, and blood plasma. We found that the measured viscosities were in good agreement with the reference values. Finally, we developed a simple smartphone application for the viscosity measurements that helped enhance the convenience and utility of the paper-based viscometer while maintaining the measurement accuracy.

3D printed microfluidic viscometer based on the co-flowing stream.

Abstract: Considering the role of viscosity in the dynamics of physical, chemical, and biological systems, accurate measurement of viscosity is essential. Although many conventional viscometers have been widely used, these conventional viscometers suffer from some drawbacks. In this study, a three-dimensional (3D) printed microfluidic viscometer was proposed based on the estimation of the pressure between two fluids to easily measure viscosity with small samples. The 3D printed microfluidic viscometer can be fabricated through amine-epoxy bonding on 3D printed blocks. By separately delivering samples and reference fluids into two inlets, an interfacial line could be induced. Based on the relation between the pressure ratio and the width of the reference flow, the viscosity (μ) of the sample can be estimated by measuring the relative width of the reference flow. The relation between the pressure and interfacial width between test samples and reference flows in the 3D printed microfluidic viscometers was analyzed by experiment and simulation to determine the effects of the mesh-like pattern of the 3D printed viscometers on the pressure estimation. To validate the proposed method, the viscosity values of glycerol mixtures measured by the 3D printed viscometer were compared with those measured by a conventional viscometer. As an application of the 3D printed viscometer, the viscosity curves for blood samples collected from diabetic and non-diabetic patients depending on their shear rates were compared. As expected, a high blood viscosity in the diabetic group was observed. Based on the experimental demonstrations, the 3D printed viscometer has strong potential to develop portable viscometers that can be translated to commercial outcomes.

High-Temperature, High-Pressure Viscosities and Densities of n-Hexadecane, 2,2,4,4,6,8,8-Heptamethylnonane, and Squalane Measured Using a Universal Calibration for a Rolling-Ball Viscometer/Densimeter

Abstract: The development of reference correlations for viscous fluids is predicated on the availability of accurate viscosity data, especially at high pressure, high temperature (HPHT) conditions. The rolling ball viscometer (RBV) is a facile technique for obtaining such HPHT viscosity data. A new, universal RBV calibration methodology is described and applied over a broad T-p region and for a wide range of viscosities. The new calibration equation is used to obtain viscosities for n-hexadecane (HXD), 2,2,4,4,6,8,8-heptamethylnonane (HMN), and 2,6,10,15,19,23-hexamethyltetracosane (squalane) from 298 – 530 K and pressures to 250 MPa. The available literature data base for HMN is expanded to 520 K and 175 MPa and for squalane to 525 K and 250 MPa. The combined expanded uncertainties are 0.6% and 2.5% for the densities and viscosities, respectively, each with a coverage factor, k = 2. The reliability of the viscosity data is validated by comparison of HXD and squalane viscosities to accepted reference correlations and HMN viscosities to available literature data. The necessity of this new calibration approach is confirmed by the large deviations observed between HXD, HMN, and squalane viscosities determined using the new, universal RBV calibration equation and viscosities determined using a quadratic polynomial calibration equation. HXD, HMN, and squalane densities are predicted with the Perturbed Chain Statistical Associating Fluid Theory using pure component parameters calculated with a previously reported group contribution (GC) method. HXD, HMN, and squalane viscosities are compared to Free Volume Theory (FVT) predictions using FVT parameters calculated from a literature correlation for nalkanes. Although the FVT predictions for HXD, a normal alkane, result in an average absolute percent deviation (∆AAD) of 3.8%, predictions for HMN and squalane, two branched alkanes, are four to 13 times larger. The fit of the FVT model for the branched alkanes is dramatically improved if the FVT parameters are allowed to vary with temperature.