Basics of pumps

Basics of Pumps
Tahseen Qamhieh
Sr. Mechanical Engineer

 What is Pump?
 Pumps Common Components
 Pumps Performance
 Pumps Classification
 Dynamic Pumps
 Centrifugal Pumps
 Pumps Curves
 Positive Displacement Pumps
 Reciprocating Pumps
 Rotary Pumps
 Pumps Inspection
Page 2
Presentation Outline

A pump is a device which moves
fluids by mechanical action from
one place to another.
BASICS OF PUMPS Page 3
What is Pump?

 Inlet – where liquid enters the pump.
This side of the pump is also called
the suction side.
 Outlet – where liquid leaves the
pump. The pressure of the liquid is
highest at this point.
 Casing – This part is to contain the
liquid inside the pump during
operation. It houses all of the pump
internal parts.
Pump Major Components

 Shaft – used to transfer power from driver
to component that moves liquid
 Driver – supply the power needed to
produce the pumping action
 Coupling – a device that connect the drive
shaft to the pump shaft
 Strainers – a device used to trap & remove
solids before they enter the pump
 Lubricating System – to lubricate pumps
bearings
 Bearings – used to support and align
moving parts of pump
Pump Auxiliary Equipment's

Pump Common Components

 Passive Feed Systems:
Use delivery methods
such as gravity to deliver
lubricants to the
bearings.
 Forced Feed Systems:
When pumps need a
greater supply of
lubricant to the bearings.
Types of Lubricating System

– Flow Rate = Pump Capacity
– Flow Rate expressed as
gallons/minute
Pump Flow Rate Definition

– A measurement of pressure.
– Weight of column liquid.
– Head expressed in Feet or
Meter
 Example: 25 feet water level =
25 feet of head at base
Pumps Head Definition

 Static Head – measured from inlet
centerline to liquid level.
 Suction Head – measured at pump
inlet.
 Discharge Head – measured at pump
outlet (Head related to pressure)
 Dynamic Head – caused by moving
liquid.
 Total Head – produced inside the pump.
Head Types

Pumps
Dynamic
Positive
Displacement
Specialty
Pumps
Axial Flow
Mixed Flow
Radial Flow
Reciprocating Rotary
Piston/Plunger
Diaphragm
Bladder
Axial
Radial
Mech.
Drive
Hydro.
Drive
Air
Drive
Gear
Lobe
Screw
Cavity
Vane
Peristaltic
Ext.
Low
Press.
High
Press.
Solen.
Drive
Int.
Centrifugal

 Energy is added to the fluid continuously
through the rotary motion of the blades.
This increase in energy is converted to a
gain in pressure energy when the liquid
is allowed to pass through an increased
area.
Principle of Operation
 Recommended media (fluid): water and
relatively thin liquids.
 Not recommended for thicker oils.

 The most common type of pump used
in industry due to its simple working
principle and relatively inexpensive
manufacturing cost.
Centrifugal Pump Principle
 Works on the principle of centrifugal
force by pushing the liquid away from
the center in tangential direction.
 Operate using kinetic energy to move fluid utilizing an impeller & a circular
pump casing. The impeller produces liquid velocity & the casing forces the
liquid to discharge from the pump converting velocity to pressure.

 Shaft – transmit the torque/power
and supporting the impeller & other
rotating parts.
 Impeller – transmit energy into the
fluid (hydraulic energy). An impeller
has vanes that pushes the liquid.
 Casing – where the impeller is fitted.
 Bearings – keep the shaft in correct
alignment with the stationary parts.
Major Parts of Centrifugal Pump

 Liquid forced into impeller.
 Vanes pass kinetic energy to liquid.
 Liquid rotates and leaves impeller.
 Volute casing converts kinetic
energy into pressure energy.
How it Works?

 Open – no shrouds or wall to
enclose the vanes.
 Semi open – shrouds or sidewall
partially enclosing the vanes.
 Closed – shrouds or sidewall
enclosing the vanes.
Types of Impeller

 Volute Casing
 Vortex Casing
 Diffuser Ring Casing
Construction of the Pump Casing

 Single Stage Pump – has just one
impeller and is better for low head
service.
 Two Stage Pump – has two impellers
mounted in series for medium head
service.
 Multistage Pump – has three or more
impellers mounted in series for high
head service.
Pumps Classification According to Number of Impellers

 Horizontal Shaft Pump
 Vertical Shaft Pump
Pumps Classification According to position of Shaft

 Radial Flow Pumps – high Pressure,
low flow pumps which accelerate fluid
along the impeller blades perpendicular
to the shaft.
 Mixed Flow Pumps – medium flow,
medium pressure pumps which push
fluid out away from the pump shaft at an
angle greater than 90°.
 Axial Flow Pumps – high flow, low
pressure pumps which lift fluid in a
direction parallel to the impeller shaft.
Pumps Classification According to the Direction of Flow

 Long-coupled pump:
pump connected to the
motor by means of a
flexible coupling. The
motor and the pump
have separate bearing
constructions
 Close-coupled pump:
pump connected to the
motor by means of a
rigid coupling.
Long-coupled and Close-coupled Pumps

End-Suction Pump
Horizontal
Multistage
Close-coupledLong-coupled
Single Stage
Close-coupled
→ The liquid runs directly
into the impeller. Inlet &
outlet have a 90° angle

In-line Pump
Horizontal
Multistage
Close-coupledLong-coupled
Single Stage
Close-coupled
→ The liquid runs directly
through the pump in-line.
The suction pipe and the
discharge pipe are placed
opposite one another and
can be mounted directly
in the piping system
Vertical
Single Stage
Long-coupled

 Curve graphs represent design
characteristics.
 The performance of a centrifugal
pump is shown by a set of
performance curves.
 The performance curves for a
typical centrifugal pump shown on
the figure as a function of the flow;
Head, Power consumption,
Efficiency and NPSH.
Pump Curves

 The QH-Curve shows the
head, which the pump is able
to perform at a given flow.
Head, the QH-Curve

 The efficiency ƞP is the relation between the
power, which the pump delivers to the water
(PH) & the power input to the shaft (P₂)
ƞP = PH / P₂ = (ρ . g . Q . H) / (P₂ x 3600)
Where: ρ is the density of the liquid in kg/m³
g is the acceleration of gravity in m/s²
Q is the flow in m³/h
H is the head in m
Efficiency, the ƞ-Curve

 For water at 20°C & with Q measured in m³/hr and H in m, the hydraulic
power can be calculated as:
PH = 2.72 . Q . H [W]
Efficiency, the ƞ-Curve
 The efficiency depends on the duty point of the pump. Therefore it
is important to select a pump, which fits the flow requirements and
ensures that the pump is working in the most efficient flow area.
 Maximum efficiency point = Provides most flow for least amount of
power.

 The P₂-Curve of most
centrifugal pump is similar to
the one shown on the figure,
where the P₂ value increases
when the flow increases.
P₂ = (Q . H . g . Ρ) / (3600 x ƞP )
Power Consumption, the P₂-Curve

 The NPSH-value of a pump is the
minimum absolute pressure that
has to be present at the suction
side of the pump to avoid
cavitation.
 The NPSH-value is measured in
(m) and depends on the flow;
when the flow increases, the
NPSH-value increases as well.
NPSH-Curve (Net Positive Suction Head)

 NPSHA combines the effect of atmospheric pressure, water temperature, supply
elevation and the dynamics of the suction piping.
NPSHA = Ha +/- Hz – Hf + Hv – Hvp
Ha: the atmospheric or absolute pressure.
Hz: the vertical distance from the surface of the water to the pump centreline.
Hf: the friction formed in the suction piping.
Hv: the velocity head at the pump's suction.
Hvp: the vapor pressure of the water at its ambient temperature.
NPSHA (Net Positive Suction Head Available)

 Cavitation:
• Is defined as formation and collapse of
vapor bubbles.
• Caused by low suction head. Means when
suction head drop below its design value.
• Higher temperatures increase chance of
cavitation
• Cavitation wears away pump components
Suction Head and Cavitation

Pumps connected in Parallel:
 Pumps connected in parallel are often used when:
− The required flow is higher than what one single
pump can supply.
− The system has variable flow requirements and
when these requirements are met by switching
the parallel connected pumps ON and OFF.
 Normally, pumps connected in parallel are of
similar type and size.
 Q = Q₁ + Q₂
 H = H₁ = H₂
Pumps Coupling of Stages

Pumps connected in Series:
 Normally, pumps connected in series are
used in systems where a high pressure is
required.
 Q = Q₁ = Q₂
 H = H₁ + H₂
Pumps Coupling of Stages

 Include all pumps which use fixed
volume cavities displaced using a
mechanical force to move fluid
through the system.
Positive Displacement Pumps
 Positive Displacement Pumps
Classification:
 Reciprocating Pumps
 Rotary Pumps

 Use linear rather than rotary motion to
move fluids.
Reciprocating Pump Principle
 Utilize a piston or diaphragm which
draws fluid in (upstroke) and pushes it
out (downstroke), using check valves
to regulate and direct flow through the
system.
 It is often used where a relatively small
quantity of liquid is to be handled and
where delivery pressure is quite large.

 Pumps that use a plunger or
piston to move media through
a cylindrical chamber.
 The pressure in the chamber
actuates the valves at both the
suction and discharge points.
Piston/Plunger Pumps

 Single Acting – pumps have
one valve on each end, where
suction and discharge take
place in opposite directions.
 Double Acting – pumps utilize
two valves on each end,
allowing suction and discharge
in both directions.
Pump Action

 Simplex – pumps have one cylinder
 Duplex – pumps have two cylinders
 Multiplex– pumps have more than two cylinders
Number of Cylinders

 Axial – Contain a number of pistons
attached to a cylindrical block which
move in the same direction as the
blocks centerline (axially)
Axial Vs. Radial
 Radial – Contain pistons arranged like
wheel spokes around a cylindrical block.
A drive shaft rotates this cylindrical block
which pushes or slings the pistons.

 Low flow pneumatic devices used mainly for
fluid sampling applications.
 Consist of a flexible squeezable bladder
encased in a rigid outer casing.
 Utilize hydrostatic pressure to draw water into
the bladder and pass it through a check valve
at the bottom of the pump. When the bladder
is full, the check valve closes to prevent
backflow, and the water is pumped up to the
surface via injected gas pressure which
squeeze the bladder.
Bladder Pumps

 Work by flexing the diaphragm out of the
displacement chamber.
 When the diaphragm moves out, the
volume of the pump chamber increases
and causes the pressure within the
chamber to decrease and draw in fluid.
The inward stroke has the opposite effect
decreasing the volume and increasing the
pressure of the chamber to move out fluid.
 Recommended media (fluid): wide range
of liquids, including liquids containing
solids and corrosive liquids.
Diaphragm Pumps

 Mechanical – operated using a
simple & robust reciprocating
mechanical linkage directly
attached to the diaphragm.
Diaphragm Pumps Drive Mechanism
 Hydraulic – Implement an
intermediate hydraulic fluid on the
opposing side of the diaphragm.

 Solenoid – have an electric
motor that controls a solenoid
magnet.
Diaphragm Pumps Drive Mechanism
 Air – pumps which use compressed
air to drive diaphragms.

 Single Acting – pumps
incorporate one diaphragm
and one set of valves.
 Double Acting – pumps
incorporate two diaphragms
and two sets of valves.
Diaphragm Pump Action

 Move fluid using rotating
mechanical motion.
 As the rotor of the pump spins
in a circular motion, liquid is
drawn into and forced out of
spaces created by the moving
parts.
Rotary Pump Principle

 The most common type of positive
displacement pump used.
 Typically, a rotating assembly of two gears
(a drive gear and an idler) moves to create
suction at the pump inlet and draw in fluid.
The liquid is then directed between the teeth
of the gears and the walls of the casing to
the discharge point. Volume decreases as
the liquid travels from inlet to outlet, causing
a buildup of pressure.
 Recommended media (fluid): oils and other
high viscosity liquids.
Gear Pumps

 Utilize two identical gears with external teeth to generate flow. The
rotation of the gears is such that the liquid comes into the inlet port and
flows into and around the outer periphery of the two rotating gears. As
the liquid comes around the periphery it is discharged to the outlet port.
External Gear Pumps

 Generate flow using a gear with externally cut teeth contained in and
meshed with a gear with internally cut teeth. As the gears come out of
mesh on the inlet side, liquid is drawn into the pump. The liquid is
forced out the discharge port by the meshing of the gears.
Internal Gear Pumps

 Similar to gear pumps in terms of
operation in that fluid flows around
the interior of the casing. Multiple
lobes on the rotating elements
provide the ability to drive large
solids & slurry-laden media.
Typically, they are available in
double-lobe or triple-lobe
configuration.
 Recommended media (fluid): liquids
which are viscous or which contain
fragile solids or are shear sensitive.
Lobe Pumps

 Use one or more screws to transfer fluids
along an axis.
 The pumping liquid from the inlet is trapped
between the teeth of the idler screws. Though
continuous, the flow can be considered as a
series of packets lying between a set of two
adjacent threads of the idler. The rotation of
the driver causes each packet of trapped liquid
to move progressively forward in the axial
direction & ultimately to the outlet.
 Recommended media (fluid): oils, fuels and
other high viscosity liquids. Also handle two-
phase liquid/gas mixtures.
Screw Pumps

 Use rotating mechanisms to
push fluids through
continuously moving open
cavities.
 Recommended media (fluid):
wide variety of thin and thick
liquids, including corrosive
liquids and liquids containing
solids.
Progressive Cavity Pumps

 Pumps create regions of low
pressure by moving fluid using a
rotating vane assembly in the
pumping chamber. Typically there
are two or more rotating vanes
that move the fluid from inlet to
outlet.
 Recommended media (fluid): oils
& other high viscosity liquids. Also
good for thin liquids like gasoline
and water.
Vane Pumps

 Consist of a tube which is squeezed by a
set of rollers or shoes to move fluid.
 By constricting the tube and increasing the
low pressure volume, a vacuum is created
to pull the liquid into the tube. Once in the
pump, the liquid is pushed through by
compressing the tube at a number of points
in contact with the rollers or shoes. The
media is moved through the tube with each
rotating or oscillating motion.
 Recommended media (fluid): wide range of
liquids, including liquids containing solids
and corrosive liquids.
Peristaltic Pumps

 Low Pressure – laboratory
grade pumps designed for
low pressure pumping
applications.
 High Pressure – industrial
grade pumps designed for
high pressure pumping
applications.
Peristaltic Pumps

 Improper Pressure or Flow:
• Pump – Foreign matter in pump, Worn or
damaged pump ports, Relief valve improperly
seated, Cavitation, Air trapped in pump.
• Suction Line – Insufficient supply of liquid,
Clogged suction line, Suction valve in wrong
position, Excessive amount of air or gas in
liquid, Inadequate suction head, Improper
liquid viscosity, Clogged strainer.
• Discharge Line – Discharge valve in wrong
position, Clogged discharge pipe.
Symptoms of Pump Problems

 Overheating:
• Pump – Cavitation, Air or vapor
trapped in pump, Improperly
installed packing.
• Bearings – Insufficient or improper
lubrication, Insufficient cooling of
lubricant, Damaged bearings.
• Coupling – Misalignment of driver
and pump shafts, Worn or
defective coupling.

 Sounds (Excessive Noise or Unusual Vibration):
• Pump – Air or vapor trapped in pump casing, Cavitation, Foreign matter in pump,
Worn or damaged parts, Rubbing of rotating and stationary parts, Bent shaft.
• Suction Line – Insufficient liquid supply, Inadequate suction head.
• Bearing – Bearing damage, Inadequate or improper lubrication.
• Coupling – Misalignment of driver and pump shafts, Worn of defective coupling.
• Motor Base – Malfunctioning driver, Driver or pump foundations not rigid.

 Check:
 Suction piping
 Suction valve packing and gasket
 Pump
 Packing
 Mechanical seals
 Pump bearings
 Discharge piping
Checking for Leaks

 Signs of Cavitation:
 Rattling noise, like marbles
 Discharge pressure fluctuations
 Overheated pump casing
 Decrease in flow
Checking for Cavitation

 Stopping or Minimizing Cavitation:
 Raise suction head above MNPSH.
 If permitted, increase pressure in
pump by temporarily restricting
discharge.
 Lower process fluid temperature (if
permitted)
Checking for Cavitation

Basics of pumps

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Basics of pumps