Pumps and compressor

 Pump operation & theory ‫الناصر‬ ‫عبد‬ ‫جمال‬ ‫كريم‬
 Rotary pump maintenance & troubleshooting ‫محمد‬ ‫رمضان‬ ‫محمد‬‫الكومى‬
 Reciprocating pump maintenance & troubleshooting ‫الضوي‬ ‫محمد‬ ‫معتز‬ ‫محمد‬
 Centrifugal Pump & maintenance ‫مصطفي‬ ‫ضياء‬ ‫محمد‬
 Compressors maintenance & troubleshooting ‫سالمة‬ ‫رفعت‬ ‫صبرى‬ ‫على‬ 
‫رزق‬ ‫مصطفى‬ ‫محمد‬ ‫مصطفى‬

● Centrifugal pumps
● Design aspects
● Pump laws
● Positive displacement pumps
● Performance comparisons
● Special purpose pumps
● Pump characteristic curves
● Performance testing

Centrifugal pumps are used to
transport fluids by the
conversion of rotational kinetic
energy to the hydrodynamic
energy of the fluid flow.
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 (casing), from
where it exits.

Explaining
 Theory of operation.
 Main parts in pumps.

 How to select a proper pump.
 Hydraulic losses.
 Flow friction.
 Recirculation.
 Incidence.

The affinity laws (Also known as the "Fan Laws" or "Pump Laws") for
pumps/fans are used in hydraulics, hydronics and/or HVAC to express
the relationship between variables involved in pump or fan
performance (such as head, volumetric flow rate, shaft speed)
and power. They apply to pumps, fans, and hydraulic turbines. The
affinity laws apply both to centrifugal and axial flows.
The laws are derived using the Buckingham π theorem. The affinity
laws are useful as they allow prediction of the head discharge
characteristic of a pump or fan from a known characteristic measured
at a different speed or impeller diameter. The only requirement is that
the two pumps or fans are dynamically similar, that is the ratios of the
fluid forced are the same.

 Law 1. With impeller diameter (D) held constant:
 Law 1a. Flow is proportional to shaft speed:
 Law 1b. Pressure or Head is proportional to the square of shaft speed:
 Law 1c. Power is proportional to the cube of shaft speed:

 Law 2. With shaft speed (N) held constant:
 Law 2a. Flow is proportional to the cube of impeller diameter:
 Law 2b. Pressure Head is proportional to the square of the impeller diameter:
 Law 2c. Power is proportional to the power 5 of impeller diameter:

 For radial flow centrifugal pumps, it is common industry practice to reduce the impeller
diameter by "trimming", whereby the outer diameter of a particular impeller is reduced by
machining to alter the performance of the pump. In this particular industry it is also common to
refer to the mathematical approximations that relate the volumetric flow rate, trimmed impeller
diameter, shaft rotational speed, developed head, and power as the "affinity laws". Because
trimming an impeller changes the fundamental shape of the impeller (increasing the specific
speed), the relationships shown in Law 2 cannot be utilized in this scenario. In this case the
industry looks to the following relationships, which is a better approximation of these variables
when dealing with impeller trimming.

 With shaft speed (N) held constant and for small variations in impeller
diameter via trimming:
 The volumetric flow rate varies directly with the trimmed impeller diameter:
 The pump developed head (the total dynamic head) varies to the square of the
trimmed impeller diameter:
 The power varies to the cube of the trimmed impeller diameter:

A positive displacement pump makes a fluid move by trapping a fixed amount and
forcing (displacing) that trapped volume into the discharge pipe.

Centrifugal pumps
 Impellers pass on velocity from the
motor to the liquid which helps move
the fluid to the discharge port.
 Flow rate varies with a change in
pressure.
 Efficiency peaks at a specific pressure;
any variations decrease efficiency
dramatically. Does not operate well
when run off the middle of the curve;
can cause damage and cavitation.
 Standard models cannot create suction
lift, although self-priming designs are
available and manometric suction lift
is possible through a non return valve
on the suction line.
Positive displacement pumps
 Traps confined amounts of liquid and
forces it from the suction to the
discharge port.
 Flow rate remains constant with a
change in pressure.
 Efficiency is less affected by
pressure, but if anything tends to
increase as pressure increases. Can
be run at any point on their curve
without damage or efficiency loss.
 Create a vacuum on the inlet side,
making them capable of creating
suction lift.

the head curve for a radial
flow pump is relatively flat
and that the head decreases
gradually as the flow
increases. Note that the
brake horsepower increases
gradually over the flow
range with the maximum
normally at the point of
maximum flow.

the head and brake
horsepower both increase
drastically near shutoff.

 https://www.youtube.com/watch?v=BaEHVpKc-1Q&t=6s
 https://www.youtube.com/watch?v=pWSyrxFJmt4
 https://en.wikipedia.org/wiki/Affinity_laws
 https://www.castlepumps.com/info-hub/positive-displacement-vs-centrifugal-
pumps
 https://www.b-k.com/technical-information/centrifugal-pump-fundamentals/pump-
characteristic-curves

pump performance
pump test
pump problems
pump maintenance
troubleshooting

THE DIFFERENCE
BETWEEN THE PUMP AND
THE TURBINE

THE HUMAN HART
It's a type of the pumps which know as a positive
displacement pump

DYNAMIC PUMPS
There are three types of dynamic pumps
that involve rotating blades called impller
blades or rotor blades which import
momentum to the fluid
For this reason this pump is called
rotodynamic pump or simply
(rotary pump)

CLASSIFICATION OF
ROTARY PUMP
They are classified by the manner in which flow
exits the pump
1: Centrifugal flow pump
the fluid enters the pump axial (in the same
direction of the shaft)
The fluid exit the pump radially ( or tangentially)
for this reason this pump is called radial - flow
pump

2:axial flow pump
Fluid enters and leaves axially
3:mixed flow pump
It's an intermediate between centrifugal and axial
pump

Axial flow pump
Mixed flow pump
Centrifugal flow pump

1:PUMP PERFORMANCE
1:mass flow rate or volume flow rate (capacity)
2:Bernolli head ( change in the head between the
outlet and the inlet
3: Water horse power
4:Break horse power

Losses in pumps are due to
1:friction.
2:internal leakage
3: flow separation on the blades
4:turbulance
So the mechanical energy which supplied must
exceeds this losses which known as the break horse
power (bhp)

PROBLEMS
One of the major problems facing industry is the limited
number of people with sufficient skills and experience to
diagnose and rectify the basic problems of the pump
The lack of skills and experience create many of these
problems
When a fuse in an electric circuit fails it doesn't mean
there's any thing wrong with the fuse
In fact the problem is in another place in the system so we
must look for the real problem instead replacing the
defected part

In the same manner
when we release 80% of all pumps
failure tends to drop the
mechanical seal and the bearing
that means we must look for the
real problem instead replacing the
defected part

PROBLEMS AND
TROUBLESHOOTING
1:speed of problem occurrence
2:frequancy of problem occurrence
3:hydroulic imbalance in a double suction
pump

1:SPEED OF PROBLEM
OCCURANCE
*an effective pump troubleshooting tool will be with the
question "when did this start"
If the problem has a sudden appearance it's failure to say
this happen due to a sudden change in the conditions that
created the problem
But there is a much more inappropriate action has been
initiated
Like what????!!!

Wear gradually takes place until the point of
failure reached
In this Way the wear is usually indicated by
a gradual reduction in performance until
the break point is reached

2:FREQUENCY OF PROBLEM
OCCURANC
A typical example of this problem is when a mechanical
seal in a particular pump fails every six months ,
regardless the type of the seal
3: hydraulic imbalance in a double
suction pump
 This leads to failure in the mechanical seal or the
bearing
This may happen at approximately 6 months ,
regardless the type of the seal or the bearing installed

MAINTAINANCE
The general rule of the maintenance is "It's better to
have a preventive maintenance"
Maintenance not mean to change the defected part it's
mean we must know the reason which caused the fault
Maintenance may tried any time but the seal - for example
- fails by the same frequency
Skills and experience come in to play here
The above condition is one where the experienced
troubleshooting would immediately consider

Reciprocating pump types
 Pump problems
 Pump maintenance
 Pump troubleshooting

 Action 1: The plunger or piston is pulled back. The action increases
the volume of the cavity. As the cavity volume expands, fluid is
drawn in through the inlet to fill the expanding cavity.

 Action 2: The piston has reached it's maximum
displacement. Since it is not moving into or out of the
cavity, fluid is not flowing through the inlet or the
outlet.
Action 3: After reaching it's maximum position, it is then
pushed back into the cavity. During this process, the
piston applies enough pressure to the fluid to overcome
the pressure in the outlet of the pump. This pressure
differential pushes the fluid from inside the cavity
through the outlet of the pump.

 Action 4: The piston reaches its maximum extension
into the cavity. Here the volume of the cavity is at a
minimum and fluid is not flowing through the inlet or
the outlet. The next action repeats the process, starting
again with action 1.

Single-acting reciprocating pump: This has one suction valve and one discharge
valve. When the piston is moved backward, suction happens and when it moves
forward, the delivery valve opens up to discharge the liquid.
Double-acting reciprocating pump: Unlike single acting pump, here there are two
suction and delivery valves. When the piston is moved forward or backward, with
each stroke, both suction and expulsion happen simultaneously. Thus it requires
two inflow pipes and two outflow pipes. Some of the common applications of these
kinds of pumps are in Salt Water Disposal, Well Service, Descaling, Hydraulic
Fracturing, and Oil & Gas Pipelines.

 High Maintenance / Short Life: The main disadvantage of a reciprocating pump is the
high maintenance and short life. There are many parts in the pump works, all constantly
changing directions. Unless careful maintenance takes place, the lifespan of the pump is
greatly reduced. While pumps such as centrifugal pumps can last 15 to 20 years with little
maintenance, a reciprocating pump requires higher levels attention and rebuilding several
times within the same time frame. The cost of a reciprocating pump rebuild is usually
inexpensive which still makes them cost competitive compared to longer lasting, higher
priced pump designs.
 Pulsations: A characteristic of reciprocating pumps is the production of pressure
pulsations through the pump inlet and outlets. The reciprocating motion of the pump
produces these pulsations. Increasing the number of pump chambers can greatly
reduce the pulsations produced, but it does not remove them completely. To negate
damage to piping and surrounding systems or the pump itself, pulsation dampeners
must be installed. Further system design can further decrease pulsations to nearly
zero. In all cases, overall system design is important when using reciprocating pumps.

BASICS
PROBLEMS
TROUBLESHOOTING
INSPECTIONS

 pump consists of an impeller rotating within a casing. Fluid enters axially through
the eye of the casing, is caught up in the impeller blades, and is whirled tangentially
and radially outward until it leaves through all circumferential parts of the impeller
into the diffuser part of the casing. The fluid gains both velocity and pressure while
passing through the impeller. The doughnut-shaped diffuser, or scroll, section of the
casing decelerates the flow and further increases the pressure.
 The blades may be open (separated from the front casing only by a narrow clearance)
or closed (shrouded from the casing on both sides by an impeller wall)

 In order to correctly identify the problem it is important to gather as
much information relating to the process as follows:
1. Reconfirm original duty requirements and/or system design.
2. Check for any process changes i.e. pressure, temperature, fluid
viscosity etc.
3.How long did the pump operate before the problem.
4. Check the appearance and condition of the pump internal
components.
5. Check when the pump was last serviced.
6.Check for any changes in pump noise or vibration.
 This will save considerable time and effort in leading to the most
appropriate solution.

Problems
2-No or low
pressure
1-No or low
flow
5-Seal
leakage
4-Excessive
noise or
vibration
3-Excessive
power
consumption

1-No or
low flow
4-viscosity is
higher than
expected
1-Pump is not
primed
2-The motor is
turning pump
in the wrong
direction
3-Insufficient
Net Positive
Suction Head
available
(NPSH)
Cavitation

2-No or
low
pressure
4-No power to
the pump
1-Valves are
closed or
there is an
obstruction in
the inlet
pipework
2-A strainer
or filter is
clogged on
the inlet
3-Pump speed
too low

3-Excessive
power
consumption
1-fluid heavier
(in either
viscosity or
specific
gravity) than
allowed for
2-Shaft bent
due to damage
- through
shipment or
operation
3-
Misalignment

4-
Excessive
noise or
vibration
1-Pump is
cavitating
2-Impeller
contact with
casing/
backplate
3-Loss of
shaft support
(bearing
failure in
motor)
• Incorrect clearance
between impeller and
backplate
• Worn bearings on
motor
• Foreign object
• Incorrect rotation
• Temperature
exceeding
pump design
limits
• Coupling/Shaf
t mis-
alignment
• Inadequate
lubrication

 Mechanical seals are precision designed and
manufactured, yet one of the most common causes of
failure in Centrifugal pump types. By design mechanical
seals are friction contact devices and can be subjected to a
very wide range and often hostile operating environments.
Selecting the correct mechanical seal is imperative
 To assist in identifying why a particular mechanical seal
has leaked it is important to record as much information
as possible:
1. How long has the seal been in operation (months, days, hours)? Is the seal subject
to continuous or intermittent running?
2. Check for any process changes i.e. pressure, speed, temperature and pumped
media details.
3. Where is the seal leaking from? i.e. seal faces and/or elastomers.
4. How badly is the seal leaking? i.e. constant or variable, only when shaft is
stationary
• Swollen, sticky or
disintegrating
• Hard or cracked

1. Lack of prime Fill pump and suction pipe completely with liquid.
2. Wrong direction of
rotation
Check motor rotation with directional arrow on pump casing.
Wrong rotation will cause pump damage.
3. Cavitation; insufficient
NPSH (depending on
installation)
a. Increase positive suction head on pump by lowering pump or
increasing suction pipe size or raising fluid level.
b. Pressurize suction vessel
1. Obstruction in liquid
passages
Dismantle pump and inspect passages of impeller and
casing. Remove obstruction
2. Speed too low Check whether motor is directly across-the-line and receiving
full voltage. Alternatively, frequency may be too low; motor may
have an open phase
1-No or low flow
2-No or low pressure

3-Excessive power consumption
1- Liquid heavier (in
either viscosity or
specific gravity) than
allowed for
Use larger driver. Consult factory for recommended
size. Test liquid for viscosity and specific gravity
2-Misalignment Realign pump and driver.
3- Shaft bent due to
damage - through
shipment or
operation
Dismantle pump and inspect shaft

Centrifugal pump inspection should be done regularly. But for different the level of
checking varies with how frequently these pump inspections are carried out. For
during routine pump inspections only the easy to monitor factors such as pressure,
temperature, vibration etc. can be checked
Routine inspections
 Check the level and condition of the oil through the sight glass on the bearing
frame
 Check for unusual noise, vibration, and bearing temperatures.
Check the pump and piping for leaks.
 Analyze the vibration.
 Inspect the discharge pressure.
 Inspect the temperature.
 Check the seal chamber and stuffing box for leaks.
 Ensure that there are no leaks from the mechanical seal.
 Adjust or replace the packing in the stuffing box if you notice excessive leaking.

monthly inspections
 Check that the foundation and the hold-down bolts are tight.
 Change the oil every three months at minimum.
 Change the oil more often if there are adverse atmospheric or other conditions that
might contaminate or break down the oil.
 Check the shaft alignment, and realign as required
Annual inspections
 Check the pump capacity.
 Check the pump pressure.
 Check the pump power
If the pump performance does not satisfy your process requirements, and the process
requirements have not changed, then do the following:
1. Disassemble the pump
2. Inspect it.
3. Replace worn parts.

Compressors are machines used to increase the total
energy level of a compressible fluid (either gas or vapor).
Molecular weight of compressed gas vary from 2
(Hydrogen) ~ 352 (uranium hexafluoride)
WHAT ARE COMPRESSORS ?

WHAT ARE COMPRESSORS
APPLICATIONS ?
Compressors can be used for:
Gas transmission through pipelines
Storage and transmission of energy (e.g. shop air
compression)
Volume reduction for storage or transportation (e.g.
LPG, LNG)
Process requirements (e.g. chemical reactions)
Energy conversion (e.g. Ref. system, heat pumps)
Compressed air provides torque and rotation power for
pneumatic tools, such as drills, brushes, nut runners,
riveting guns and screwdrivers

COMPRESSOR TYPES
DYNAMIC POSITIVE DISPLACEMENT
Ejector Centrifugal Axial Rotary Reciprocating
Vane Liquid Ring Screw Lobe
Single Acting
Double Acting
Free Piston
Labyrinth
Diaphragm

Centrifugal (Radial) Compressor
Centrifugal Compressor

These compressors take air in at the
center or “eye "of the rotor. Due to the
high rotational speeds of the rotor, the air
is accelerated by the blades and forced
radially to the edge of the rotor at high
velocity by centrifugal force. There, the air
is received by the diffuser, which in turn,
converts the high velocity to pressure
energy.

ROTARY SCREW COMPRESSOR
1. Male rotor
2. Female rotor
3. Timing gear
4. Rotor bearings
5. Drive shaft
6. Compressor casing

How it Works?
1.As the rotors revolve, the space between the un meshing lobes increase allowing
inlet air or gas to fill up the intervening space, until the male lobe is disengaged from
the female lobe along its whole length.
The helices of the male and female rotors are designed to permit complete charging
of the inter – lobe space before they remesh.
2. On completion of the filling operation the inlet ends of the male and female rotors
pass the inlet port and become sealed in the casing.
3. With continuing rotation, the male and female lobes begin to re-engage each
other, the volume of this space is reduced and compression

A-Air is drawn in through the intake valve.
B-Air is contained between the rotor and the stator wall.
C-Air is compressed by decreasing volume. Oil is continually injected
to cool, seal and lubricate.
D-High pressure air passes into the primary oil separator.
E-Remaining traces of oil are removed in a final separator element,
providing high quality air.
F-System air passes through the after cooler, removing most of the
condensate.
G-Oil is circulated by differential internal air pressure. It passes
through an air-blast oil cooler and filter before being returned into the
compressor.
H-Air flow is regulated by an inbuilt modulation system.

ADVANTAGES
Long life and reliability by design
Quiet as standard
Slow Speed
High quality air
Ease of maintenance
Package Options (Power ranges 2 hp to 10 hp)

Lobe compressor
WORKING PRINCIPLE

It employs two Twin Lobe impellers mounted on parallel shafts, rotating
in opposite direction within a casing closed at the ends by side plates.
As the impellers rotate, air is drawn into one side of the casing and
forced out of the opposite side against the existing pressures
Blowers are constant volume machines, which deliver a
fixed discharge against the system back pressure.
No attempt should ever be made to control the capacity of
compressor by means of throttle valves in the intake or discharge
piping. This increases the power load on the motor and may
seriously damage the compressor
available for flow rates from 25m3/hr to 10,000 m3/hr
working pressures upto 1 Kg/cm2.

RECIPROCATING COMPRESSOR WORKING PRINCIPLE &
COMPONENTS
1- Piston (s).
2- Piston rings.
3- Cylinder (s)
4- Valves (suction valve & discharge valve).
5- Driving mechanism (crank shaft,
connecting rod, cross head and piston rod).
6- Suitable frame

1- Suction Stroke
1- The piston moves from position (A) to position (B). This create
vacuum inside the cylinder. The differential pressure exists across
the suction valve (inlet valve). Inlet valve open.
2- Gas (or air) is drawn into the cylinder via (through) the suction
valve.
In the suction stroke the suction valve is open, the discharge valve is
closed, the piston movement from (A) to (B).
3- When the piston reach position (B) it stop before change the
direction of movement from (B) towards (A). At this moment both
valves (suction and discharge) are closed

2- Discharge Stroke
1- The gas is trapped in the cylinder.
2- The piston moves from (B) to (A). The volume of gas decrease and its
pressure increases and the temperature also.
3- When the gas pressure inside the cylinder becomes higher than the pressure
of the gas in the discharge manifold, the discharge valve open and the gas
passes through the discharge valve to outside the cylinder.
4- The piston keep going pushes the gas outside the cylinder until it reaches
again position (A). When the piston reaches position (A), it completes one
complete cycle.

Surge
Dirty inlet air filter.
Too small inlet pipe (remote-mounted air filter).
High interstage air temperatures
Increase in water temperature
Increase in inlet air temperature.
Low Seal Air Pressure
Seal air regulator malfunctioning
Damaged seal air line.
Leaking fitting.
Leaking seals.
Troubleshooting

Low System Air Pressure
Incorrect setpoint.
Incorrect valve calibration
Bad controller
Dirty inlet filter.
Leaking bypass valve.
High Vibration
Low oil temperature.
High oil pressure.
Incorrect coupling alignment.
Excessive grease in coupling.
Bad motor bearings.
Low Oil Pressure
Dirty oil filter.
Leaking check valve.
Wrong size pump.
High Oil Temperature
High water temperature
Incorrect oil.
Heat exchanger radiating fins dirty.
Inadequate water flow.

Failure to Start
No power to motor starter
Blown fuse.
Overloads tripped.
Low voltage.
Bad motor starter.
Failure to Load
Inlet valve stuck
No control air signal.
Controller setpoint too low.
High Air Temperature
Inadequate water flow.
High water temperature
Water control valve thermostat out of
calibration

Lubrication
oil injected into the compressor lubricates the bearings, gears, and rotors.
The lubricant cools the compressed air to about 40°C above ambient
temperature and helps seal running clearances in the rotor housing

Oil coolant life VS temperature

Pumps and compressor

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