Milnars Pumps Internship Report: Manufacturing Process of Centrifugal Pumps

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1.1 General
Internship is the process of on-the-job training, which particularly beneficial for students with
major in technical courses. International University of Business Agriculture and Technology
(IUBAT) provide that glorious opportunity to their students of having an internship within
their bachelor program. For these purpose industry people are invited to IUBAT to talk about
their companies and experiences, often some technical courses are entirely conducted by
them. The four month internship program is another, possibly most effective, way of
achieving industry orientation. Internship helps the students to link-up their academic
experience with industry practices. I have tried my best to combine the both together. The
company I was sent for internship is Milnars Pumps Ltd. It is one of the leading pump
Manufacture companies in Bangladesh.
1.2.1. Objectives
The main objective of the report is to show the total working procedure of manufacturing
process and testing of centrifugal and submersible pumps the related other aspects of the
concept Milnars Pumps Ltd.
1.2.2. The specific objective of this report includes
 To study centrifugal pumps practically.
 To study metal casting process, pattern allowance, core making and heat treatment
process of centrifugal.
 To study the different type of metal casting furnace.
 To study different type of machine operation of centrifugal pump.
 To study testing of centrifugal & submersible pumps.
 To study different types of pump assemblies.
 To suggest probable solution of the identified problem.

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1.3 Scope
The internship report is concentrating on to instate and to shine the feasibility into the existing
industry and the sources are referred text and internet. It is containing in-depth study from
Milnars Pumps Ltd source considering the existing structure of the report. In this report I have
only focused on the manufacturing process of centrifugal pumps of the company, not on the
overall product of the industry.
1.4 Methodology
A qualitative research method has been used to carry out this study of practicum in Milnars
Pumps Ltd. They introduced us industrial foundry work in there factory. I introduce with
Induction furnace, pattern and core making, various type of machine operations. There use sand
mold casting and casting materials are cast iron, mild steel, bronze. The information of this report
has been collected from the following sources
1.5 Limitations
During Practicum in Milnars Pumps Ltd, I have got a lots of information and they are very
much cooperative and they help us a lot. This report has been prepared for only the
Centrifugal Pump & Submersible Pump. Nothing is described about the other pumps like
turbine pump, reciprocating pump, rotary pump. i focused on the manufacturing process only.
 Project time was insufficient.
 There was some safety problem.
 Updated tools is not sufficient.
 Technical term is not sufficient.
 Special tools is not sufficient& some spares parts have no available.

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Chapter: Two
Company Overview

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2.1 Introduction
Milnars Pumps Limited (MPL) has a history of over four decades. It was originally founded
in 1961 in the name of KSB Pumps Company Limited as an affiliate of KSB Germany at time
when the country was just on the verge of making a breakthrough in agricultural production of
food through small localized mechanical Irrigation system. Its factory was established at
Tongi, 20 Km north of Dhaka City on an area covering about 3.50 acres. After 1972
independence of Bangladesh, the parent company KSB Ag of Germany took direct control of
the management and renamed it as KSB Pumps Company (Bangladesh) Limited. Later in
1980, after obtaining majority of share from KSB, its operation started under the name
MILNARS PUMPS LTD. Under the new management presently, MPL is wholly owned by
AFTAB GROUP. Aftab Group is one of the leading multidisciplinary Industrial and business
house of Bangladesh. AftabGroup is involved in Banking, Engineering/manufacturing, agro-
industrial productions, garments, textile and multifarious trading activities in Bangladesh and
real-estate business in USA. The company has its own foundry in its premises at Tongi
Works. Backed-up with an on-job solid experience of more than four decades, the MPL
products are the result of forward looking techniques, modern machining and accurate &
precision tooling under the inspiring and dedicated professionalism of its 12 highly qualified
engineers and 175 skilled work personnel. Very recently, the company underwent extensive
and exhaustive program. Under the program, Induction Furnace has been installed with well-
equipped laboratory for casting of quality stainless steel (SS), other alloy steel and
sherardized graphite iron (SG) products. This modern plant is the only and first of its kind in
Bangladesh and can meet the demand of casting of different type of products of different
qualitative specification required in pump valve and other machine part/component
manufacturing. MPL pumps and its other products are manufactured according to DIN
standard and to highest design meeting international quality. Every product has to undergo
comprehensive inspection and tests in company’s most modern test bed in 2002. MPL
obtained ISO9001:2000 certification for Quality Management System, as the first and only
Pump and casting industry in Bangladesh. MPL current product lines what we believe to be
among the best and finest available in this part of the world. Hundreds and thousands of MPL
pumps can be seen at work all over Bangladesh in surface and ground water irrigation
projects, Hydro projects, And municipal water supplies as well as in various industrial
enterprises.

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2.1.1CompanyLocation
Head Office
Uttara Bank Bhaban(5th Floor)
90, Motijheel Commercial Area, Dhaka-1000
Bnagladesh, G.P.O Box No. 428
Fax : 880-2-9559431, 9563319
E-mail :sales@milnarspumps.com, milnars@bdmail.com
Web : www.milnarspumps.com
Phone : 9563526,9563436,9567203
Factory Location
Aftab Complex, Cherag Ali 89-90,Tongi I/A.
Gazipur-1704
Fax : 9815549
Phone : 9802385

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2.1.2 Vision
The company’s vision is to make progress possible through excellence in technology,
integrity and unsurpassed customer services. The company principles evolve around the idea
of providing high quality customer services with reliability and innovative practices through
persistent teamwork of responsible employees. The management of MPL strongly appreciates
the diversity in the vast amount of knowledge and experience their people bring with them to
the company. They also acknowledge the professional specialization of each company
personnel and believe that there is always something one can teach and learn from others;
hence they actively encourage everyone to work collaboratively together.
2.1.3 Mission
We manufacture and market a selected range of standard and engineered pumps and castings
of world class quality. Our efforts are directed to have delighted customers in the water,
sewage, oil, energy, and industry and building services sectors. In line with the Group
strategy, we are committed to develop into a center of excellence in water application pumps
and be a strong regional player. We want to market valves, complete system solutions and
foundry products including patterns for captive, automotive and other industries. We will
develop a world class human resource with highly motivated and empowered employees.
2.1.4 Socialcommitment
MPL places particular value on social welfare and environmental protection. Working under
the name of MPL Care, our Corporate Social Responsibility program is focused to provide a
sustainable infrastructure and basic amenities to underprivileged students at schools in the
rural areas of Pakistan. Our commitment towards our Country shines through the efforts we
put in our business and our corporate social responsibility.
2.1.5MPLCode of Conduct
The Code of Conduct constitutes the basis of compliance activities at MPL. It describes the
key legal and business policy principles that we use in our relationships with customers,
suppliers and other business partners as well as our internal cooperation. It also determines
our conduct on financial markets and in the various countries in which we work. The Code
aims to support employees in their day-to-day work

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2.1.6 Managementstructure
Figure 1: Management structure
General
Manager
Asistant
Manager
Project
Asistant
Manager
Foundry
Supervisor
Manager
Palaning
Sr.
Foremen(Quali
ty Control)
Inspector
(Quality
Control)
Draft man
Store officer Store clerk
Sub Asst.
Engineer
Planing
Assistant
Jr. Store
officer
Store clerk
Asistant
Manager
Production
Production
Codinator
Foremen
Production
Foremen
Maintains
Asistant
Manager
Personal
Time Keeper
Production
Engineer

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2.2 Company product profile and their detail
2.2.1 Product Profile:
a. ETA 40-20
b. ETA 150-26
1. Submersible Pump: 2 Models
a. Sub-B7B
b. Sub-B12B
2. Turbine Pump
3. High Pressure Multistage Pump: 2 Models
a. MOVI-30
b. MOVI-40
4. Domestic Pump
5. Sluice Valve
6. N/Return Valve
7. Jaw Plate

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2.2.2 ProductDetails of MPL
a. Centrifugal pump
Materials of construction
Volute casing, Impeller, Suction cover, Bearing stool etc. are made of Cast Iron(Bronze or SS
for special requirement)Shaft made from cold drawn carbon steel(SS for special requirement)
Specifications
Size NW 40 to 250 mm
Capacity Q Up to 550 m³/hr
Total Head H Up to 100 meter
Discharge Pressure P Up to 8.50 bar
Temperature T -10 to 130° C
Speed N Up to 2900 rpm
Applications
 Organic and Inorganic Liquids.
 Drugs and Pharmaceuticals
 Refineries, Fertilizer Plant, Petrochemical and Chemical.
 Process Industries.
 Dyes and Intermediates.
 Agricultural undertakings.
 General water supply duties for Municipal.

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b. Sluice Valves
Materials of construction
The selection of the correct material of construction for valves body from the wide
choice available is government by the pressure, the temperature and the nature of the
fluid flowing through the valves.
Standard execution
Body, dome, wedge gate, Stuffing box and hand wheel are of Cast Iron.
Face ring in body and on the gate are of Bronze, an alloy of high wearing qualities
material naturally developed for use in valves and fittings.
Spindle of forged bronze upto valve size NW 100 and stainless steel for NW 125, 150
& 200.
c. High pressure multistage pump
Specifications
Size NW 32 40
Capacity Q upto 42 m³/hr (0.41 cusec)
Total Head H upto 400 M (1300 ft)
Discharge Pressure P upto 40 Bar (570 psi)
Temperature T -10° To +140 °C
Speed N upto 2900 Rpm

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Applications
Irrigation, water, General water supply, Fountains, Pressure Boosting, Pumping of Boiler
Feed water, Cooling water and Hot water Circulation, Pumping of Condensates, firefighting
etc.
d. Deepwell Turbine Pump
Water Lubricated, vertical, Single stage or Multi stage Turbine Pump
Specifications
Well Diameter D 8″ to 20″
Delivery size NW 3″ to 8″
Bowl size A 5.5″ to 11.5″
Capacity upto 300 m³/hr
Total Head H upto 100 meter
Applications
 General water supply duties for Municipal.
 Refineries, Fertilizer Plant, Petrochemical and Chemical.
e. Submersible Pump
Specifications
Well Diameter D 6″ To 14″
Delivery size NW 50 to 250 mm

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Capacity Q Up to 3 0 m³/hr
Total Head H Up to 450 meter
Speed N Up to 2900 rpm
Voltage V 360 to 440 v
Motor rating HP Up to 250
Applications
 Pressure boosting.
 Industrial water Supply for Trade and Industry.
 Process Industries.
f. ReflexValve
Specifications
Reflux Valve is a one way shut-off device. Flap opens in one direction automatically
permitting the flow, while reversal of flow is prevented as flap door closes under the action of
gravity and back pressure.
Applications
 Irrigation & drainage.
 Pressure boosting.
 Industrial water Supply for Trade and Industry.

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g. Domestics Pumps
Applications
Used for domestic water lifting purpose.
[Any of the above products can be made from any special material as per customer’s
requirement. Also manufacture Parts and products of special alloy steel and Iron as required
by customer]
2.5 Production Capacityof Milnars Pumps Ltd.
Milnars Pumps Ltd. is involved in the assembly and manufacturing of pumps which are
essentially devices for lifting and movement or transfer of water or any other fluid. The
company’s present yearly production capacity is 20,000 Centrifugal pumps, 1,500 Deep Well
Turbine Pumps, Submersible Pumps, High Pressure Industrial Pumps and Domestic pumps of
various design and capacities, MPL also manufactures Sluice and Non-Return valves from
diameter 37 mm to 200 mm sizes.
2.6 Commitment to Customer
Our success is based upon our customer focus. We listen to and connect with customer. We
anticipate their needs and make it easy for them to do business with us. We keep promises.
We offer internal and external customer value and quality services to enrich lives and enhance
business success. We treat them with dignity and respect.
2.7 Certificate and Award and SocialActivities
In 2002, MPL obtained ISO9001:2000 certification for Quality Management System, as the
first and only Pump and casting industry in Bangladesh. MPL’s current product lines what we

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believe to be among the best and finest available in this part of the world. Hundreds and
thousands of MPL pumps can be seen at work all over Bangladesh in surface and ground
water irrigation project, BWDB Hydro projects, And Municipal Water Supplies as well as in
various industrial enterprises.
2.8 Organizationalactivities analysis
2.8.1 Marketing Mix
The marketing mix is probably the most famous marketing team. Its elements are the basic,
technical components of a marketing plan. Overall sales activities are run by two departments
one is Direct Sales and other is Dealer Sales. The department runs under the very able
guidance of Mr. Kader Khan GM, Sales, whose service background and experience of man
management has been a key factor for the success of the department.
1. Products:
 Centrifugal pump.
 Sluice Valves.
 Movi.
 Deep well.
 Turbine pump.
 Submersible pump.
 Reflux valve.
 Domestic pumps.
1. Place: Country wide.
2. Price: Competitive.
3. Promotion: Competitive.

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2.8.2 Analysis of products of MPL:
Strengths
A firm’s strengths are its resources and capabilities that can be used as a basis for developing
a competitive advantage.
 Patents
 Strong brand names.
 Cost advantages.
 Specialist marketing expertise.
 A new, innovative product or service and location of business.
Weaknesses
The absence of certain strengths may be viewed as a weakness. For example, each of the
following may be considered weaknesses.
 Poor reputation among customers.
 Lack of access to the best natural resources
 Lack of access to key distribution channels
 Undifferentiated products or services
Opportunities
The external environmental analysis may reveal certain new opportunities for profit
and growth.
 An unfulfilled customer need.
 Arrival of new technologies.
 Removal of international trade barriers.
 A developing market such as the internet.
 Market vacated by an ineffective competitor.
 Shifts in consumer tastes away from the firm’s products.
 Emergence of substitute products.
 Price wars with competitors.
 Competitor has new, innovative product or service.

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Chapter: Three
Pump Terminology

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NPSHr– NPSH required – is a function of the pump design and is the lowest value of NPSH
at which the pump can be guaranteed to operate without significant Cavitation. There is no
absolute criterion for determining what this minimum allowable NPSH should be, but pump
manufacturers normally select an arbitrary drop in total dynamic head (differential head) of
3% as the normal value for determining NPSHr.
NPSH – Net positive suction head – total head at pump suction branch over and above the
vapour pressure of the liquid being pumped.
NPSHa— NPSH available – is a function of the system in which the pump operates and is
equal to the absolute pressure head on the liquid surface plus the static liquid level above the
pump centreline (negative for a suction lift) minus the absolute liquid vapour pressure head at
pumping temperature minus the suction friction head losses.
Cavitation – Process in which small bubbles are formed and implode violently; occurs when
NPSHa<NPSHr.
Density (specific weight of a fluid)– Weight per unit volume, often expressed as pounds per
cubic foot or grams per cubic centimeter.
Flooded Suction – Liquid flows to pump inlet from an elevated source by means of gravity.
Flow – A measure of the liquid volume capacity of a pump. Given in gallons per minute
(GPM), liters per second and cubic meters per hour.
Head – A measure of pressure, expressed in meters for centrifugal pumps. Indicates the
height of a column of water being moved by the pump(without friction losses).
Pressure – The force exerted on the walls of a tank, pipe, etc. by a liquid. Normally measured
in pounds per square inch(psi) or kilopascals (kpa).
Prime – Charge of liquid required to begin pumping action when liquid source is lower than
pump. Held in pump by a foot valve on the intake line or by a valve or chamber within the
pump.
Self/Dry Priming – Pumps that draw liquid up from below pump inlet (suction lift), as
opposed to pumps requiring flooded suction.

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Specific Gravity – The ratio of the weight of a given volume of liquid to pure water.
Pumping heavy liquids (specific gravity greater than 1.0) will require more drive kilowatts.
Static Discharge Head – Maximum vertical distance (in meters) from pump to point of
discharge with no flow.
Strainer – A device installed in the inlet of a pump to prevent foreign particles from
damaging the internal parts.
Sump – A well or pit in which liquids collect below floor level; sometimes refers to an oil or
water reservoir.
Total Head – Sum of discharge head, suction lift, and friction loss.
Viscosity – The “thickness” of a liquid or its ability to flow. Most liquids decrease in
viscosity and flow more easily as they get warmer.
Valves Bypass Valve – Internal to many pump heads that allow fluid to be r ecirculated if a
given pressure limit is exceeded.
Check Valve – Allows liquid to flow in one direction only. Generally used in discharge line
to prevent reverse flow.
Foot Valve – A type of check valve with a built-in strainer. Used at point of liquid intake to
retain liquid in system, preventing loss of prime when liquid source is lower than pump.
Relief Valve – Used at the discharge of a positive displacement pump. An adjustable, spring
loaded valve opens when a preset pressure is reached. Used to prevent excessive pressure
buildup that could damage the pump or motor.

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Pump Installation Information
Figure 1: Different types of heads
Static Head – The hydraulic pressure at a point in a fluid when the liquid is at rest.
Friction Head – The loss in pressure or energy due to frictional losses in flow.
Discharge Head – The outlet pressure of a pump in operation.
Total Head – The total pressure difference between the inlet and outlet of a pump in
operation.
Suction Head – The inlet pressure of a pump when above atmospheric pressure.
Suction Lift – The inlet pressure of a pump when below atmospheric pressure.

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Chapter: Four
The Centrifugal
Pump

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4.1 Definition of Centrifugal Pump
A centrifugal pump is a rotodynamic pump that uses a rotating impeller to increase the
velocity of a fluid. Centrifugal pumps are commonly used to move liquids through a piping
system. The fluid enters the pump impeller along or near to the rotating axis and is accelerated
by the impeller, flowing radially outward into a diffuser or volute chamber, from where it
exits into the downstream piping system. Centrifugal pumps are used for large discharge
through smaller heads.
Figure 2: A centrifugal pump
4.2 Working Mechanismof a Centrifugal Pump
A centrifugal pump works by the conversion of the rotational kinetic energy, typically
From an electric motor or turbine, to an increased static fluid pressure. This action is
described by Bernoulli's principle. The rotation of the pump impeller imparts kinetic energy to
the fluid as it is drawn in from the impeller eye (centre) and is forced outward through the
impeller vanes to the periphery. As the fluid exits the impeller, the fluid kinetic energy
(velocity) is then converted to (static) pressure due to the change in area the fluid experiences
in the volute section. Typically the volute shape of the pump casing (increasing in volume), or
the diffuser vanes (which serve to slow the fluid, converting to kinetic energy in to flow work)

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are responsible for the energy conversion. The energy conversion results in an increased
pressure on the downstream side of the pump, causing flow.
Cavitation is the problems in the pump. It is defined as the phenomenon of formation of
vapor bubbles of a flowing liquid in a region where the pressure of the liquid falls below its
vapor pressure. Cavitation is usually divided into two classes of behavior: inertial (or
transient) Cavitation and non-inertial Cavitation. Inertial Cavitation is the process where a
void or bubble in a liquid rapidly collapses, producing a shock wave. Such Cavitation often
occurs in pumps, propellers, impellers, and in the vascular tissues of plants. Non-inertial
Cavitation is the process in which a bubble in a fluid is forced to oscillate in size or shape due
to some form of energy input, such as an acoustic field. Such Cavitation is often employed in
ultrasonic cleaning baths and can also be observed in pumps, propellers etc.
Figure 3: Main components of a centrifugal pump

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4.3 Different Types of Centrifugal Pump
Centrifugal Pumps are classified into three general categories:
a. Axial Flow Pumps
Axial-flow pumps differ from radial-flow in that the fluid enters and exits along the same
direction parallel to the rotating shaft. The fluid is not accelerated but instead "lifted" by the
action of the impeller. They may be likened to a propeller spinning in a length of tube. Axial-
flow pumps operate at much lower pressures and higher flow rates than radial-flow pumps.
b. Radial Flow Pumps
Often simply referred to as centrifugal pumps. The fluid enters along the axial plane, is
accelerated by the impeller and exits at right angles to the shaft (radially). Radial-flow
pumps operate at higher pressures and lower flow rates than axial and mixed-flow pumps.
Mixed-flow pumps function as a compromise between radial and axial-flow pumps. The
fluid experiences both radial acceleration and lift and exits the impeller somewhere between
0 and 90 degrees from the axial direction. As a consequence mixed-flow pumps operate at
higher pressures than axial-flow pumps while delivering higher discharges than radial-flow
pumps. The exit angle of the flow dictates the pressure head-discharge characteristic in
relation to radial and mixed-flow.
c. Mixed Flow Pumps
Mixed-flow pumps function as a compromise between radial and axial-flow pumps. The fluid
experiences both radial acceleration and lift and exits the impeller somewhere between 0 and
90 degrees from the axial direction. As a consequence mixed-flow pumps operate at higher
pressures than axial-flow pumps while delivering higher discharges than radial-flow pumps.

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The exit angle of the flow dictates the pressure head-discharge characteristic in relation to
radial and mixed-flow.
4.4 Different Parts of Centrifugal Pump:
1. Impeller. 2. Volute.
3. Discharge Nozzle. 4. Casing.
5. Bearings. 6. Seal.
7. Suction Nozzle. 8. Shaft.
9. Oil Ring.
Figure 4: Different parts of a centrifugal pump

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Impellers
The impeller of the centrifugal pump converts the mechanical rotation to the velocity of the
liquid. The impeller acts as the spinning wheel in the pump.
An impeller is a rotating component of a centrifugal pump, usually made of iron, steel,
bronze, brass, aluminum or plastic, which transfers energy from the motor that drives the
pump to the fluid being pumped by accelerating the fluid outwards from the center of rotation.
The velocity achieved by the impeller transfers into pressure when the outward movement of
the fluid is confined by the pump casing. Impellers are usually short cylinders with an open
inlet (called an eye) to accept incoming fluid, vanes to push the fluid radially, and asp lined,
keyed or threaded bore to accept a drive-shaft.
The impeller made out of cast material in many cases may be called rotor, also. It is cheaper
to cast the radial impeller right in the support it is fitted on, which is put in motion by the
gearbox from an electric motor, combustion engine or by steam driven turbine.
The rotor usually names both the spindle and the impeller when they are mounted by bolts.
The casting process, as mentioned above, is the primary method of impeller manufacture.
Smaller size impellers for clean water maybe cast in brass or bronze due to small section
thickness of shrouds and blades. Recently, plastic has also been introduced as casting
material.
Figure 5: Impeller

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Volute Casing
The volute of a centrifugal pump is the casing that receives the fluid being pumped by
the impeller, slowing down the fluid's rate of flow. A volute is a curved funnel that increases
in area as it approaches the discharge port. The volute converts kinetic energy into pressure by
reducing speed while increasing pressure, helping to balance the hydraulic pressure on
the shaft of the pump. The name "volute" is inspired by the resemblance of this kind of casing
to the scroll-like part near the top of an Ionic order column in classical, called a volute.
Figure 6: Volute Casing

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Discharge Nozzle
A discharge nozzle being located at the discharge opening of a flexible container being
deformed by external pressure to discharge the content. Liquid channel in the nozzle is open
at all times from the inlet on the container body side to the discharge opening and a part
thereof is constituted of a gap passage defined by a plurality of faces. The gap passage has
such dimensions that the content liquid stagnates under normal pressure due to its viscosity or
surface tension and does not flow through the gas passage easily and the content can be
discharged by pressing the container body. The discharge nozzle is provided with a function
for preventing the content in the fluid channel thereof and the outer air from flowing back into
the container body when the pressing force is released.
Figure 7: Discharge Nozzle
Break Bearing Stool
Break bearing Stool is made by cast iron. B.B Stool mainly uses for contains ball bearings, oil
seal, Lubricating oil and pump shaft. The electric motors rotating motion is past form B.B
stool by pump shaft. B.B stool fixed with base with buffer for avoid vibration. Its size
depends on volute casing.

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Figure 8: Break bearing stool
Shaft Sleeve
A shaft sleeve is shaped like a cylindrical hollow metal tube which is mounted over the shaft,
this offers the right amount of protection during the packing. Pump shaft, most of the times,
offer apt protection from corrosion, erosion. If we talk about the standard function of the shaft
sleeve, it would be to protect the shaft from packing wear at stuffing box.
The application of the shaft sleeve is commonly in single stage pumps. The placement of both
the sealing gland and the impeller is not direct on the shaft. The sleeve is strategically placed
amid the impeller’s bore. As far as this type of assembly is concerned, sleeve remains the
wearable part and the best part is that you don’t have to spend more as compared to the shaft.
The key task of the impeller sleeves is to offer the right amount of protection to the shaft from
damage. Various different functions, which are performed by the sleeve, are given some
specific names, in order to specify their function.
There is a prevention for sleeve rotation via a key; most of the times it is the impeller’s key. It
is through the sleeve that the impeller’s axial thrust is transferred to the external shaft nut. For
a pump with larger head, having an axial load on the sleeve is practical. The key advantages
of the design comprise of easiness and assembly & maintenance is hassle free. Right amount
of space is offered for a cartridge type mechanical seals and large seal chamber.

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There are manufacturers which prefer the sleeve, where the sleeve’s impeller end is weaved
with a thread that matches on the shaft. Especially, for this type a key is of no use and both
left & right hand threads are being replaced. This helps in tightening the frictional hold of the
packing while being on the sleeve. For the pumps having hanging impellers, varied forms of
sleeves are being put into use. There are mechanical seals which possess a cartridge design, it
may be tested for the leakage before the pump is being actually installed. In the earlier days, a
hook type sleeve used to be quite popular. The cartridge type mechanical seals has become
more and more popular, owing to which the hook type sleeves are less preferred.
Figure 9: Pump Shaft Sleeve
Wear rings
Wear rings are sacrificial components installed on the casing and impeller to inhibit fluid
from recalculating back to suction from the discharge. They provide a renewable restriction
between a closed impeller and the casing. Wear rings are often installed on both the front and
back of the impeller. When wear rings are installed on the back of the impeller, another set of
rings is installed in the back cover.

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Figure 10: Wear ring
Stuffing boxes
The stuffing box is a chamber or a housing that serves to seal the shaft where it passes
through the pump casing.
In a stuffing box, 4–6 suitable packing rings are placed and a gland (end plate) for squeezing
and pressing them down the shaft.
The narrow passage, between the shaft and the packing housed in the stuffing box, provides a
restrictive path to the liquid, which is at a high pressure within the pump casing.
The restrictive path causes a pressure drop, prevents leakage resulting in considerable friction
between the shaft and the packing, and causes the former to heat up. It is thus good practice to
tighten the gland just enough to allow for a minimal leak through the packing. This slight
leakage of the liquid acts as a lubricant as well as a coolant. Obviously, this cannot be allowed
for hazardous and toxic liquids, but then gland packings are also not used in such applications.
When pumps are handling dirty or high-pressure liquid, lantern rings are used. These are rings
with holes drilled along its circumference.
A lantern ring substitutes one of the packing rings in the stuffing box and is situated at the
pump end or midway between the packings.

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Ball Bearing
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation
between the bearing races.
The purpose of a ball bearing is to reduce rotational friction and
support radial and axial loads. It achieves this by using at least two races to contain the balls
and transmit the loads through the balls. In most applications, one race is stationary and the
other is attached to the rotating assembly (e.g., a hub or shaft). As one of the bearing races
rotates it causes the balls to rotate as well. Because the balls are rolling they have a much
lower coefficient of friction than if two flat surfaces were sliding against each other.
Ball bearings tend to have lower load capacity for their size than other kinds of rolling-
element bearings due to the smaller contact area between the balls and races. However, they
can tolerate some misalignment of the inner and outer races.
Ball bearings tend to have lower load capacity for their size than other kinds of rolling-
element bearings due to the smaller contact area between the balls and races. However, they
can tolerate some misalignment of the inner and outer races.
Figure 11: A ball bearing

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Gasket
A gasket is a mechanical seal which fills the space between two or more mating surfaces,
generally to prevent leakage from or into the joined objects while under compression.
Gaskets allow "less-than-perfect" mating surfaces on machine parts where they can fill
irregularities. Gaskets are commonly produced by cutting from sheet materials.
Gaskets for specific applications, such as high pressure steam systems, may contain asbestos.
However, due to health hazards associated with asbestos exposure, non-asbestos gasket
materials are used when practical.
It is usually desirable that the gasket be made from a material that is to some degree yielding
such that it is able to deform and tightly fill the space it is designed for, including any slight
irregularities. A few gaskets require an application of sealant directly to the gasket surface to
function properly.
Some (piping) gaskets are made entirely of metal and rely on a seating surface to accomplish
the seal; the metal's own spring characteristics are utilized (up to but not passing, the
material's yield strength). This is typical of some "ring joints" (RTJ) or some other metal
gasket systems. These joints are known as R-con and E-con compressive type joints.
.
Figure 12: Gaskets

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Gland
A gland is a general type of stuffing box, used to seal a rotating or reciprocating shaft against
a fluid. The most common example is in the head of a tap (faucet) where the gland is usually
packed with string which has been soaked in tallow or similar grease. The gland nut allows
the packing material to be compressed to form a watertight seal and prevent water leaking up
the shaft when the tap is turned on. The gland at the rotating shaft of a centrifugal pump may
be packed in a similar way and graphite grease used to accommodate continuous operation.
The linear seal around the piston rod of a double acting steam piston is also known as a gland,
particularly in marine applications. Likewise the shaft of a hand pump or wind pump is sealed
with a gland where the shaft exits the borehole.
Other types of sealed connections without moving parts are also sometimes called glands; for
example, a cable gland or fitting that connects a flexible electrical conduit to an enclosure,
machine or bulkhead facilitates assembly and prevents liquid or gas ingress
Couplings
Couplings for pumps usually fall in the category of general-purpose couplings. General-
purpose couplings are standardized and are less sophisticated in design. The cost of such
coupling is also on the lower side.
In these couplings, the flexible element can be easily inspected and replaced. The alignment
demands are not very stringent.
4.5 Pump efficiency
When we speak of the efficiency of any machine, we are simply referring to how well it can
convert one form of energy to another. If one unit of energy is supplied to a machine and its
output, in the same units of measure, is one-half unit, its efficiency is 50 percent. As simple as
this may seem, it can still get a bit complex because the units used by our English system of
measurement can be quite different for each form of energy. Fortunately, the use of constants
brings equivalency to these otherwise diverse quantities. A common example of such a
machine is the heat engine, which uses energy in the form of heat to produce mechanical
energy. This family includes many members, but the internal combustion engine is one with

35
which we are all familiar. Although this machine is an integral part of our everyday lives, its
effectiveness in converting energy is far less than we might expect.
The efficiency of the typical automobile engine is around 20 percent. To put it another way,
80 percent of the heat energy in a gallon of gasoline does no useful work. Although gas
mileage has increased somewhat over the years, that increase has as much to do with
increased mechanical efficiency as increased engine efficiency itself. Diesel engines do a
better job but still max out around 40 percent. This increase is due, primarily, to its higher
compression ratio and the fact that the fuel, under high pressure, is injected directly into the
cylinder.
Energy usage
The energy usage in a pumping installation is determined by the flow required, the height
lifted and the length and friction characteristics of the pipeline. The power required to
drive a pump ( ), is defined simply using SI units by:
where:
is the input power required (W)
is the fluid density (kg/m3)
is the standard acceleration of gravity (9.80665 m/s2)
is the energy Head added to the flow (m)
is the flow rate (m3/s)
is the efficiency of the pump plant as a decimal

36
The head added by the pump ( ) is a sum of the static lift, the head loss due to friction and
any losses due to valves or pipe bends all expressed in meters of fluid. Power is more
commonly expressed as kilowatts (103 W) or horsepower (multiply kilowatts by 0.746). The
value for the pump efficiency may be stated for the pump itself or as a combined efficiency
of the pump and motor system.
The energy usage is determined by multiplying the power requirement by the length of time
the pump is operating.
4.6 Problems of centrifugalpumps
• Cavitation—the NPSH of the system is too low for the selected pump.
• Air leaks in suction piping—If liquid pumped is water or other non-explosive, and
explosive gas or dust is not present.
• Discharge system head too high.
 Wear of the Impeller—can be worsened by suspended solids.
 Corrosion inside the pump caused by the fluid properties.
 Overheating due to low flow.
 Leakage along rotating shaft.
 Lack of prime—centrifugal pumps must be filled (with the fluid to be pumped) in
order to operate surge.
4.7 Centrifugal pumps for solids control
An oilfield solids control system needs many centrifugal pumps to sit on or in mud tanks.
The types of centrifugal pumps used are sand pumps, submersible slurry pumps, shear
pumps, and charging pumps. They are defined for their different functions, but their
working principle is the same.

37
4.8 Magneticallycoupledpumps
Small centrifugal pumps (e.g. for garden fountains) may be magnetically coupled to avoid
leakage of water into the motor. The motor drives a rotor carrying a pair of permanent
magnets and these drag round a second pair of permanent magnets attached to the pump
impeller. There is no direct connection between the motor shaft and the impeller so no
gland is needed and, unless the casing is broken, there is no risk of leakage.
4.9 Priming
Priming is the process in which the impeller of a centrifugal pump will get fully sub merged
in liquid without any air trap inside. This is especially required when there is a first start up.
But it is advisable to start the pump only after primping. If want to pump the vapors out of
casing then you have to run the pump at a speed equal to it design speed multiplied by the
ratio of specific gravity of air to water.(In case of pumping water) which is practically
impossible. Liquid and slurry pumps can lose prime and this will require the pump to be
primed by adding liquid to the pump and inlet pipes to get the pump started. Loss of "prime"
is usually due to ingestion of air into the pump. The clearances and displacement ratios in
pumps used for liquids and other more viscous fluids cannot displace the air due to its lower
density.
A "self-priming" centrifugal pump overcomes the problem of air binding by mixing air with
water to create a fluid with pumping properties much like those of regular water. The pump
then gets rid of the air and moves water only, just like a standard centrifugal pump. It is
important to understand that self-priming pumps cannot operate without water in the casing.
In order for a centrifugal pump, or self priming, pump to attain its initial prime the casing
must first be manually primed or filled with water. Afterwards, unless it is run dry or drained,
a sufficient amount of water should remain in the pump to ensure quick priming the next time
it is needed.
Reciprocating and rotary pumps are self-priming. This is an important consideration where a
prime cannot be maintained on the pump. Centrifugal pumps are not inherently self-priming,
although some manufacturers do specially design self-priming units. External priming
sources, such as an educator or vacuum pump can also be employed.

39
Chapter Five
Manufacturing
Process of
Centrifugal Pump

40
Manufacturing Process
Manufacturing process of a centrifugal pump is a combination work. Every parts of a
centrifugal pump produce individually maximum of its parts are made by casting process
some are made by machine operation. The operations are dividing by some section such as
1. Foundry shop.
2. Machine shop.
3. Assembly Section.
4. Testing Section.
Figure 15: Machine shop of MPL
5.1 Foundry Shop
Foundry shop is the place where the metal casting is prepared by melting and pouring the
molten metal into moulds. A foundry is an operating plant which manufactures castings of
metal, both ferrous and non-ferrous. Metals are processed by melting, pouring, and casting.
Iron is the most common base element processed in a modern foundry. However, other
metals, such as, aluminum, copper, tin, and zinc, can be processed.
Foundry section can have the following processes:

41
 Melting
 Furnace
 Mold making
 Pouring
 Shakeout
 Degating
 Heat treating
 Surface cleaning
 Finishing
5.1.1 Metal casting work
Casting metal is a 6,000-year-old process still used in both manufacturing and fine art. The
founder melts metal, usually aluminum, bronze and cast iron in a crucible, pours it into a
mold, then removes the mold material or the casting once the metal has cooled and solidified.
The products of the metal founding industry are manufactured in a single step from liquid
metal without intermediate operations of mechanical working such as rolling or forging.
Casting is a manufacturing process by which a liquid material is usually poured into a mold,
which contains a hollow cavity of the desired shape, and then allowed to solidify. The
solidified part is also known as a casting, which is ejected or broken out of the mold to
complete the process.
Pattern making work
A poor casting may be produced from a good pattern. But a good casting will not be made
from a poor pattern. In casting, a pattern is a replica of the object to be cast, used to prepare
the cavity into which molten material will be poured during the casting process. Patterns used
in sand casting may be made of wood, metal, plastics or other materials. Patterns are made to
exacting standards of construction, so that they can last for a reasonable length of time,
according to the quality grade of the pattern being built, and so that they will reputably
provide a dimensionally acceptable casting. Under certain circumstances an original item may
be adapted to be used as a pattern.

42
Figure 16: Pattern of Volute casing
Pattern allowance
Pattern allowances in order to produce a casting of proper size and shape depend partly on
product design, mould design, shrinkage and contraction of the metal being cast. A pattern is
always made larger than the required size of the casting considering the various allowances.
These are the allowances which are usually provided in a pattern.
1. Shrinkage allowance
2. Draft allowance
3. Distortion or camber allowance
4. Rapping or Shaking allowance
5. Finishing allowance

43
Core making work
Cores are utilized for castings with internal cavities or passages. A core is a body usually
made of sand used to produce a cavity in or on a casting cores are placed in the mould cavity
before casting to from the interior surfaces of the casting.
Figure 17: Core making
Prepare a Mold
Good castings cannot be produced without good mold. Because importance of the mold. The
first step in the sand casting process is to create the mold for the casting. In an expendable
mold process, this step must be performed for each casting. A sand mold is formed by
packing sand into each half of the mold. The sand is packed around the pattern, which is a
replica of the external shape of the casting. When the pattern is the cavity that will form the
casting remains. Any internal features of the casting that cannot be formed by the pattern are
formed by separate cores which are made of sand prior to the formation of the mold. Further
details on mole-making will be described in the next section. The mold-making time includes
positioning the pattern, packing the sand, and removing the pattern the mold-making time is a
affected by the size of the part, the number of cores, and the type of sand mold. If the mold
type requires heating or baking time, the mold-making time is substantially increased. The use
of lubricant also improves the flow the metal and can improve the surface finish of the

44
casting. The lubricant that is used is chosen based upon the sand and molten metal
temperature.
The sand casting may be made in are:
 Green sand mold
 Core sand mold
 Facing sand mold
 Backing sand mold
 Parting sand mold
 Dry sand mold
 Loam sand mold
 Cement bonded mold
 System sand mold
Prepare a mold Cavity they use some hand tools, those are:
1. Wedge
2. Gaggers
3. Blow can
4. Bellows
5. Floor rammer
6. Adjustable clamp
7. Clamp
8. Rapping iron
9. Strike
10. Rammer
11. Bench rammers
12. Molder's shovel
13. Six-foot rule
14. Cutting pliers
15. Riddle

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Rising
In addition to acting as a reservoir, a riser mitigates the hydraulic ram effect of metal entering
the mold and vents the mold. It must be the last to solidify, and to serve efficiently must
conform to the following principles. The volume of a riser must be large enough to supply all
metal needed. The gating system must be designed to establish a temperature gradient toward
the riser. The area of the connection of the riser to the casting must be large enough not to
freeze too soon. On the other hand, the connection must not be so large that the solid riser is
difficult to remove from the casting.
Induction furnace
The principle of induction melting is that a high voltage electrical source from a primary coil
induces a low voltage, high current in the metal, or secondary coil. Induction heating is
simply a method of transferring heat energy.
Induction furnaces are ideal for melting and alloying a wide variety of metals with minimum
melt losses, however, little refining of the metal is possible. There are two main types of
induction furnace coreless and channel.
Figure 18: Induction furnace
Coreless induction furnace
The heart of the coreless induction furnace is the coil, which consists of a hollow section of
heavy duty, high conductivity copper tubing which is wound into a helical coil. Coil shape is

46
contained within a steel shell and magnetic shielding is used to prevent heating of the
supporting shell. To protect it from overheating, the coil is water-cooled, the water bing
reticulated and cooled in a cooling tower. The shell is supported on trunnions on which the
furnace tills to facilitate pouring.
The crucible is formed by ramming a granular refractory between the coil and a hollow
internal former which is melted away with the first heat leaving a sintered lining.
The power cubmicle converts the voltage and frequency of main supply, ot that required for
electrical melting. Frequencies used in induction melting vary from 50 cycles per second
(mains frequency) to 10,000 cycles per second (high frequency). The higher the operating
frequency, the greater the maximum amount of power that can be applied to a furnace of
given capacity and the lower the amount of turbulence induced.
When the charge material is molten, the interaction of the magnetic field and the electrical
currents flowing in the induction coil produce a stirring action within the molten metal. This
stirring action forces the molten metal to rise upwards in the centre causing the characteristic
meniscus on the surface of the metal. The degree of stirring action is influenced by the power
and frequency applied as well as the size and shape of the coil and the density and viscosity of
the molten metal. The stirring action within the bath is important as it helps with mixing of
alloys and melting of turnings as well as homogenizing of temperature throughout the
furnace. Excessive stirring can increase gas pick up, lining wear and oxidation of alloys.
The coreless induction furnace has largely replaced the crucible furnace, especially for
melting of high melting point alloys. The coreless induction furnace is commonly used to melt
all grades of steels and irons as well as many non-ferrous alloys. The furnace is ideal for
remolding and alloying because of the high degree of control over temperature and chemistry
while the induction current provides good circulation of the melt.

47
Figure 19: Coreless induction furnace
Channel induction furnaces
The channel induction furnace consists of a refractory lined steel shell which contains the
molten metal. Attached to the steel shell and connected by a throat is an induction unit which
forms the melting component of the furnace. The induction unit consists of an iron core in the
form of a ring around which a primary induction coil is wound. This assembly forms a simple
transformer in which the molten metal loops comprises the secondary component. The heat
generated within the loop causes the metal to circulate into the main well of the furnace. The
circulation of the molten metal effects a useful stirring action in the melt.
Channel induction furnaces are commonly used for melting low melting point alloys and or as
a holding and superheating unit for higher melting point alloys such as cast iron. Channel
induction furnaces can be used as holders for metal melted off peak in coreless induction
induction units thereby reducing total melting costs by avoiding peak demand charges.

48
Figure 20: Induction furnace
5.1.2 Pouring
In a foundry, molten metal is poured into molds. Pouring can be accomplished with gravity,
or it may be assisted with a vacuum or pressurized gas. Many modern foundries use robots or
automatic pouring machines for pouring molten metal. Traditionally, molds were poured by
hand using ladles.
Figure 21: Pouring molten metal

49
5.1.3 Degasification
In the case of aluminum alloys, a degassing step is usually necessary to reduce the amount of
hydrogen dissolved in the liquid metal. If the hydrogen concentration in the melt is too high,
the resulting casting will be porous as the hydrogen comes out of solution as the aluminum
cools and solidifies. Porosity often seriously deteriorates the mechanical properties of the
metal.
An efficient way of removing hydrogen from the melt is to bubble argon or nitrogen through
the melt. To do that, several different types of equipment are used by foundries. When the
bubbles go up in the melt, they catch the dissolved hydrogen and bring it to the top surface.
There are various types of equipment which measure the amount of hydrogen present in it.
Alternatively, the density of the aluminum sample is calculated to check amount of hydrogen
dissolved in it.
In cases where porosity still remains present after the degassing process, porosity sealing can
be accomplished through a process called metal.
5.1.4 Shakeout
The solidified metal component is then removed from its mold. Where the mold is sand based,
this can be done by shaking or tumbling. This frees the casting from the sand, which is still
attached to the metal runners and gates - which are the channels through which the molten
metal traveled to reach the component itself.
5.1.5 Degating
Degating is the removal of the heads, runners, gates, and risers from the casting. Runners,
gates, and risers may be removed using cutting torches, band saws or ceramic cutoff blades.
For some metal types, and with some gating system designs, the spruce, runners and gates can
be removed by breaking them away from the casting with a sledge hammer or specially
designed knockout machinery. Risers must usually be removed using a cutting method (see
above) but some newer methods of riser removal use knockoff machinery with special designs
incorporated into the riser neck geometry that allow the riser to break off at the right place.

50
The gating system required to produce castings in a mold yields leftover metal, including
heads, risers and spruce, sometimes collectively called spruce, that can exceed 50% of the
metal required to pour a full mold. Since this metal must be remelted as salvage, the yield of a
particular gating configuration becomes an important economic consideration when designing
various gating schemes, to minimize the cost of excess spruce, and thus melting costs
5.1.6 Heat Treating
Heat treating is a group of industrial and metalworking processes used to alter the physical,
and sometimes chemical, properties of a material. The most common application
is metallurgical. Heat treatments are also used in the manufacture of many other materials,
such as glass. Heat treatment involves the use of heating or chilling, normally to extreme
temperatures, to achieve a desired result such as hardening or softening of a material. Heat
treatment techniques include annealing, case hardening, precipitation strengthening,
tempering, normalizing and quenching. It is noteworthy that while the term heat
treatment applies only to processes where the heating and cooling are done for the specific
purpose of altering properties intentionally, heating and cooling often occur incidentally
during other manufacturing processes such as hot forming or welding.
Figure 22: Heat treating

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5.1.7 Surface cleaning
After degating and heat treating, sand or other molding media may adhere to the casting. To
remove this surface is cleaned using a blasting process. This means a granular media will be
propelled against the surface of the casting to mechanically knock away the adhering sand.
The media may be blown with compressed air, or may be hurled using a shot wheel. The
media strikes the casting surface at high velocity to dislodge the molding media (for example,
sand, slag) from the casting surface. Numerous materials may be used as media, including
steel, iron, other metal alloys, aluminum oxides, glass beads, walnut shells, baking powder
among others. The blasting media is selected to develop the color and reflectance of the cast
surface. Terms used to describe this process include cleaning, bead blasting, and sand
blasting. Shot preening may be used to further work-harden and finish the surface.
5.1.8 Finishing
After completing all of casting the final step in the process usually involves grinding, sanding,
or machining the component in order to achieve the desired dimensional accuracies, physical
shape and surface finish.
Removing the remaining gate material, called a gate stub, is usually done using a grinder or
sanding. These processes are used because their material removal rates are slow enough to
control the amount of material. These steps are done prior to any final machining.
After grinding, any surfaces that require tight dimensional control are machined. Many
castings are machined in CNC milling centers. The reason for this is that these processes have
better dimensional capability and repeatability than many casting processes. However, it is
not uncommon today for many components to be used without machining. A few foundries
provide other services before shipping components to their customers. Painting components to
prevent corrosion and improve visual appeal is common. Some foundries will assemble their
castings into complete machines or sub-assemblies. Other foundries weld multiple castings or
wrought metals together to form a finished product.
More and more the process of finishing a casting is being achieved using robotic machines
which eliminate the need for a human to physically grind or break parting lines, gating
material or feeders. The introduction of these machines has reduced injury to workers, costs
of consumables whilst also reducing the time necessary to finish a casting. It also eliminates

52
the problem of human error so as to increase repeatability in the quality of grinding. With a
change of tooling these machines can finish a wide variety of materials including iron, bronze
and aluminum.
Figure 23: After casting
5.2 Defects ofcasting
A casting defect is an undesired irregularity in a metal casting process. Some defects can be
tolerated while others can be repaired, otherwise they must be eliminated. They are broken
down into five main categories: gas porosity, shrinkage defects, mold material
defects, pouring metal defects, and metallurgical defects. Logical classification of casting
defects presents great difficulties because of the wide range of contributing causes, however
rough classification may be made by grouping the defects under certain broad types of origin
such as.
 Blowhole is a kind of cavities defect, which is also divided into pinhole and
subsurface blowhole. Pinhole is very tiny hole. Subsurface blowhole only can be seen
after machining.
 Burning-on defect is also called as sand burning, which includes chemical burn-on,
and metal penetration.
 Sand inclusion and slag inclusion are also called as scab or blacking scab. They are
inclusion defects. Looks like there are slag inside of metal castings.

53
 Sand hole is a kind of shrinkage cavity defect. They are empty holes after sand
blasting.
 Cold lap or also called as cold shut. It is a crack with round edges. Cold lap is because
of low melting temperature or poor gating system.
 Joint flash is also called as casting fin, which is a thin projection out of surface of
metal castings. Joint flash should be removed during cleaning and grinding process.
 Misrun defect is a kind of incomplete casting defect, which causes the casting
uncompleted. The edge of defect is round and smooth.
 Shrinkage defects include dispersed shrinkage, micro-shrinkage and porosity.
 Shrinkage cavities are also called as shrinkage holes, which is a type of serious
shrinkage defect.
 Shrinkage depression is also a type of shrinkage defect, which looks like depressed
region on the surface of metal castings.
 Elephant skin is a type of surface defect, which cause irregular or wrinkle shapes
surfaces.
 Veins defect is also called as rat tail, which looks like many small water flow traces on
the surface of metal castings.
5.3 Machine operation
I found several machine in MPL machine shop. Operators use these machine for different
purposes. Casting the product need machine operation to remove runner and riser, surface
finishing, turning, facing, drilling, boring, knurling, slot cutting etc. Complete those
operations use some machine those are:
Turning: produce straight, conical, curved, or grooved work-pieces.
Facing
In machining, facing is the act of cutting a face, which is a planar surface, onto the work-
piece. Within this broadest sense there are various specific types of facing, with the two most
common being facing in the course of turning and boring work (facing planes perpendicular
to the rotating axis of the work-piece) and facing in the course of milling work (for
example, face milling). Other types of machining also cut faces (for

54
example, planning, shaping, and grinding), although the term "facing" may not always be
employed there. Unless the work is held on a mandrel, if both ends of the work are to be
faced, it must be turned end for end after the first end is completed and the facing operation
repeated. The cutting speed should be determined from the largest diameter of the surface to
be faced. Facing may be done either from the outside inward or from the center outward. In
either case, the point of the tool must be set exactly at the height of the center of rotation.
Because the cutting force tends to push the tool away from the work, it is usually desirable to
clamp the carriage to the lathe bed during each facing cut to prevent it from moving slightly
and thus producing a surface that is not flat. In the facing of casting or other materials that
have a hard surface, the depth of the first cut should be sufficient to penetrate the hard
material to avoid excessive tool wear.
Figure 24: Lathe operation
Boring
Boring is the process of enlarging a hole that has already been drilled(or cast), by means of
a single-point cutting tool , for example as in boring a gun barrel or an engine cylinder.
Boring is used to achieve greater accuracy of the diameter of a hole, and can be used to cut a
tapered hole. Boring can be viewed as the internal-diameter counterpart to turning, which cuts
external diameters.
There are various types of boring. The boring bar may be supported on both ends (which only
works if the existing hole is a through hole), or it may be supported at one end (which works

55
for both through holes and blind holes). Line boring (line boring, line-boring) implies the
former. Back boring (back boring, back-boring) is the process of reaching through an existing
hole and then boring on the "back" side of the work-piece (relative to the machine headstock).
Because of the limitations on tooling design imposed by the fact that the work-piece mostly
surrounds the tool, boring is inherently somewhat more challenging than turning, in terms of
decreased tool holding rigidity, increased clearance angle requirements (limiting the amount
of support that can be given to the cutting edge), and difficulty of inspection of the resulting
surface (size, form, surface roughness). These are the reasons why boring is viewed as an area
of machining practice in its own right, separate from turning, with its own tips, tricks,
challenges, and body of expertise, despite the fact that they are in some ways identical.
Parting
Parting is the operation by which one section of a work-piece is severed from the remainder
by means of a cutoff tool. Because cutting tools are quite thin and must have considerable
overhang, this process is less accurate and more difficult. The tool should be set exactly at the
height of the axis of rotation, be kept sharp, have proper clearance angles, and be fed into the
work-piece at a proper and uniform feed rate.
Threading
Threading is the process of creating a screw thread. More screw threads are produced each
year than any other machine element. There are many methods of generating threads,
including subtractive methods deformative or transformative methods additive methods (such
as 3D printing); or combinations thereof.
There are various methods for generating screw threads. The method chosen for any one
application is chosen based on constraints—time, money, degree of precision needed (or not
needed), what equipment is already available, what equipment purchases could be justified
based on resulting unit price of the threaded part (which depends on how many parts are
planned), etc.
In general, certain thread-generating processes tend to fall along certain portions of the
spectrum from tool room-made parts to mass-produced parts, although there can be
considerable overlap. For example, thread lapping following thread grinding would fall only
on the extreme tool room end of the spectrum, while thread rolling is a large and diverse area

56
of practice that is used for everything from micro lathe lead screws (somewhat pricey and
very precise) to the cheapest deck screws (very affordable and with precision to spare).
Threads of metal fasteners are usually created on a thread rolling machine. They may also be
cut with a lathe, tap or die. Rolled threads are stronger than cut threads, with increases of 10%
to 20% in tensile strength and possibly more in fatigue resistance and wear resistance.
Knurling
Knurling is a manufacturing process, typically conducted on a lathe, whereby a pattern of
straight, angled or crossed lines is cut or rolled into the material
Figure 25: Lathe operations

57
a. Center lathe operation
general operations done with the lathe are grooving, turning, cutting, sanding The and
etc. if anyone wants to operate the lathe machine then he must first know about the
feeds, cutting speed, depth of the cut and usage of tool should be considered. Each
lathe operation has got its own factors that need to be considered before doing the
work. The factors should be used properly so that one can avoid from mishandling and
mishaps while performing any kind of lathe operation. With every cut desired the
speed, depth and feed of the lathe machine is changed for precision.
Figure 26: Dead Center
A lathe center
A lathe centre, often shortened to centre, is a tool that has been ground to a point to accurately
position a work-piece on an axis. They usually have an included angle of 60°, but in heavy
machining situations an angle of 75° is used.
The primary use of a centre is to ensure concentric work is produced; this allows the work-
piece to be transferred between machining (or inspection) operations without any loss of
accuracy. A part may be turned in a lathe, sent off for hardening and tempering and then
ground between centers in a cylindrical grinder. The preservation of concentricity between the
turning and grinding operations is crucial for quality work.
A center is also used to support longer work-pieces where the cutting forces would deflect the
work excessively, reducing the finish and accuracy of the work-piece, or creating a hazardous
situation.
A centre lathe has applications anywhere that a centered work-piece may be used; this is not
limited to lathe usage but may include setups in dividing heads, cylindrical grinders, tool and

58
cutter grinders or other related equipment. The term between centres refers to any machining
operation where the job needs to be performed using centers
Figure 27: Lathe
A live center
Live center is constructed so that the 60° center runs in its own bearings and is used at the
non-driven or tailstock end of a machine. It allows higher turning speeds without the need for
separate lubrication, and also greater clamping pressures. CNC lathes use this type of center
almost exclusively and they may be used for general machining operations as well. Spring
loaded live centers are designed to compensate for center variations, without damage to the
work-piece or center tip. This assures the operator of uniform constant tension while
machining. Some live centers also have interchangeable shafts. This is valuable when
situations require a design other than a 60° male tip.

59
A drive
Center is used in the driving end of the machine (headstock). It consists of a dead center
surrounded by hardened teeth. These teeth bite into the softer work-piece allowing the work-
piece to be driven directly by the center. This allows the full diameter of the work-piece to be
machined in a single operation, these contrasts with the usual requirement where a carrier is
attached to the work-piece at the driven end. They are often used in woodworking or where
softer materials are machined. Drive Centre is also known as Grip center in some industrial
circles. Another modification made to the Drive center is that Shell End Mills are modified
and used instead of hardened pins that enable better gripping and also that used of used Shell
end mills after grinding the edges. This prevents breakdown time due to pin breakage.
b. Turret lathe
The particular sphere of the turret, and the use of the various tools and tool-holding devices,
can be best explained by illustrating and describing some of the more important operations in
the machining of castings of the usual forms.
Some of the practical observations applicable to the handling of the work and the tools are
given, and their importance should be fully realized by the novice in attempting turret-lathe
work.
Great care should be used to have all tools, tool-holders, attachments, fixtures, etc., securely
clamped in place, so that there will be no danger of their working loose, and vibration will be
eliminated as far as possible.
The tools should be ground to the correct shape, and the finishing tools should be carefully
stoned with a fine-grained oil-stone so that their cutting edges will be smooth and keen. They
will then do much smoother work, and the cutting edges will last much longer.
Generally there must be a roughing and a finishingcut, the same as in an ordinary lathe. In the
turret lathe the two cuts are made by different tools, so as to avoid constant changes of
adjustment.
Stop-gages should be carefully set so that correct dimensions may be produced when the
turret slide or cross-slide, as the case may be, is run firmly against the stop, but so that there is
no straining or forcing of it. Unless care is used in this respect, correct dimensions cannot be
maintained.
Proper speeds must be used, according to the rialto be machined and the diameter of the work.
The same speeds will be used as for engine lathes. When tapping or desire used, the speed, on
the cut, must be very materially reduced.

60
In chucking comparatively thin cylindrical work, it should be held by the outside, as there is
much less danger of breaking it than if it is held by the inside.
In machining heavy-rimmed balance wheels, they are frequently held by the inside of the rim
so as to leave the outside and face clear for the tools.
Pulleys and similar light wheels are frequently held by the arms, which rest against suitable
supports so as to avoid distortion and to leave the rims and hub free for machining operations.
In boring operations, particularly deep holes, the tool should be made with a long guiding end
or pilot, which may enter a bushing in the main spindle of the machine before the tool
commences to cut. This will reduce vibration and chatter, insure a true hole, and prolong the
life of the tool.
When the piece of work is comparatively long-that is, projects to a considerable distance from
the chuck-the outer end should be run in a center rest similar to that on an engine lathe, to
hold it true and rigid, and to insure true and accurate work.
Figure 28: A Turret lathe
The turret lathe has been in use since the mid-19th century. Its development was an important
one for manufacturers. Before the turret lathe came into existence, making quality metal tools
or components was dependent on the skill of the operator. Once it started being used in
manufacturing plants, it meant that tools and other parts could be made quicker and at a lower
cost
d. Milling machine operation
Milling is the machining process of using rotary cutters to remove material from a work-piece
advancing (or feeding) in a direction at an angle with the axis of the tool. It covers a wide
variety of different operations and machines, on scales from small individual parts to large,

61
heavy-duty gang milling operations. It is one of the most commonly used processes in
industry and machine shops today for machining parts to precise sizes and shapes.
Milling can be done with a wide range of machine tools. The original class of machine tools
for milling was the milling machine (often called a mill). After the advent of computer
numerical control (CNC), milling machines evolved into machining centers (milling machines
with automatic tool changers, tool magazines or carousels, CNC control, coolant systems, and
enclosures), generally classified as vertical machining centers (VMCs) and horizontal
machining centers (HMCs). The integration of milling into turning environments and of
turning into milling environments, begun with live tooling for lathes and the occasional use of
mills for turning operations, led to a new class of machine tools, multitasking machines
(MTMs), which are purpose-built to provide for a default machining strategy of using any
combination of milling and turning within the same work envelope.
Figure 29: Milling machine
Process
Milling is a cutting process that uses a milling cutter to remove material from the surface of a
work-piece. The milling cutter is a rotary cutting tool, often with multiple cutting points. As
opposed to drilling, where the tool is advanced along its rotation axis, the cutter in milling is
usually moved perpendicular to its axis so that cutting occurs on the circumference of the
cutter. As the milling cutter enters the work-piece, the cutting edges (flutes or teeth) of the

62
tool repeatedly cut into and exit from the material, shaving off chips (swarf) from the work-
piece with each pass. The cutting action is shear deformation; material is pushed off the work-
piece in tiny clumps that hang together to a greater or lesser extent (depending on the
material) to form chips. This makes metal cutting somewhat different (in its mechanics) from
slicing softer materials with a blade.
The milling process removes material by performing many separate, small cuts. This is
accomplished by using a cutter with many teeth, spinning the cutter at high speed, or
advancing the material through the cutter slowly; most often it is some combination of these
three approaches.[2] The speeds and feeds used are varied to suit a combination of variables.
The speed at which the piece advances through the cutter is called feed rate, or just feed; it is
most often measured in length of material per full revolution of the cutter.
There are two major classes of milling process:
 In face milling, the cutting action occurs primarily at the end corners of the milling
cutter. Face milling is used to cut flat surfaces (faces) into the work-piece, or to cut
flat-bottomed cavities.
 In peripheral milling, the cutting action occurs primarily along the circumference of
the cutter, so that the cross section of the milled surface ends up receiving the shape of
the cutter. In this case the blades of the cutter can be seen as scooping out material
from the work-piece. Peripheral milling is well suited to the cutting of deep slots,
threads, and gear teeth.
Types of teeth
The teeth of milling cutters may be made for right-hand or left-hand rotation, and with either
right-hand or left-hand helix. Determine the hand of the cutter by looking at the face of the
cutter when mounted on the spindle. A right-hand cutter must rotate counterclockwise; a left-
hand cutter must rotate clockwise. The right-hand helix is shown by the flutes leading to the
right; a left-hand helix is shown by the flutes leading to the left. The direction of the helix
does not affect the cutting ability of the cutter, but take care to see that the direction of
rotation is correct for the hand of the cutter.

63
Saw Teeth
Saw teeth similar to those shown in Figure 8-3 are either straight or helical in the smaller sizes
of plain milling cutters, metal slitting saw milling cutters, and end milling cutters. The cutting
edge is usually given about 5 degrees primary clearance. Sometimes the teeth are provided
with off-set nicks which break up chips and make coarser feeds possible.
Helical Milling Cutters
Milling cutters are cutting tools typically used in milling machines or machining centres to
perform milling operations (and occasionally in other machine tools). They remove material
by their movement within the machine (e.g. a ball nose mill) or directly from the cutter's
shape.
MetalSlitting Saw Milling Cutter
The metal slitting saw milling cutter is essentially a very thin plain milling cutter. It is ground
slightly thinner toward the center to provide side clearance. These cutters are used for cutoff
operations and for milling deep, narrow slots, and are made in widths from 1/32 to 3/16 inch.
Side Milling Cutters
Side milling cutters are essentially plain milling cutters with the addition of teeth on one or
both sides. A plain side milling cutter has teeth on both sides and on the periphery. When
teeth are added to one side only, the cutter is called a half-side milling cutter and is identified
as being either a right-hand or left-hand cutter. Side milling cutters are generally used for
slotting and straddle milling.
Interlocking tooth side milling cutters and staggered tooth side milling cutters are used for
cutting relatively wide slots with accuracy. Interlocking tooth side milling cutters can be
repeatedly sharpened without changing the width of the slot they will machine.

64
Figure 30: Various Types of Milling cutter
After sharpening, a washer is placed between the two cutters to compensate for the ground off
metal. The staggered tooth cutter is the most washers are placed between the two cutters to
compensate for efficient type for milling slots where the depth exceeds the width.
End Milling Cutters
An end mill is a type of milling cutter, a cutting tool used in industrial milling applications. It
is distinguished from the drill bit in its application, geometry, and manufacture. While a drill
bit can only cut in the axial direction, a milling bit can generally cut in all directions, though
some cannot cut axially.
End mills are used in milling applications such as profile milling, tracer milling, face milling,
and plunging.

65
Figure 31: Taper used in milling machine
T-SlotMilling Cutter
The T-slot milling cutter is used to machine T-slot grooves in worktables, fixtures, and other
holding devices. The cutter has a plain or side milling cutter mounted to the end of a narrow
shank. The throat of the T-slot is first milled with a side or end milling cutter and the
headspace is then milled with the T-slot milling cutter.
Woodruff Key slot Milling Cutters
The Woodruff key slot milling cutter is made in straight, tapered-shank, and arbor-mounted
types. The most common cutters of this type, under 1 1/2 inches in diameter, are provided

66
with a shank. They have teeth on the periphery and slightly concave sides to provide
clearance. These cutters are used for milling semi cylindrical keyways in shafts.
Figure 32: Woodruff Key slot cutter
e) Shaper machine operation
Shaper
A shaping machine is used to machine surfaces. It can cut curves, angles and many other
shapes. It is a popular machine in a workshop because its movement is very simple although it
can produce a variety of work.

67
Figure 33: Shaper Machine
Lubricating the shaper
 Oil reservoir Motor Sliding surface of the tool head.
 Oil pressure gauge
 Table support surface Clapper pin.
 Feed screw.
 Oil feed box
 Oil hole of ram.
.
Operation
The work-piece mounts on a rigid, box-shaped table in front of the machine. The height of the
table can be adjusted to suit this work-piece, and the table can traverse sideways underneath
the reciprocating tool, which is mounted on the ram. Table motion may be controlled
manually, but is usually advanced by an automatic feed mechanism acting on the feed screw.
The ram slides back and forth above the work. At the front end of the ram is a vertical tool
slide that may be adjusted to either side of the vertical plane along the stroke axis. This tool-
slide holds the clapper box and tool post, from which the tool can be positioned to cut a
straight, flat surface on the top of the work-piece. The tool-slide permits feeding the tool

68
downwards to deepen a cut. This adjustability, coupled with the use of specialized cutters and
tool holders, enable the operator to cut internal and external gear tooth profiles, splines,
dovetails, and keyways.
The ram is adjustable for stroke and, due to the geometry of the linkage, it moves faster on the
return (non-cutting) stroke than on the forward, cutting stroke
f. Grinding operation
Grinding
Grinding is an abrasive machining process that uses a grinding wheel as the cutting tool.
A wide variety of machines are used for grinding:
 Hand-cranked knife-sharpening stones (grindstones)
 Handheld power tools such as angle grinders and die grinders
 Various kinds of expensive industrial machine tools called grinding machines
 Bench grinders often found in residential garages and basements
Parts of grinding Machine
 Base.
 Work table.
 Wheel head and slide.
 Head stock and tail stock.
 Spindle.
Application
To remove a very small amount of metal from that work-piece to bring its dimension with in
very close tolerance after all the rough finishing. To obtained batter surface finish on the
surface.
Abrasive
An abrasive is a hard material which can be used to cut or wear away other material. It is
externally hard and tough and when fractured, it forms sharp cutting edge and corner.

69
Abrasive materials are sand stone or solid quartz, emery (50-60%) crystalline Al2O3+ Iron
oxide, corundum (75-95%) crystalline Al2O3+ Iron oxide, diamonds and garnet.
Drilling Operation
Drill Machine
Drill machine is one of the simplest and accretes machine tool used in production shop and
tool room. Drilling is a process of making hole.
 Drilling.
 Boring.
 Countersinking.
 Trepanning
 Rivet spanning.
 Reaming.
 Polishing.
 Counter boring.
 Spot facing.
 Toping

70
Parts of drilling machine
 Base.
 Column.
 Table.
 Drill Head.
 Electric motor.
 Gear box.
Illustrate work holding methods
 Machine vise.
 Clamping block.
 Angle plate.
 Parallel strips.
 Tool makers clamps.

71
Chapter Six
Pump Assembly
Section

72
Pump Assembly Section
When the machining is done and all the parts are completed as fit to assemble, the following
works is done in the assembly shop:
 The assembly of the pump is carried in the vertical position. This prevents the risk of
shaft or bowl assembly to develop sag. The bowl bushing clearance is typically 9 mils
and in a horizontal position it is bound to touch after 3–4 bowl assemblies as the bowl
have a spigot fits of 2–3 mils. In a vertical position, these get distributed.
 The jack-bolt in the suction piece must be used to position the end of the shaft to allow
for accurate spacing of the impellers.
 Impellers fitted with collets in comparison to those held by splitting; keys, snap rings,
and others need a lot more attention. Excessive tightening of the cullet can lead to
cracking of the impeller in the hub area.
 After the pump bowls have been assembled, the lift should be checked and the rotor
should to rotated by hand to check for any rubbing of internals.
 If the length of the pump is large, column sections have to be assembled in a
horizontal position.
 The assembled positions should be rotated 180° with installation of every additional
component. This aids in staggering the alignment clearances, fits through the length of
the columns, and helps to keep the assembly along the shaft centerline.
 After the columns have been fitted, the discharge head is installed. At this stage, the
shaft extension length can be compared with the ones taken before dismantling of the
pump. Deviations of 1/16th to 1/8th are considered as normal and can be compensated
with the use of gaskets.
The shaft extension maybe supported and the shaft can be locked before dispatching it to the
site. If the jack bolt at the suction bell is left in place, it should accompany a warning tag to
remove it before installation.
Every part of a pump those are individually produce in side this factory those parts are
assembled together in this section. Centrifugal pumps are rot dynamic pumps and operate

73
normally primed. They are in widespread use, and are deployed primarily in the pumping of
water. Their applications include use in shipbuilding, the process industries and in water
supply systems. They are compact and relatively simple in design. The parts are shown here
symmetrically.
The assembly process begins at the pump shaft, which has undergone checks for runouts,
condition of steps/shoulders, keyways, and fits.
6.1 Bearing assembly
 Always keep the cover on grease can so that no dirt can enter.
 Be sure the instrument with which you take the grease from the can is clean. Avoid
using a wooden paddle, but rather use a steel blade or putty knife that can be wiped off
smooth and clean
 In cases where a grease gun is used to introduce grease into bearing chamber, observe
the same caution regarding the cleanliness of the gun, especially the nozzle and the
grease fittings.
 The bearing should be pressed on squarely. Do not cock it on to the shaft. Be sure that
the sleeve used to press the bearing on is clean, cut square, and contacts the inner race
only.
 The bearing should be pressed firmly against shaft shoulder. The shoulder helps to
support and square the bearing.
 In case the fits are tight, the bearings maybe heated using an induction heater with a
de-magnetizing cycle. The temperature should not increase beyond 110 ºC.
 The bearings should be lubricated.
 Fit the cone of bearing to shaft with large diameter against retainer. It is advisable to
preheat bearing cone. (Preheat should not exceed 210°F.) Warm an suggests using an
induction heater or oven to heat the bearings.
 This assembly should then be wrapped in a plastic cover while the bearing housing is
made ready.
 Prior to placing the rotor in the bearing housing, it is insured that it is spotlessly clean.
 Oil is smeared on the bearing housing bores.
 Shaft with the mounted bearings is tapped in the bearing housing till the outer race of
the inboard bearing rests against the step.

74
6.2 Seal assembly
 The stationary seat is firmly clamped with the seals in the seal end plate.
 Place expeller ring (flat on bench (gland seal up).
 Drop neck ring into gland recess so it rests on the retaining lip.
 Stand shaft sleeve on end and place through neck ring.
 Assemble gland halves, insert gland clamp bolts, and fully tighten. Place gland into
expeller ring, pushing it down to compress the packing rings. Insert gland bolts and
snug nuts sufficiently to hold shaft sleeve.
 Fit shaft sleeve o-ring on shaft and slide up to labyrinth. apply anti-seize lubricant to
exposed shaft, including threads.
 Insert assembled expeller ring into frame plate, tapping into position with a mallet.
Locate expeller ring with the grease inlet at top.
 Fit second shaft sleeve o-ring and push into recess in the end face of the shaft sleeve.
 Place expeller onto the shaft and press up to the shaft sleeve.
 Assembly of gland lubricating parts is done after all other parts of pump have been
assembled.

6.3 Impeller and casing assembly
 Once the sleeve with rotary head is placed, the compression is achieved after installing
the impeller and locking it to the shaft with the help of the nut.
 After the impeller is fixed, it is a good idea to measure the run out of the impeller
wearing ring in this installed condition. This should be within 0.05 mm.
 The casing gasket is placed in the pump casing.
 The casing is then bolted to the seal-housing flange, once again taking care of the
match marks.
 The bolts are tightened to the specified torque value.
Installation of coupling, lines, and fittings
 The pump coupling half can now be mounted onto the shaft.
 Shaft end should preferably be flush with the coupling half. However, if it was not so

75
originally, this should have been recorded and kept along similar lines.
 The sealant lines, oil level gages, cooling water lines, or any other should be fitted.
 After the blind flanges are removed, the pump nozzles should be completely covered
by a tape.
 The pump is ready for installation at site.

76
Chapter: Seven
Pump Testing Section

77
Pump Testing Section
The basis of centrifugal pump testing is a direct function of its criticality to its application. For
example, an ordinary garden water pump would not require the same kind of attention as a
boiler feed water pump in a major power plant or a firewater pump in a refinery.
The criticality of any pump equipment is based on the following criteria:
Failure can affect plant safety
Essential for plant operation and where a shutdown will curtail the
process throughput
No standby or installed spares.
Large horsepower pumps
High capital cost and expensive to repair or longer repair lead time
Perennial pumps that wreck on the slightest provocation of an off-duty
operation
Finally, pump trains, where better operation could save energy or
improve yields are also likely candidates.
Once the criticality of a pump can be ascertained based on the factors mentioned, the pumps
can be classified as:
• Critical
• Essential

78
• General purpose.
After this categorization, the type of maintenance philosophy can be assigned. The pumps,
which fall in the category of critical machines, are usually maintained with the predictive and
proactive techniques.
 The essential category pumps are assigned with preventive maintenance whereas
maintenance for the general-purpose pumps maybe less stringent.
 In actual operations, a mix and match of techniques is applied with a prime intention
of maximizing runtime lengths and reducing downtime and costs.
 The present day focus on continuous process plant pumps is to adopt a mix of
Predictive and Preventative Maintenance (PPM)
There are four areas that should be incorporated in a PPM program. Individually, each one
will provide information that gives an indication of the condition of the pump; collectively,
they will provide a complete picture as to the actual condition of the pump.
These include:
• Performance monitoring
• Vibration monitoring
• Oil and particle analysis
• System analysis.
7.1 Performance monitoring
The following six parameters should be monitored to understand how a pump is performing:
1. Suction pressure (Ps)
2. Discharge pressure (Pd)
3. Flow (Q)
4. Pump speed (N)
5. Pump efficiency (η)
6. Power.
Analysis of efficiency or inefficiency can help one to determine whether the losses are
on account of:

79
• Hydraulic losses
• Internal recirculation
• Mechanical losses.
Direct reading thermodynamic pump efficiency monitors (such as the Yates meter) are now
available and capable of interpreting the pump’s operating efficiency in a dynamic manner by
measuring and computing the rise in temperature (albeit in mk) of the fluid as it moves from
the suction to the discharge side of the pump.
Motor efficiency obtained from the manufacturer of the electric motor and drive losses are
factored in to the software program, to then calculate the operating efficiency of the pump.
This reading could be compared with the pump’s commissioning data and drop in
performance or efficiency could be determined.
7.2 Required Equations
Head H=Suction gauge reading×0.346+Delivery gauge reading ×10.21+0.34 (m)
Discharge Q={372-V notch high/304.8}2.47×2.52 (m3/hr)
W.H.P= (Head ×Discharge×2.727/746) (kw)
I.H.P= (Watt meter reading/.746) (kg)
Efficiency ηc=W.H.P/I.H.P
7.4 Requirements
There is some terms those are very important to test properly those are:
a. Check Valve
Most centrifugal pumps cannot run dry; ensure that the pump is always full of liquid. In
residential systems, to ensure that the pump stays full of the liquid use a check valve (also
called a foot valve) at the water source end of the suction line. Certain types of centrifugal
pumps do not require a check valve as they can generate suction at the pump inlet to lift the
fluid into the pump. These pumps are called jet pumps and are fabricated by many
manufacturers Gould’s being one of them.
b. Do not let a pump run at zero flow

80
Do not let a centrifugal pump operate for long periods of time at zero flow. In residential
systems, the pressure switch shuts the pump down when the pressure is high which means
there is low or no flow.
c. Pressure Gauges
Make sure your pump has a pressure gauge on the discharge side close to the outlet of the
pump this will help you diagnose pump system problems. It is also useful to have a pressure
gauge on the suction side; the difference in pressure is proportional to the total head. The
pressure gauge reading will have to be corrected for elevation since the reference plane for
total head calculation is the suction flange of the pump.
Figure 34: A pressure Gauge
a. Flow and pressure relationship of a pump
When the flow increases, the discharge pressure of the pump decreases, and when the flow
decreases the discharge pressure increases.
b. Suction Valves
Gate valves at the pump suction and discharge should be used as these offer no resistance to
flow and can provide a tight shut-off. Butterfly valves are often used but they do provide
some resistance and their presence in the flow stream can potentially be a source of hang-ups

81
which would be critical at the suction. They do close faster than gate valves but are not as leak
proof.
c. Eccentric Reducer
Always use an eccentric reducer at the pump suction when a pipe size transition is required.
Put the flat on top when the fluid is coming from below or straight (see next Figure) and the
flat on the bottom when the fluid is coming from the top. This will avoid an air pocket at the
pump suction and allow air to be evacuated.
d. Use a multi-stage turbine pump for deep well
For deep wells (200-300 feet) a submersible multi-stage pump is required. They come in
different sizes (4" and 6") and fit inside your bore whole pipe.
e. Flow control
If you need to control the flow, use a valve on the discharge side of the pump; never use a
valve on the suction side for this purpose.
f. Plan ahead for flow meters
For new systems that do not have a flow meter, install flanges that are designed for an orifice
plate in a straight part of the pipe and do not install the orifice plate. In the future, whoever
trouble-shoots the pump will have a way to measure flow without the owner having to incur
major downtime or expense. Note: orifice plates are not suitable for slurries.
g. Avoid pockets and high points
Avoid pockets or high point where air can accumulate in the discharge piping. An ideal pipe
run is one where the piping gradually slopes up from the pump to the outlet. This will ensure
that any air in the discharge side of the pump can be evacuated to the outlet.
h. Location of control valves

82
Position control valves closer to the pump discharge outlet than the system outlet. This will
ensure positive pressure at the valve inlet and therefore reduce the risk of Cavitation’s. When
the valve must be located at the outlet such as the feed to a tank, bring the end of the pipe to
the bottom of the tank and put the valve close to that point to provide some pressure on the
discharge side of the valve making it easier to size the valve, extending its life and reducing
the possibility of Cavitation’s.
Figure 35: Pump test branch
i. Water hammer
Be aware of potential water hammer problems. This is particularly serious for large piping
systems such as are installed in municipal water supply distribution systems. These systems
are characterized by long gradually upward sloping and then downward sloping pipes.
Solutions to this can involve special pressure/vacuum reducing valves at the high and low
points or additional tanks which provide a buffer for pressure surges.
j. The right pipe size
The right pipe size is a compromise between cost (bigger pipes are more expensive) and
excessive friction loss (small pipes cause high friction loss and will affect the pump
performance). Generally speaking, the discharge pipe size can be the same size as the pump
discharge connection, you can see if this is reasonable by calculating the friction loss of the
whole system. For the suction side, you can also use the same size pipe as the pump suction

83
connection, often one size bigger is used .A typical velocity range used for sizing pipes on the
discharge side of the pump is 9-12 ft/s and for the suction side 3-6 ft/s.
A small pipe will initially cost less but the friction loss will be higher and the pump energy
cost will be greater. If you know the cost of energy and the purchase and installation cost of
the pipe you can select the pipe diameter based on a comparison of the pipe cost vs power
consumption.
k. Pressure at high point of system
Calculate the level of pressure of the high point in your system. The pressure may be low
enough for the fluid to vaporize and create a vapor pocket which will be detrimental to the
performance of the system. The pressure at this point can be increased by installing a valve at
some point past the high point and by closing this valve you can adjust the pressure at the
high point. Of course, you will need to take that into account in the total head calculations of
the pump.
7.5 Quality Assurance
Quality Assurance refers to administrative and procedural activities implemented in a quality
system so that requirements and goals for a product, service or activity will be fulfilled. It is
the systematic measurement, comparison with a standard, monitoring of processes and an
associated feedback loop that confers error prevention. This can be contrasted with quality
control which is focused on process output.
Two principles included in Quality Assurance are: "Fit for purpose", the product should be
suitable for the intended purpose; and "Right first time", mistakes should be eliminated. QA
includes management of the quality of raw materials, assemblies, products and components,
services related to production, and management, production and inspection processes.
7.5.1 Statisticalcontrol
Statistical control is based on analyses of objective and subjective data. Many organizations
use statistical process control as a tool in any quality improvement effort to track quality data.

Milnars Pumps Internship Report: Manufacturing Process of Centrifugal Pumps

Milnars Pumps Internship Report: Manufacturing Process of Centrifugal Pumps

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