Visco II Viscosity Measurement
Breaking Through with New Viscosity Measurement Technology: Announcing the VISCO II
- Motor Speeds: Infinitely variable from 0.1-600 RPM for pre- cise shear rate control
- Zeroing capability at the touch of a button
- Calibration verified with certified fluids
- Torque range high is 30.0 oz-in
- Torque range low is 0.001 oz-in
- Resolution is +/- 0.001 oz-in
- Viscosity range is 1- 16,400,000 cP
- Windows-based touch screen control
With over fifty years of experience and a com- mitment to excellence, Vibrac has established itself as a worldwide leader in the manufacture of torque and friction measuring equipment for both production and laboratory applications. Our proven history of expertise in the measurement of flea torques has expanded into new markets using our new, patented viscosity measurement technology. With resolution of +/- 0.001 oz-in, Vibrac's viscometer will combine both accuracy and precision.
In response to the desire of various industries to obtain a new generation viscometer, Vibrac has designed a new line of programmable viscometers that combine a touch screen app with 100% digital patented technology and a micro-processor to bring a new level of accuracy and simplicity.
Meet the VISCO II
Vibrac’s Visco II is a Couette-style rotational viscometer and uses standard rotors and bobs. The stationary bob used on Vibrac’s viscometer can either be an end-capped hollow core or a solid bob. A rotor is then applied over the bob. The resulting test cell can be programmed to rotate at designated speeds. Continuous measurements can be made under a given set of conditions. Clockwise and counterclockwise profiles and results can be stored in its memory.
Calibration verification is performed through the use of certified calibration fluids. Calibration verification frequency will depend on usage and upon requirements of your quality program.
Vibrac’s Visco II viscometer comes with either a mounted touch screen panel or a separate tabletop version.
The main menu displays the primary features for the user.
Selecting a Test
A user-friendly menu displays the library of tests that have been created to make the operator’s job simple and efficient. There are no size limitations on the size of the library and a USB backup feature is included.
This menu enables the user to select the special features that best suit the viscosity test to be performed.
Test Sequence Screen
The user can create a viscosity test with multiple steps in either the clockwise or counter-clockwise direction, or create tests that include steps in both directions, including oscillating tests. The operator will select the rotor and bob to be used.
End of Test
The results are displayed in graph format. They can also be displayed in numerical format for the selected test profile, as shown on the next picture.
Show Data Screen
The Rotor and Bob
Vibrac’s viscometer employs a stainless steel fixed bob, threaded rotor and an external sample cup. As the rotor is rotated, the drag of the fluid on the internal bob is measured in torque which is then converted into a viscosity reading.
Viscometer Information Request
Let us know what you are testing and we can let you know how the Visco II can help. Simply Email Us at email@example.com or call us on +44 (0) 845 055 9626. We will want to know the following information:
- What type of fluid or medium are you testing?
- What is the range of viscosity you expect to see? What speeds do you normally do your testing?
- Are there any special considerations and/or requirements we should be aware of?
Viscosity and the Study of Flow
The study of fluids and viscosity is nothing new. The great Greek mathematician, Ar- chimedes (c. 287 BC– c. 212 BC) studied fluids and buoy- ancy. Leonardo da Vinci stu ied the effects of fluid flow when he observed and experimented with water flowing over objects.
All liquids exhibit viscosity. Like other substances on Earth, liquids are made of molecules. How well a fluid flows depends on the internal friction of those molecules. Viscosity is essentially fluid friction and the resistance of a fluid to flow or shear. Isaac Newton (1642-1727)was the first to experiment and theorize viscous drag by placing fluid between two plates, one being fixed and the other moving. Jean Louis Poiseuille (1797-1869) was a French physician and physiologist who in 1846 published what is now known as Poiseuille’s Law, or the study of liquid through pipes. (Think blood flow; he was a physician, after all.)
Isaac Newton’s theories of fluids contributed to how we classify them today. Fluids are defined as either Newtonian or non-Newtonian.
Newtonian vs. non-Newtonian Fluids
Newton observed that some liquids have a constant flow, or viscosity. A fluid’s viscosity is affected by temperature and/or shear rate.
A Newtonian fluid will be affected by temperature and its viscosity remains constant no matter which spindle or speed is used. Water, milk, ethanol, mineral oil and glycerine are examples. A non-Newtonian fluid, however, changes its viscosity as the shear rate is varied. Take solid honey or yogurt and stir it over time and it becomes thinner. Its viscosity decreases with shear over time. This is known as thixotropic behavior. Rheopectic behavior is defined as viscosity increasing over time as it’s sheared at a constant rate. Making fresh whipped cream is a perfect example; the longer you whip it, the thicker it becomes. Paint is an example of shear-thinning, or when viscosity decreases with increased shear rate. Shear-thickening is characterized by an increased viscosity with an increase in shear rate. Cornstarch in water is an example of shear-thickening.
Other examples of non-Newtonian fluids are nail polish, fruit juice conce trate and toothpaste. Non-Newtonian fluids can be time dependent or time independent. The latter’s viscosity changes in response to shear rate and temperature.