February 2004

Examples of Viscosity Measurement With Sine-Wave Vibro Viscometer SV-10
Concerning Typical Lubricants (Viscosities at 40°C and 100°C in Particular)
Marketing Division, A&D Co., Ltd.
Introduction
The results of viscosity measurement with the sine-wave vibro viscometer SV-10 concerning four types oflubricants provided from a customer as sample will be described hereinafter.
Sample and Instrument
1. Sample
Viscosities of four typical lubricants, described below, provided by a customer for determining viscosity weremeasured.
1: Hydraulic oil, standard type
2: Diesel engine oil, standard type
3: Automatic transmission fluid, luxurious type
4: Gasoline engine oil
2. Instrument
The sine-wave vibro viscometer SV-10 (made by A&D Co., Ltd.), which measures viscosity by vibrating its
sensor plates immersed in a sample at relatively low frequency (approx. 30Hz) of sine-wave, was used as themeasuring instrument of viscosity. Since the instrument produces low frequency and very small amplitude(approx. 0.4mmpp), it does not impair the composition of the sample unlike a rotational viscometer. The
instrument can measure viscosity of a sample according to the temperature of the entire sample due to the small
thermal capacity of the sensor plate, and it is also possible to perform real-time measurement of the correlation
between the viscosity and temperature of the sample. The instrument can measure viscosities ranging from
0.3mPa·s to 10000mPa·s (10Pa·s) with no need to change the sensor plates during the measurement, thus
continuous measurement of viscosity is possible from low to high viscosities.

MethodThis viscosity measurement, as shown in Fig.1, was performed while observing the behavior displayed inreal-time on the screen of a personal computer connected to the viscometer SV-10 via RS232C interface.
The procedure of the viscosity measurement was as follows; after completely washing and drying a 200ml glass
beaker, an unopened tank of the sample was rolled over several times slowly enough to agitate the content before
approx. 150ml of the sample was poured into the beaker, and then viscosity measurements were performed on a
hot stirrer.
1. The height of the sensor unit (head) of SV-10 was adjusted to fix the sensor plates in the prescribed position.
2. The hot stirrer was rotated to stir the sample slowly, preventing it from making viewable ruffles on the liquidsurface.
3. The viscosity measurement was started at room temperature and the viscosity was measured for approx. fiveminutes.
4. The heater of the hot stirrer was turned on and measurement was continued while heating the sample until thetemperature of the sample reached approx. 110°C.
5. The hot stirrer was turned off when the temperature of the sample reached approx. 110°C, and the sample wasleft at room temperature to naturally cool to approx. 30°C while the viscosity continued to be measured.
In brief, for each sample of the four lubricants, a continual viscosity measurement was performed following theabove procedure 1 to 5 while stirring slowly and continually changing the temperature of the sample from approx.
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25°C (room temperature) to 110°C and to approx. 30°C (around room temperature) in order to burden the sample
with a temperature load on heating, followed by cooling.
At the same time, the relative dial setting position of the hot stirrer’s revolving speed was not changed during themeasurement. The data about the viscosity and temperature of the sample during the measurement wastransmitted in real-time to the computer via RS232C, and sampling was made at intervals of five seconds.

SampleHot Stirrer
Fig. 1 View of Viscosity Measurement

Fig. 2 Viscosity Measuring Unit

Result and Review
Table 1 shows the viscosities (readings of SV-10) of the four lubricants measured at 40°C and 100°C on heatingand cooling.
The sine-wave vibro viscometer SV-10, under its measuring principles, produces a relative indication of themeasured viscosity (instrument reading) as a product of the specific gravity and the viscosity. Therefore, anabsolute viscosity can be obtained by dividing the viscosity shown in Table 1 by the specific gravity of thesample.
Additionally, a kinetic viscosity can be obtained by dividing the absolute viscosity, which is calculated as above,by the density (here, the same as the specific gravity) of the sample.
Table 1. Viscosities (readings of SV-10) of the four lubricants measured at 40°C and 100°C on heating and cooling
40°C
SV-10 Viscosity Measurement Values (mPa·s)
1: Hydraulic oil, standard type
2: Diesel engine oil, standard type
3: Automatic transmission fluid, luxurious type
4: Gasoline engine oil

Heating

39.2
85.1
21.3
49.5

Cooling

38.5
83.2
21.3
48.8

100°C
Average

38.9
84.2
21.3
49.2

Heating

5.56
9.32
5.11
8.11

Cooling

5.80
9.37
5.34
8.17

Average

5.68
9.35
5.23
8.14

For each sample, Figures 4 to 7 show the graphs, which were created with the graph function of thecommunication software WinCT-Viscosity, equipped as standard with SV-10, of the continual behavior of theviscosity and temperature during the measurement.
Figs.4a&b show the graphs of the viscosity and temperature of Hydraulic oil, standard type while being stirred
slowly as well as heating from 25°C room temperature to 110°C, followed by cooling naturally to 30°C again(around room temperature). Fig.4a, the graph on the left, shows the elapsed time plotted along the horizontal axis
and the viscosity (in red) and the temperature (in blue) plotted along the vertical axes on the left and rightrespectively. The blue curve on the graph shows the process of change in temperature; the process of heating
followed by cooling appears in the shape of a mountain. On the other hand, the viscosity (in red) appears in aU-shaped curve, which is in inverse proportion to the temperature curve. Fig.4b, the graph on the right, shows thetemperature plotted along the horizontal axis and the viscosity plotted along the vertical axis in order to define thecorrelation between the viscosity and temperature. As shown in the graph, a nonlinear inverse correlation between
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the viscosity and temperature can be observed. In addition, since the curves on both heating and cooling processes
are almost superposed, it is considered an excellent repeatability of viscosity measurement with the sample andSV-10’s measuring system.
In the same way, Figs.5a and 5b show the results of Diesel engine oil, standard type, Figs.6a and 6b show those ofAutomatic transmission fluid, luxurious type), and Figs. 7a and 7b show those of Gasoline engine oil.

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Fig.4a Viscosity Change (in red) in Relation to Temperature Change (inFig.4b Correlation Between the Temperature and Viscosity ofblue) of Hydraulic oil, standard type (Changes With Time)

Hydraulic oil, standard typeFig.5a Viscosity Change (in red) in Relation to Temperature Change (inFig. 5b Correlation Between the Temperature and Viscosity ofblue) of Diesel engine oil, standard type (Changes With Time)

Diesel engine oil, standard type

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Fig.6a Viscosity Change (in red) in Relation to Temperature Change (inFig.6b Correlation Between the Temperature and Viscosity ofblue) of Automatic Transmission Fluid, Luxurious Type (Changes With

Automatic Transmission Fluid, Luxurious TypeTime)Fig.7a Viscosity Change (in red) in Relation to Temperature Change (inFig.7b Correlation Between the Temperature and Viscosity ofblue) of Gasoline Engine Oil (Changes With Time)

Gasoline Engine Oil

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Conclusion
1. Viscosities of four typical types of lubricants were measured with the viscometer SV-10.
2. The facts that the correlation between the viscosity and temperature of each sample is in a nonlinear inverse
correlation on both the heating and cooling processes and that during the processes viscosity at the sametemperature shows almost the same value, which is considered an excellent repeatability, were confirmed.
3. Since excellent measurement repeatability is observed as described in 2 above, the viscosities of each sample at
representative temperatures 40°C and 100°C are shown in Table 1 as a summary of the results. It is consideredthat the significant individual differences between the samples can be distinguished by measuring the viscosity of
the four lubricants at the above mentioned two points of temperature using the sine-wave vibro viscometer SV-10,
although significant difference tests should be repeated a greater number of times with more samples before
making such determination.

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