Electromechanical works :PUMP BASIC TRAINING

PUMP TECHNOLOGY
PUMP TECHNOLOGY
• SECTION 1 - PUMP TERMS
GLOSSARY,CONVERSION TABLE & USEFUL
FORMULA
• SECTION 2 - CENTRIFUGAL PUMPS, POSITIVE
DISPLACEMENT PUMPS, COUPLINGS & SEALS
• SECTION 3 - SYSTEM HEADS, PUMP PERFORMANCE
CURVES & PUMP SELECTION GUIDE
• SECTION 4 - AFFINITY LAWS, PUMPS IN
SERIES/PARALLEL
NPSHR & CAVITATION,
DENSITY/PH/VISCOSITY
SECTION 5 - PUMP INSTALLATION
PUMP TESTING
PUMP TROUBLESHOOTING

SECTION 1
• GLOSSARY
• CONVERSION TABLE
• USEFUL FORMULA
PUMP TECHNOLOGY
PUMP TECHNOLOGY

Classification of Pumps
Classification of Pumps
RECIPROCATING
POSITIVE DISPLACEMENT
ROTARY JET PERIPHERAL
SINGLE STAGE MULTI-STAGE RADIAL FLOW MIXED FLOW AXIAL FLOW
SELF-PRIMING NON SELF-PRIMING VOLUTE DIFFUSER
SINGLE VOLUTE DOUBLE VOLUTE
SINGLE SUCTION DOUBLE SUCTION
CLOSED SEMI-OPEN OPEN IMPELLER
SINGLE STAGE MULTI-STAGE
SELF-PRIMING NON SELF-PRIMING SUBMERGED
CENTRIFUGAL
KINETIC
PUMP
Not discussed in
this training module.

PUMP TECHNOLOGY – GLOSSARY OF TERMS
• ABSOLUTE PRESSURE – The pressure above absolute
zero, equal to barometric pressure plus gauge pressure
Absolute
Pressure
Barometric
Pressure
Gauge
Pressure
Atmospheric
Pressure
Pressure Above Atmospheric
Barometric
Pressure
Absolute
Pressure
Vacuum
Atmospheric
Pressure
Pressure below Atmospheric

• AFFINITY LAWS – the mathematical relationship between
flow rate, head, power & speed of centrifugal pump
• CAVITATION – is a term given to the formation of vapour
bubbles (cavities) in areas of low pressure & their
subsequent collapse upon reaching regions of higher
pressure. Usually results in a noisy pump and severe erosion
damage.
• DISCHARGE HEAD – is the static level of the final free
surface of the liquid relative to the pump suction centreline
• DRY RUNNING – pump put into operation without being
filled with fluid.

BEST EFFICIENCY POINT (BEP)
BEST EFFICIENCY POINT (BEP) – is the ideal operating point for a pump, where the power
– is the ideal operating point for a pump, where the power
going in is the closest to the power coming out & the pump shaft experiences the least amount of
going in is the closest to the power coming out & the pump shaft experiences the least amount of
vibration.
vibration.

CHARACTERISTIC CURVE
CHARACTERISTIC CURVE - is a graphical display showing the pump
- is a graphical display showing the pump
performance
performance under varying conditions of flow & head. It can be refer as
under varying conditions of flow & head. It can be refer as
Performance Curve
Performance Curve

• FLOW RATE – is the external fluid flow delivered by a
pump per unit of time Usually expressed in litres per second
(l/s) or cubic metres per hour (m3/h)
• GAUGE PRESSURE - is the pressure measured by a
gauge. The pressure reading is above atmospheric pressure.
• HEAD – a measure of the energy in a particular fluid
expressed in the context of the length of column of that fluid
that the energy will support. It is usual express head in
metres of liquid being pumped (m)
• PRESSURE – An expression of the force per unit area
within a medium. It is another form of energy within the
fluid and is often expressed in kilopascals( kPa)

• NET POSITIVE SUCTION HEAD – is the total head at
the pump suction branch above the vapour pressure of the
liquid being pumped. Mainly two types of NPSH
• NET POSITIVE SUCTION HEAD REQUIRED
(NPSHR) – A characteristic of the pump relating to casing
and impeller design and can be determined by performance
testing
• NET POSITIVE SUCTION HEAD AVAILABLE
(NPSHA)– A characteristic of the system and can be
calculated from system values
• NPSHA > NPSHR – to avoid cavitation.

• SHUT OFF HEAD – Shown on the characteristic curve and represents the head
condition at zero flow.
Shut
Off
Head
Head

SECTION 2
• CENTRIFUGAL PUMPS
• POSITIVE DISPLACEMENT PUMPS
• COUPLINGS & SEALS
PUMP TECHNOLOGY
PUMP TECHNOLOGY

Column Type Sump Pump Vertical Line Shaft Pump

Horizontal Single Stage Split Case Pump

Vertical Multistage Centrifugal Pump

Casing
The prime purpose of the casing is to energy from the fluid leaving the
impeller into useful pressure energy. The design of the casing is of
equal importance to that of the impeller. There are two types of
casing design
1. Volute
2. Guide Vane ( Diffuser)

The double volute design is actually two single
volute designs combined together.
Although this drawing does not show it clearly,
the total throat area of the two volutes is the
same as the single volute design.
Double volute pumps were created to eliminate
most of the radial thrust caused by operating off
the pump's best efficiency point (BEP).
The single volute pump impeller will
deflect either 60° or 240° from the
cut water depending upon which side
of the pump's best efficiency point
(BEP) you are operating.

Cartridge
Seal
Standard Seal
Metal Bellows
Seal
Multi-Spring
Seal

Standard seal
Welded bellows balanced seal
Multi-spring balanced seal
Cartridge seal
assembly

Gear
Coupling
Spacer
Coupling
Pin & Bush
Coupling
Jaw
Coupling

Closed Impeller: suitable for clean liquids (max 0,1% solids).
- Very fine powder can lock impeller and wear ring.
-Some solids can cross the impeller, but long parts clog it immediately.
-No AIR if possible. – Very low NPSH.
Open Impeller: suitable for dirty liquids or containing gas and air. Solids
can cross the impeller, but they cannot be abrasive. Wearing ruine
adjustment between impeller and wearing plate. So performances
decrease a lot. Very good with gas and air. Offen used in flotation plants
(max. 10% air). Very low NPSH . Performance are about 5 – 10% lower
than closed impeller.
Channel Impeller: suitable for dirty liquids containing solids that can
cross the impeller. Fine powder don’t lock the impeller because tolerances
between impeller and wear ring is higher than in closed impellers. Not
suitable with long solid parts. Very good NPSH .
Vortex Impeller: suitable for dirty liquids containing big solid parts, also
long pieces like part of plastic bags. Gas and air can be conveyed without
problem. No problem with “soft” abrasive . Attention: very abrasive parts
must be pumped with special pumps.

Plunger
Pump
Piston
Pump
POSITIVE DISPLACEMENT PUMP
POSITIVE DISPLACEMENT PUMP

SLIDING SHOE
PUMP
LOBE PUMP -
ROTARY

SECTION 3
• SYSTEM HEADS
• PUMP PERFORMANCE CURVES
• PUMP SELECTION GUIDE
PUMP TECHNOLOGY
PUMP TECHNOLOGY

Determination of System Head
Determination of System Head
Every centrifugal pump installation will have its own unique set of
operating conditions. To determine the correct pump selection, it is
necessary to calculate the system resistance at rated capacity and
various flow rates above and below the rated capacity. This
involves:-
1) Static head on suction and discharge side of pump
2) Pressure difference in suction and discharge reservoirs
(if applicable)
3) Entrance & Exit losses
4) Friction losses in pipes and fittings

STATIC HEAD
STATIC HEAD
• Static head exists in the system as a result of the
physical positions of the suction reservoir and the
discharge reservoir.
• The vertical height difference between the free
surfaces of the suction and discharge reservoir is a
measure of the static head

Static suction head
(+Hs)
Positive Suction Head

Static suction
lift (-Hs)
Suction Lift

Static suction head
(Hs)
Static discharge
head (Hd)
TOTAL STATIC
HEAD (H)
Total Head with Positive Suction

Static suction
lift (Hs)
Static discharge
head (Hd)
TOTAL STATIC
HEAD (H)
Total Head with Suction Lift

Friction Loss
Friction Loss
• Friction losses will vary with pumping capacity and
need to be calculated for the system of pipes and
fittings to be used in the installation
• Different sizes of pipes and different pipe materials
display different friction loss characteristics
• These characteristics can be obtained from
tabulations in Industry reference books

• Section 1
- Head loss tables for various pipe
sizes and materials
(Pg 9-102)
• Section 2
- Head loss through various fittings
- Friction losses for viscous liquids
- Flow through orifices and nozzles
- Worked Examples
(Pg 105 – 151)
PUMP INDUSTRY AUSTRALIA FRICTION HANDBOOK

Friction Loss
Friction Loss
Flow rate 15l/s

1.Total length of pipe in system is
suction: 1.5m
discharge: 380m
total: 1.5 + 380 = 381.5m
For a flow of 15 L/s through 100 mm of schedule 40 pipe:
Pipe friction loss = 3.19 m/100 m of pipe (Table A3)
The head loss due to pipe friction will be:
f
h = 381.5 x 3.19
100
= 12.17m
SOLUTION

2. The resistance coefficient for the various fittings in the system as obtained from the
tables for 100 mm schedule 40 pipe will be:
Suction
Standard 90 degree flanged elbow (Section 2.1.2) K = 0.51
Hinged disc foot valve (Section 2.1.3) K = 1.28
Discharge
Standard 90 degree flanged elbow (Section 2.1.2) K = 0.51
Flanged swing check valve (Section 2. 1.3) K = 0.85
Gate valve (Section 2 .1.2) K = 0.14
Sudden enlargement at exit (Section 2.1.5) K = 1.00
The total resistance coefficient for the fittings on the pump suction and discharge and
sudden enlargement at exit will be:
K = 0.51 x 3 + 1.28 + 0.85 + 0.14 + 1.0
K= 4.8
For a flow of 15 L/s through 100 mm of schedule 40 pipe.
0.17
2g
V2

 The head loss due to fittings in the system will be:
0.82m
0.17
4.8
2g
v
k
h
2
f 



Velocity head = m (Table A3)

3. The total system head is equal to the sum of the total static head and
the head losses due to friction in pipes and fittings.
i.e. H = 80 + 12.17 + 0.82
= 93m

Pump Performance Curves
Pump Performance Curves
Plotting the variation of the Head (H) with Flow
(Q) at a constant speed is called the pump
characteristic or Pump Performance Curve.
A complete pump performance curve would
include efficiency and power curves for the
capacity range of the pump.

Performance Curves
Performance Curves
How do we obtain performance curves?
The hydraulic properties are determined by testing at
a constant speed with a dynamometer while the Head
(H) and Flow (Q) are altered by throttling the
discharge valve.
By plotting the points of flow against head for the
various positions of the discharge valve, a Head/Flow
(HQ) curve is obtained.
This curve gives us the fundamental hydraulic
performance of a pump at a nominated speed

Performance Curve
Performance Curve
If the power is simultaneously measured with the
dynamometer for the various discharge valve openings,
the Power (P) and Efficiency () points can be calculated
and plotted on the curve.
The Net Positive Suction Head Required (NPSHR) curve
can be determined by laboratory testing and can also be
included to show the suction capabilities of the pump at
various rates of flow.

Pump Selection Guide
Pump Selection Guide
1. For required duty make preliminary pump selection using
selection (tombstone) charts. Decide on 2900 rpm or 1450
rpm
2. Go to individual performance curve for more detail
3. Select impeller diameter, determine kW requirement of
driver and check suction capability of pump (take into
account density & viscosity where applicable)

Pump Selection Guide cont’d
Pump Selection Guide cont’d
4. Select material of construction for liquid being pumped
(check material charts for liquids other than water)
5. Check maximum working pressure & temperature does not
exceed
• Casing material limitation
• Mechanical seal or packed gland limitation
6. Check maximum allowable suction pressure does not exceed
mechanical seal or packed gland limitation

SECTION 4
• AFFINITY LAWS
• PUMPS IN SERIES/ PARALLEL
• NPSHR & CAVITATION
• DENSITY/PH/VISCOSITY
PUMP TECHNOLOGY
PUMP TECHNOLOGY

Effect of change of Speed
Effect of change of Speed
The Affinity Laws:
A. Flow directly proportional to speed:
2
1
2
1
N
N
Q
Q

B. Total head proportional to speed squared:
2
2
1
2
1
]
[
N
N
H
H

C. Power proportional to speed cubed:
3
2
1
2
1
]
[
N
N
P
P


Example of speed change:
A pump running at 3000 r.p.m. is capable of 12 l/s at 60m head and
requires 18.5 kw. What is equivalent duty at 2700 r.p.m.?
l/s
8
.
10
3000
2700
12
1
2
1
2 




N
N
Q
Q
m
6
.
48
3000
2700
60
2
2
1
2
1
2 ]
[
]
[ 




N
N
H
H
kw
49
.
13
3000
2700
5
.
18
3
3
1
2
1
2 ]
[
]
[ 




N
N
P
P

Effect of change of Impeller Diameter
Effect of change of Impeller Diameter
A similar law governs the performance obtained for impeller
turn downs.
A. Flow directly proportional to impeller diameter:
2
1
2
1
D
D
Q
Q

B. Total head proportional to impeller diameter squared:
2
2
1
2
1
]
[
D
D
H
H

C. Power proportional to impeller diameter cubed:
3
2
1
2
1
]
[
D
D
P
P


Example of impeller change:
A pump running at 3000 r.p.m. is capable of 12 l/s at 60m head and requires
18.5 kw. What is equivalent duty if the impeller was reduced from 350mm to
300mm diameter.?
l/s
28
.
10
350
300
12
1
2
1
2 




D
D
Q
Q
m
08
.
44
350
300
60
2
2
1
2
1
2 ]
[
]
[ 




D
D
H
H
kw
65
.
11
350
300
5
.
18
3
3
1
2
1
2 ]
[
]
[ 




D
D
P
P

When one pump is discharging into the suction of an
identical pump, they deliver the same amount & each pump
adds energy to the liquid by increasing its pressure.
For series operation the combined performance curve is
obtained by adding vertically the heads at the same flow
rate.
Pumps in Series
Pumps in Series

A multistage pump
is a good example
of pumps segments
operating in series.
Top section of the
curve shows H-Q of
combined pump
Bottom section of
curve shows
•Efficiency
•Power absorbed
on a per stage basis

When two or more pumps discharge simultaneously into a
common delivery line.
For parallel operation the combined performance curve is
obtained by adding horizontally the flow rates at the same
heads.
Pumps in Parallel
Pumps in Parallel

NPSH
Net Positive Suction Head is a method of
defining pump suction conditions that allow us
to predict whether cavitation will occur in a
particular pump under given suction conditions.
The NPSHA (of the system) needs to be
evaluated and compared with the NPSHR of the
pump under consideration.
NPSH is usually expressed in linear terms - metres

NPSHA must be greater than NPSHR
(a safety margin of 0.5 m should be observed)

v
s H
H
NPSHA 

v
s
H
H = Total Absolute Suction Head at Pump Suction
= Vapour Head of Pumped Liquid

density
s²)
gravity(m/
1000
press(kPa)
Vap.
H
loss
friction
static
density
)
s²
gravity(m/
1000
press(kPa)
Atm.
H
v
s








All need to expressed in common terms – normally head (metres)
Where gravity= acceleration due to gravity – Australia 9.80 m/s²

Cavitation
Cavitation is the formation & subsequent collapse of
vapour bubbles in the liquid flow & is one of the most
significant causes of pump performance &
maintenance problems.
The pressure at the eye of the impeller must be
sufficient to maintain the fluid being pumped in its
liquid state. For this reason it is important to know the
properties of the fluid being pumped and particularly
it’s vapour pressure at the pumping temperature.

The important points are:
1.A liquid will vaporise if the local pressure is reduced to
equal the liquid vapour pressure
2.This results in a dramatic increase in volume compared
with the original liquid
3.This is the mechanism for vapour bubble formation in a
liquid under conditions of localised low pressure
4. After formation in localised low pressure areas, these
vapour bubbles will shortly encounter higher pressures
again. This results in rapid collapse of the bubbles, in the
order of 0.003 seconds. Severe mechanical damage to
surrounding surfaces may result.

AVOIDING CAVITATION
AVOIDING CAVITATION
• Ensure NPSHA is greater than NPSHR for all
pump operating conditions
• Check properties of liquid pumped at pumping
temperature. Re-check the vapour pressure at
this temperature
• Remedies for cavitation problems are not
simple and are often expensive to apply

EFFECT OF LIQUID pH value of pump material selection
EFFECT OF LIQUID pH value of pump material selection
pH Values
Neutral Alklinity
Acidity
pH 7 14
0
• Sour
•Turns blue litmus paper red
•Releases hydrogen upon
contact with various metals
• Slimy and bitter
• Turns red litmus paper blue
• Absorbs carbon dioxide
Soapy Water
Lemon Juice

pH Value & Materials of Construction
pH Value & Materials of Construction
pH Value Material of Construction
0 - 4 Corrosion resistant alloy steels
4 - 6 All Bronze
6 - 8 Bronze fitted/ Standard Construction
8 - 10 All Iron
10 - 14 Corrosion resistant alloys

VISCOSITY
VISCOSITY
• Viscosity means resistance to internal shear
of the liquid. The higher the viscosity the
less easy the liquid is to pour. It is normally
measured in centistokes or SSU.
• Viscosity of most liquids varies with
temperature, at higher temperature, the
viscosity reduces.
• Higher viscous fluids (above 3000SSU) are
best handled with a positive displacement
pump.

• Using a centrifugal pump to handle viscous
fluids affects the following pump
characteristics :
– Reduction in capacity
– Reduction in head
– Increase in power
– Decrease in pump efficiency
VISCOSITY
VISCOSITY

In the viscosity correction tables the following
In the viscosity correction tables the following
units are used
units are used
• Qvis – Viscous Capacity (m3/h)
• Hvis – Viscous Head (m)
• ηvis – Viscous Efficiency (%)
• Pvis – Viscous Power
• Qw – Water Capacity (m3/h)
• Hw – Water Head (m)
• ηw -Water Efficiency (%)
• SG – Density of Liquid
• Cq - Capacity Correction Factor
• Ch –Head Correction Factor
• Cn –Efficiency Correction Factor

Equations
Equations
• Qvis = Cq x Qw
• Hvis = Ch x Hw
• ηvis = Cη x ηw
Qvis x Hvis x SG
• Pvis = 102 x ηvis

E80-32 @ 1450rpm
100m3/h @ 30m Oil 100 cts SG1
63.6 85 105.8 127
30
33.5
35.8
36.7
62.5 72.0 74.5 72.0
100
0.97
0.97 0.95 0.93 0.9
0.70
61.6 82.45 102.6 123.2
35.6 34.0 31.2 27.0
43.8 50.4 52.2 50.4
1
13.6 15.2 16.7 17.9

E80-32 @ 1450rpm
100m3/h @ 30m Oil 100 cts SG1
63.6 85 105.8 127
30
33.5
35.8
36.7
62.5 72.0 74.5 72.0
100
0.97
0.97 0.95 0.93 0.9
0.70
61.6 82.45 102.6 123.2
35.6 34.0 31.2 27.0
43.8 50.4 52.2 50.4
0.9
12.2 13.6 15 16.2

105.8m3/h @
33.5m
SG = 0.9
SG = 1

SECTION 5
• PUMP INSTALLATION
• PUMP TESTING
• PUMP TROUBLESHOOTING
PUMP TECHNOLOGY
PUMP TECHNOLOGY

System Design Considerations
System Design Considerations
To achieve optimum pump performance and
reliable operation, it is important to pay attention to
the way the pump is installed
•Design of suction chamber and pipework
•Design of Discharge pipework
•Proper pipe support & reduced transmission of
vibration to fixed structures
•Levelling of pumping unit & alignment on site

Installation of Pumpsets
Good installation starts with good design
• Intake design – submergence, vortex formation
• Suction pipework – sizing, continuously rising, suction
lift, flooded suction, footvalves, strainers
• Pump positioning, mounting, foundations – concrete
base, spring mounts, inertia bases
• Discharge pipework & valves – size, types of bends,
valves

Air Pocket
Air Pocket
Air Pocket
Recommended Not Recommended

B.P.O. Pump Unit
Spacer Spring mounts

Typical HSC pump installation to minimize vibration

Levelling of pump on concrete foundation

Pre-commissioning Checklist
Stage 1
1. Ensure that driver is isolated, coupling & pipe flanges
disconnected
2. Check base is level, anchored & grouted into position
3. Check pump & driver are firmly attached to base
4. Check suction & discharge pipework is aligned to pump flanges
& correctly supported. PIPEWORK LOADS MUST NOT BE
TRANSMITTED TO PUMP FLANGES
5. Inspect both suction & discharge pipework & ensure both are
free of installation debris
6. Turn pump by hand to ensure free rotation
7. Check coupling alignment

Pre-commissioning Checklist
Stage 2
1. Replace suction & discharge flange bolts, activate
driver as required
2. Check direction of rotation for driver
3. Re-connect coupling & check alignment
4. Ensure suction valve is open to allow flow of liquid
5. Run pump unit to ensure all is satisfactory
6. Check for leaks at pump flanges & gland area

Flexible Mounts
Rubber pipe couplers

Common Types of Couplings
Pin & Bush
Standard spacer
Typical components
Tyre

Typical Alignment Problems
Angular Eccentricity
Combination

Alignment Methods
Taper gauge
Straight edge
Dial gauge

Australian Standard for Pump Performance Testing
Rotodynamic Pumps
AS2417 – 1980 (standard shown on most curves used in Australia). This code was
equivalent to ISO 2548 and both have been superseded
Current Australian Standard:– AS2417 - 2001
Current ISO Standard :– ISO 9906 – 1999 (identical to AS2417 - 2001)
AS2417 – 2001 AS2417 - 1980
Grade 1 Class A
Grade 2 Class B
Annex A Class C

2001
1980
Grade 1
(class A)
Grade 2
(class B)
Annex A1
(class C)
Flow rate ± 4.5% ± 8% ± 9%
Total head ± 3% ± 5% ± 7%
Input power ± 2% ± 4% + 9%
Efficiency - 3% - 5% - 7%

Flow Rate Measurement Methods
1.Measurement by weighing
2.Volumetric method
3.Differential pressure devices
(orifice/nozzle/venturi)
4.Thin plate weirs
5.Velocity area methods
6.Tracer methods
7.Flow meters

Pressure Measuring Methods
1.Liquid column manometer
2.Dead weight manometer
3.Spring pressure gauges
4.Transducers

Pump Power Input Measurement
1.Electrical method – using motor of
known efficiency
2.Torque method – using a torque
meter/dynamometer

Speed of Rotation Measurements
1.Direct indicating tachometer
2.Tachometric alternator/dynamo
3.Optical or magnetic counter
4.Stroboscope

Even the best pump can give trouble
Even the best pump can give trouble
• Pumps are selected based on nominated
conditions of service at the design stage.
However, these conditions are not always met on
site
• Trouble-shooting may need to be undertaken if
the pump is not performing to expectations
• Careful observation of all system parameters will
verify if the pump is operating at the design
condition.

Trouble shooting
Trouble shooting
•If possible, have pump test curve available. This should be an
accurate prediction of performance
•Fit good quality pressure gauges to suction and discharge pipework
close to pump flanges.
•Have tachometer available to verify pump speed
•Have multimeter available to measure motor voltage and current
By taking a few measurements, it should be possible to determine
the pump operating point and compare it with the design conditions.

Trouble Shooting
No Discharge or Insufficient Discharge:
1. Pump not primed properly – re-prime and repeat operation
2. Speed too low – driver speed is incorrect
3. System head too high – system head has been incorrectly
calculated.
4. Wrong direction of rotation – change driver DOR if possible
5. Impeller plugged – open pump and check impeller vanes are not
blocked
6. Insufficient NPSHA – Pump may be cavitating
7. Strainer clogged – remove strainer and clean
8. Impeller damaged – repair or replace impeller

Trouble Shooting
Trouble Shooting
Insufficient Pressure:
1. Speed too low – check speed of driver is correct
2. System head to low – pump operating point below design point.
Re-check system calculations.
3. Air entrapment – vent all air for the system. Recheck intake
submergence, and eliminate the possibility of leaks
4. Impeller damaged – repair or replace
5. Wrong direction of rotation – reverse DOR of driver if possible
6. Impeller diameter too small – fit larger impeller or increase driver
speed if possible

Trouble Shooting
Trouble Shooting
Excessive power:
1. Speed higher than that used for pump selection - Recheck
calculations. Adjust speed to suit actual conditions
2. System head is higher than rated (axial & mixed pumps) – pump
may be operating in high kW zone near closed valve
3. Specific gravity or viscosity of fluid is higher than used in
calculations for power. Re-check power calculations
4. Impeller binding due to misalignment – rotate pump by hand; re-
check alignment
5. Bent shaft causing binding on bearings- replace shaft
6. Pump operating point is not in accordance with design and too far
to right of BEP – recheck system head calculations.

Trouble Shooting
Excessive noise:
1. Loose or broken parts of the driver
2. Loose pump parts
3. Pump mounting not sufficiently rigid
4. Driver running too fast
5. Blocked strainer or pump partially or completely obstructed
6. Bent shaft or shaft misalignment
7. Lubrication failure
8. Insufficient submergence causing air entrainment or trapped air in
suction line
9. Pump over-discharging or inadequate NPSHA causing cavitation

Sealing Problems
One of the most common problems
experienced with centrifugal pumps is
seal leakage.
1. Packed gland
2. Mechanical seals

1. Packed Gland
shaft sleeve
gland plate
lantern ring
packing

2. Mechanical Seal
spring sleeve
seal plate
gasket
mechanical seal

Wide wear track
Centre/off centre
Even/uneven wear
Various Seal Problems

Chipping
Scoring/erosion
Coking/crystallizing
Various Seal Problems

Electromechanical works :PUMP BASIC TRAINING

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Editor's Notes