kinematic viscosity

kinematic viscosity of lube oil properties

1. Duhok Polytechnic University
Zakho Technical Institute
Petroleum Department



Scientific Report


Name: Taha Samir Ali

Stage: 2
nd
Stage

Subject: Petroleum and Gas Technology
2
LAB

Experiment: Standard Test Method for Viscosity of Transparent
Liquids (The Calculation of Dynamic Viscosity) D445

Experiment No. : 1

2. Objective:
∎To determine the kinematic viscosity (ʋ) of a transparent
petroleum product.
∎To calculate the dynamic viscosity using kinematic viscosity.

Introduction:
The viscosity of a fluid is a measure of resistance to flow. It is a
useful property petroleum production, refining and
transportation. It is used in calculation of power required in
mixers or to transfer a fluid, the amount of pressure drop in a pipe
or column. Dynamic viscosity (sometimes called absolute
viscosity) is the ratio between the applied shear stress and rate of
shear of a liquid, it is the product of kinematic viscosity and the
density of the a liquid, both at the same temperature. It has units
called poise (p) and its hundredth is called centipoises (cp).
Kinematic viscosity is the absolute viscosity of a fluid divided by its
density at the same temperature of measurement. It is the
measure of a fluid's resistance to flow under determine kinematic
viscosity, a fixed volume of the test fluid is allowed to flow
through a calibrated capillary tube (viscometer) that is held at a
controlled temperature. The kinematic viscosity, in centistokes
(cSt), is the product of the measured flow time in seconds and
calibration constant of the viscometer. The unit of k dimensions
centimeters-squared usually expressed in centistokes, cSt
(mm
2
/s), so that 1 st= 100cSt. kinematic viscosity of many
petroleum fuels is important for their proper

3. use, for example flow of fuels through pipelines, injection nozzles,
and orifices, and the determination of the temperature range for
proper operation of the fuel in burners. The quantity of oil flowing
up a wick is related to the viscosity and surface tension of
kinematic viscosity, ʋ is related to the dynamic viscosity. µ as
described by the following equation: ʋ= µ /?????? Viscosity Index (VI)
is an arbitrary scale used to show the magnitude of viscosity
changes in lubricating oils with changes in temperature. Oils with
low VI number such as Vi-0 have high dependence of viscosity
change on temperature. The viscosity of oils with high VI number
as VI=100, will s II change with temperature, but again not as
much as low viscosity is affected by the following factors:
∎Oil composition: described by API, as API increases, oil viscosity
decreases.
∎Temperature: oil viscosity decreases with temperature rise.
∎Dissolved gas: as solution gas oil ratio increases, oil viscosity
decreases.
∎Pressure: oil viscosity increases almost linearly with pressure.

4. Apparatus: The apparatus consists of
viscometer, U-shaped glass tube, the arm, L has
larger diameter and a reservoir at the bottom, it
is used to fill the viscometer with sample. The
other arm, N with capillary has two bulbs; the
bulb has two marks E &F 1- A 2- Viscometer
holder, 3 Temperature control bath, 4
Temperature controller, 5 Temperature
measuring device 6 Timing device.
Procedure:
1- Adjust and maintain the viscometer bath a required test
temperature.
2- Select a clean, dry, calibrated viscometer having a range
covering the estimated kinematic viscosity (that is, a wide
capillary for a very viscous liquid and a narrower capillary for a
more fluid liquid). The flow time shall not be less than 200 s.
3- Charge the viscometer and draw the test portion into the
working capillary and timing bulb, place rubber stoppers into the
tubes to hold the test portion in place, and insert the viscometer
into the bath.
4 Allow the viscometer to reach bath temperature (10-15
minutes).
5- Remove the stopper from capillary arm and allow the sample
flowing freely, measure, in seconds to within 0.1s, the me
required for the meniscus to pass from the rst (E) to the second

5. (F) kinematic viscosity of the sample. mark, (the me should not be
less than 200s).

6- Find the viscometer constant from the table and calculate of
the sample.


Results & calculations:
Record the measured flow time, t in seconds Find the viscometer
constant, C from the table. Calculate the kinematic viscosity, n,
from the measured flow time, t, and the viscometer constant, C,
by means of the following equation Where:


ʋ=??????.??????

ʋ= kinematic viscosity, mm
2
/S

, C= Calibration constant of the
viscometer, (mm
2
/s)/s, and t=mean flow time, s.
calculate the dynamic viscosity, ʋ, from the calculated kinematic
viscosity, ʋ, and the density, ??????, by means of the following
equation: Where ʋ= dynamic viscosity, mPa.s(cp)
??????=density, g/cm
3
, at the same temperature used for the
determination of the kinematic viscosity, and ʋ= kinematic
viscosity, mm
2
/s (cSt)

6. Discussion:

1- What is the importance of viscosity measurement for the
following:
 Crude oil
 Lubricating oil
 Fuel oil
- For crude oil is depending on its geographic origin, so the viscosity and
its API degree are important for classification light crude oils flow easily
and contain more volatile components while heavy crude oils are can be
highly viscous and show a higher density, Intermediate oils are in
between these extremes, for lubricant oil , viscosity is most important
factor that should be measure different lubricants oils varies with its
viscosity as long as we need to use the lubricant oil for different uses , for
fuel oil's viscosity of fuel oil plays an important role in the quality of
combustion inside a diesel engine.

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, for example, when honey is cold it
has a high viscosity and can be difficult to pour. When heated in
microwaves, the viscosity decrease and the honey flows more freely.

7. 3- What is viscosity index?
- 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.

4- How can you calibrate a viscometer?
-When you have a viscometer with unknown viscosity constant (c) so
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 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:


Viscosity Constant (C)=
kinematic viscosity(ʋ)
????????????????????????(??????)