fuels & lubricants laboratory manual
TRANSCRIPT
Fuels & Lubricants
Laboratory Manual
T. Kishen Kumar Reddy, Ph.D.(Drexel)
Professor of Mechanical Engg. & RECTOR
Jawaharlal Nehru Tech.University Hyderabad
Hyderabad, Telangana, India
August 2014
MISSION STATEMENT
The primary objective of this laboratory is to determine properties
of several fuels and lubricants, compare them with standards so
as to get an idea about it’s quality. This lab will supplement
theoretical inputs in the basic sciences and engineering courses.
Teams of students will participate in several experiments over the duration of
the Laboratory course. Each member of the team will produce a technical
report of their findings which should include:
a problem statement,
a description of any required calculations (including a
sample calculation),
a copy of the raw data sheet,
a discussion of the experimental results including an
assessment of experimental uncertainty, and
conclusions.
Fuel: A fuel is a solid, liquid or gaseous substance which
on burning or oxidation releases significant amounts of
energy. Generally, it refers to hydrocarbon fuels but there
are other types of inorganic fuels as well such as those used
in rockets, missiles, etc.
Solid – Coal*(Anthracite/Bituminous/Sub-Bituminous/Lignite/Peat),
Wood, Cow dung, Agro-waste, Garbage-urban, etc.
Liquid – Crude oil* and its derivatives* such as:
Gasoline, Aviation Turbine Fuel, Light Diesel Oil,
Kerosene etc.
Gaseous – Natural Gas* and Compressed Natural
Gas*, Liquefied Petroleum Gas*, Biogas, Acetylene
* denotes fossil fuels which are non-renewable
RANK OF COAL
Laboratory testing of fuels can be broadly classified into
seven groups based on the following characteristics:
1. Volatility - Distillation, Vapour pressure, Flash and Fire Point
2. Combustion – Antiknock quality (Octane number), Ignition Quality
Cetane number), Calorific Value, Burning Quality
3. Viscosity and Consistency – Viscosity: Engler, Saybolt,
Redwood & Kinematic; Viscosity Index, Penetration Tests.
4. Melting Point – Freezing point; Cloud point, Pour Point; Drop point
of Grease, Setting Point of Wax, Softening Point of Bitumen.
5. Oxidation - Induction period of Gasoline, Stability Tests of Lube oils,
Residue on Evaporation, Gum Content
6. Corrosion and Protection – Total Sulfur, Doctor Test, Acidity and
Alkalinity; Corrosion protection properties
7. Sundry Tests – Ash, Carbon Residue, Asphaltenes, Dilution Test,
Dielectric Strength, De-emulsification
Need for the measurement of fuel properties:
Flash & Fire Pts. – Important from the point of view of
safety, as low flash petroleum products have potential for
fire hazards in storage and/or handling.
Viscosity – of a liquid is a measure of its resistance to flow.
It plays an important role in the design of fuel pumps.
Calorific Value - is a measure of the heat producing capacity
of a fuel. The designers of Boilers, Furnaces, Engines, etc
need to know the type of fuel to be used and pertinent
properties.
Carbon Residue – It gives an indication of the coke forming
tendency of the fuel. The Board of Revenue utilizes this
property for classification of fuels for excise duty purposes.
It is also used in design calculations of vessels.
Lubricant: is a solid, liquid or gaseous substance
introduced under pressure, in between two rubbing surfaces
under relative motion; thereby lessening the friction and
abrasion, and keeping the surfaces apart. Classified as:
Mineral lubricants: are products obtained from fractional
distillation of crude oil:-
Lubricating oils,
Vaseline's, and
Paraffin waxes
Fixed Oils & Fats: Animal products or vegetable oils. Distinction between oil and fat is a matter of temperature. Below -20°C all
oils become fats and > 50°C, all fats become oils. These are known as
fixed oils because unlike mineral oils, they either decompose by
distillation at comparatively low temps. or oxidize, thus they become
thick, gummy and corroding with little lube value. Many animal fats have
greater lube power than mineral oils of same viscosity, but they
decompose under heat, setting free acids, which attack metals.
Lubricating Oils are characterized by:
Physical properties such as: flash and fire point, viscosity,
oiliness, cold test, volatility and specific gravity.
Chemical properties such as: Acidity, Saponification Value,
Insoluble residue and demulsibility.
Lube oils are used under varied conditions, and a lubricant
is selected according to the requirements. Thus,
knowledge of various properties is essential for selecting a
proper lubricant for a particular machine.
Use of lubricants & Properties Tested:
Automotive Lubricants: Engine Oils, Gear
Oils, Transmission Oils, Specialty Oils (Flash Point, Pour
Point, K. Viscosity, Viscosity Index) and Greases (type of soap,
worked penetration @ 25°C, Drop Point)
Industrial Lubricants: Bearing Oils & Greases;
Compressor Oils (Conradson Carbon Residue), Gear Oils
(Timken OK Load), Heat Treatment Oils, Heat Transfer
Oils, Hydraulic Oils, Cutting Oils, Railroad Oils
(Saponificn. Value, C Residue) , Refrigeration Oils (Floc Point,
Dielectric Strength), Rust Preventive Oils, Rubber
Processing Oils (+ Asphaltenes, Polar Compds., Aromatics,
Saturates), Textile Machinery Oils (Saponificn. Value),
Turbine Oils, Speciality Oils, Industrial Greases (type
of soap, worked penetration @ 25C, Drop Point)
ABEL’S FLASH AND FIRE POINT TESTING (< 50°C)
I. AIM:
To determine the flash and fire points of the given fuel oil using Abel’s flash and fire
point tester.
II. APPARATUS :
Abel’s Flash and Fire point tester, thermometers of suitable range and given oil to
be tested.
III. THEORY :
The fire hazards involved in the storage and handling of fuel oils are indicated by
the flash and fire points. However, there is no correlation between flash and fire
points of an oil and its ignition temperature.
IV. FLASH POINT:
Flash point is minimum temperature at which an oil gives off sufficient vapours to
form inflammable mixture with air that ignite momentarily when exposed to a flame
or an electric spark. Presence of water and volatile organic substances modify the
flash point.
V. FIRE POINT:
Fire point is the minimum temperature at which an oil produces a mixture of its
vapours and air that will burn continuously once ignited, even after the removal of
test flame. The fire point is 25 – 50°C above flash point
The flash and fire points are found under two conditions of
surroundings, that is, open and closed. When the cup is open, flash
point is known as open flash point, when closed by a lid, it is closed
flash point.
In open cup, the oil is heated with the upper surface of the oil
exposed to the room. The vapours rise above the surface of the oil,
and are influenced by the air currents inside the room. The air inside
the room is cool and thereby cools the rising vapours. Thus for open
cup flash point a higher temperature is reached due to cool air than
for the closed flash point; the difference is greater, the higher the
flash point of the oil. A lubricant with a higher flash point is more
safe. An oil with open cup flash point less than 150 C is not used as a
lubricant. The open flash point of all lubricating oils ranges from 150
C – 340 C. The flash points of fixed oils are > than for mineral oils of
similar viscosities (230-330 C for open cup).
Flash Point for Commercial Fuels
Fuel Oil 65 °C Power Kerosene 27 °C
PENSKY MARTEN’S
FLASH & FIRE POINT
APPARATUS (> 50°C)
PENSKY MARTEN'S FLASH AND FIRE POINT TESTING
I. AIM:
To determine the flash and fire points of the given fuel oil using Pensky
Marten's flash and fire point tester.
II. APPARATUS :
Pensky Marten's Flash and Fire point tester, thermometers of suitable
range and given oil to be tested.
III. THEORY :
The fire hazards involved in the storage and handling of fuel oils are
indicated by the flash and fire points. However, there is no correlation
between flash and fire points of an oil and its ignition temperature.
IV. FLASH POINT:
Flash point is minimum temperature at which an oil gives off sufficient
vapours to form inflammable mixture with air.
V. FIRE POINT:
Fire point is the minimum temperature at which an oil produces a mixture
of its vapours and air that will burn continuously once ignited, even after
the removal of test flame.
Viscosity:
When two surfaces are entirely separated by a film
of lubricant the frictional force is entirely due to
viscosity of lubricant. The two surfaces are said to
operate in hydrodynamic or 'fluid film" friction. The
Viscosity of fluid is defined as the shearing force per
unit area required to produce a velocity gradient of
unit volume.
(F/A)
Viscosity = ------------
(dV/dY)
where F = Force required to produce the velocity
gradient; A = Area of liquid film.
V = Fluid velocity at a distance Y from stationary
plate.
The Viscosity of a fluid is an important property
in the analysis of liquid behavior and fluid
motion near solid boundaries.
The viscosity is the fluid resistance to shear or
flow and is a measure of the adhesive/ cohesive
or frictional fluid property.
The resistance is caused by intermolecular
friction exerted when layers of fluids attempts to
slide by another.
The knowledge of viscosity is needed for proper
design of required temperatures for storage,
pumping or injection of fluids
The viscosity measures the resistance to the flow
of a fluid and is inversely proportional to its fluidity.
Greater the viscosity of a fluid, greater is the load
under which it can maintain a continuous film, for
liquids it decreases and for gases it increases with
temperature.
The change per degree C is greater for mineral oils.
The viscosities of oils when measured under great
pressure are greater than the viscosities which are
measured under atmospheric pressure. The
viscosities are usually measured at 40°C and 60°C.
Viscosity and Specific Gravity of some Typical Liquids
centiPoise
(cP)
centiStokes
(cSt)
Saybolt
Second
Universal
(SSU)
Typical liquid Specific Gravity
1 1 31 Water 1.0
3.2 4 40 Milk -
12.6 15.7 80 No. 4 fuel oil 0.82 - 0.95
16.5 20.6 100 Cream -
34.6 43.2 200 Vegetable oil 0.91 - 0.95
88 110 500 SAE 10 oil 0.88 - 0.94
176 220 1000 Tomato Juice -
352 440 2000 SAE 30 oil 0.88 - 0.94
820 650 5000 Glycerine 1.26
1561 1735 8000 SAE 50 oil 0.88 - 0.94
1760 2200 10,000 Honey -
5000 6250 28,000 Mayonnaise -
15,200 19,000 86,000 Sour cream -
17,640 19,600 90,000 SAE 70 oil 0.88 - 0.94
SAYBOLT VISCOMETER I. AIM: To determine the viscosity of a lubricating oil by using a Saybolt
viscometer.
II. APPARATUS : Saybolt viscometer, stop watch and water bath thermometers.
III. THEORY : Viscosity of lubricating oils is measured by an instrument known as
viscometer. Most of the viscometers are of efflux type. In these, a measured
volume of oil at a particular temperature is allowed to efflux through a capillary
tube and the time of flow is noted in seconds. Saybolt viscometer is employed
by the oil industry in U.S.A. The units of dynamic viscosity stokes in MKS units
is centipoise and in the SI system are Mpa-s. Similarly the units of Kinematic
viscosity ν in Mks and SI units are centistoke and mVs respectively.
VISCOSITY: Viscosity is a measure of resistance to relative translational
motion of adjacent layers of a fluid. It is a property of a fluid. The units of
viscosity is poise and centipoise.
Specific Viscosity : Specific Viscosity is the ratio of the viscosity of fluid to the
viscosity of water at 20°C. Since the water has a viscosity of 1 cp at 20°C.
Kinematic Viscosity (v): Kinematic viscosity is defined as the ratio of dynamic
viscosity to the density of the fluid.
An instrument used in the measurement of the
degree Engler, a measure of viscosity; the
kinematic viscosity ν in stokes for this instrument
is obtained from the equation
ν = 0.00147t - 3.74/t,
where t is the efflux time in seconds.
Degree Engler: A measure of viscosity;
the ratio of the time of flow of 200 milliliters
of the liquid through a viscometer devised
by Engler, to the time for the flow of the
same volume of water.
Engler's Viscometer
Aim: To find the viscosity of a given sample of Lubricating oil
Appartus: Engler Viscometer, 200cc of standard flask, Thermometer,
Stop Watch, Spirit Level
Description: The apparatus consists of an oil cup made of brass is
placed centrally in a bath containing water. Inside the oil cup there are
three gauges to the level of its tips in which oil is to be poured. There is
a standard orifice at the center of the base of the cup. The lower end of
the oil cup is provided with a thermometer for recording the temperature
of the oil and to insert a Bakelite valve sticks. The whole bath is centrally
located for the purpose to stop or to allow the flow of the oil through the
orifice. The oil cup is surrounded by a water bath, which is heated by
means of an electric heating element. The bath is provided with stirrer
and a thermometer holding device. The whole apparatus is mounted on
a tripod stand, which can be leveled by the adjustment of leveling feet.
Procedure:
Clean the oil cup & dry it.
Pour the water in the water bath & level the instrument filter
Filter the oil and pour it into oil cup up to the mark.
In a careful and controlled manner heat the water and stir it
continuously until desired temperature is reached.
Stop stirrer and place the clean 200cc flask below the orifice,
Lift the valve stick by means of Hydrometer.
Determine the specific gravity of the oil at different temperatures and
use these densities for further calculations.
Calculate the kinematic and absolute viscosity and tabulate the
results.
Kinematic Viscosity = At - (B/t) centistokes.
Where A&B are Engler Viscometer constants A=0.147, B=374
Time taken for 200cc of oil to flow through the orifice at particular temperature.
Absolute Viscosity = Kinematic Viscosity x Density
Redwood viscometer: A standard British-
type viscometer in which the viscosity
is determined by the time, in seconds,
required for a certain quantity of liquid
to pass out through the orifice under
given conditions; used for determining
viscosities of petroleum oils.
BOMB CALORIMETER (SOLIDS & LIQUIDS)
AND
JUNKER’S CALORIMETER (GASES)
PURPOSE:- Bomb calorimeter is used to determine the
enthalpy of combustion, ΔHcomb, for hydrocarbons.
CxHyOz(s) + (2x+y/2-z)O2(g) -> x CO2 (g)+y H2O(l)
Since combustion reactions are exothermic (gives
off heat); Δ Hcomb is negative.
SIGNIFICANCE:- Measure the heat producing capacity of
the solid /liquid/gaseous fuels
INTRODUCTION:- During oxidization of many materials
energy is released. The materials which produce
significant amount energy are general identified as fuels.
FUELS:- The fuels generally implies hydrocarbon fuels.
The fuels and their major uses are given in the table
FUELS USES
Solid
1.1 Coal(*)
a. Anthracite -steel making
b. Bituminous - electricity generation,
industrial boilers and furnaces
c. Sub- Bituminous -do
d. Lignite - electricity generation
e. peat -do
1.2 woods - cooking, small industries
1.3 cow dung - cooking
1.4 agro-waste - industrial boiling
1.5 garbage-urban - electric power generation
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FUEL USES ------------------------------------------------------------------------------------------------------
2.liquid
2.1 crude oil (*) - electricity generation,
industrial furnace and boilers.
2.2 crude oil derivatives
a. aviation turbine fuel (AFT) - gas turbines used in aviation and
military aircraft, ships, Tanks.
b. light diesel oil - tractors, Boilers and Furnaces.
kerosene - furnace, cooking, boilers
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GASEOUS USES
3.1 natural gas(*) and CNG)* - electricity Generation,
furnaces,
petrochemical and
fertilizer production,
boilers, cooking,
automobiles and
buses.
3.2 biogas - domestic cooking
3.3 liquefied petroleum gas LPG (*) - domestic and
commercial cooking,
Industrial furnace
3.4 Acetylene welding
A destructive-distillation method
for estimation of carbon residues
in fuels and lubricating oils. Also
known as Conradson carbon
test.
LAB REPORT
WRITING