2012 02-12 emet135 week 2 presentation

Fluid Power System
Functions and Components
 Fluid power systems perform fiveFluid power systems perform five
functions during operation:functions during operation:
 Energy conversionEnergy conversion
 Power unit groupPower unit group
 Fluid distributionFluid distribution
 Conductors groupConductors group
 Fluid controlFluid control
 Control valves groupControl valves group
 Work performanceWork performance
 Actuators groupActuators group
 Fluid maintenanceFluid maintenance
 Fluid Maintenance groupFluid Maintenance group

CHAPTER 3CHAPTER 3
Basic Physical Principles andBasic Physical Principles and
Applications of Fluid PowerApplications of Fluid Power
SystemsSystems
© Permission granted to reproduce for educational purposes only

This Lesson Discusses The
Basic Physical Properties
Followed By Fluid Power
System
This lesson follows Chapter 3 in the Fluid Power
book by James R. Daines

ObjectivesObjectives
 Nature of electricity and the basic methods used forNature of electricity and the basic methods used for
electrical measurement.electrical measurement.
 Operation of basic electrical circuits.Operation of basic electrical circuits.
 Characteristics associated with the fluids used in fluidCharacteristics associated with the fluids used in fluid
power systems.power systems.

ObjectivesObjectives
 Design and operation of the six basic machines.Design and operation of the six basic machines.
 Factors that affect energy in fluid power systems.Factors that affect energy in fluid power systems.
 Potential power of a fluid power system is established.Potential power of a fluid power system is established.
 Nature of heat and how it is measured in fluid powerNature of heat and how it is measured in fluid power
systems.systems.

Simple MachinesSimple Machines
 A picture of the machines that exist in our society today.A picture of the machines that exist in our society today.

 The machines shown in the last slide areThe machines shown in the last slide are
complex in nature, but all machines fall intocomplex in nature, but all machines fall into
the category of six basic types of machines:the category of six basic types of machines:
 LeverLever
 Inclined planeInclined plane
 WedgeWedge
 ScrewScrew
 PulleyPulley
 Wheel and axleWheel and axle

 LeversLevers

 Inclined planeInclined plane  WedgeWedge
Photo courtesy of handiramp.com

 ScrewScrew

 PulleyPulley
Dynamic Graphics

 Wheel and axleWheel and axle
Creatas

BRANCHES OF MECHANICS TO SHOW HOWBRANCHES OF MECHANICS TO SHOW HOW
FLUIDS INTERTWINES WITH THE OTHERFLUIDS INTERTWINES WITH THE OTHER
BRANCHESBRANCHES
S tatics D yn am ics
R ig id B od ies
(Th in g s th at d o n ot ch an g e sh ap e)
D eform ab le B od ies
(T h in g s th at d o ch an g e sh ap e)
In com p ressib le C om p ressib le
F lu id s
M ech an ics
T yp e title h ere

Basic Principles ofBasic Principles of
MechanicsMechanics
 Work, energy, torque, or power describe the specifiedWork, energy, torque, or power describe the specified
forces exerted while moving fixed distances in givenforces exerted while moving fixed distances in given
periods of time.periods of time.
 Fluid power systems are required to do thisFluid power systems are required to do this

 Energy is the capacity to do workEnergy is the capacity to do work
 Force is the overall effort needed to produce, change, orForce is the overall effort needed to produce, change, or
stop motionstop motion
 Pressure is force exerted over a unit areaPressure is force exerted over a unit area
Basic Principles ofBasic Principles of
MechanicsMechanics

 WorkWork
 Movement of a force through a specified distance.Movement of a force through a specified distance.
 W = F x dW = F x d
 units are ft lb, Joulesunits are ft lb, Joules
 Thermal energy Btu or caloriesThermal energy Btu or calories
 Electrical energy kWhElectrical energy kWh
 EnergyEnergy
 Ability to perform useful work.Ability to perform useful work.
 Stored energy is called potential energyStored energy is called potential energy
 Motion energy is called kinetic energy units are ft lb, JoulesMotion energy is called kinetic energy units are ft lb, Joules
 Thermal energy Btu or caloriesThermal energy Btu or calories
 Electrical energy kWhElectrical energy kWh
Work and EnergyWork and Energy

 StrokeStroke
 Force applied through a selected distance.Force applied through a selected distance.
 PowerPower
 Rate which work is doneRate which work is done
 Mechanical is measured in horsepower, electrical powerMechanical is measured in horsepower, electrical power
in kWin kW
Work, Energy and PowerWork, Energy and Power

 Torque or momentTorque or moment
 Ability of a force to cause rotation about a particular axisAbility of a force to cause rotation about a particular axis
 Force times Distance (F x d)Force times Distance (F x d)
 Units are lb ft and N mUnits are lb ft and N m
 Examples are torque wrenches and torque multipliersExamples are torque wrenches and torque multipliers
TorqueTorque

 Mechanical advantageMechanical advantage
 relationship between the effort put into a machinerelationship between the effort put into a machine
and the resistance overcomeand the resistance overcome
 Mechanical efficiencyMechanical efficiency
 comparison of the work input and work output of acomparison of the work input and work output of a
machinemachine
 Calculated by dividing the work output of theCalculated by dividing the work output of the
machine by the work inputmachine by the work input
 Expressed as a percentage and is always lessExpressed as a percentage and is always less
than 100% due to lossesthan 100% due to losses
Mechanical MeasurementsMechanical Measurements

 ThermodynamicsThermodynamics
 the science dealing with the properties of matter related tothe science dealing with the properties of matter related to
heat and the conversion of energy from one form toheat and the conversion of energy from one form to
anotheranother
 HeatHeat
 generated when you have a pressure drop but no workgenerated when you have a pressure drop but no work
donedone
 Type of kinetic energyType of kinetic energy
 Measured in British thermal units (Btu) or caloriesMeasured in British thermal units (Btu) or calories
Principles of Heat TransferPrinciples of Heat Transfer

 TemperatureTemperature
 the rate of molecular movement within athe rate of molecular movement within a
substancesubstance
 measured in degreesmeasured in degrees
 Fahrenheit scale (United States)Fahrenheit scale (United States)
 Celsius scale (everywhere else)Celsius scale (everywhere else)
 Rankine scale (often used in scientific and engineeringRankine scale (often used in scientific and engineering
calculations)calculations)
 Kelvin scale (often used in scientific and engineeringKelvin scale (often used in scientific and engineering
calculations)calculations)

 Sensible heatSensible heat
 Feeling ofFeeling of ““hothot”” oror ““coldcold”” that can be measured using a thermometerthat can be measured using a thermometer
 Latent heatLatent heat
 heat needed to change the state of a substance without changingheat needed to change the state of a substance without changing
its temperatureits temperature
 Examples are ice converted to water and water converted to steamExamples are ice converted to water and water converted to steam

 Heat may be moved using three modes of transferHeat may be moved using three modes of transfer::
 ConductionConduction
 ConvectionConvection
 Using physical means to transfer heat energyUsing physical means to transfer heat energy
 RadiationRadiation
 Transfers heat by electromagnetic raysTransfers heat by electromagnetic rays

 An atom is the smallest identifiable part of an elementAn atom is the smallest identifiable part of an element
 Composed of:Composed of:
 ElectronsElectrons (–)(–)
 Neutrons (+)Neutrons (+)
 Protons (no charge)Protons (no charge)
Electricity and MagnetismElectricity and Magnetism

 An atom is the smallest identifiable part of an elementAn atom is the smallest identifiable part of an element
 Composed of:Composed of:
 ElectronsElectrons (–)(–)
 Neutrons (+)Neutrons (+)
 Protons (no charge)Protons (no charge)
 Electrical flowElectrical flow
 occurs when electrons leave outer orbital paths and move other freeoccurs when electrons leave outer orbital paths and move other free
electrons through the substance along with themelectrons through the substance along with them
 MagnetismMagnetism
 ability of a material to attract ironability of a material to attract iron
 Think of how a magnet attracts objects containing ironThink of how a magnet attracts objects containing iron

 Electrical current is used to magnetize iron and iron alloysElectrical current is used to magnetize iron and iron alloys
 http://www.youtube.com/watch?v=l9MF7dp6MbY&NR=1&feature=fvhttp://www.youtube.com/watch?v=l9MF7dp6MbY&NR=1&feature=fv

 Electricity may be produced using the lines of force that surroundElectricity may be produced using the lines of force that surround
a magneta magnet
 When an electrical conductor cuts these magnetic lines of force,When an electrical conductor cuts these magnetic lines of force,
electricity is producedelectricity is produced
 Electrical output is dependent on the number of lines cut and theElectrical output is dependent on the number of lines cut and the
speed with which they are cutspeed with which they are cut
 This is calledThis is called electromagnetic inductionelectromagnetic induction

 Electricity flowing in a conductor involves:Electricity flowing in a conductor involves:
 Electrical current (amperage)Electrical current (amperage)
 Potential (voltage)Potential (voltage)
 Resistance (ohms)Resistance (ohms)
 Ohm’s Law is the relationship between these elementsOhm’s Law is the relationship between these elements
Amperage = VoltsAmperage = Volts ÷÷ OhmsOhms
I = EI = E ÷÷ RR

 Types of current flow used in electrical circuitsTypes of current flow used in electrical circuits
 Direct current (dc)Direct current (dc)
 Electrons flow in one direction onlyElectrons flow in one direction only
 Alternating current (ac)Alternating current (ac)
 Electrons flow first in one direction, stop, and then reverse their direction ofElectrons flow first in one direction, stop, and then reverse their direction of
flowflow

 Electrical circuits are made up of four basic elementsElectrical circuits are made up of four basic elements
 ConductorsConductors
 Control devicesControl devices
 Loading devicesLoading devices
 Electrical energy sourceElectrical energy source
 Electrical circuits may be connected using either a seriesElectrical circuits may be connected using either a series
or parallel formator parallel format

 Series circuitSeries circuit
 all loads are on a single current flow pathall loads are on a single current flow path
 If one load is shorted, all current flow stopsIf one load is shorted, all current flow stops

 Parallel circuitParallel circuit
 All loads have an individual current flow path for each oneAll loads have an individual current flow path for each one
 If one load is shorted, current flow continues to all the otherIf one load is shorted, current flow continues to all the other
loadsloads

 FluidFluid
 Liquids and gases are both considered fluidsLiquids and gases are both considered fluids
 Each substance is able to flow and each can adjust its shape to fitEach substance is able to flow and each can adjust its shape to fit
the container in which it is heldthe container in which it is held
General Characteristics ofGeneral Characteristics of
FluidsFluids

 MoleculesMolecules
 Small particles that bond in such a way to give material distinctiveSmall particles that bond in such a way to give material distinctive
characteristics.characteristics.
 SolidSolid
 Molecules are bonded in a rigid lattice, maintaining shapeMolecules are bonded in a rigid lattice, maintaining shape
 LiquidLiquid
 Molecules that conform to the shape of their container, thus do notMolecules that conform to the shape of their container, thus do not
maintain shape.maintain shape.
 Volume is constantVolume is constant
 Act similar to a solidAct similar to a solid
 GasGas
 Molecules that conform to the shape of their container, thus do notMolecules that conform to the shape of their container, thus do not
maintain shape.maintain shape.
 Expand to fill volume of container placed inExpand to fill volume of container placed in
Fluid NatureFluid Nature

 Specific weightSpecific weight
 weight of a specified volume of a substance at a given temperatureweight of a specified volume of a substance at a given temperature
and pressureand pressure
 Specific gravitySpecific gravity
 comparison of the weight of a substance to the weight of an equalcomparison of the weight of a substance to the weight of an equal
volume of watervolume of water
 Float tube hydrometer is used to measure thisFloat tube hydrometer is used to measure this
Fluid PropertiesFluid Properties

 Force applied to a fluid divided by the area of the fluidForce applied to a fluid divided by the area of the fluid
 P=F/AP=F/A
 Units are psi, psf, N/m squared, PaUnits are psi, psf, N/m squared, Pa
PressurePressure

 Gauge pressureGauge pressure
 Absolute pressureAbsolute pressure
 VacuumVacuum
 HeadHead
 AtmosphereAtmosphere
Pressure MeasurementPressure Measurement
Scales for FluidsScales for Fluids

 Gage Pressure
 Measured relative to atmosphere
 Psig, psi
 Absolute Pressure
 Measured relative to a perfect vacuum
 Psi(abs), psia
Pressure Measurement inPressure Measurement in
FluidsFluids

 At normal atmospheric pressure:At normal atmospheric pressure:
 If gauge scale reads 0 psi, then absolute scale reads 14.7 psiIf gauge scale reads 0 psi, then absolute scale reads 14.7 psi
FluidsFluids

 Barometer
 Instrument that measures atmospheric pressure
 Standard piece of meteorological data used by weather
forecasters to predict the future
FluidsFluids

 Perfect vacuumPerfect vacuum
 Lowest possible pressure attained in natureLowest possible pressure attained in nature
 Absolute – psiaAbsolute – psia
 Gauge – psigGauge – psig
 Head
 Pressure from the weight of a fluid at it’s base
FluidsFluids

 Manometer
 U-tube containing some liquid such as water, oil, or mercury that
is immiscible with the fluid whose pressure is being measured.
 Measures pressure at a certain point
 Blood pressure example
FluidsFluids

Pascal’s PrinciplePascal’s Principle
 Pressure applied to a confined fluid is transmitted in allPressure applied to a confined fluid is transmitted in all
directions to every portion of the fluiddirections to every portion of the fluid
 Reaction of confined molecules to an applied loadReaction of confined molecules to an applied load
 Describes fluid in static systemsDescribes fluid in static systems
 Neglects pressure variations within a fluid that may be causedNeglects pressure variations within a fluid that may be caused
by the weights of standing columns of fluidby the weights of standing columns of fluid
 Valid for both liquids and gases, even though there areValid for both liquids and gases, even though there are
different compressibility and temperature factors to a gasdifferent compressibility and temperature factors to a gas

BernoulliBernoulli’’s Theorems Theorem
 In a volume of flowing fluid, total energy is theIn a volume of flowing fluid, total energy is the
same at every point in its path of flowsame at every point in its path of flow
 Simply put, when the fluid speed increases, theSimply put, when the fluid speed increases, the
pressure decreasespressure decreases

Gas Reactions to Pressure andGas Reactions to Pressure and
TemperatureTemperature
 Ideal gas lawsIdeal gas laws
 used in pneumatic systemsused in pneumatic systems
 relate how real gases react to pressure, temperature, and volumerelate how real gases react to pressure, temperature, and volume
changeschanges
 BoyleBoyle’’s laws law
 constant temperatureconstant temperature
 CharlesCharles’’ lawlaw
 constant pressureconstant pressure
 Gay-LussacGay-Lussac’’s laws law
 constant volumeconstant volume
 General gas lawGeneral gas law
 Combination of all threeCombination of all three

 Compression ratio
 ratio of initial to final volumes
 v1/v2
 example is internal combustion engines
 Ratio of compression
 ratio of final pressure to initial pressure
 p2/p1
 example is compressors
Gas Reactions to Pressure andGas Reactions to Pressure and
TemperatureTemperature

Properties of Gases
 Raising temperature of gas increases velocity, internal energy,
and volume of molecules
 higher viscosity of gas due to increase rate of interaction between
molecules
 Raising temperature of a liquid decreases viscosity

Week 2 Lab Assignment
1. Build a basic hydraulic and pneumatic circuit from Week 1
using Automation Studio software in Lab.
Graded Lab Assignment

Week 2 Homework
Assignment
In Lab Manual, do for homework grade:
1. Chapter 3 Key Terms Sheets
2. Chapter 3 Quiz
Graded Homework
Assignment

2012 02-12 emet135 week 2 presentation

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