Basic mechanical engineering lab manual (bmep 101-102) by varun pratap singh

Basic Mechanical Engineering
Lab Manual
(BMEP-101/102)
B.Tech. 1st
and 2nd
Semester
Department of Mechanical Engineering
By
Mr. Varun Pratap Singh
Assistant Professor
Department of Mechanical Engineering
College of Engineering Roorkee

Disclaimer
This document does not claim any originality and cannot be used as a substitute for
prescribed textbooks. The information presented here is merely a collection by the
subject faculty members for their respective teaching assignments. Various sources as
mentioned at the end of the document as well as freely available material from the
internet were consulted for preparing this document. The ownership of the information
lies with the respective authors or institutions. Further, this document is not intended to
be used for commercial purpose and the subject faculty members are not accountable
for any issues, legal or otherwise, arising out of the use of this document. The subject
faculty members make no representations or warranties concerning the accuracy or
completeness of the contents of this document and specifically disclaim any implied
warranties of merchantability or fitness for a particular purpose. The subject faculty
members shall be liable for any loss of profit or any other commercial damages,
including but not limited to special, incidental, consequential, or other damages.

Text References
1. e-Krishi Shiksha: http://ecoursesonline.iasri.res.in/
Video Reference
1. YouTube Channel: BEST MECHANICAL ENGINEERING
https://www.youtube.com/channel/UC4vN8jWyjDlyRfryqQ3izsQ/featured
2. YouTube Channel: All About Mechanical Engineering
https://www.youtube.com/channel/UCaI6gazNIAsclpelpAuCynw
3. YouTube Channel: Yantriki: The power of Machines
https://www.youtube.com/channel/UC4YmXloYijid3FKvLoXMDCA
4. YouTube Channel: LEARN AND GROW
https://www.youtube.com/channel/UCCqGTvGZgWw8mFX5KYTHCkw
5. YouTube Channel: Learn Engineering
https://www.youtube.com/c/LearnEngineering/featured
6. YouTube Channel: Mech Learner
https://www.youtube.com/channel/UChg4N8Rkxqy49cd1c91fwoQ
7. YouTube Channel: EnggOnline
https://www.youtube.com/channel/UCuKdhLcpIlsy5yKCMxDXJiQ
8. YouTube Channel: Fizică
https://www.youtube.com/channel/UCw1H787zqIj9ZtTQK2eat3Q/featured
9. YouTube Channel: Khan Academy
https://www.youtube.com/c/khanacademy/featured
10. YouTube Channel: Professor Dave Explains
https://www.youtube.com/c/ProfessorDaveExplains/featured
11. YouTube Channel: ANUNIVERSE 22
https://www.youtube.com/c/ANUNIVERSE22/featured
12. YouTube Channel: Let's Grow Up
https://www.youtube.com/channel/UCLgCKWviabKF5dINmgY669g
13. YouTube Channel: MECHANICAL TECH HINDI
https://www.youtube.com/channel/UC4G0by2AWtWgKkWIekLVQ3Q
14. YouTube Channel: The Automotives
https://www.youtube.com/c/TheAutomotives/featured
15. YouTube Channel: Cementpdm
https://www.youtube.com/channel/UCIml98oACppTHe76U-8IgSA
16. YouTube Channel: Lesics
https://www.youtube.com/channel/UCqZQJ4600a9wIfMPbYc60OQ
17. YouTube Channel: Samim Academy
https://www.youtube.com/channel/UCDmbvOmOLN5ym6tpyBWwPmQ
18. Youtube Channel: The Efficient Engineer
https://www.youtube.com/channel/UCXAS_Ekkq0iFJ9dSUIkcAkw

Basic Mechanical Engineering Lab Manual (BMEP-101/102)
List of Experiments:
S.No. NAME OF EXPERIMENTS
1. To study the Cochran, Locomotive Fire-Tube Boiler and Babcock & Wilcox Boilers.
2. To study the working & function of mountings and accessories in boilers.
3. To study 2-Stroke & 4-Stroke diesel engines.
4. To study 2-Stroke & 4-Stroke petrol engines.
5. To prepare stress-strain diagram for mild steel and cast iron specimens under tension and
compression respectively on a U.T.M.
6. To determine the Rockwell hardness no. of a specimen on the respective machines.
7. To determine the Brinell hardness no. of a specimen on the respective machines.
8. To determine the Impact strength of a specimen in Izod & Charpy Test.
9. Study of Refrigerator and refrigeration cycle
10. Study of Air Conditioner and its components

EXPERIMENT No:1
AIM: - To study the Cochran, Locomotive Fire-Tube Boiler and Babcock & Wilcox Boilers.
APPARATUS USED: - Model of Cochran, Locomotive Fire-Tube Boiler and Babcock & Wilcox
Boilers.
THEORY: - A closed vessel in which steam is produced from water by combustion of fuel.
According to A.S.M.E, “combustion of apparatus for producing or recovering heat together with the
apparatus for transferring the heat so made available to the fluid being heated and vaporized.
The primary requirements of steam generator or boiler are:
1. Water 2. Water drum 3. Fuel for heating
CLASSIFICATION OF BOILERS
Because of differences in features and characteristics of different boilers, the boilers can be
classified on the basis of the following:
 Content of tubes
 Firing method
 Mode of heating
 Pressure of steam
 Mode of circulation of working
fluid (water)
 Purpose of utilization
 Position and number of drums
 Gas passage
 Nature of draft
 Nature of heat source
 Circulation of working fluid
 Nature of Fluid used
 Boiler shell material
 Type of Fuel
 Shape of tubes and their spatial
position
 Boiler size and rating
TYPES OF BOILERS: -
a. Fire tube boiler
b. Water tube boiler
In the water tube boilers, the water is inside the tube & hot gases surrounds the tubes. For understand
difference between fire tube boiler and water tube boiler refe link.
https://www.youtube.com/watch?v=u9IzXdiRBJc&list=PLfxgbb0UqKTjd6AT2J1nj5I0c9TuHkA4
W&index=4
The various fire tube boiler are following:
(i) Lancashire boiler
(ii) Locomotive boiler
(iii) Scotch marine
(iv) Cochran boiler
(v) Cornish boiler
The various water tube boiler is following:
(i) Babcock & Wilcox boiler
(ii) Sterling boiler
(iii) Lamont boiler
(iv) Loffler boiler
(v) Benson boiler
(vi) Velox boiler

Comparative advantages and disadvantages of fire-tube and water-tube boilers:
Sr. No. Parameters Fire-tube boilers
Water-tube
boilers
1
Rate of steam
generation
slow quick
2.
Suitability for power
plants
unsuitable suitable
3.
Operating steam
pressure
Limited to 24.5 x 105
N/m2 Limited to 200 x
105
N/m2
4. Chances of explosion Less More
5.
Risk of damage due
to explosion
Much more Much less
6. Water treatment
Not very necessary as minor scaling
would not go far enough to cause
overheating and tube-bursting
Required as scaling
will lead to tube-
bursting
7. Floor space required Much Less
8.
Cost and construction
problem
More Much less
9. Transportation
Inconvenient due to large size of
the shell
Comparatively
easier
10.
Skill required for
efficient operation
Less More
11. Operating cost Less High
12. Overall efficiency Upto 75% Upto 90%

COCHRAN BOLIER
https://www.youtube.com/watch?v=sJEYSia8jTU (In English)
https://www.youtube.com/watch?v=AMBbxlAXd2A (In Hindi)
SPECIFICATIONS :-
Size = 1m. dia. X 2m. high (evaporation 20 kg/hr)
= 3m.dia.x 6m.high (evaporation 3000kg/hr)
Heating surface = 10 to 25 times grate area
Heating pressure = upto 20bar
Efficiency = 70 to 75 %
Fig: Cochran Boiler
CONSTRUCTION AND WORKING:
Simply vertical boilers of the fire tube type find favor in small plats requiring small quantities of
steam and where the floor area is limited. The most common application are steam rollers, pile
drivers, steam shovels, portable hoisting rigs and certain other mobile applications.
The coal is fed through the fire door to the grate with fire bars on it. The boiler can also work
as an oil fired unit by fitting an oil burner at fire door. The grate is then dispensed with and a lining of
fire bricks are provided beneath the furnace. The furnace has no riveted seams exposed to flame and

is pressed hydraulically from one plate to finished shape. This makes the furnace suitable to resist the
intense heat produced by the combustion of fuel.
The coal, on burning, produces hot flue gases and these hot products of combustion from the
fire box enter through the small flue pipe into the combustion chamber which is lined with fire
bricks on the outer wall of the boiler. The dome shaped furnace and the combustion chamber prevent
the loss which could otherwise occur because of combustion being retarded and much unburnt and
combustible matter leaving the furnace. The unburnt fuel is deflected back to the grate and complete
combustion is achieved in combustion chamber where high temperatures are maintained.
The hot gases passing through the horizontal smoke tubes give their heat to the water and in
doing so convert water into steam which gets accumulated in the upper portion of the shell from
where it can be supplied to the user. The flue tubes are generally of 62.5 mm. external dia. And are
165 in number. The crown of the shell is made hemispherical in shape which gives the maximum
space and strength for a certain weight of material in the form of plates. Finally, the flue gases are
discharged to the atmosphere through the smoke box and the chimney.
Parts of Cochran Boiler:
All the parts of Cochran Boiler are explained below:
1. Shell 2. Combustion Chamber 3. Grate 4. Ash Pit
5. Fire hole 6. Furnace 7. Flue Pipe 8. Fire brick Lining
9. Fire Tubes 10. Chimney 11. Manhole 12. Smokebox
13. Hemispherical Dome
An Explanation for the parts of Cochran Boiler:
The detailed explanation for the parts of Cochran Boiler is as follows.
1.Shell:
It has a cylindrical drum with a hemispherical dome at its top.
2.Combustion Chamber
Burning of fuel takes place in the combustion chamber.
3.Grate
It is the sectioned platform on which the fuel(Coal) is burnt.
4.Ash Pit:
Ash is collected from the burnt fuel placed on the grate which will deposit into the Ash pit.
5.Fire hole:
It is the hole provided to the shell to fire(burn) the fuel.
6.Furnace:
It is the region where combustion takes place and without a furnace, it is not possible to get the steam.
7.Flue Pipe:
The hot gases enter into the combustion chamber through the flue pipe only. It is a small passage that
connects the combustion chamber and firebox.
8.Fire Brick Lining:
This helps in the combustion of the fuel. After striking brick lining, the flue gases pass through the
horizontal tubes.
9.Fire Tubes:
This boiler has multi-tubular fire tubes. The fire tubes help in the exchange of heat from the hot flue
gases to the water surrounded around it. The hot flue gases from the combustion chamber travel to the
smokebox through these fire tubes only.

10.Chimney:
The chimney is attached to the smokebox which is used to transfer the flue gases coming from the fire
tubes, to the environment.
11.Manhole:
A manhole is provided for inspection and cleaning of the boiler.
12.Smokebox:
It is used to collect the flue gases and unburned fuel coming out from the combustion chamber.
13.Hemispherical Dome:
The steam is deposited in this dome after its generation from water.
Other Boiler mountings and accessories attached to this boiler are:
Pressure Gauge:
It measures the pressure of steam inside the boiler.
Water level Indicator:
The water level in the boiler is indicated by the water level indicator.
Safety Valve:
It blows off the steam when it reaches beyond the safety level inside the boiler.
Blow off Cock:
It is used to blow off the impurities present in the boiler water.
Applications of Cochran Boiler:
The applications of Cochran Boiler are as follows.
 It is used in refining units
 It is used in paper and pulp manufacturing plants.
 It is also useful in chemical processing plants.
Advantages of Cochran Boiler:
The advantages of Cochran Boiler are as follows.
 Low initial installation cost.
 Transportation of the Cochran boiler is easy.
 Easy to operate and handle.
 It requires less floor area.
Disadvantages of Cochran Boiler:
The disadvantages of Cochran Boiler are as follows.
Low rate of steam generation.
It has a limited pressure range.
The installation requires a large area due to its vertical design.
Inspection and maintenance are difficult.
Recommended Videos
1. THERMAL POWER PLANT कै से काम करता है?
https://www.youtube.com/watch?v=7vKnGuA-UaM

Locomotive Fire-Tube Boiler
1. https://www.youtube.com/watch?v=3-chU6fuJPg (In Hindi)
3. https://www.youtube.com/watch?v=r9PMDJxN3zY (In English)
Features and characteristics
 The locomotive boiler is shown in below mentioned figure.
 internally fired,
 horizontal, multi-tubular, fire tube,
 natural circulation,
 artificial draft,
 portable boiler.
 It is so designed that it is capable of meeting the sudden and fluctuating
demands of steam which may be imposed on it because of variation of power
and speed.
 The steam pressure ranges from 12.6 bar to 21 bar and the capacity varies
from 900 to 4000 kg per hour.
Uses
It is mainly used in locomotives though it may also be used for stationary power service where semi-
portability is desired.
Construction
It consists of a cylindrical steel shell or barrel with a rectangular fire-box/furnace at the back end and
a small smoke box at the front end. The fire-box has a combustion chamber with fire grate at the
bottom. The fire box is water cooled on all the three sides except the bottom. A fire door is provided
in the fire box through which coal is introduced into the grates. The fire brick arch in the fire box is
provided to deflect the flames and hot flue gases upwards so that they come in close contact with the
heating surface of the fire box. Ash pit is provided under the grate for depositing the ash.
Fig. Locomotive Boiler
The horizontal fire tubes are placed longitudinally inside the shell through which the hot gases pass
from the furnace to the smoke box. These tubes are always immersed in water. Some of these tubes

are of larger diameter and others of smaller diameter. The superheated tubes of small diameter are
placed inside the fire-tubes of larger diameter. A smoke box door in front of the smoke box gives
access to fire tubes for cleaning, inspection and repairing of the boiler.
A short chimney is provided on the smoke box to discharge hot gases from the smoke box into the
atmosphere. The height of the chimney is kept low so that when the locomotive is passing through a
tunnel or under a bridge, the chimney does not strike against the top. Moreover, a high chimney is
likely to create unbalancing and friction while the engine is in motion.
The steam dome is located at the Centre of the shell from which steam is supplied to superheater to
steam engine. The function of dome is to increase the steam release capacity and to increase the
distance of steam from water line which reduces priming.
The various mountings and accessories such as feed check valve, safety valve, whistle etc., are
attached to the boiler.
Working
(i) Path of Flue gas: The hot gaseous products from fire box pass through the series of fire tubes and
pass out to the smoke box from where they go out into the atmosphere through a short chimney. In
this boiler the flue gas completes its path only in one pass. During the travel of hot gases from the
grate to the chimney, they give heat to the water and generate steam.
(ii) Path of steam flow: The water is pumped into the boiler and heated through heating surface of
the boiler until steam is produced. The steam so generated is collected over the water surface in the
steam dome. The dry saturated steam from steam dome is then supplied to the steam engine by
turning lever fitted in the cab. In order to get superheated steam, the steam from steam dome is
directed into the superaheaters tubes through the Superheater header with the help of a regulator and
lever arrangement. The superheated steam thus formed is supplied to the steam engine by a
superheater exit pipe attached to the superheater exit header.
(iii) Draft system:
Because the chimney is short, the draft produced by natural circulation is not possible so the artificial
draft has to the created to drive out the burnt gases.
The artificial draft is created by either motion of steam engine on rails or periodic rush of spent steam
from the steam engine or a blower is mounted at the inlet of the chimney.
Advantages
 The compactness,
 high steaming capacity,
 mobility and low cost of installation.
Weaknesses
 Corrosion in the water legs,
 not capable of meeting very high overloads,
 joint leakages,
 sluggishness of water circulation
 limited maximum steam pressure of 20 bars are the weaknesses in this boiler.

BABCOCK & WILCOX BOILER
1. https://www.youtube.com/watch?v=drKzWXItr5Q (In Hindi)
2.https://www.youtube.com/watch?v=1naB_pM9Nso&list=PLfxgbb0UqKTjd6AT2J1nj5I0c9TuHk
A4W&index=3 (In English)
WATER TUBE-BOILERS
As discussed under boiler classification, in a water-tube boiler, the water flows inside horizontally,
vertically or through inclined tubes and flue gasses flow over the tubes. Under this category, the
Babcock Wilcox water-tube boiler is discussed as under. The water tube boilers are used exclusively,
when pressure above 10bar and capacity in excess of 7000kg./hr. is required.
Fig. Babcock Wilcox Boiler
Babcock Wilcox Water-Tube Boiler
Features and characteristics
 This boiler is
 a stationary
 longitudinal drum,
 externally fired,
 natural circulation,

 water tube boiler.
 It is suitable for all types of fuels.
 Evaporative capacity in this boiler ranges from 1800 to 40,000 kg/h.
 Operating pressures ranges from 11.5 to 17.5 bar. But the operating pressures may be
as high as 42 bar.
Uses
As it is suitable for small size thermal power plants, it may be used for stationary or marine
purposes.
DIMENSION & SPECIFICATIONS:
Diameter of the drum
Length of the drum
Size of the water tubes
Size of the super heater tubes
Working pressure
1.22 to 1.83m.
6.096 to 9.144m.
7.62 to 10.16cm.
3.84 to 5.71cm.
40bar (max.)
Steaming capacity 40000kg./hr.(max.)
Efficiency 60-80%
CONSTRUCTION & WORKING:-
Babcock & Wilcox boiler with longitudinal drum. It consists of a drum connected to a series
of front end and rear end header by short riser tubes. To these headers are connected a series of
inclined water tubes of solid drawn mild steel.
The inclination of tubes to the horizontal is about 15 degree or more. A hand hole is provided
in the header in front of each tube for cleaning & inspection of tubes. A feed valve is provided to fill
the drum and level of water indicates by water level indicator. Fire is burnt on the grate. The hot gases
are forced to move upwards between the tubes by baffle plates provided. The water from the drum
flows through the inclined tubes via down take header & goes back into the steam the steam space of
the drum. The steam then enters through the anti-priming pipe and flows in the super heater tubes
where it is further heated and is finally taken out through the main stop valve and supplied to the
engine when needed.
Working
(i) Path of Flue gas: The hot gases from the furnace first rise upwards and then go down and then
rise up again outside the water tube before it finally come out in the atmosphere through the chimney.
The flow path of hot gases is shown by the arrows outside the tubes. During their travel they give heat
to water and steam is formed.
(ii) Path of steam-water circulation: Feed water is supplied into the drum by a feed water inlet pipe.
As the water in the water tube near the uptake header comes in contact with the hot gases at higher
temperature, that portion of water gets evaporated. As a result the mixture of hot water and steam from
this portion of the tube rises in the uptake header and then arrives in the steam water drum. In the
steam drum, the steam vapors escape the water surface and collected in the upper half of the drum. On

other hand, the cold water flows from the drum to the water tubes through the down-take header. Thus
a continuous natural cycle of water in boiler is completed.
(iii) Superheater arrangement: When superheated steam is desired to be produced, the steam
accumulated in the steam space in the drum is allowed to enter into the superheater tubes via
antipriming pipe. The flue gases passing over the superheater tubes produce superheated steam. The
superheated steam from superheater tube is then finally supplied to the work generating device through
a steam stop valve.
(iv) Draft system: The supply of air to the grate is usually done naturally with the help of a chimney.
APPLICATIONS: -
The steam generated is employed for the following purpose :
1. For generating power in steam engines or steam turbines.
2. In the textile industries for sizing & bleaching etc. and many other industries like sugar mills,
chemical industries.
3. For heating the building in cold weather & for producing hot water supply.
4. Steam turbine propelled ships and other marine vessels.
5. Agriculture field machineries, saw mills etc.
6. Steam locomotive.
7. To study steam to the steam engine for driving industries hoists, road rollers, in road
constructions, pumps in coal mine.
PRECAUTIONS :-
 Do not feed water fully the drum.
 Water level should be checked properly.
 Pressure should not be over the rating pressure.
 Clean the boiler time to time.
 Boiler operator should be present there.
VIVA-QUESTIONS: -
 What is the main pre-requirement for boilers ?
 How many types of water tube boilers ?
 How many types of fire tube boilers ?
 How many types of mountings in boiler ?
 What is the functions of mountings ?
 How many types of accessories in boiler ?
 What is the functions of accessories ?
 Why use super heater & air-pre-heater ?

EXPERIMENT No:2
https://www.youtube.com/watch?v=_WEBDgdh5g4 (In Hindi)
https://www.youtube.com/watch?v=rgg-shjBNzU (In English)
AIM:- To study the working and function of mountings & accessories in boiler.
APPARATUS USED: - Model of Mounting & accessories in boiler.
THEORY :- For efficient operation and maintenance of safety, the boiler equipped with two
categories of components and elements.
First categories include the fittings which are primarily indicated for the safety of the boiler and for
complete control of the process of steam generation. These units are called mountings.
The mounting from an integral part of the boiler and are mounted on the body of the boiler itself.
The following mountings are usually installed on the boiler.
1. Two safety valve
2. Two water level indicators/Water Gauge
3. Pressure gauge
4. Fusible plug
5. Steam stop valve
6. Feed check valve
7. Blow- of cock
8. Man and mud hole
9.Steam Scrubbers/Anti-priming pipe
10. Air vents and vacuum breakers
11. Soot blowers
Second categories include the components which are installed to increase the efficiency of the
steam power plants and help in the proper working of the boiler unit. These fitting are called boiler
accessories. The following accessories are given below.
1. Air pre-heater
2. Economizer
3. Super heater
4. Feed pump and
5. Injector
FUNCTION, LOCATION AND WORKING OF MOUNTINGS AND ACCESSORIES: -
A) SAFETY VALVE:- The function of the safety valve is to permit the steam in the boiler to
escape to atmosphere when pressure in the steam space in the boiler. The safety valve operates in the
principle that a valve is pressed against its seat through some agency such as sturt, screw or spring by
external weight or force. when the steam force due to boiler pressure acting under the valve exceeds
the external force, the valve gets lifted off its seat and some of the steam rushes out until normal
pressure is restored again.

The commonly used safety valves are given below:
i) Dead weight safety valve
https://www.youtube.com/watch?v=WtnilTaGfPw (In Hindi)
ii) Lever safety valve
https://www.youtube.com/watch?v=J6vMtt2xVEI (In Hindi)
iii) Spring loaded safety valve
https://www.youtube.com/watch?v=6vUx2R9HNIg (In English)
iv) High steam- low water safety valve
https://www.youtube.com/watch?v=r4XoMoBKfsQ (In English)
(a) (b)
Fig. Dead Weight Safety Valve in (a) closed and (b) open position
B) WATER LEVEL INDICATOR:- https://www.youtube.com/watch?v=Nz_Cx9q2L5Y
The function of the water level indicator is to ascertain constantly and exactly the level of water in the
boiler shell. It is fitted in the front of the boiler from where it is easily visible to the operator. The unit
consists of a strong glass tube whose ends pass through stuffing boxes consists of heat resisting rubber
packing to prevent leakage steam and water. The flanges are bolted to front end plate of the boiler, the
upper flange being fitted to the steam space and the lower to water space in the boiler. There are two
cocks namely steam cock and water cock which communicate the boiler shell spaces to the gauge glass
tube. When the handle of the cocks is vertical, they are in operation and the water level in the tube
corresponds to water level in the shell. A red mark on the glass tube indicates the safe water level.

Fig: Water Level Indicator/Water gauge (a) under normal condition (b) under condition when the
glass tube breaks
C) FUSIBLE PLUG:- https://www.youtube.com/watch?v=g8ef74c8qRc
The function of the fusible plug is to extinguish the fire in the event of the boiler shell falling below a
certain specified limit. We know that when the water on heating transforms into steam, the level of
water in the boiler falls down. If the water is not replenished and the steam generation continues then
the parts, which have been uncovered by water uncovered by water may get overheated and
subsequently are melted. To safeguard against this eventuality, we use fusible plug.
The fusible plug is inserted at the box crown or over the combustion chamber at the lowest
permissible water level.
Fig.: A fusible plug (a) Under normal condition (b) Under condition when water level low

D) PRESSURE GAUGE: https://www.youtube.com/watch?v=QEms_Bgxd2A&t=0s (In Hindi)
https://www.youtube.com/watch?v=dOVofYasYT8 (In English)
Each boiler has to be provided with a pressure gauge, which record the pressure at which the steam is
being generated in the boiler. The gauge is usually mounted at the front top of the boiler shell or drum.
The gauge has to be clearly visible to the attendant so that he can easily record the pressure reading.
Fig.: Bourden’s pressure gauge with water filled U-tube siphon attachment
E) BLOW OFF COCK: - https://www.youtube.com/watch?v=XyhNoEDzS3A (In Hindi)
The blow of cock serves to drain out the water from the boiler periodically for any one of the following
reasons:
1) To discharge mud, scale and other impurities which settle down at the bottom of the boiler?
2) To empty the boiler for internal cleaning and inspection.
3) To lower the water level rapidly if the level becomes too high.
The unit is fitted at the lowest portion of the boiler. It may be mounted directly to the
boiler shell or through an boiler elbow pipe, which is fitted to the boiler shell.

Fig.: Blow off cock (a) close (b) open
F) FEED CHECK VALVE:- https://www.youtube.com/watch?v=bKJQ39hneck (In Hindi)
The feed check valve has the following two functions to perform:-
1. To allow the feed water to pass into the boiler.
2. To prevent the back flow of water from boiler in the events of the failure of the feed pump.
Fig.: Feed check valve (a) under normal condition (b) under condition when there is failure of
the feed pump
G) STOP VALVE: - https://www.youtube.com/watch?v=TowMHrl1Scc (In Hindi)
https://www.youtube.com/watch?v=0ZH8VLueoBw ( In English)
The function of the steam stop valve is to shut off or regulate the flow of steam from the boiler to the
steam pipe or from the steam pipe to the engine. When used for the former purpose, it is called junction
valve. Usually the junction valve means a regulating valve of larger size and a stop valve refers to a
regulating valve of smaller size.
The junction valve is mounted on the highest part of the steam space of the boiler and is connected to
the steam pipe, which carries the steam to the engine.

Fig.:
Steam stop valve (a) open and (b) close positions
H) MAN HOLES:- These are door to allow men to enter inside the boiler for the inspection and
repair.
Function: Man holes and hand holes are required for cleaning, inspection and repairing of the boiler.
The manhole is provided for the entrance of a man inside the boiler shell whereas hand hole is for a
hand.
Location: The manhole is provided on the boiler shell at a convenient place.
Construction: Generally, they are elliptical in shape and cover is provided. The size of the man hole
is usually 400 mm x 300 mm.
I) SOOT BLOWERS: https://www.youtube.com/watch?v=O0XhpMkr3C4 (Animation)
https://www.youtube.com/watch?v=JlHQqzkcZ6g (Technical)
Function: It is used to blow soot and the combustion products from the tube surfaces.
Location: It is located near the water tubes inside the boiler as shown in Fig
Fig.: Soot blower

BOILER ACCESSORIES
The boiler accessories are auxiliary devices which are installed either inside or outside the boiler. The
boiler accessories are used to increase the efficiency of the boiler and for proper functioning of boiler.
The following accessories are generally used in the boiler:
(a) Economizer
(b) Air preheater
(c) Superheater
(d) Feed pump
(i) Duplex
(ii) Injector
(e) Steam trap
(f) Steam separator
(g) Pressure reducing valve.
Relative Position of Superheater, Economizer and Air Preheater
The relative positions of the air pre-heater, economizer and superheater are shown in Fig.
Fig. Relative Position of Superheater, Economizer and Air Pre-heater.
I) AIR PRE HEATER: https://www.youtube.com/watch?v=2Lrka5qGcbA (Detailed Video)
https://www.youtube.com/watch?v=XuLfASz0YkU (In Hindi)
https://www.youtube.com/watch?v=-LOTzt6GuRk (In English)
Air heater or air pre-heater are waste heat recovery device in which the air on its way to the furnace is
raised in temperature by utilizing the heat of the exhaust gases. Air pre-heater are classified into the
following two categories.
 Recuperative Air heater
 Regenerative Air heater

Fig.: Tubular Air Preheaters
Fig.: Plate air-preheater
K) STEAM SUPER HEATER: https://www.youtube.com/watch?v=y5jsjBndgq8 (In English)
The steam generated by a simple boiler in generally wet or at the driest saturated. Steam super heater
is a surface heat exchanger in which the wet steam is first dried at the same temperature and pressure
and then raised to temperature above the saturation temperature at constant pressure. Heat of flue

gasses utilized in super heating the steam and as the super heater is placed in the path of the flue gasses.
Since superheating result in the increased efficiency and economy of the steam plant.
L) FEED WATER EQUIPMENT: - The pressure inside a steaming boiler is high and so the feed
water has to be raised in pressure before its entry can be affected in the boiler. Feed pump is a device
which raised the pressure of water and forces it into the boiler.
M) ECONOMISER: https://www.youtube.com/watch?v=ULa3LjFB0os (In English)
The economizer is a device, which serves to recover some of the heat being carried by exhaust flue
gasses. The heat thus recovered is utilized in raised temperature in feed water being supplied to the
boiler. If the water at raised and thus there is a saving in the consumption of fuel. The economizer unit
is installed in the path of the flue gasses between the boiler and the chimney.
Fig.: Lancashire boilers fitted with an economiser
VIVA-QUESTIONS :-
 What is the main pre-requirement for boilers ?
 How many types of water tube boilers ?
 How many types of fire tube boilers ?
 How many types of mountings in boiler ?
 What is the functions of mountings ?
 How many types of accessories in boiler ?
 What is the functions of accessories ?
 Why use super heater & air-pre-heater ?

EXPERIMENT NO: 3
https://www.youtube.com/watch?v=AqLbfiUmE7Y (Working of a Two Stroke Engine -In Hindi)
https://www.youtube.com/watch?v=bQ5u7bLs1F0 (Working of a Four Stroke Engine in Hindi with
Animation)
AIM:- To study the two stroke & four stroke Diesel engine.
APPARATUS USED:- Model of two stroke & four stroke Diesel engine.
THEORY/INTRODUCTION:- Any type of engine or m/c which drives heat energy from
the combustion of fuel or any other source and converts this energy into mechanical work is
termed as a heat engine.
Heat engines may be classified into two main classes as follows:-
1. Internal combustion engine
2. External combustion engine
Recommended Videos for this practical: (In English)
1. Difference Between Internal and External Combustion Engine
https://www.youtube.com/watch?v=9rTYXPJULkQ&list=PLdoIhVhbPQV7DMtBGlFZQQUP66FU
rFJq4&index=2 ( In English)
2. Classification of Internal Combustion Engine
https://www.youtube.com/watch?v=0x67uVtqFqw&list=PLdoIhVhbPQV7DMtBGlFZQQUP66FUr
FJq4&index=2
3. Terminology of Internal Combustion Engine
https://www.youtube.com/watch?v=4XJbaurVizs&list=PLdoIhVhbPQV7DMtBGlFZQQUP66FUrF
Jq4&index=3
4. Basic components of Internal Combustion Engine
https://www.youtube.com/watch?v=RM0A1kQuXI4&list=PLdoIhVhbPQV7DMtBGlFZQQUP66F
UrFJq4&index=4
5. Difference Between Petrol (S.I) Engine And Diesel (C.I) Engine
https://www.youtube.com/watch?v=orcm9bfs88w&list=PLdoIhVhbPQV7DMtBGlFZQQUP66FUrF
Jq4&index=5
MAIN PARTS OF THE DIESEL ENGINE:
1. CYLINDER & CYLINDER HEAD
2. PISTON
3. PISTON RINGS
4. GUDGEON PIN
5. CONNECTING ROD
6. CRANK SHAFT
7. CRANK
8. ENGINE BEARING
9. CRANK CASE
10. FLY WHEEL
11. GOVERNOR
12. VALVES
13. FUEL PUMP & INJECTOR UNIT
14. CAM & CAM SHAFT

Fig: Four Stroke Diesel Engine
WORKING PROCESS OF FOUR STROKE DIESEL ENGINES
https://www.youtube.com/watch?v=31lrsp77ym0&list=PLdoIhVhbPQV7DMtBGlFZQQUP66FUrFJq4&index=10 (In English)
The various stroke of a four stroke diesel cycle engine are given below:-
A. SUCTION STROKE :- During this stroke the piston moves from TDC to BDC, the inlet
valve open and proportionate air is sucked in the engine cylinder. In fig. shown by line 5-1.
B. COMPRESSION STROKE :- In this stroke, the piston moves (1-2) towards TDC and
compressors the enclosed fuel air drawn in the engine cylinder during suction. Both the inlet
and exhaust valves remain closed during the stroke.
C. EXPANSION STROKE :- When the fuel is ignited by the spark plug the hot gases are
produced which drive or through the piston from T.D.C to B.D.C and thus the work is
obtained in this stroke. A injector which inject and & combustion takes place at constant
pressure (2-3). Both the valves remain closed during the start of this stroke but when the
piston just reaches the B.D.C the exhaust valve opens.
D. EXHAUST STROKE:- This is the last stroke of the cycle. Here the gases from which
the work has been collected become useless after the completion of the expansion stroke and
are made to escape through exhaust valve to the atmosphere. This removed of gas is
accomplished during this stroke. The piston moves from B.D.C to T.D.C and the exhaust
gases are driven out of the engine cylinder. This is also called scavenging. This is represented
by the line (1-5).

Fig: Working of Four Stroke Diesel Engine
WORKING PROCESS OF TWO STROKE DIESEL ENGINE:
https://www.youtube.com/watch?v=Kk8B-jLx_8M (In Hindi)
https://www.youtube.com/watch?v=MU1bYqmPKa4&list=PLdoIhVhbPQV7DMtBGlFZQQUP66FUr
FJq4&index=14 (In English)
In two stroke engine, the working cycle is completed into two stroke of the piston or one
revolution of crankshaft. In two stroke engine the intake and compression processes are
completed during the inward stroke and Expansion & exhaust process during the outward
stroke.
Fig: Working process of two stroke diesel engine
In figure shows a two stroke diesel engine the cylinder L is connected to a closed
crank chamber . during the upward stroke of the piston M, the gases in L are compressed and
at the same time fresh air enters the crank chamber through the valve V. when the piston moves down
wards, Valve closes and the air in the crank chamber is compressed.

(i) The piston is moving upwards & is compressing air which has previously been supplied to L.
Injector inject and Ignition takes place at the end of the stroke. The piston then travels downwards
due to expansion of the gases.
(ii) And near the end of this stroke the piston uncovers the exhaust port (E.P) and the
burnt exhaust gases escape through this port.
(iii) The transfer port (T.P) then is uncovered immediately and the compressed air from the crank
chamber flows into the cylinder and is deflected upwards by the hump provided on the head of the
piston. It may be noted that the incoming air helps the removal of gases from the engine cylinder. The
piston then again starts moving from B.D.C to T.D.C and the charge gets compressed when E.P and
T.P are covered by the piston; thus the cycle is repeated.
APPLICATIONS: -
 I.C. engines are used in all road vehicles i.e. automobiles trucks, tractors etc.
 I.C. engines are widely used in rail road, aviation & marine.
 I.C. engines are extensively used in lawn mover’s boats, concretes mining equipment etc.
 Petrol engine are used in light motor vehicles.
VIVA-QUESTIONS: -
What is scavenging?
Why the piston of a two stroke engine is made deflector type?
What is the ratio between speed of crankshaft to the speed of a camshaft?
How is an I.C. engine started?
What is supercharging? how and where is it done?
Recommended Videos:
2 Stroke Engine Vs 4 Stroke Engine
https://www.youtube.com/watch?v=kU5G20s4ILA&list=PLC53WshdV8imtkYFGnn8wRanJaOWtr
Nnq&index=2
Petrol Engine Vs Diesel Engine: Difference | Comparison
https://www.youtube.com/watch?v=D9PF8JIVy3k&list=PLC53WshdV8imtkYFGnn8wRanJaOWtr
Nnq&index=2

EXPERIMENT No:4
AIM:- To study the two stroke & four stroke petrol engine.
APPARATUS USED:- Model of two stroke & four stroke petrol engine.
THEORY/INTRODUCTION:- Any type of engine or m/c which drives heat energy from
the combustion of fuel or any other source and converts this energy into mechanical work is
termed as a heat engine.
Heat engines may be classified into two main classes as follows:-
1. Internal combustion engine
2. External combustion engine
MAIN PARTS OF THE PETROL ENGINE:
https://www.youtube.com/watch?v=RM0A1kQuXI4&list=PLdoIhVhbPQV7DMtBGlFZQQUP66F
UrFJq4&index=4 (In English)
1. CYLINDER & CYLINDER HEAD
2. PISTON
3. PISTON RINGS
4. GUDGEON PIN
5. CONNECTING ROD
6. CRANK SHAFT
7. CRANK
8. ENGINE BEARING
9. CRANK CASE
10. FLY WHEEL
11. GOVERNOR
12. VALVES
13. SPARK PLUG
14. CARBURATOR
15. CAM & CAM SHAFT
Fig: Different Components of Four Stroke Petrol Engine

WORKING PROCESS OF OTTO FOUR STROKE ENGINES
https://www.youtube.com/watch?v=E_fR6jOpxN4&list=PLdoIhVhbPQV7DMtBGlFZQQUP6
6FUrFJq4&index=8 (In English)
The various stroke of a four stroke (Otto) cycle engine are given below: -
Fig: Working Process of Otto Four Stroke Engines
A. SUCTION STROKE: - During this stroke the piston moves from TDC to BDC, the inlet
valve open and proportionate fuel-air mixture is sucked in the engine cylinder. In fig. shown
by line 5-1.
B. COMPRESSION STROKE :- In this stroke, the piston moves (1-2) towards TDC and
compressors the enclosed fuel air mixture drawn in the engine cylinder during suction. Both the inlet
and exhaust valves remain closed during the stroke.
C. EXPANSION STROKE :- When the mixture is ignited by the spark plug the hot gases
are produced which drive or through the piston from T.D.C to B.D.C and thus the work is
obtained in this stroke. A spark plug which ignites the mixture & combustion takes place at
constant volume (2-3). Both the valves remain closed during the start of this stroke but when
the piston just reaches the B.D.C the exhaust valve opens.
D. EXHAUST STROKE: - This is the last stroke of the cycle. Here the gases from which
the work has been collected become useless after the completion of the expansion stroke and
are made to escape through exhaust valve to the atmosphere. This removed of gas is
accomplished during this stroke. The piston moves from B.D.C to T.D.C and the exhaust

gases are driven out of the engine cylinder. This is also called scavenging. This is represented
by the line (1-5).
WORKING PROCESS OF TWO STROKE PETROL ENGINE:
https://www.youtube.com/watch?v=J2rMh5tg8Ts&list=PLdoIhVhbPQV7DMtBGlFZQQUP66
FUrFJq4&index=13 ( In English)
In two stroke engine, the working cycle is completed into two stroke of the piston or
one revolution of crankshaft. In two stroke engine the intake and compression processes are
completed during the inward stroke and Expansion & exhaust process during the outward stroke.
In figure shows a two stroke petrol engine the cylinder L is connected to a closed crank chamber.
During the upward stroke of the piston M, the gases in L are compressed and at the same time fresh
air and fuel (petrol) mixture enters the crank chamber through the valve V. when the piston moves
down wards, V closes and the mixture in the crank chamber is compressed (in fig.).
Fig: Working Process of Two Stroke Petrol Engine
1. The piston is moving upwards & is compressing an explosive charge which has
previously been supplied to L. Ignition takes place at the end of the stroke. The
piston then travels downwards due to expansion of the gases.
2. And near the end of this stroke the piston uncovers the exhaust port (E.P) and the
burnt exhaust gases escape through this port.
3. The transfer port (T.P) then is uncovered immediately and the compressed charge
from the crank chamber flows into the cylinder and is deflected upwards by the
hump provided on the head of the piston. It may be noted that the incoming air petrol
mixture helps the removal of gases from the engine cylinder, if in case these exhaust
gases do not leave the cylinder the fresh charge gets diluted and efficiency of the
engine will decreases. The piston then again starts moving from B.D.C to T.D.C and

the charge gets compressed when E.P and T.P are covered by the piston, thus the
cycle is repeated.
APPLICATIONS: -
 I.C. engines are used in all road vehicles i.e. automobiles trucks, tractors etc.
 I.C. engines are widely used in rail road, aviation & marine.
 I.C. engines are extensively used in lawn mover’s boats, concretes mining equipment etc.
 Petrol engine are used in light motor vehicles.
Table: Comparison of SI and CI engines
SI Engine CI Engine
Fuel used is petrol, LPG or CNG etc. Fuel used is Diesel oil.
It works on OTTO cycle. It works on Diesel or Dual combustion cycle.
Power Required to start the engine is less Power required to start the engine is more.
Compression ratio is low in the range of 7 to 9. Compression ratio is high in the range of 15 to 24.
Fuel supply system is either through carburetor or
through Electronic Multi Point Fuel Injection (MPFI)
system.
Fuel supply system is any type of high pressure
fuel injection system like Direct Injection (D.I.), Common Rail
Diesel Injection (CRDI) etc.
Maximum pressure does not exceed 60 bars. So SI
engine is comparatively light in weight.
Maximum pressure exceeds up to 120 bar or even more. So,
more robust construction and heavier than SI Engine.
High RPM, Low Torque Low RPM, High Torque
Power output is governed by controlling the quantity
of fresh charge supply to engine. So SI Engine uses
quantity governing.
Power output is governed by controlling the quantity of fuel
only to be injected while air quantity remains same. So CI
engine uses quality governing.
Its running cost is high. (Less fuel efficiency) Its running cost is low. (More fuel efficiency)
Its initial cost is low. Its initial cost is high.
It’s maintenance cost is low. Its maintenance cost is high.
Not used in case of high power requirement due to
lesser fuel efficiency
Not used in case of low power requirement due to bulky and
costly.
It has high power to weight ratio. It has low power to weight ratio
Their use is limited to two-wheeler automobiles and
personal cars only. May also be used in some other small
applications where light engine is primary requirement.
These are used in heavy-duty vehicles, Electric Gen Sets and
other heavy-duty power applications where low running cost is
primary requirement.

Figure: Comparison of SI and CI engines
Table: Comparison of two stroke cycle and four stroke cycle
engines
Four Stroke Cycle Engine Two-Stroke Cycle Engine
1) Working cycle of engine completes in four strokes of
piston or two revolutions of engine.
1) Working cycle completes in only two strokes of piston or
one revolution of engine.
2) One Stroke is working and next three strokes are idle.
So torque output is not so uniform hence heavy flywheel will
be needed to smooth the pulsating torque.
2) Each alternate stroke is power/working stroke. So more
uniform torque is obtained hence lighter flywheel is sufficient.
3) Due to only one working stroke in two revolutions of
engine, power output will be less.
3) Due to one working stroke for each revolution of engine,
power output will be more. Theoretically, it should be double
than that of a same size of 4-S Engine but in actual it is about
1.3 times of a 4-S engine
4) For a given power, the weight of engine is more because
of valve operating mechanism and also because of less
power output as discussed in previous point of comparison.
4) For a given power, the engine is light and compact due to
absence of valve operating mechanism and also due to more
power output of engine as discussed in previous point of
comparison.
5) Because of the above mentioned facts, the cooling and
lubrication requirements are less. Life is more because of
less wear and tear.
5) Because of above mentioned facts, the cooling and
lubricating requirements are more. Life is less because of more
wear and tear.
6) High Initial Cost. 6) Low Initial Cost.
7) High Thermal Efficiency. 7) Low Thermal Efficiency due to poor scavenging.
8) Part load efficiency better than 2-S Engine. 8) Part-load efficiency is poor than a 4-S Engine.
9) It is used where thermal efficiency and long life is more
important.
9) It is used where compactness and light weight of engine is
more important than to be fuel efficient.

VIVA-QUESTIONS: -
 What is scavenging?
 Why the piston of a two stroke engine is made deflector type?
 What is the ratio between speed of crankshaft to the speed of a camshaft?
 How is an I.C. engine started?
 What is supercharging? how and where is it done?
Recommended Videos:
1. How an engine works - comprehensive tutorial animation
https://www.youtube.com/watch?v=zA_19bHxEYg

2. How a Car Engine Works
https://www.youtube.com/watch?v=ZQvfHyfgBtA
3. Understanding Anti-lock Braking System (ABS)
https://www.youtube.com/watch?v=98DXe3uKwfc
4. Electric Car कै से काम करती है?
https://www.youtube.com/watch?v=0cTHN9RaUiY
5. Autonomous car / self-driving car - How it works! (Animation)
https://www.youtube.com/watch?v=gEy91PGGLR0
6. अपने कार की steering और power steering को समझना
https://www.youtube.com/watch?v=O3sCpxwSh6E
7. Automatic या Manual transmission
https://www.youtube.com/watch?v=iHPzx6VtiSs
8. सीटबेल्ट | यह कै से काम करती है?
https://www.youtube.com/watch?v=42DFtFIr_8g
9. Electric cars Vs Petrol cars
https://www.youtube.com/watch?v=2UzIQhGZWDE

EXPERIMENT No: 5
https://www.youtube.com/watch?v=D8U4G5kcpcM (In English)
https://www.youtube.com/watch?v=2jElnzjx-LU (In English)
https://www.youtube.com/watch?v=AcPt6OafTe0 ( In Hindi)
AIM :- To prepare stress-strain diagram for mild steel and cast iron specimens under
tension and compression respectively on a U.T.M.
APPARATUS :- A UTM, mild steel specimen, Vernier caliper/micrometer, dial gauge &
graph paper.
Fig: UTM
THEORY :- Various m/c and structure components are subjected to tensile loading in
numerous application. For safe design of these components, there ultimate tensile strength
and ductility one to be determine before actual use. Tensile test can be conducted on UTM.
A material when subjected to a tensile load resists the applied load by developing
internal resisting force. These resistances come due to atomic bonding between atoms of the
material. The resisting force for unit normal cross-section area is known as stress.
The value of stress in material goes on increasing with an increase in applied tensile
load, but it has a certain maximum (finite) limit too. The minimum stress, at which a material
fails, is called ultimate tensile strength.

The end of elastic limit is indicated by the yield point (load). This can be sen during
experiment as explained later in procedure with increase in loading beyond elastic limit
original cross-section area (Ao) goes on decreasing and finally reduces to its minimum value
when the specimen breaks.
Fig: Specimen Specification
ABOUT OF UTM & ITS SPECIFICATIONS: -
The tensile test is conducted on UTM. It is hydraulically operates a pump, oil in oil sump,
load dial indicator and central buttons. The left has upper, middle and lower cross heads i.e;
specimen grips (or jaws). Idle cross head can be moved up and down for adjustment. The
pipes connecting the lift and right parts are oil pipes through which the pumped oil under
pressure flows on left parts to more the cross-heads.
SPECIFICATIONS :-
1. Load capacity = 0-40000 kgf.
2. Least count = 8kgf.
3. Overall dimension =
4. Power supply = 440V
PROCEDURE :-
1. The load pointer is set at zero by adjusting the initial setting knob.
2. The dial gauge is fixed and the specimen for measuring elongation of small amounts.
3. Measuring the diameter of the test piece by Vernier caliper at least at three places and
determine the mean value also mark the gauge length.
4. Now the specimen is gripped between upper and middle cross head jaws of the m/c.
5. Set the automatic graph recording system.
6. Start the m/c and take the reading.
7. The specimen is loaded gradually and the elongation is noted until the specimen breaks.

Fig: Stress Strain diagram for ductile material
Fig: Stress Strain diagram for different material

OBSEVATION :-
 Initial diameter of specimen d1 = ------
 Initial gauge length of specimen L1 = -----
 Initial cross-section area of specimen A1 = ----
 Load of yield point Ft. = -----
 Ultimate load after specimen breaking F = -----
 Final length after specimen breaking L2 = ------
 Dia. Of specimen at breaking place d2 = -------
 Cross section area at breaking place A2 = ----
CALCULATION:-
 Ultimate tensile strength = ------
 Percentage elongation % = ------
 Modulus of elasticity E = --------
 Yield stress = --------
 % reduction in area = -------
PRECAUTIONS :-
1. The specimen should be prepared in proper dimensions.
2. The specimen should be properly to get between the jaws.
3. Take reading carefully.
4. After breaking specimen stop to m/c.
RESULT :-
CONCLUSION :-
VIVA-QUESTIONS (Set-1) :-
 Which steel have you tested ? what is its carbon content ?
 What general information are obtained from tensile test regarding the properties of a material ?
 Which stress have you calculated : nominal stress or true stress ?
 What kind of fracture has occurred in the tensile specimen and why ?
 Which is the most ductile metal ? How much is its elongation?
VIVA QUESTIONS (Set-2):
Define the following terms
1. Elasticity. 2. Plasticity 3. Rigidity 4. Ductility 5. Toughness 6. Brittleness
7. Stress. 8. Strain 9. Tensile Stress 10. Shear Stress 11. Limit of Proportionality 12.
Elastic Limit 13. Yield Point 14. Upper Yield Point 15. Lower Yield Point 16. Strain
Hardening. 17. Proof Stress. 18. Modulus of Resilience.
19. Resilience. 20. Percentage Elongation 21. Percentage Reduction in Area 22.
True Stress 23. True Strain 24. Ultimate Strength 25. Breaking Strength
26. Elastic Constants 27. Young’s Modulus 28. Shear Modulus or Modulus or Rigidity
29. Bulk Modulus 30. Poissons/Ratio 31. Modulus of Elasticity for Mild Steel,
Copper, Aluminum, Cost Iron etc. 32. Examples for Ductile Materials 33. Examples for Brittle

Materials 34. Examples for Malleable Materials 35. Failure of Ductile Material under
Tension 36. Failure of Brittle Material under Tension.
.
Recommended Videos:
1. Vickers Hardness Test
https://www.youtube.com/watch?v=7Z90OZ7C2jI
2. Ultrasonic Testing
https://www.youtube.com/watch?v=UM6XKvXWVFA

Experiment No: 6
ROCKWELL HARDNESS TEST
https://www.youtube.com/watch?v=G2JGNlIvNC4 (In English)
https://www.youtube.com/watch?v=gZLULc3GgaA (In Hindi)
1. AIM: To determine the Rockwell Hardness of a given test specimen
II. APPARATUS: Rockwell Hardness testing machine, Test specimen.
III. THEORY:
HARDNESS-It is defined as the resistance of a metal to plastic deformation against Indentation,
scratching, abrasion of cutting. The hardness of a material by this Rockwell hardness test method is
measured by the depth of Penetration of the indenter. The depth of Penetration is inversely proportional
to the hardness. Both ball or diamond cone types of indenters are used in this test. There are three
scales on the machine for taking hardness readings. Scale “A” with load 60 kgf or 588.4 N and
diamond indenter is used for performing tests on thin steel and shallow case hardened steel.
Scale “B” with load 100 kgf or 980.7 N and 1.588 mm dia ball indenter is used for performing tests
on soft steel, malleable iron, copper and aluminum alloys. First minor load is applied to overcome the
film thickness on the metal surface. Minor load also eliminates errors in the depth of measurements
due to spring of the machine frame or setting down of the specimen and table attachments.
The Rockwell hardness is derived from the measurement of the depth of the impression
EP = Depth of penetration due to Minor load of 98.07 N.
Ea = Increase in depth of penetration due to Major load.
E = Permanent increase of depth of indentation under minor load at 98.07 N even after removal of
Major load.
This method of test is suitable for finished or machined parts of simple shapes.
IV. PROCEDURE:
1. Select the load by rotating the Knob and fix the suitable indenter.
2. Clean the test-piece and place n the special anvil or work table of the machine.
3. Turn the capstan wheel to elevate the test specimen into contact with the indenter point.
4. Further turn the wheel for three rotations forcing the test specimen against the indenter. This will
ensure that the Minor load of 98.07 N has been applied
5. Set the pointer on the Scale dial at the appropriate position.
6. Push the lever to apply the Major load. A Dash Pot provided in the loading mechanism to ensure
that the load is applied gradually.
7. As soon as the pointer comes to rest pull the handle in the reverse direction slowly. This releases
the Major, but not Minor load. The pointer will now rotate in the reverse direction.
8. The Rockwell hardness can be read off the scale dial, on the appropriate scale, after the pointer
comes to rest.

Fig: Rockwell hardness testing machine diagram
V. OBSERVATIONS:
Material of test piece =
Thickness of test piece =

Hardness Scale used =
Minor Load =
Major Load =
VI. PRECAUTIONS:
1. For testing cylindrical test specimen, use V-type platform.
2. Calibrate the machine occasionally using standard test blocks.
3. For thin metal prices place another sufficiently thick metal piece between the test specimen and
the platform to avoid any damage which may likely occur to the platform.
4. After applying Major load, wait for some time to allow the needle to come to rest. The waiting
time vary from 2 to 8 seconds.
5. The surface of the test piece should be smooth and even and free from oxide scale and foreign
matter.
6. Test specimen should not be subjected to any heating or cold working.
7. The thickness of test piece or of the layer under test should be at least 8 times the permanent
increase of depth of “E”.
8. The distance between the centers of two adjacent indentation should be at least 4 indentation to
the edge of the test piece should be at least 2.5 times the diameter of the indentation.
VII. VIVA QUESTIONS:
1. Define Hardness.
2. Applications of Rockwell Hardness A – Scale, B-Scale, C-Scale.
3. Type of Indentor used in the Three Different Scales of Rockwell Hardness Test.
4. Different Types of Hardness Testing Methods.
5. Size of the Ball to be used in Ball Indentor of Rockwell Hardness Test.
6. Diameters of the different Balls used in Brinell Hardness Test.
7. Selection of Load in Brinell Hardness Test.
8. Selection of Load in Rockwell Hardness Test.

EXPERIMENT NO:7
BRINELL HARDNESS TEST
https://www.youtube.com/watch?v=RJXJpeH78iU (In English)
https://www.youtube.com/watch?v=v62_MjWwSRM ( In Hindi)
I. AIM: To determine the Brinell hardness of the given test specimen.
II. APPARATUS: Brinell hardness machine, test specimen. Brinell Microscope
III. THEORY:
INDENTATION HARDNESS-A number related to the area or to the depth of the impression made
by an indenter or fixed geometry under a known fixed load. This method consists of indenting the
surface of the metal by a hardened steel ball of specified diameter D mm under a given load F(kgf)
and measuring the average diameter d mm of the impression with the help of Brinell microscope fitted
with a scale. The Brinell hardness HB is defined, as the quotient of the applied force F divided by the
spherical area of the impression.
HB = Test load in kgf/surface area of indentation
IV. PROCEDURE:
1. Select the proper size of the ball and load to suit the material under test
2. Clean the test specimen to be free from any dirt and defects or blemishes.
3. Mount the test piece surface at right angles to the axis of the ball indenter plunger.
4. Turn the platform so that the bal is lifted up.
5. By shifting the lever apply the load and wait for some time.
6. Release the load by shifting the lever.
7. Take out the specimen and measure the diameter of indentation by means of the Brinell
microscope.

8. Repeat the experiment at other positions of the test piece.
9. Calculate the value of HB.
V. OBSERVATIONS:
Test Piece Material =
Diameter of Ball “D” =
Load selection F/D2 =
Test Load F =
Load application time =
Least count of Brinell Microscope =
Fig: Brinell hardness testing machine diagram

VI. PRECAUTIONS:
1. The surface of the test piece should be clean.
2. The testing machine should be protected throughout the test from shock or vibration.
3. The test should be carried out at room temperature.
4. The distance of the center of the indentation from the edge of the test piece should be at least 2.5
times the diameter of the indentation and the distance between the center of two adjacent indentations
should be at least
4 times the diameter of the indentation.
5. The diameter of each indentation should be measured in two directions at right angles and the mean
value of the two readings used for the purpose of determining the hardness number.
LIST OF PARTS
1. Main Lever 2. Hanger
3. Hanger Ve (Female) 4. Hanger Vee (Male)
5. Weight Hanger 6. Weight
7. Bottom Weight 8. Cover
9. Frame 10. Operating Lever
11. Spindle Spring 12. Spindle Shaft
13. Main Nkife Edge 14. Pivot Vee
15. Pivot Knife Edge 16. Spindle Bushing
17. Spindle 18. Ball Holder
19. Flatanvil 20. Adaptor
21. Elevating Screw 22. Adaptor
23. Hand Wheel 24. Metering Valve
Recommended Videos:

EXPERIMENT NO: 8
IZOD IMPACT TEST
https://www.youtube.com/watch?v=tpGhqQvftAo ( In English)
https://www.youtube.com/watch?v=bf_lxCwm004 ( In Hindi)
I. AIM: To perform the Izod Impact test on Metals.
II. APPARATUS: Izod impact testing machine, test specimen, Vernier caliper, steel rule
III. THEORY:
IMPACT STRENGTH: The high resistance of material to fracture under suddenly applied loads.
The types of test pieces are used for this test as given.
i. Square cross-section ii. Round cross-section
The specimens may have single, two or three notches. The testing machine should have the following
specifications. Angle between top face of grips and face holding the specimen vertical = 900 Angle of
tip of hammer = 750
 10
Angle between normal to the specimen and the underside face of the
Hammer at striking point = 100  10
Speed of hammer at impact = 3.99 m/sec
Striking energy = 168 N-M or Joules.
Angle of drop of pendulum = 900
Effective weight of pendulum = 21.79 kg.
Minimum value of scale graduation = 2 Joules.
Permissible total friction loss of corresponding energy = 0.50%
Distance from axis of rotation of distance between base of specimen notch and the point of specimen
hit by the hammer = 22 mm  0.5 mm.
The longitudinal Axis of the test piece shall lie in the plane of swing of the center of gravity of the
hammer. The notch shall be positioned so that it is in the plane of the hammer. The notch shall be
positioned so that its plane of symmetry coincides with the top face of the grips. For setting the
specimen. The notch impact strength I is calculated according to the following relation.
I=K/A
Where I = Impact Strength in Joules/m2
IV. PROCEDURE:
1. For conducting Izod test, a proper striker is to be fitted firmly to the bottom of the hammer with the
help clamping piece.
2. The latching take for Izod test is to be firmly fitted to the bearing housing at the side of the columns.
3. Adjust reading pointer along with pointer carrier on 168 J reading on the dial when the pendulum
is hinging free vertically.
4. The frictional loss of the machine can be determined by free fall test. Raise the hammer by hands
and latch in. Release the hammer by operating liver, the pointer will then indicate the energy loss due

to friction. From this reading confirm that the friction loss is not exceeding 0.5% of the initial potential
energy. Otherwise friction loss has to be added to the final reading.
5. Now raise the pendulum by hands and latch in with latch
6. The specimen for Izod test is firmly fitted in the specimen support with the help of clamping screw
and élan key. Care is to be taken that the notch on the specimen should face to pendulum striker.
7. After ascertaining that there is no person in the range of swinging pendulum. Release the pendulum
to smash the specimen.
8. Carefully operate the pendulum brake when returning after one swing to stop the oscillations.
9. Read off position of reading pointer on dial and not indicated value.
10. Remove the broken specimen by loosening the clamping screw.
The notch impact strength depends largely on the shape of the specimen and the notch.
The values determined with other specimens therefore may not be compared with each other.
V. OBSERVATION TABLE:
(a) (b)
Fig: Geometry of the (a) Charpy V-notch impact specimen (b) Izod impact specimen

Figure: Izod & Charpy Impact Test

EXPERIMENT: 9
https://www.youtube.com/watch?v=7NwxMyqUyJw (In English)
https://www.youtube.com/watch?v=JOr4V8_ZvFU (In Hindi)
AIM: Study on refrigeration Test Rig.
THEORY: Theory of Vapor compression refrigeration cycle is explained.
Figure 1: Vapor Compression Test Rig
A vapor compression refrigeration system is an improved type of air refrigeration system in which a
suitable working substance, termed as refrigerant is used. It condenses and evaporates at temperatures
and pressures close to the atmospheric conditions. The refrigerant used does not leave the system but
is circulated throughout the system alternately condensing and evaporating. The vapor compression
refrigeration system is now days used for all purpose refrigeration. It is used for all industrial purpose
from a small domestic refrigerator to a big air conditioning plant. The vapor compression refrigeration
cycle is based on the following factor: 1. Refrigerant flow rate. 2. Type of refrigerant used. 3. Kind of
application viz air-conditioning, refrigeration, dehumidification etc. 4. The operation design
parameters. 5. The system equipment’s/ components proposed to be used in the system.

The vapor compression refrigeration cycle is based on a circulating fluid media, viz, a refrigerant
having special properties of vaporizing at temperatures lower than the ambient and condensing back
to the liquid form, at slightly higher than ambient conditions by controlling the saturation temperature
and pressure. Thus, when the refrigerant evaporates or boils at temperatures lower than ambient, it
extracts or removes heat from the load and lower the temperature consequently providing cooling. The
super-heated vapour pressure is increased to a level by the compressor to reach a saturation pressure
so that heat added to vapour is dissipated/ rejected into the atmosphere, using operational ambient
conditions, with cooling medias the liquid from and recycled again to form the refrigeration cycle. The
components used are: 1. Evaporator 2. Compressor 3. Condenser and receiver 4. Throttling device,
The refrigeration cycle can be explained schematically in the two diagrams i.e. Pressure enthalpy
diagram Temperature entropy diagram.
The working of vapour compression refrigeration cycle and function of each above component is
given below.
(a)

(b)
(c)
Figure 2: Components of vapor refrigeration system

Fig: A Schematic and P-V diagram for a typical refrigeration cycle
Evaporator:
The liquid refrigerant from the condenser at high pressure is fed through a throttling device to an
evaporator at a low pressure. On absorbing the heat to be extracted from Media to be cooled, the liquid
refrigerant boils actively in the evaporator and changes state. The refrigerant gains latent heat to
vaporize at saturation temperature/ pressure and further absorbs sensible heat from media to be cooled
and gets fully vaporized and superheated.
Compressor:
The low temperature, pressure, superheated vapor from the evaporator is conveyed through suction
line and compressed by the compressor to a high pressure, without any change of gaseous state and
the same is discharge into condenser. During this process heat is added to the refrigerant and known
as heat of compression ratio to raise the pressure of refrigerant to such a level that the saturation
temperature of the discharge refrigerant is higher than the temperature of the available cooling
medium, to enable the superheated refrigerant to condense at normal ambient condition. Different
types of compressors are reciprocating, rotary and centrifugal and are used for different applications.
Condenser:
The heat added in the evaporator and compressor to the refrigerant is rejected in condenser at high
temperature/ high pressure. This superheated refrigerant vapor enters the condenser to dissipate its
heat in three stages. First on entry the refrigerant loses its super heat, it then loses its latent heat at
which the refrigerant is liquefied at saturation temperature pressure. This liquid loses its sensible heat,
further and the refrigerant leaves the condenser as a sub cooled liquid. The heat transfers from
refrigerant to cooling medium (air or water) takes place in the condenser. The sub-cooled liquid from
condenser is collected in a receiver (wherever provided) and is then fed through the throttling device
by liquid line to the evaporator. There are several methods of dissipating the rejected heat into the
atmosphere by condenser. These are water-cooled, air cooled or evaporative cooled condensers.
In the water-cooled condenser there are several types viz. Shell and tube, shell and coil, tube in tube
etc. In Evaporative cooled condenser, both air and water are used. Air-cooled condensers are prime

surface type, finned type or plate type. The selecting of the type depends upon the application and
availability of soft water.
Throttling device:
The high-pressure liquid from the condenser is fed to evaporator through device, which should be
designed to pass maximum possible liquid refrigerant to obtain a good refrigeration effect. The liquid
line should be properly sized to have minimum pressure drop.
The throttling device is a pressure-reducing device and a regulator for controlling the refrigerant
flow. It also reduces the pressure from the discharge pressure to the evaporator pressure without any
change of state of the pressure refrigerant.
The types of throttling devices are:
1.Capillary tubes 2. Hand expansion valves 3. Thermostatic expansion valve
The most commonly used throttling device is the capillary tube for application up-to approx. 10
refrigeration tons. The capillary is a copper tube having a small dia-orifice and is selected, based on
the system design, the refrigerant flow rate, the operating parameters (such as suction and discharge
pressures), type of refrigerant, capable of compensating any variations/ fluctuations in load by
allowing only liquid refrigerant to flow to the evaporator.
CONCLUSION:
Various components of the vapour compression system have been studied.
Recommended Videos:
1. 100 TON BLOCK ICE PLANT
https://www.youtube.com/watch?v=p5MT4XqFjVI
2. Industrial Refrigeration system Basics - Ammonia refrigeration working principle
https://www.youtube.com/watch?v=peVAaLIJJ6c
3. Ice Plant (Parts & Working)
https://www.youtube.com/watch?v=gwHutErsUk8

EXPERIMENT:10
https://www.youtube.com/watch?v=gVLhrLTF878 ( In English)
https://www.youtube.com/watch?v=9t5OsUCCONY ( In Hindi)
AIM: To study function and working of different parts of an Air Conditioning equipment.
APPARATUS: A model of window room air conditioner.
THEORY: A room air conditioner is a compact air conditioner unit which can be placed in a particular
room for its air conditioning. The room may be an office, a residential room such as bed room, living
room etc. The window type units are air cooled and are mounted in a window or wall of room to be
air conditioned. They do not need any ductwork. It has a complete refrigeration plane, i. e. compressor,
condenser, refrigerant, valves and evaporator coils
Fig: A fictitious pressure-volume diagram for a typical refrigeration cycle
The units are also provided with thermostat control and filtering equipment.
A window room air conditioner is shown in Fig.
A window type air conditioner consists of following sub-assembles:
Sub assembly Parts
1. System assembly a. Evaporator
b. Capillary
c. Condenser
d. Strainer
e. Compressor
2. Motor, fan and blower assembly
a. Fan
b. Blower motor
c. Motor mounting brackets

3. Cabinet and grill assembly
a. Cabinet
b. Grill
4. Switch board panel
a. Selector switch
b. Relay
c. Thermostat
d. Fan motor capacitor
WORKING:
The cool and low pressure vapour refrigerant is drawn from the evaporator to the compressor and it is
compressed to high pressure and temperature. Generally, in this refrigerant is Freon gas i.e. R-12 or
R- 22 and a hermetic compressor is used. The high pressure and temperature gas runs through a set of
coils so it can dissipate its heat and it condenses into liquid. The liquid is passed through the capillary
and then flows into the evaporator. As refrigerant comes out of capillary, its temperature and pressure
falls. This low temperature and pressure gas runs through a set of coils that allow the gas to absorb
heat and cool down the air inside the building. The compressor draws this low pressure vapour and
cycle is repeated. Most air conditioner also functions as dehumidifiers. They take excess water or
moisture from the air and exit to atmosphere through the pipe.
Some factors should be kept in mind while selecting an air conditioner for a room:
1. Size of the room
2. Wall construction, whether light or heavy
3. Heat gain through ceiling and proportion of outside wall area which is covered with glass
4. Whether the room is to be used in the day time or at night only. The exposure to the sun of the
walls of the room to be air conditioned and Room Ceiling height
5. Number of persons likely to use the room
6. Miscellaneous heat loads such as wattage of lamps, radio, television, computer, etc.

(a) Window AC
(b) Split AC
CONCLUSION:
The model of Air conditioner was demonstrated and its working was studied.
Recommended Videos:
1. Working and operation of AHU in Hindi
https://www.youtube.com/watch?v=1bhPqleGb8w
2. LG Multi Split Introduction
https://www.youtube.com/watch?v=F7k-I9x08V0

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