Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (The Calculation of Dynamic Viscosity)

Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (The Calculation of Dynamic Viscosity)

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University of Zakho
Faculty of Engineering
Department of Petroleum Engineering
2014-2015




Name of Student: Yasir Ammar Ahmed
Class 2 / 2
nd
stage


Experiment NO. 8
Standard Test Method for Kinematic Viscosity of
Transparent and Opaque Liquids (The Calculation of
Dynamic Viscosity)

Experiment contacted on: 14/12/2014
Report submitted on: 19/1/2015

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Contents

1.1 Objectives ---------------------------------------------------------------------------- Page 3
1.2 Introduction ------------------------------------------------------------------------- Page 3
1.3 Apparatus and Materials --------------------------------------------------------- Page 4
1.4 Procedure ---------------------------------------------------------------------------- Page 4
1.5 Result and Calculation ------------------------------------------------------------ Page 5
1.6 Discussion --------------------------------------------------------------------------- .Page 5
1.7 Conclusion --------------------------------------------------------------------------- Page 8

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Standard Test Method for Kinematic Viscosity
of Transparent and Opaque Liquids (The
Calculation of Dynamic Viscosity)
1.1 Objectives:
 To determine the kinematic viscosity (�) of Diesel Sample.
 To calculate the dynamic viscosity of Diesel sample using kinematic viscosity.
1.2 Introduction:
Viscosity is an internal property of a fluid that offers resistance to flow. Viscosity
determine the fluidity of fluids, it's useful property in petroleum production refining
and transportation , it is used in reservoir simulators to estimate the rate of oil or
gas to flow and their production, and it is needed in calculation of power required in
mixers or to transfer fluid, the amount of pressure drop in pipe or column, flow
measurement devices and design and operation of oil/water separations, A high
viscosity implies a high resistance to flow while a low viscosity indicates a low
resistance to flow. Viscosity varies inversely with temperature. Viscosity is also
affected by pressure; higher pressure causes the viscosity to increase, and
subsequently the load-carrying capacity of the oil also increases. This property
enables use of thin oils to lubricate heavy machinery. The load carrying capacity also
increases as operating speed of the lubricated machinery is increased. Two methods
for measuring viscosity are commonly employed: shear and time.
When viscosity is determined by directly measuring shear stress and shear rate, it is
expressed in centipoise (cP) and is referred to as the absolute or dynamic viscosity.
In the oil industry, it is more common to use kinematic viscosity, which is the
absolute viscosity divided by the density of the oil being tested. Kinematic viscosity
is expressed in centistokes (cSt). Viscosity in centistokes is conventionally given at
two standard temperatures: 40C and 100C (104F and 212F ).

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1.3 Apparatus and Materials:
1. 150 mL viscometer.
2. Timing device.
3. Temperature measuring device.
4. Temperature controller.
5. A vacuum device.
6. Rubber stopper.
7. Holder.
8. Sample Diesel.

1.4 Procedure:
1. Adjust the viscometer bath at required test temperature.
2. Select clean , dry , calibrated viscometer having range covering the estimated
kinematic viscosity.
3. Charge the viscometer and draw the test portion into the working capillary
and timing bulb, place the rubber stoppers into the tubes to hole the test
portion in place, and insert the viscometer in the bath.
4. Allow the viscometer to reach the bath temperature ( 10 – 15 min)
5. Remove the stopper from capillary arm and allow the sample to flowing
freely, measure in seconds within 0.1s , the time required for the meniscus to
pass from the start flowing line to the end line.( the flow time should not be
less than 200 s ).
Viscometer

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6. Find the visocme3eter constant form the table and calculate the kinematic
viscosity of the sample.
1.5 Result and Calculations:
Time = 686 seconds , viscometer constant ( C ) = 0.035 mm
2
/S
2
Density from 1
st
experiment = 0.846 g/mL
�=?????? .�
�=0.035 ×686=24.01 mm
2
/S
2

�= � .??????
=24.01 ×0.846=20.3 ??????�
1.6 Discussion
1. What is the importance of viscosity measurement for the following:
 Crude oil
 Lubricating oils
 Fuel oils
A/ for Crude oil is really a complex mixture of various components. Depending on its
geographic origin, its chemical composition and consistency vary. The different
types of crude oil need to be classified for further treatment. Both a crude oil's
viscosity and its API (American Petroleum Institute) Degree are important
parameters for classification, API Degrees indicate whether a crude oil floats on
water or sinks. Light crude oils flow easily and contain more volatile components,
while heavy crude oils can be highly viscous and show a higher density. Intermediate
oils are in-between these extremes. The advantage of measure viscosity is firstly, a
crude oil's flow behavior is important for smooth extraction and transport. Even in a
pipeline, which is subject to temperature changes, the oil should always remain
liquid, secondly, not every refinery can process every type of crude oil. The heavier
an oil is, the more difficult it is to refine. A crude oil must suit the refinery's
equipment, thirdly, in case of an accident with subsequent oil spill, the type of oil
determines the steps taken to minimize the effect on the environment.
For lubricant oil , viscosity is the most important factor that should be measured ,
different lubricants oils varies with its viscosity , as long as we need to use the
lubricant oil for different uses , different lubricant oil with different viscosity is
needed , so by measuring viscosity of lubricant oil we can select the suitable
lubricant oil for the suitable purpose.

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For fuel oil's Viscosity of fuel oil plays an important role in the quality of combustion
inside a diesel engine. It is imperative to keep the viscosity of fuel oil in the right
range in order to get the right kind of engine efficiency. In high viscosity values it will
supply the combustion chamber with smaller amounts of flue, which in connection
with already set coefficient of excess air, will result in a greater chimney loss, also, in
effect, leading to poor combustion efficiency. In addition, the burner pump will
prematurely wear or even be damaged, due to higher resistance of flow and higher
pressure. The shape and size of the nozzle designed for lower viscosity of fuel will
not facilitate a good spray – and thus complete combustion. Negative effect of this
can only be overturned by the advice mentioned above.
at a lower viscosity – will “over pour”, that is, will hand larger quantities of fuel to
the combustion chamber than necessary. The excess fuel at calibrated air input will
not be completely burned out and soot will be formed, the emissions will show an
excess amount of CO and unburned hydrocarbons (measured in the exhaust gases
as hydrogen). By reducing the amount of fuel into the chamber we will not obtain,
on the other hand, a proper pressure in the nozzle of the burner, which will result in
a lower fuel spray and thus deepening of the losses on energy. The only advice is to
exchange the nozzle and re-adjust the burner according to the measurement of
emissions.
2. Explain the behavior of liquid and gas viscosity with temperature rise.
When a liquid heats up, its molecules become excited and begin to move. The
energy of this movement is enough to overcome the forces that bind the molecules
together, allowing the liquid to become more fluid and decreasing its viscosity. For
example, when syrup is cold it has a high viscosity and can be difficult to pour.
When heated in a microwave, the viscosity decreases and the syrup flows more
freely.
In gases when the temperature increases it will increase the viscosity of gases which
the molecules are more or less free, except for discrete scattering events with other
molecules. Unless the gas is ionized, the collision cross section varies little with
impact velocity. Therefore, as the temperature (free velocity) increases, the
molecules carry more momentum and collide more often. That means more viscous
momentum transport.
3. What is viscosity index(VI) and how can you calculate it?
Viscosity index (VI) is an arbitrary measure for the change of viscosity with
variations in temperature. The lower the VI, the greater the change of viscosity of
the oil with temperature and vice versa. It is used to characterize viscosity changes
with relation to temperature in lubricating oil. The viscosity of liquids decreases

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as temperature increases. The viscosity of a lubricant is closely related to its ability
to reduce friction. Generally, the least viscous lubricant which still forces the two
moving surfaces apart is desired. If the lubricant is too viscous, it will require a large
amount of energy to move (as in honey); if it is too thin, the surfaces will come in
contact and friction will increase.
Viscosity
Index
Classification
..35 Low
35..80 Medium
80..110 High
110.. Very High
The viscosity index can be calculated using the following formula:

where V indicates the viscosity index, U the kinematic viscosity at 40 °C (104 °F), and
L & H are various values based on the kinematic viscosity at 100 °C (212 °F) available
in ASTM D2270.
4. How can you calibrate a viscometer?
When you have a viscometer with unknown viscosity constant (c) you can't use it
because you don’t have the viscosity constant to calculate the kinematic viscosity ,
for this purpose we have to calibrate the viscometer to determine the viscosity
constant of viscometer, to calibrate a viscometer you should have a liquid of known
kinematic viscosity that have been determined before of a standard liquid that have
a known kinematic viscosity, after that we have to do the test as the given
procedure and record the time that the fluid will take it to flow from the start point
to end point, after that we have to rearrange the kinematic viscosity equation to
calculate the viscosity constant of the viscometer, the equation will be like this:
????????????�??????��??????�?????? ??????����??????�� (??????)=
????????????�??????�??????�???????????? ????????????�??????��??????�?????? (??????)
�??????�?????? (�)

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1.7 Conclusion
The viscosity of a fluid is a measure of its resistance to gradual deformation by shear
stress ortensile stress. For liquids, it corresponds to the informal concept of
"thickness". For example, honey has a much higher viscosity than water. A high
viscosity implies a high resistance to flow while a low viscosity indicates a low
resistance to flow. The kinematic viscosity is the ratio of the dynamic viscosity μ to
the density of the fluid ρ. It is usually denoted by the Greek letter nu (ν). , it is used
in reservoir simulators to estimate the rate of oil or gas to flow and their production,
and it is needed in calculation of power required in mixers or to transfer fluid, the
amount of pressure drop in pipe or column, flow measurement devices and design
and operation of oil/water separations.