Stop Measuring Viscosities the Hard Way
Are you struggling with an expensive rheometer that only produces unstable
results when testing low viscosity (e.g. below 100 mPa•s) samples? Drawing on
A&D’s proven sensor technology for high-resolution analytical balances, the
RV-10000A Tuning Fork Vibro Rheometer is a breakthrough alternative to
conventional methods in the research of non-Newtonian fluid properties,
especially for ease and precision in low viscosity measurements
Tuning Fork Vibro Rheometer - Principle of Operation
Two thin sensor plates in a tuning fork arrangement are driven with electromagnetic
force to vibrate at their natural (resonant) frequency of 30 Hz within the sample
fluid. Viscosity is then calculated based on the proportional relationship between the
viscous resistance of the sample fluid and the amount of electric current required to
drive and maintain the sensor plates at a constant vibration amplitude.* 1
This is an application of the electromagnetic equilibrium mechanism employed by
A&D’s high-end weighing devices, including microbalances whose scale interval is as
small as 1 ìg (1/1,000,000 of 1 g).
How the shear rate is changed
The sensor plate amplitude of the RV-10000A can be altered between the minimum of
0.07 mm and the maximum of 1.2 mm (peak to peak) while the frequency is kept at
30 Hz, which will cause variation in shear rate. By this means, you can easily quantify
the viscous behaviors of non-Newtonian fluids in response to different shear rates.
The tuning fork vibro method is recognized as a Japanese industrial standard for viscosity measurement of liquids (JIS Z8803).
The viscometer that uses this method is also accredited as a standard device for the Japan Calibration Service System (JCSS)
along with capillary and rotational viscometers
Advantages
Wide Continuous Measurement Range—From 0.3 mPa• s
The RV-10000A has a single viscosity detection system that can measure from very
low to high viscosity without interruption (max. 0.3 to 25,000 mPa•s), which realizes
high versatility and allows measurement of various types of fluids with just one
instrument. It also allows continuous monitoring of viscosity variation with time,
temperature as well as shear rate.
Extremely High Sensitivity
The sensor sensitivity heightened through sharp resonance phenomena even detects viscosities around
the level of water with unparalleled precision. Such sensitivity even realizes measurements, for
example, for finding the cloud point of surfactants and controlling the drinking sensation of beverages.
Excellent Repeatability
The RV-10000A achieves repeatability as high as 1% of the measured value (by standard deviation) for
the entire measurement range, providing you with consistent results and enabling reliable
comparisons of those results.
Relationship Between Vibration Amplitude, Shear Rate and Viscosity
Simultaneous Measurements of Temperature and Viscosity
The temperature sensor (0 to 160 °C range) located between the two viscosity sensor plates
allows measurement of viscosity’s dependence on temperature as accurately as possible
Sample Fluid Temperature Control
By using the provided water jacket with a
commercially available temperature control
tank, you can control the sample fluid
temperature (between 0 and 100 °C) in order to
measure the viscosity at a constant temperature
or see how the viscosity varies with temperature
Easy Setup and Very Quick Measurement
Compared with conventional methods, it takes much less time for you to set the
sample fluid, start measurement, and obtain the viscosity value (the RV-10000A
requires only 20 seconds to stabilize). Moreover, since the sensor plates have a very
small thermal capacity, they cause minimal temperature change to the sample fluid
upon immersion, also contributing to fast and stable viscosity measurement.
It is very easy to clean the sensor after
measurement as well – all you need to do is
wipe off the sample residue with alcohol.
Little Interference to the Sample Fluid
The low-frequency, low-amplitude vibration causes only minute displacement in the
sample fluid and keeps changes to its temperature and physical structure to a
minimum. This enables highly stable measurements of viscosity variations over a long
period of time. It also enables the measurement of fluids such as foams (e.g. whipped
cream) without breaking their tiny air bubbles or dispersion systems (e.g. colloids)
while they are settling
Measurements of Fluids in Motion
The two sensor plates vibrate in opposite directions,
meaning that even if the sample fluid is flowing or
being stirred during measurements, the errors of
each sensor plate are cancelled out by those of the
other. It is therefore possible, for example, to
measure the viscosity of a flowing fluid in a
production line and maintain data compatibility
between the laboratory and the field.
Easy Calibration by Yourself
Both one-point and two-point calibrations are possible using either viscosity standards
(available as accessories) or fluids of known viscosities. With the RV-10000A, there is
no need to spend time and money having the instrument calibrated by an outside
specialist.
Simplified Calibration Function
For a viscosity range around 1 mPa• s, a highly useful, simplified calibration function is available. You
only have to prepare purified water and perform a simple one-key operation, and the RV-10000A will
automatically calibrate itself using stored information on the viscosity of purified water at each
temperature.
RV-10000A – Controller Section
The dedicated controller can automatically
change the sensor plate amplitude and take
data in the manner you programmed. It
also shows and graphs measured values in
real time so that viscosity changes as a
function of time, temperature, and/or shear
rate* 4 become plainly visible.
The results can be saved in CSV format and
graph screens as JPEG images in a USB
flash drive.
In Auto mode, the sensor plate amplitude automatically
goes from 0.07 mm to 1.2 mm and back to 0.07 mm again
according to one of three preset types of measurement
conditions: Quick, Standard and Fine modes, from which
you can make a choice of how finely to change the
amplitude (8, 13 or 114 levels) and how long to take for the
measurement (7.5, 25 or 60 minutes in total).
Auto mode helps when you want to take a quick scan of the
physical properties of the sample fluid.
Program mode allows you to more freely design the
measurement conditions, by setting either amplitude
changes in steps (Step mode) or two amplitude points so
that it linearly (in scales of 0.01 mm) increases and then
decreases between them (Fine mode). This mode is
especially useful for testing the sample fluid within a
specific amplitude (shear rate) or viscosity range.
The measurement conditions set in Step mode can be saved
for later measurements with the same conditions (up to 10
programs).
