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Frequently Asked Questions
Viscometers SV10/100

 

Question

General

Temperature

Sensor plate

Calibration

 

Answer

General

What system does the SV Series apply in order to measure viscosity?            Top

  • The SV Series vibrates its two sensor plates like a tuning fork while keeping a constant frequency and amplitude, and measures the driving electric current that is varied to keep the constant vibration according to viscosity change during measurement. The SV Series displays viscosity converted from the measured driving electric current.

Do the sensor plates rotate?            Top

  • No. The sensor plates vibrate at 30Hz.

At what amplitude is the sensor plate vibrated?            Top

  • At just about 0.4mm. Thus, it causes less damage to the structure of sample.

To which part of the sensor plate should be covered with a sample fluid?            Top

  • The target level of immersion is the most narrowed place just above the round part of each sensor plate. Adjust this level to the level of the fluid surface.

Does it affect the measurement result if the immersion level of the sensor plates change ?            Top

  • Although it depends on viscosity of each sample fluid, if the level changes by 1mm with SV-10 in low viscosity range, measurement error of approx. 2-3%, and with SV-100 in high viscosity range, approx. 10-15%, could be produced.

What amount of sample is necessary?            Top

  • Just about 35ml for the standard Sample Cup is enough to perform measurement.

How can I measure viscosity with a smaller sample amount?            Top

  • We offer you an accessory for smaller sample measurement, the Small Sample Cup (AX-SV-34), enabling measurement of only 10ml sample.

Is there any way I can measure kinds of highly acidic fluid in a small amount?            Top

  • We offer you the Glass Sample Cup (AX-SV-35) for small sample measurement, another accessory enabling viscosity measurement of approx. 13ml. If a sample amount need not be small, a commercial glass beaker can be also used without problems.

What has most effect on viscosity measurement?            Top

  • Temperature is one of the most influential factors on viscosity. In general when temperature is low viscosity becomes high, and temperature is high viscosity becomes low.

Is it possible to change the vibration frequency?            Top

  • No, it is not. This frequency is unchangeably fixed at 30Hz. 30Hz is the most sensitive resonance point that is obtainable within the measurable range of viscosity. In the production line the vibration frequency is adjusted within +/-0.02Hz to enhance the measurement accuracy.

Is it possible to set shear rate?            Top

  • It is impossible under the system of the SV Series. However, in measurement of Newtonian fluid the results are not affected by setting of (in relation to the rotational viscometer) what is called shear rate, or rotating speed of spindle, rpm. For measurement of Non-Newtonian fluid, it necessitates a predetermination of either shear rate or shear stress, which are not in proportion.

Is there any compatibility between the measurement results of the rotational viscometer and the SV Series?            Top

  • In case of the standard fluid, which is a Newtonian fluid, conformity in the results is observed. In measurement of Non-Newtonian fluid, the viscosity value measured at low rotational speed with the rotational viscometer, since a rotational speed of spindle, rpm, is determined for setting shear rate, may be approx. 10 times as high as that with the SV Series.

Why do the rotational viscometer and the SV Series differ in measurement results of Non-Newtonian fluid?            Top

  • The difference in results is merely due to the difference of their measurement systems, thus both results are correct in their own ways. For example, if you change shear rate, as measurement condition of rotational viscometer, by increasing the rotational speed, rpm, the measured viscosity changes. This shows that measurement results depend on measurement conditions and that those results are both valid.

Why does the viscosity of a Non-Newtonian fluid change with time from start of measurement?            Top

  • Viscosity change of a Non-Newtonian fluid appears as its physical structure is changed or damaged when stirred, beaten or pressed with stress. In measurement with the SV Series, viscosity usually decreases in the beginning as the vibration starts breaking the fluid structure around the sensor plates, but then stabilizes after a period time. In case of the rotational viscometer it causes greater damage to fluid structure and takes longer to stabilize the result in measurement than the SV Series does.

How long does a viscosity measurement take.            Top

  • The SV Series displays viscosity just about 15 seconds after pressing the Start key, and continues displaying real-time measurement values from then on.

Temperature

Is it possible to measure sample temperature with the SV Series?            Top

  • Yes. The SV series comes equipped with a temperature sensor placed between the two sensor plates, which enables constant accurate temperature measurement.

What temperature range does the SV Series cover?            Top

  • Standard measurement ranges from 0 °C to 160 °C.

How can I change the sample temperature during measurement?            Top

  • Use the Water Jacket (AX-SV-37) to connect the temperature-controllable Water Bath. Or you can use a heater to heat the sample during measurement. It is possible to monitor changes in viscosity with temperature changes if you refrigerate the sample before measurement and then heat it with a heater or just leave it at room temperature during measurement.

What is the lowest temperature the SV Series can measure?            Top

  • We guarantee the temperature measurement down to 0 °C. SV Series displays temperature even down to 20 to 30 °C below freezing, but we cannot guarantee the accuracy of +/-1 °C or higher.

Is the temperature unit display selectable between Centigrade and Fahrenheit?            Top

  • Yes. Select the temperature unit °C or °F from the function setting. You can choose a combination with the viscosity unit of your choice.

Sensor plate

What is the sensor plate made of?            Top

  • It is made of gold-plated stainless steel SUS304.

Why is the sensor plate gold-plated?            Top

  • Because it protects the sensor plate from highly acidic fluids during measurements.

How long does the sensor plate last?            Top

  • It depends on the use conditions and frequency of use. The sensor plates are basically not expendable parts and can be used semi-permanently.

The sensor plate looks fragile. Is it easily bended or broken?            Top

  • The thickness of the sensor plate is approx. 0.3mm. It is much stronger than it looks. Although it may yield when pressed or hit with great impact, you can recover it by straightening it and use it without harming measurement accuracy.

What should I do if the sensor plate is broken?            Top

  • The sensor plate is replaceable. After replacement, please perform calibration. Please note that simply replacing the sensor plates for SV-10 with the sensor plates for SV-100 cannot make model change since their shapes are different.

Calibration

How often should I perform calibration?            Top

  • You do not have to regularly perform calibration since usually the calibration values will not shift and produce errors as a result. We recommend that you follow your company protocol if it mandates regular calibration.

Is calibration difficult?            Top

  • The SV Series has user-friendly calibration function. Just prepare the standard fluids. You can choose from one-point calibration or two-point calibration.

Is it possible to correct input of incorrect values after a calibration?            Top

  • You can re-input correct calibration values by performing another calibration. It is also possible to recall the factory calibration values (SV-10 at 1mPas and 1000mPas / SV-100 at 1000mPas and 10000mPas) that are stored in the nonvolatile memory easily by using the “CLr” function.

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