1 introduction pumps

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Pumps: Introduction

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PumpsINTRODUCTION


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Pumps: Introduction

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INTRODUCTIONA PumpConvertsMechanical Energy intoHydraulic Energy.

The Mechanical Energy is delivered to the Pumpvia a

PrimeMover such as an ElectricMotor.


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Pumps: Introduction

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Due to Mechanical Action, PumpCreatesPartial Vacuum at Inlet.

This ForcesFluid through the InletLine and into the Pump.The Pump then pushes the Fluid into the System.

Pumps Do NotPumpPressure, They produce Fluid Flow.

Pressure is the result of Resistance to FlowClassifications of Pumps:

1. Dynamic (Non-Positive Displacement) Pumps

2. Positive Displacement Pumps


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Pumps: Introduction


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Pumps Introduction

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Positive Displacement

Diaphragm

Piston

Plunger

ReciprocatingRotary

Gear

Vane

Screw

PUMP

Mixed flow

Axial flow

Centrifugal

Rotodynamic

Others


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1. DynamicPumpsor

Non-Positive Displacement PumpsThey used for Low-Pressure, High-Volume FlowApplications

This type of Pump is primarilyused for

Transporting Fluids from One Location to Another

Although these Pumpsprovide Smooth ContinuousFlow,Their FlowOutput is reduced as circuit Resistance is increased

When the Resistance of the External Systembecomes Infinitely Large

(For Example, a valve is closed in the outlet line)PumpwillproduceNoFlow


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The 2 Most Common Types of Dynamic Pumps are:The CentrifugalThe Axial Flow, or PropellerPumps.


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2. Positive Displacement Pumps

PumpingAction of a Simple Piston Pump


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The Principle on which AllPositiveDisplacement Pumps is basedcan be Illustratedwith a Simple Syringe.


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A Positive Displacement PumpejectsFixed Amount of Fluidinto Hydraulic System per revolution of Pump Shaft Rotation.

Pump Output Flow, NeglectingLeakage,

is Constant and NotDependent onSystem Pressure.

This makes them well Suited for Fluid Power Systems.

Such a Pump is capable of Overcoming the Pressureresulting from the MechanicalLoads on the System

as well as The Resistance to Flow due to Friction.

If a Positive Pump has its DischargeLineopen to the Atmosphere, There will be Flow,

but there will be No discharge Pressureabove Atmospheric

because there is essentially no Resistanceto Flow.If the Discharge Line is Blocked,

Then we have Theoretically InfiniteResistance to Flow.Hence, there is NoPlacefortheFluid to go.


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The Pressure will Rise until some ComponentBreaksunless Pressure Relief is provided.

This is the Reason a Pressure Relief Valve is neededWhen a Positive Displacement Pump is used

When the Pressure reaches a Set Value,The ReliefValve will Open to allowFlow Backto the Tank.

Pressure ReliefValve determinesMaximum Pressure Levelthat the System will Experience regardless of

the Magnitude of the LoadResistance

Pressure Relief Valves are NotNeededWhen Pressure-Compensated Pumps are used.

Positive Displacement Pumps can be Classified byThe Type of Motionof Internal Elements

The Motionmay be either Rotary or Reciprocating.


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There are essentially 3 Basic Types:

1. Gear Pumpsa. External Gear Pumps

b. Internal Gear Pumpsc. Lobe Pumpsd. Gerotor Pumpe. Screw Pumps

2. Vane Pumps

a.UnbalancedVane Pumpsb.BalancedVane Pumps

3. Piston Pumpsa. Axial Design (Bent Axis or Swash Plate).b. Radial Design

UnbalancedVane Pump have PressureCompensationCapability,which AutomaticallyProtects the Pump against Overpressure.


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GEAR PUMPS

External Internal

GEARPUMPS

Lobe Gerotor

P I t d ti


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VANEPUMPS

BasicDesign VariableDisplacement& Pressure Compensated

UnbalancedVan

Pump

BalancedVanePump

P mps Introd ction


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PISTON PUMPS

Bent-Axis Design

SwashPlate Design

AxialPiston Pump RadialPiston Pump

Pumps Introduction


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The "FamilyTree" of PositiveDisplacement Pumps

Pumps Introduction


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GraphicSymbols representing Fluid Power Pumps

Pumps Introduction


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Figure 6 Positive Displacement Pump

QversusNand

PversusQ

Pumps Introduction


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Performance Curves ofCentrifugalandPositive Pumps

Pumps Introduction


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1 introduction pumps

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