Viscosimeter Viscosity

For non-New tonian fluids, viscosity data are very important. Every impeller has an average fluid shear rate related to speed. For example, foi a flat blade turbine impeller, the average impeller zone fluid shear rate is 11 times the operating speed. The most exact method to obtain the viscosity is by using a standard mixing tank and impeller as a viscosimeter. By measuring the pow er response on a small scale mixer, the viscosity at shear rates similar to that in the full scale unit is obtained. 

Flussigkeits-. liquid, fluid, hydraulic, hydrostatic. -bad, n. liquid bath, -dichtemesser, m. hydrometer, -druck, m. pressure of a liquid, hydrostatic pressure, -ffirderung, /. conveyance of liquids, -gemisch, n. mixture of liquids, liquid mixture, -grad, m. degree of fluidity viscosity. -gradmesser, m. viscosimeter. -Unse, /. (Micros.) immersion objective, -mass, n. liquid measure, -menge. 

Viskositats-messer, m. viscosimeter, viscometer. -zahl,/. viscosity number or value. Vistra. Viatra (an acetate rayon). T.N. visuell, a. visual. 

ZUhflussigkeit,/. viscosity refractoriness. Zabfldfisigkeitsmesser, m. viscosimeter, viscometer,... 

Zahigkeits-einheit, /, unit of viscosity (or tenacity or ductility), -grad, m. (degree of) viscosity or ductility or tenacity, -mass, n. measure of ductihty (or tenacity or viscosity), -messer, m. viscosimeter, -probe, /. tough ness (or ductihty or viscosity) test or sample,... 

Viscosities of the blends and composites were measured in shear flow with a Gottfert Rheograph 2002 capillary viscosimeter. The shear rate was investigated from 100-10000 s" . The L D ratio of the capillary die was 30 mm 1 mm. Rabinowitch correction was made to the measurements, but Bagley correction was not applied. 

Viscosity is normally determined by measuring the time required for a fixed volume of a fluid, at a given temperature, to flow through a calibrated orifice or capillary tube. The instmments used to measure the viscosity of a liquid are known as viscosimeters. 

For most practical purposes, it will serve to know the relative viscosity of the fluid. Relative viscosity is determined by timing the flow of a given quantity of the hydraulic fluid through a standard orifice at a given temperature. There are several methods in use. The most acceptable method in the United States is the Saybolt viscosimeter. Figure 40.17. 

Carrots (Boleo) were peeled by 2% NaOH at 88-96°C for 4 minutes, minced by a meat mincer (2 mm) and homogenised for 2 minutes by an ULTRA-TURRAX T25 homogenizer (from Jahne Kunkel). The carrot mash was preheated to 45°C (20 minutes) before the enzyme preparations, 25 mg enzyme protein/kg mash, were added. The enzymes were dissolved in water to give a dilution of 5% (v/v) of the carrot mash. The mash was incubated at 45°C under stirring (60 rpm) for 2 hours, before the enzymes were inactivated at 86°C for 5 minutes in a microwave oven. Finally the purees were homogenised for 1 minute by ULTRA TURRAX. The viscosity of the puree was measured by a BROOKFIELD viscosimeter Model DV-n + with spindle A from HELIPATH SPINDLE SET at 2.5 rpm thermosta-ted at 50°C. The stability of the puree was measured as the sediment (in %) after centrifugation in 10 ml tube a 1660 x g for 10 minutes. 

Pectin lyase (PNL) activity was measured spectrophotometrically by the increase in absorbance at 235 nm of the 4,5-unsaturated reaction products. Reaction mixtures containing 0.25 ml of culture filtrate, 0.25 ml of distilled water and 2.0 ml of 0.24% pectin from apple (Fluka) in 0.05M tris-HCl buffer (pH 8.0) with ImM CaCl2, were incubated at 37 C for 10 minutes. One unit of enzyme is defined as the amount of enzyme which forms Ipmol of 4,5-unsaturated product per minute under the conditions of the assay. The molar extinction coefficients of the unsaturated products is 5550 M cm [25]. Also viscosity measurements were made using Cannon-Fenske viscometers or Ostwald micro-viscosimeter, at 37°C. Reaction mixtures consisted of enzyme solution and 0.75% pectin in 0.05 M tris-HCl buffer (pH 8.0) with 0.5 mM CaCl2. One unit is defined as the amount of enzyme required to change the inverse specific viscosity by 0.001 min under the conditions of reaction. Specific viscosity (n p) is (t/to)-l, where t is the flow time (sec) of the reaction mixture and t is the flow time of the buffer. The inverse pecific viscosity (n p ) is proportional to the incubation time and the amount of enzyme used [26]. Units of enzyme activity were determined for 10 min of reaction. 

Endo-pectinases were determined by reduction of viscosity of a 1% (w/v) pectin solution at 30 C and pH 4.2 using an Ostwald viscosimeter as previously described (9). One unit was defined as the amount of enzyme which reduced the initial viscosity of the solution by 50%. 

The total activity of the enzymatic mixture was determined from the percentage reduction of viscosity [12] during the depolymerization of solutions, buffered at different pH values, containing 1 % (w/v) of the polygalacturonic acid or 0.5% (w/v) of pectin. A Cannon-Fenske viscosimeter, (ASTM series n° 150) kept at the constant temperature of 25 °C, was used to carry out the tests. 

The need for a viscosimeter capable of online measurement of the intrinsic viscosity of a polymer sample arose when it was shown that polymer molecules elute in order of decreasing hydrodynamic volume.81 The hydrodynamic volume can be related to the product of intrinsic viscosity and molecular weight. 

The on-line viscosimeters currently available are adaptations of the classical dilute solution capillary viscosimeters. They work on the principle of measuring the pressure drop across a capillary with a differential pressure transducer. The pressure drop can be related to the reduced or inherent viscosity of the sample via Poiseuille s law.84 Intrinsic viscosity is determined using the equation ... 

The laboratory technique for measuring viscosity is called viscometry (sometimes viscosimetry), and the device in the laboratory used to measure viscosity is called a viscometer (sometimes viscosimeter). 

Viscosity at 100°F - 0.1153 0.0010 poises. Use a calibrated Ubbelohde Viscosimeter in accordance with Method A of Method 30 5... 

Potter, F. E., Deysher, E. F. and Webb, B. H. 1949. A comparison of torsion pendulum type viscosimeters for measurement of viscosity in dairy products. J. Dairy Sci. 32, 452-457. 

Oil viscosity is measured in a rolling-ball viscosimeter or a capillary viscosimeter, either designed to simulate differential liberation. Measurements are made at several values of pressure in a stepwise process. The liquid used in each measurement is the liquid remaining after gas has been removed at that pressure. See page 6 of Table 10-1. 

See also Saybolt Universal Viscosity and Viscometer (or Viscosimeter). 

Saybolt Second Universal or Saybolt Universal Second viscosity measure. The time (in seconds) for 60 ml of fluid to flow through a Saybolt Universal Viscosimeter at 40°C to 100°C. Crankcase or oil reservoir of an internal combustion engine. Boundary between two phases. The term surface and interface are often used interchangeably. 

Polymethylsiloxane varnishes are toluene-butanol solutions of polymers with colour ranging from yellow to brown. Their viscosity at 20 °C (according to the VS-4 viscosimeter) should not exceed 60 s. The gelatinisa-tion time may vaiy (depending on the method of hydrolytic condensation) in a rather wide range, from 0.5 to 60 minutes the solid (nonvolatile) residue content is from 40 to 55%. The varnish layer should diy at 125 5 °C for not more than 40 minutes. 

Polyphenylsilsesquioxane varnish is a transparent liquid ranging in colour from light yellow to light brown (the viscosity is 10-20 s according to the VS-4 viscosimeter, the acidity number should not exceed 10 mg of KOH/g). 

If relatively high concentrations of suspended material are used, the viscosity of the suspension should be determined by an appropriate viscosimeter. 

Viscosity and Plasticity—Viscosity and plasticity are closely related. Viscosity may be defined as the force required to move a unit-area of plane surface with unit-speed relative to another parallel plane surface, from which it is separated by a layer of the liquid of unit-thickness. Other definitions have been applied to viscosity, an equivalent one being the ratio of shearing stress to rate of shear. When a mud or slurry is moved in a pipe in more or less plastic condition the viscosity is not the same for all rates of shear, as in the case of ordinary fluids. A material may be called plastic if the apparent viscosity varies with the rate of shear. The physical behavior of muds and slurries is markedly affected by viscosity. However, consistency of muds and slurries is not necessarily the same as viscosity but is dependent upon a number of factors, many of which are not yet clearly understood. The viscosity of a plastic material cannot be measured in the manner used for liquids. The usual instrument consists of a cup in which the plastic material is placed and rotated at constant speed, causing the deflection of a torsional pendulum whose bob is immersed in the liquid. The Stormer viscosimeter, for example, consists of a fixed outer cylinder and an inner cylinder which is revolved by means of a weight or weights. 

Measurement of Consistency—As a rule the determination of viscosity of fine-particle suspensions, such as most pigments and clays, involves little difficulty. Many types of viscosimeters for plastic materials are available and have been discussed by Bingham (1922). However, when rather large particles are in suspension, say in making... 

Figure 2 shows the viscosities of the polymer solutions as measured at 25° 0.05 °C. in an Ubbelohde viscosimeter employing a concentration of 0.52 gram of polymer per 100 ml. of m-cresol. The viscosimeter had a flow time of more than 100 sec. for the pure solvent. 

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