Pumps n Mech

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PUMPS

AND PUMPING MECHANISM

TAHREEM ANSARI- 02

NEHA BHIMANI-06DEVIKRUPA CHOUTA-10

VINALI DALAL-12



Pump

A pump is a deviceused to move fluids,such as gases, liquids or

slurries. A pumpdisplaces a volume byphysical or mechanicalaction. Pumps fall intotwo major groups:1.positivedisplacement pumps2. rotodynamicpumps.





Rotary-type pumps Gear pump This uses two meshed gears

rotating in a closely fitted casing.Fluid is pumped around the outer

periphery by being trapped in thetooth spaces. It does not travelback on the meshed part, since theteeth mesh closely in the centre.Widely used on car engine oilpumps.



Progressing cavity pump Widely used for pumping difficult materials

such as sewage sludges, contaminated withlarge particles, this pumps consists of aspiral shaped rotor, about 10 times as longas its width. This can be visualised as a

central core of diameter x, with typical acurved spiral wound around of thicknesshalf x, although of course in reality it ismade from one casting. This shaft fits insidea heavy duty rubber sleeve, of wallthickness typically x also. As the shaft rotates, fluid is gradually forced up therubber sleeve. Such pumps can developvery high pressure at quite low volumes.

Roots-type pumps The low pulsation rate and gentle

performance of this Roots-type positivedisplacement pump is achieved due to acombination of its two 90° helical twistedrotors, and a triangular shaped sealing lineconfiguration, both at the point of suctionand at the point of discharge. This design

produces a continuous and non-vorticulessflow with equal volume. High capacityindustrial "air compressors" have beendesigned to employ this principle as well asmost "superchargers" used on internalcombustion engines.



Reciprocating-type pumps

Reciprocating pumps are those which causethe fluid to move using one or more oscilatingpistons, plungers or membranes (diaphragms).

Reciprocating-type pumps require a system of

suction and discharge valves to ensure that thefluid moves in a positive direction.

Pumps in this category range from having"simplex" one cylinder, to in some cases"quad" four cylinders or more. Most reciprocating-type pumps are "duplex" (two) or"triplex" (three) cylinder. The pumps can be

powered by air, steam or through a belt drivefrom an engine or motor. This type of pump was used extensively in the

early days of steam propulsion (19th century)as boiler feed water pumps.

Reciprocating pumps are typically used forpumping highly viscous fluids includingconcrete and heavy oils and specialapplications demanding low flow rates



Compressed-air-powered

double-diaphragm pumps One modern application of positive

displacement diaphragm pumps arecompressed-air-powered double-diaphragm pumps. Run oncompressed air these pumps are

intrinsically safe by design, althoughall manufacturers offer ATEX certified models to comply withindustry regulation. Commonly seenin all areas of

industry from shipping to process, SandPiper They are relatively inexpensive and

can be used for almost any dutyfrom pumping water out of bunds,to pumping hydrochloric acid fromsecure storage (dependant on howthe pump is manufactured -elastomers / body construction).



Rotodynamic pumps

Rotodynamic pumps (or dynamic pumps) are those in which kinetic energy isadded to the fluid by increasing the flow velocity.

This increase in energy is converted to a gain in potential energy (pressure)when the velocity is reduced prior to or as the flow exits the pump into thedischarge pipe. This conversion of kinetic energy to pressure can be explainedby the First law of thermodynamics or more specifically by Bernoulli's principle.

These types of pumps have a number of characteristics: Continuous energy Conversion of added energy to increase in kinetic energy (increase in velocity) Conversion of increased velocity (kinetic energy) to an increase in pressure head One practical difference between dynamic and positive displacement pumps is

their ability to operate under closed valve conditions. Positive displacement pumps physically displace the fluid; hence closing a valve

downstream of a positive displacement pump will result in a continual build upin pressure resulting in mechanical failure of either pipeline or pump.

Dynamic pumps differ in that they can be safely operated under closed valveconditions (for short periods of time).



Centrifugal pump

A centrifugal pump is arotodynamic pump that uses arotating impeller to increase thepressure and flowrate of a fluid.

Centrifugal pumps are the most common type of pump used tomove liquids through a pipingsystem. The fluid enters the pumpimpeller along or near to therotating axis and is accelerated bythe impeller, flowing radiallyoutward or axially into a diffuser orvolute chamber, from where it exits

into the downstream piping system. Centrifugal pumps are typically used

for large discharge through smallerheads.

Centrifugal pumps are most oftenassociated with the radial flow type.

The term "centrifugal pump" can beused to describe all impeller type

rotodynamic pumps including theradial, axial and mixed flow





Mixed flow pumps The fluid experiences both

radial acceleration and lift

and exits the impellersomewhere between 0-90degrees from the axialdirection.

As a consequence mixedflow pumps operate at

higher pressures than axialflow pumps while deliveringhigher discharges than radialflow pumps.



Eductor-jet pump Eductor-jet pump This uses a jet, often of steam, to

create a low pressure. This lowpressure sucks in fluid and propels

it into a higher pressure region. Application Metering pump for gasoline and

additives. Early applications includes the

use of the windmill or watermill topump water.

Today, the pump is used forirrigation, water supply, gasolinesupply, air conditioning systems,refrigeration, chemical movement,sewage movement, flood control,marine services, etc.



Specifications

Pumps are commonly rated by horsepower, flow rate,outlet pressure in feet (or metres) of head,inlet suction in suction feet (or metres) of head.

The head can be simplified as the number of feet ormetres the pump can raise or lower a column of water at atmospheric pressure.

From an initial design point of view, engineers often

use a quantity termed the specific speed to identifythe most suitable pump type for a particularcombination of flow rate and head.



Pumps as public water supplies

First European by Taccola depiction of apiston pump,,

One sort of pump once common worldwidewas a hand-powered water pump over awater well where people could work it toextract water, before most houses hadindividual water supplies.

From this came the expression "parishpump" for "the sort of matter chatteredabout by people when they meet when they

go to get water", "matter of only localinterest". Water from pitcher pumps are more might

cause gastrointestinal related diseases. prone to contamination since it is drawn

directly from the soil and does not undergofiltration, this



` Today, hand operated village pumps are considered

the most sustainable low cost option for safe watersupply in resource poor settings, often in rural areasin developing countries. A hand pump opens accessto deeper groundwater that is often not polluted andalso improves the safety of a well by protecting thewater source from contaminated buckets. Pumps likethe Afridev pump are designed to be cheap to build

and install, and easy to maintain with simple parts.However, scarcity of spare parts for these type of pumps in some regions of Africa has diminished theirutility for these areas.



The power added to the fluid flow by the pump (Po), is definedusing SI units by:

PO is the output power of the pump (W)

is the fluid density (kg/m3) g is the g ravitational constant (9.81 m/s2) H is the energ y Head added to the flow (m) Q is the flow rate (m3/s) Power is more commonly expressed as kW (103 W) or

horsepower (divide kW by 0.746), H is eqivalent to the pressure

head added by the pump when the suction and discharg e pipesare of the same diameter. The power required to drive thepump is determined by dividing the output power by the pumpefficiency

Pumping power



Pump efficiency Pump efficiency is defined as the ratio of the power

imparted on the fluid by the pump in relation to the

power supplied to drive the pump. One important part of system design involves

matching the pipeline headloss-flow characteristicwith the appropriate pump or pumps which will

operate at or close to the point of maximumefficiency.

Pump efficiency is an important aspect and pumpsshould be regularly tested.

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Pumps n Mech