Ubbelohde viscosimeters

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

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. 

The amount of fluid exiting a pipe with cross-sectional area A = n/4 cf is given by Equation (2.4-10), which is used for the determination of dynamic viscosity with a Ubbelohde viscosimeter ... 

Ubbelohde viscosimeters build according to ISO 3105 or DIN 51562, as shown in Fig. 3.1b have the advantage that the hanging level of the capillary accounts for the same mean height h of the outgoing Uquid and therefore for the hydrostatic pressure. 

The Cannon-Fenske viscosimeter build according to DIN 51336 (Fig. 3.1c) can be used to measure non-transparent liquids that leave a film on the glass in the area of the measurement points and therefore do not allow for exact time taking. A specialty is the multi-level Ubbelohde viscosimeter shown in Fig. 3.Id, which can be used to investigate the dependence of the viscosity on the shear rate. Because of the various heights of the fluid levels, different pressures and therefore different shear rates affect the liquid. Thus it can be determined if the measured viscosities are independent of the shear stress or the shear rate. 

Besides these viscosimeters, several other special-purpose designs have been developed (Micro Ubbelohde viscosimeter DIN 51562 Cannon-Ubbelohde semi micro viscosimeter ISO 3105 BS/IP/U-tube viscosimeter DIN 51372 BS/IP/SL viscosimeter ISO 3105 Vogel-Ossag DIN 51561). Those are tailored to specific needs and are not further discussed at this point. 

Experiments on carbon dioxide accumulation were carried out in circulation systems with a gas chromatography analysis of the gas sphere. Kinematic and intrinsic viscosities of PVA water solutions were measured in a Ubbelohde viscosimeter with the hung level. 

The experimental part of the viscosimetric method used in this study is based upon an automatization of the FIP method (49). A calibrated capillary viscosimeter of the Ubbelohde type (nr. 2453723 Jenaer Glas-werk, Schott Gen., Mainz) is used. The length of the capillary is 13 cm and its diameter is 0.096 cm, determined experimentally by filling the capillary with Hg. The volume of the bulb is 0.71 cm3. 

Other Methods. The procedure used for determining volume changes resulting from mixing two solutions in Linderstrom-Lang dila-tometers at 30°C has been described previously (4). Viscosities were measured at 30 °C using a Cannon-Ubbelohde dilution viscosimeter immersed in a bath thermostated to within 0.01 °C. 

Viscosity measurements were carried out by Ubbelohde-type capillary viscosimeter. The surface tension and kinetic energy corrections were neglected. 

Even under normal ambient pressure relatively high shear rates occur at the wall of capillary viscosimeters (especially for small capillary diameters and low viscosity liquids), that can lead to a falsification of the results for so-called non-Newtonian liquids (see later in this monograph). In Tables 3.1 and 3.2 the maximum occurring shear rates for the admissible minimal running times tniin of the capillary are given for the standard Ubbelohde capillary viscosimeter (ISO 3105) and the Micro Ubbelohde capillary viscosimeter (DIN 51562). 

Table 3.1. Parameters for Ubbelohde Capillary Viscosimeters (ISO 3103 and DIN 51562) with Ref. numbers 501.., 530.., 532.., capillary number (No.), capillary diameter (D), capillary constant (K), minimum measurable flow time (fmin)> maximum shear rate at minimum flow time (fjnax) and kinematic viscosity range (v)...

FIGURE 5.203 Capillary tube viscosimeters used to measure kinematic viscosity (a) modified Ostwald, (b) Ubbelohde, (c) Fitz Simmons. (Gulf Oil Corporation.)... 

Kinematic viscosity may be determined directly by means of Ubbelohde, FitzSimmons modification, or modified Ostwald viscosimeter pipettes (D445). A series of these pipettes which cover the entire useful range of viscosity may be suspended in a single constant-temperature bath. Great accuracy is possible with these instruments, and a somewhat smaller sample is satisfactory, but each instrument must be calibrated. The pipette method must be used for gasoline, naphthas, or kerosene, because turbulent rather than streamline flow occurs in the large orifices of the Saybolt equipment. The viscosity of kerosene is sometimes determined in the Saybolt thermoviscosimeter, and thermoviscosity (at 60 F) is related to the kinematic and Saybolt Universal viscosity (at 60 F) approximately as follows ... 

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