Fluid Flow - Pumps

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INTRODUCTION TO PUMP

A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by

mechanical action. Pumps can be classified into three major groups according to the

method they use to move the fluid: direct lift, displacement, and gravity pumps.Pumps operate by some mechanism (typically reciprocating or rotary), and

consume energy to perform mechanical wor by moving the fluid. Pumps operate via

many energy sources, including manual operation, electricity, engines, or wind power ,

come in many si!es, from microscopic for use in medical applications to large industrial

pumps.

"echanical pumps serve in a wide range of applications such as pumping water from

wells, aquarium filtering, pond filtering and aeration, in the car industry for water#

cooling and fuel injection, in the energy industry for pumping oil and natural gas or for

operating cooling towers. $n the medical industry, pumps are used for biochemical

processes in developing and manufacturing medicine, and as artificial replacements for

body parts, in particular the artificial heart and penile prosthesis.

$n biology, many different types of chemical and bio#mechanical pumps

have evolved, and biomimicry is sometimes used in developing new types of mechanical

pumps.

PUMP SELECTIONS

%he following factors influence the choice of pump for a particular operation:

i. %he quantity of liquid to be handled. %his primarily affects the si!e of the pump and

determines whether it is desirable to use a number of pumps in parallel.

ii. %he head against which the liquid is to be pumped. %his will be determined by the

difference in pressure, the vertical height of the downstream and upstream reservoirs

and by the frictional losses which occur in the delivery line. %he suitability of a

centrifugal pump and the number of stages required will largely be determined by

this factor.iii. %he nature of the liquid to be pumped. &or a given throughput, the viscosity largely

determines the friction losses and hence the power required. %he corrosive nature

will determine the material of the construction both for the pump and the pacing.

'ith suspensions, the clearance in the pump must be large compared with the si!e of

the particles.

https://en.wikipedia.org/wiki/Liquidhttps://en.wikipedia.org/wiki/Gashttps://en.wikipedia.org/wiki/Slurryhttps://en.wikipedia.org/wiki/Reciprocating_motionhttps://en.wikipedia.org/wiki/Rotationhttps://en.wikipedia.org/wiki/Energyhttps://en.wikipedia.org/wiki/Mechanical_workhttps://en.wikipedia.org/wiki/Engineshttps://en.wikipedia.org/wiki/Wind_powerhttps://en.wikipedia.org/wiki/Water_well_pumphttps://en.wikipedia.org/wiki/Water_well_pumphttps://en.wikipedia.org/wiki/Aquarium_filterhttps://en.wikipedia.org/wiki/Pondhttps://en.wikipedia.org/wiki/Aerationhttps://en.wikipedia.org/wiki/Car_industryhttps://en.wikipedia.org/wiki/Water_coolinghttps://en.wikipedia.org/wiki/Water_coolinghttps://en.wikipedia.org/wiki/Fuel_injectionhttps://en.wikipedia.org/wiki/Energy_industryhttps://en.wikipedia.org/wiki/Pumping_(oil_well)https://en.wikipedia.org/wiki/Natural_gashttps://en.wikipedia.org/wiki/Cooling_towerhttps://en.wikipedia.org/wiki/Medical_industryhttps://en.wikipedia.org/wiki/Artificial_hearthttps://en.wikipedia.org/wiki/Penile_prosthesishttps://en.wikipedia.org/wiki/Evolutionary_biologyhttps://en.wikipedia.org/wiki/Biomimicryhttps://en.wikipedia.org/wiki/Liquidhttps://en.wikipedia.org/wiki/Gashttps://en.wikipedia.org/wiki/Slurryhttps://en.wikipedia.org/wiki/Reciprocating_motionhttps://en.wikipedia.org/wiki/Rotationhttps://en.wikipedia.org/wiki/Energyhttps://en.wikipedia.org/wiki/Mechanical_workhttps://en.wikipedia.org/wiki/Engineshttps://en.wikipedia.org/wiki/Wind_powerhttps://en.wikipedia.org/wiki/Water_well_pumphttps://en.wikipedia.org/wiki/Water_well_pumphttps://en.wikipedia.org/wiki/Aquarium_filterhttps://en.wikipedia.org/wiki/Pondhttps://en.wikipedia.org/wiki/Aerationhttps://en.wikipedia.org/wiki/Car_industryhttps://en.wikipedia.org/wiki/Water_coolinghttps://en.wikipedia.org/wiki/Water_coolinghttps://en.wikipedia.org/wiki/Fuel_injectionhttps://en.wikipedia.org/wiki/Energy_industryhttps://en.wikipedia.org/wiki/Pumping_(oil_well)https://en.wikipedia.org/wiki/Natural_gashttps://en.wikipedia.org/wiki/Cooling_towerhttps://en.wikipedia.org/wiki/Medical_industryhttps://en.wikipedia.org/wiki/Artificial_hearthttps://en.wikipedia.org/wiki/Penile_prosthesishttps://en.wikipedia.org/wiki/Evolutionary_biologyhttps://en.wikipedia.org/wiki/Biomimicry


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iv. %he nature of power supply. $f the pump is to be driven by an electric motor or

internal combustion engine, a high#speed centrifugal or rotary pump will be preferred

as it can coupled directly to the motor. imple reciprocating pumps can be connected

to steam or gas engines.

v. $f the pump is used only intermittently, corrosion problems are more liely than with

continuous woring.

vi. %he cost and mechanical efficiency of the pump must always be considered, and it

may be advantageous to select a cheap pump and pay higher replacement or

maintenance costs rather than to install a very epensive pump of high efficiency.

TYPES OF PUMP

A. PUMPING EQUIPMENT FOR LIQUID

*. +-$P+-A%$/0 P1"P

i) Piston pump

ii) Plunger or +am Pump


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iii) 2iaphragm Pump


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iv) "etering Pump

3. P$%$4#

2$P5A-"/%

+%A+6 P1"P

i) 0ear Pump

ii)

5obe Pump


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iii) -am Pump


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iv) 4ane Pump

v) &leible 4ane Pump

vi) &low $nducer 7


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Peristaltic Pump

vii) "ono Pump


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viii)

crewPump

) -entrifugal Pump


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B. PUMPING EQUIPMENT FOR GASES

*. &ans and +otary compressor

3. -entrifugal and %urbocompressor


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8. +eciprocating Piston -ompressor


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9. Air#5ift

Pump


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. 4acuum Pump

WORKINGPRINCIPLES

(HOW IT WORK)

*.

+-$P+-A%$/0P1"P

i. Piston P!".

%hey use

contracting and

epanding

cavities to

move fluids.

-avities epand and contract in an reciprocating (bac and forth; up and down)

motion rather than a circular (rotary) motion. Piston pumps use a mechanism to

create a reciprocating motion along an ais, which then builds pressure in a cylinder

or woring barrel to force gas or fluid through the pump. %he pressure in the

chamber actuates the valves at both the suction and discharge points. %here is two

types of piston pumps which is:

A. Aial piston pump.

-ontains a number of pistons attached to a cylindrical bloc which

move in the same direction as the bloc


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piston housing and cylindrical bloc centerlines determines

the piston stroe. %hese pumps have a low noise level, very

high loads at the lowest speeds and high efficiency,rror:

+eference source not found .

ii. P#n$%& O& R'! P!"

%his pump is the same in principle as the piston type but differs in that the gland

is at one end of the cylinder maing its replacement easier that with the standard

piston type. %he sealing of piston and ram pumps has been much improved, but

because of the nature of the fluid frequently used, care in selecting and

maintaining the seal is very important.

iii. Di'"&'$! P!"

2iaphragm pump moves gases, liquids or gas#liquid miture via a reciprocating

diaphragm. %hey are highly reliable because they do not include parts that rub

against each other. %hey also contains no sealing or lubricating oils within the

pumping head meaning there is no chance of oil vapor leaage or contamination

of the handled media.

2iaphragm pumps wor by fleing the diaphragm out of the displacement

chamber. 'hen the diaphragm moves out, the volume of the pump increases and

causes the pressure within the chamber to decrease and draw in fluid. %he inward

stroe has the opposite effect, decreasing the volume and increasing the pressure

of the chamber to move out fluid. %his operation is very similar to the draw in,

push out, concept of human breathing.

i. T% !%t%&in$ "!"

"etering pumps are designed to dispense precise amount of fluids and measured

flow control. %hey feature a high level of repetitive accuracy and are capable of

pumping a wide range of chemicals. "etering pumps transfer media in two stages:

the intae stroe and the output stroe. 2uring the intae stroe, liquid is pulled into

the pump cavity past the inlet chec valve. 2uring the output stroe, the inlet valve

closes, the outlet valve opens, and the fluid is forced out. %he flow may be varied by

changing the stroe length or by adjusting the cycle frequency. "etering pumps are


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usually driven by a constant speed A- motor, although different drive mechanisms

may be used depending upon the application at hand. %he drive mechanism translate

the rotary motion of the driver into reciprocating movement. $ndustrial duty metering

will submerge this portion of the pump in an oil bath to assure sufficient lubrication

and reliability during continuous operation.

3. P$%$4#2$5P5A-"/% +%A+6 P1"P

i. T% $%'& "!" 'n* t% #o+% "!"

0ear pumps transports liquids using rotating gears. pecifically, they are rotary

positive displacement pumps, which utili!e a rotating mechanism or assembly to

cause this contraction and epansion. %ypically, a rotating assembly of two gears (a

drive gear and an idler) moves to create suction at the pump inlet and draw in fluid.

%he liquid is then directed between the teeth of the gears and the walls of the

casing to the discharge point. 4olume decreases as the liquid travels from inlet to

outlet, causing a buildup pressure. Pressure relief valves are typically built#in to the

pump to protect the pumping system from closed valve in the discharge piping.

&low in gear pumps is determined by the si!e of the cavity (volume) between the

gear teeth, the speed of rotation (rpm) of the gears, and the amount of slippage

(reverse flow). lip increases as pump wears.

ii. T% ,'! "!"

A rotating cam is mounted eccentrically in a cylindrical casing and a very small

clearance is maintained between the outer edge of the cam and the casing. As the

cam rotates it epels liquid from the space ahead of it and sucs in liquid behind

it. %he delivery and suction sides of the pump are separated by sliding valve

which rides on the cam. %he characteristics again are similar to those of the gear

pump.

iii. T% 'n% "!"

%he rotor of the vane pump is mounted off center in the cylindrical casing. $t carries

rectangular vanes in a series of slots arranged at intervals round the curved surface of

the rotor. %he vanes are thrown outwards by a centrifugal action and the fluid is


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carried in the space bounded by adjacent vanes, the rotor and the casing. "ost of the

wear is on the vanes and this can be readily be replaced.

i. T% -#%i+#% 'n% "!"%he pumps described above will not handle liquids containing solid particles in

suspension, and the fleible vane pump has been developed to overcome this

disadvantage. $n this case, the rotor is an integral elasomer molding of a hub

with fleible vanes which rotates in a cylindrical casing containing a crescent#

shaped bloc, as in the case of the internal gear pump.

. T% -#o/ in*,%& o& "%&ist'#ti, "!"

%his is a special form of pump in which a length of silicone rubber or other

elastic tubing, typically 8 to 3 mm diameter, is compressed in a stages by means

of a rotor. %he tubing is fitted to a curved trac mounted concentrically with a

rotor crying three rollers. As the rollers rotate, they flatten the tube against the

trac at the points of contact. %hese >flats? move the liquid by positive

displacement, and the flow can be precisely controlled by the speed of the motor.

i. T% !ono "!"

Another eample of a positive acting rotary pump is the single screw#etruder

pump typified by the "ono#pump which a specially shaped helical metal rotor

revolves eccentrically within a double#heli, resilient rubber stator of twice the

pitch length of the metal rotor. A continuous forming cavity is created as the

rotor turns# the cavity progressing towards the discharge, advancing in front of a

continuously forming seal line and thus carrying the pumped material within.

ii. S,&%/ "!"

crew pumps are rotary, positive displacement pumps that can have one or more

screws to transfer high or low viscosity fluids along an ais. Although progressive

cavity pumps can be referred to as a single screw pumps, typically screw pumps have

two or more intermeshing screws rotating aially clocwise or counterclocwise.

ach screw thread is matched to carry a specific volume of fluid. 5ie gear pumps,

screw pumps may have a stationary screw with a rotating screw or screws. &luid is


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transferred through successive contact between the housing and the screw flights

from one thread to the net.

iii. C%nt&i-$'# P!"

-entrifugal pumps operate using inetic energy to move fluid, utili!ing an

impeller and circular pump casing. A vacuum is created in the pump which

draws fluid to the impeller by suction. %he impeller produces liquid velocity and

the casing forces the liquid to discharge from the pump, converting velocity to

pressure. %his is accomplished by offsetting the impeller in the casing and by

maintaining a close clearance between the impeller and the casing at the

cutwater. =y forcing fluid through without cupping it, centrifugal pumps can

achieve very high flow rates.

APPLICATIONS

A. +-$P+-A%$/0 P1"P

0. Piston P!" o& R'! P!".

%he piston or ram pump may be used for injections of small quantities if

inhibitors to polymeri!ation units or of corrosion inhibitors to high pressuresystems, and also for boiler water feed application.

1. Di'"&'$! P!"

2iaphragm pumps are commonly called >mud hogs? and >mud sucer? because

of their use in pumping slurries and waste water in shallow depths. %hey are

capable of handling all sorts of aggressive media including gases and gas7 liquid

miture, and can achieve very high pressures. %hey should not be used to pump

dangerous or toic gases, since diaphragm pumps are not hermetically sealed.

5arger models of this pumps type are used to move heavy sludge and debris#filled

wastes from trenches and catch basins, applications where centrifugal pumps

perform poorly due to high discharge volumes and low water levels which would

cause them to lose their prime.


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maller models are typically use in chemical metering or dosing applications

where very constant and precise amounts of liquid delivery are required.

2. M%t%&in$ P!"

"etering pumps are generally used in applications with one or more of the

following conditions: low flow rates required; high accuracy feed required; high

system pressure; corrosive, ha!ardous or high temperature media; slurry or high

viscosity media and controlled dosing.

=. P$%$4#2$5P5A-"/% +%A+6 P1"P

0. G%'& P!" 'n* Lo+% P!"

0ear pumps are a popular pumping principle and are often used as lubrication pumps in machine tools, in fluid power transfer units, and as oil pumps in

engine. -ommon gear applications include, various fuel oil and lube oil,

chemical additive and polymer metering, chemical miing and blending,

industrial and mobile hydraulic applications, acids and caustic and low

volume transfer or application.

1. 3'n% P!"

'hile vane pump can handle moderate viscosity liquids, they ecel at

handling low viscosity liquids. vane pumps have no internal metal#to#metal

contact and self#compensate for wear, enabling them to maintain pea

performance on this non#lubricating liquids. %hey are used to handle aerosol

and propellants, in aviation service they are used in handling fuels, lubes,

refrigeration coolants, bul transfer og 5P0 and /@ 8, 5P0 cylinder filling,

and alcohols. $n refrigeration, they are used to deal with freons, ammonia.

5astly, they are also used to handle solvents and aqueous solutions.

2. F#%i+#% 3'n% P!"

%he most common application for fleible impeller pumps is in the marine

industry, where they are used as ballast and bilge pumps in small and medium

si!ed marine craft. %hey are ideal for handling fluids that are delicate, usually

with relatively low viscosities, and are also used across the pharmaceutical,


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cosmetic, and food industries. anitary versions of this pump are available,

with &2A approved rubber materials for the impeller.

4. F#o/ In*,%& o& P%&ist'#ti, "!"

%hese pumps have been particularly useful for biological fluids where all

forms of contact must be avoided. %hey are being increasingly used and are

suitable for pumping emulsions, creams, and similar fluids in laboratories and

small plants where the freedom from glands, avoidance or aeration, and

corrotion resistance are valuable, if not essential.

5. Mono P!"

%he mono pumps gives a uniform flow and is quiet in operation. $t will pump

against high pressures; the higher the required pressure, the longer are the

stator and the rotor and the greater the number of turns. %he pump can handle

corrosive and gritty liquids and is etensively used for feeding slurries to filter

presses. $t must never run dry. %he "ono "erlin 'ide %rout pump is used for

highly viscous liquids.

6. S,&%/ P!"

%Ps: ewage $nlet Pumps

n most %P


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level because the pump efficiency (hence energy consumption) is almost

uneffected by changing levels. Also the screw pump will automatically pump

less when the level in front of the pump decreases.

$ndustrial 'aste 'ater $n the industry you can find several varied applications for crew Pumps:

-ooling 'ater utfall Pumps

+efineries: for oily sludge and waste water Potato processing industry

ugar industry

7. C%nt&i-$'# P!"

$n energy and oil industry, it is use in refineries and power plants. =uilding

services also used this pump for pressure boosting, heating installations, fire

protection sprinler systems, drainage and air conditioning. $n industry and

water engineering it is used for boiler feed applications, water supply

(municipal, industrial), wastewater management, irrigation, sprinling,

drainage and flood protection. %he -hemical and Process $ndustries used it for

paints, chemicals, hydrocarbons, pharmaceuticals, cellulose, petro#chemicals,

sugar refining, food and beverage production. 5astly secondary systems used

it to handle coolant recirculation, condensate transport, cryogenics,refrigerants.

NPSH ( NET POSITIVE SUCTION HEAD)

%he margin of pressure over vapor pressure, at the pump suction no!!le, is /et Positive

uction @ead (/P@). /P@ is the difference between suction pressure (stagnation) and

vapor pressure. $n equation form:

NPSH 8 Ps 9 P'"

'here:

/P@ F /P@ available from the system, at the pump inlet, with the pump running

Ps F tagnation suction pressure, at the pump inlet, with the pump running


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Pvap F 4apor pressure of the pumpage at inlet temperature

ince vapor pressure is always epressed on the absolute scale, suction pressure must

also be in absolute terms. $n 1.. customary units, both pressures must be in psia. 0auge

pressure is converted to absolute pressure by adding atmospheric pressure. $n equation

form:

'+so#t% "&%ss&% 8 $'$% "&%ss&% : 't!os"%&i, "&%ss&%

%he above equation provides an answer in units of pressure (psi). %his can be converted

to units of head (feet) by the following equation:

8 1.20";SG

'here:

h F @ead, feet

p F Pressure, psi

0 F pecific gravity of the liquid

SAMPLE CALCULATION

tagnation suction pressure is determined to be *#psig at a sea level installation. %he

vapor pressure of the liquid is B#psia. -alculate /P@ in P$ and feet for a C.G 0 liquid

NPSH 8 Ps 9 P'"

8 0 : 04.7 9 <

8 7.7 PSI

NPSH 8 1.20";SG

8 (1.20) (7.7);=.>

8 0>.< FEET

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Fluid Flow - Pumps