Viscosity is a measure of the resistance of a fluid, which is being deformed by either shear stress or tensile stress. In everyday term (for fluids only), viscosity is 'thickness'. Various methods have been invented for measuring viscosity. Each of these methods is selected and used in the industry where it is most suitable. However, applications of viscosity measurements are recently expanding into new fields such as measurements of polymeric solutions, adhesive agents, coating materials, abrasives, engine oils, biodiesel fuels, and even soft drinks, cosmetics and human blood.

Meanwhile, demands are rising for a measuring system that can minimise the energetic interference to a sample liquid such as rotative force and barycentric shift in order to measure the viscous property that is inherent to the liquid. Moreover, there are increasing requirements for measuring continuously a wide range of viscosities in order to observe a viscosity change caused by a temperature change, the curing of an adhesive agent, etc.

To meet this challenge, A&D Company Ltd, Japan has introduced a new technology, i.e, tuning-fork vibration method to measure viscosity that satisfies the above requirements.

The recently developed, tuning-fork vibration viscometer not only realised downsizing and price-reduction of the instrument but also made it possible to perform wide-range, continuous measurements from 0.3 mPa's (equivalent of acetone) up to 10,000 mPa's.

More recently, measurements with as small as 2 ml sample liquid have become possible, whose applications including the viscosity measurements of such fluids as resist inks for liquid crystals and human blood. The high-performance, tuning-fork vibration viscometer is rapidly expanding its scope of applications to where viscosity measurements used to be impossible. Meanwhile, due to quality control requirements in offshore manufacturing, the precision and the user-friendliness of the tuning-fork vibration viscometer have also been gaining attention at the production level.

Sine-Wave Vibro Viscometers are available from A&D India, a direct subsidiary of A&D Company, Japan, a well known name in the field of Test & Measuring Instruments. A&D's Vibro Viscometer has a unit to detect viscosity of a sample, which is composed of two thin sensor plates that vibrate as shown above. It drives the sensor plates to vibrate at uniform Sine-Wave vibration in reverse phase, like a tuning-fork.

To resonate the measuring system, the sensor plates are driven with electromagnetic force at the same frequency as resonance, which is characteristic of each structure. The use of resonance is the most prominent feature of this viscometer.

When the detection unit vibrates, it produces sizable magnitude of reaction force on the supporting unit of sensor plates via the spring plates. Each sensor plate is driven in reverse phase against the other at the same vibration frequency and amplitude in order to cancel the reaction force. This enables it to obtain stable sine-wave vibration.

The electromagnetic drive unit controls the vibration of the sensor plates in a sample at uniform amplitude, utilizing the resonance of the detection unit. The driving electric current as the exciting force is detected as the magnitude of the viscidity which is present between the sensor plates and the sample. The viscosity coefficient is given by the correlation between the driving electric current and the magnitude of the viscidity.

The resonance of the detection unit allows viscosity detection with high sensitivity in lower viscosity ranges, and also effectively acquires a driving force with just a small amount of electric current.

Thus, it is possible to measure viscosity while maintaining a wide dynamic range and high resolution. The newly developed SV method (Tuning-fork Vibration Method) achieves accuracy with repeatability as high as 1 % of Reading in viscosity measurement. There is no need to exchange sensor plates during continuous measurement. This is different from rotational viscometers, which require several kinds of rotors, and in which continuity of viscosity measurement is disturbed and lost when exchanging them.

The SV Series comes equipped with the WinCT-Viscosity, Windows Communication Tools Software. With WinCT-Viscosity, you can create real time graphs of data on viscosity and temperature.

In addition, the scaling function is available and the logarithm display is selectable in the function. Saving the measurement data by "CSV" file and opening it with WinCT-Viscosity is very easy and convenient for analyzing sample fluid viscosity.

Technology & Features

• A&D Viscometer is a revolution in the industry to find the viscosity
• A&D's Sine Wave Vibro is arguably world's most user friendly and fastest viscometer which gives result in just 15 seconds
• Achieves a measurement accuracy of repeatability (standard deviation) of 1%
• Accuracy of 1% on the result value and not the full range
• Continuous measurement over a wide range of viscosity without replacing the sensor plates
• No need to change the sensor plates in compare to rotational type:
• One sensor plate is applicable for full range of viscometer.
• No need to do a trial and error method to choose the right spindle as done in rotational type. Just dip the sensor plates in the liquid and get the viscosity.
• The temperature sensor to measure the sample temperature is installed as standard. The temperature sensor is located between the two sensor plates. So, the accurate detection of the relation between temperature and viscosity is possible
• Measurement of a non-Newtonian fluid containing bubbles:
• A thin plate type sensor does not deform the sample structure. Thus, non-Newtonian fluid can be measured in a stable way. And, a sample containing bubbles can be measured without breaking the bubbles.
• The viscometer can be calibrated using a standard liquid of viscosity or a sample of a known viscosity. Calibration allows the viscometer to maintain the accuracy constantly
• Easy to clean the sensor plates. Clean with plain water or alcohol with help of soft cotton and it ready for next use
• As due to the movement of just 30 Hz vibration of Sensor Plates, it will not damage of change the viscosity of sample, unlike the rotational type
• Any beaker or any sample cup can be used to check viscosity and can be used directly in a tank or drum
• Can also test viscosity below 0?C
• Software WinCT-Viscosity gives graph for a clear and accurate result and throughout change in viscosity along with change in temperature.

WinCT-Viscosity Software

• WinCT-Viscosity is equipped as a standard accessory of Viscometer SV series
• This Software enables A&D's Sine-wave Vibro viscometer SV series the progress of measurement in real time on the computer, and
• RSVisco: Graphic software to create graphs of the measured results and the progress of viscosity measurement

(A&D Instruments India Pvt Ltd, Gurgaon. Tel: 0124-4715561, 4715555. Mobile: 095609-12200. Fax: 91-124-4715599. Email: info@aandd.in)