Capillary Viscometer Views
These devices also are known as glass capillary viscometers or Ostwald viscometers, named after Wilhelm Ostwald. Another version is the Ubbelohde viscometer, which consists of a U-shaped glass tube held vertically in a controlled temperature bath. In one arm of the U is a vertical section of precise narrow bore (the capillary). Above this is a bulb, with it is another bulb lower down on the other arm. In use, liquid is drawn into the upper bulb by suction, then allowed to flow down through the capillary into the lower bulb. Two marks (one above and one below the upper bulb) indicate a known volume. The time taken for the level of the liquid to pass between these marks is proportional to the kinematic viscosity. Most commercial units are provided with a conversion factor, or can be calibrated by a fluid of known properties.
CANNON offers many types of glass capillary viscometers that are not listed in our catalog. Examples include Atlantic, Cannon Master and Ubbelohde Master, Cannon-Ubbelohde Filter-Stick Dilution, Fitzsimons, Lantz-Zeitfuchs, Methylcellulose, SIL, and other viscometers. We can also manufacture glass capillary viscometers with customer-specified constants. Viscometers with special constants, added temps, and before/after data are available by special order at an additional cost.
Special reverse flow viscometers have been designed for testing opaque liquids. Reverse flow viscometers wet the timing section of the viscometer capillary only during the actual measurement. The Cannon-Fenske Opaque, Zeitfuchs Cross-Arm, and BS/IP/RF U-Tube viscometers are all reverse flow types. Reverse flow viscometers must be cleaned, dried, and refilled before a repeat measurement can be made. In contrast, other viscometer types commonly used to measure transparent liquids allow the same sample to be repeatedly drawn up into the capillary, permitting multiple measurements for verification.
In most glass capillary viscometers, the samples flow under gravity. When liquids are too viscous to flow readily under gravity, vacuum viscometers may be used to measure viscosity (in mPanbull;s or cP). In these instruments a vacuum is applied to one end of the viscometer to pull the liquid through the capillary into the timing bulb(s). CANNON offers several types of vacuum viscometers, including the Cannon-Manning Vacuum, the Asphalt Institute Vacuum, and the Modified Koppers Vacuum. Like the Cannon-Fenske Opaque viscometer, these are all ld"reverse flowerd" viscometers. Vacuum viscometers require a vacuum that is very accurately controlled. The CANNON DVR-1000 or DVR-1500 Digital Vacuum Regulator is an ideal instrument for maintaining constant vacuum.
Capillary Viscometer Images
