Post on 16-Aug-2015
REVIEW
Fluid Power System Functions and Components
Fluid power systems perform Fluid power systems perform five functions during operation:five 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 and Basic Physical Principles and
Applications of Fluid Power Applications of Fluid Power SystemsSystems
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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
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ObjectivesObjectives
Nature of electricity and the basic methods used Nature of electricity and the basic methods used for electrical measurement.for electrical measurement.
Operation of basic electrical circuits.Operation of basic electrical circuits.
Characteristics associated with the fluids used in Characteristics associated with the fluids used in fluid power systems.fluid power systems.
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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 Potential power of a fluid power system is established.established.
Nature of heat and how it is measured in fluid Nature of heat and how it is measured in fluid power systems.power systems.
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Simple MachinesSimple Machines
A picture of the machines that exist in our society A picture of the machines that exist in our society today.today.
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Simple MachinesSimple Machines
The machines shown in the last slide are The machines shown in the last slide are complex in nature, but all machines fall complex in nature, but all machines fall into the category of six basic types of into the category of six basic types of machines:machines: LeverLever Inclined planeInclined plane WedgeWedge ScrewScrew PulleyPulley Wheel and axleWheel and axle
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Simple MachinesSimple Machines
LeversLevers
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Simple MachinesSimple Machines
Inclined planeInclined plane WedgeWedge
Photo courtesy of handiramp.com
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Simple MachinesSimple Machines
ScrewScrew
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Simple MachinesSimple Machines
PulleyPulley
Dynamic Graphics© Permission granted to reproduce for educational purposes only
Simple MachinesSimple Machines
Wheel and axleWheel and axle
Creatas
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BRANCHES OF MECHANICS TO SHOW HOW BRANCHES OF MECHANICS TO SHOW HOW FLUIDS INTERTWINES WITH THE OTHER FLUIDS INTERTWINES WITH THE OTHER
BRANCHESBRANCHES
S ta tics D yn am ics
R ig id B od ies(Th in g s th a t d o n o t ch an g e sh ap e)
D eform ab le B od ies(Th in g s th a t d o ch an g e sh ap e)
In com p ress ib le C om p ress ib le
F lu id s
M ech an icsTyp e tit le h ere
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Basic Principles of Basic Principles of MechanicsMechanics
Work, energy, torque, or power describe the Work, energy, torque, or power describe the specified forces exerted while moving fixed specified forces exerted while moving fixed distances in given periods of time.distances in given periods of time.
Fluid power systems are required to do thisFluid power systems are required to do this
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Energy is the capacity to do workEnergy is the capacity to do work
Force is the overall effort needed to produce, Force is the overall effort needed to produce, change, or stop motionchange, or stop motion
Pressure is force exerted over a unit areaPressure is force exerted over a unit area
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Basic Principles of Basic Principles of MechanicsMechanics
WorkWork Movement of a force through a specified distance.Movement of a force through a specified distance.
W = F x d W = 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
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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 Mechanical is measured in horsepower, electrical
power in kWpower in kW
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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
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TorqueTorque
Mechanical advantageMechanical advantage relationship between the effort put into a relationship between the effort put into a
machine and the resistance overcomemachine and the resistance overcome
Mechanical efficiencyMechanical efficiency comparison of the work input and work comparison of the work input and work
output of a machineoutput of a machine Calculated by dividing the work output of Calculated by dividing the work output of
the machine by the work inputthe machine by the work input Expressed as a percentage and is always Expressed as a percentage and is always
less than 100% due to lossesless than 100% due to losses
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Mechanical Mechanical MeasurementsMeasurements
ThermodynamicsThermodynamics the science dealing with the properties of matter the science dealing with the properties of matter
related to heat and the conversion of energy from related to heat and the conversion of energy from one form to anotherone form to another
Heat Heat generated when you have a pressure drop but no generated when you have a pressure drop but no
work donework done Type of kinetic energyType of kinetic energy Measured in British thermal units (Btu) or caloriesMeasured in British thermal units (Btu) or calories
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Principles of Heat Principles of Heat TransferTransfer
TemperatureTemperature the rate of molecular movement within a the 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 Rankine scale (often used in scientific and
engineering calculations)engineering calculations) Kelvin scale (often used in scientific and Kelvin scale (often used in scientific and
engineering calculations)engineering calculations)
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Principles of Heat Principles of Heat TransferTransfer
Sensible heat Sensible heat Feeling of Feeling of ““hothot”” or or ““coldcold”” that can be measured using a that can be measured using a
thermometerthermometer
Latent heat Latent heat heat needed to change the state of a substance without heat needed to change the state of a substance without
changing its temperaturechanging its temperature Examples are ice converted to water and water converted Examples are ice converted to water and water converted
to steamto steam
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Principles of Heat Principles of Heat TransferTransfer
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
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Principles of Heat Principles of Heat TransferTransfer
An atom is the smallest identifiable part of an elementAn atom is the smallest identifiable part of an element
Composed of:Composed of: Electrons (–) Neutrons (+)Neutrons (+) Protons (no charge)Protons (no charge)
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Electricity and MagnetismElectricity and Magnetism
An atom is the smallest identifiable part of an An atom is the smallest identifiable part of an elementelement Composed of:Composed of:
Electrons (–) Neutrons (+)Neutrons (+) Protons (no charge)Protons (no charge)
Electrical flowElectrical flow occurs when electrons leave outer orbital paths and move occurs when electrons leave outer orbital paths and move
other free electrons through the substance along with themother free electrons 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
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Electricity and MagnetismElectricity and Magnetism
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=fvwp
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Electricity and MagnetismElectricity and Magnetism
Electricity may be produced using the lines of force that Electricity may be produced using the lines of force that surround a magnetsurround a magnet When an electrical conductor cuts these magnetic lines of When an electrical conductor cuts these magnetic lines of
force, electricity is producedforce, electricity is produced Electrical output is dependent on the number of lines cut and Electrical output is dependent on the number of lines cut and
the speed with which they are cutthe speed with which they are cut This is called This is called electromagnetic inductionelectromagnetic induction
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Electricity and MagnetismElectricity and Magnetism
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 Ohm’s Law is the relationship between these elements elements Amperage = Volts Amperage = Volts Ohms Ohms
I = E I = E R R
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Electricity and MagnetismElectricity and Magnetism
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 only Electrons flow in one direction only Alternating current (ac) Alternating current (ac)
Electrons flow first in one direction, stop, and then reverse their Electrons flow first in one direction, stop, and then reverse their direction of flowdirection of flow
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Electricity and MagnetismElectricity and Magnetism
Electrical circuits are made up of four basic Electrical circuits are made up of four basic elementselements ConductorsConductors Control devicesControl devices Loading devicesLoading devices Electrical energy sourceElectrical energy source
Electrical circuits may be connected using either a Electrical circuits may be connected using either a series or parallel formatseries or parallel format
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Electricity and MagnetismElectricity and Magnetism
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
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Electricity and MagnetismElectricity and Magnetism
Parallel circuitParallel circuit All loads have an individual current flow path for each All loads have an individual current flow path for each
one one If one load is shorted, current flow continues to all If one load is shorted, current flow continues to all
the other loadsthe other loads
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Electricity and MagnetismElectricity and Magnetism
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 Each substance is able to flow and each can adjust its
shape to fit the container in which it is heldshape to fit the container in which it is held
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General Characteristics of General Characteristics of FluidsFluids
MoleculesMolecules Small particles that bond in such a way to give material Small particles that bond in such a way to give material
distinctive characteristics.distinctive 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 Molecules that conform to the shape of their container, thus do not maintain shape.do not 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 Molecules that conform to the shape of their container, thus
do not maintain shape.do not maintain shape. Expand to fill volume of container placed inExpand to fill volume of container placed in
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Fluid NatureFluid Nature
Specific weightSpecific weight weight of a specified volume of a substance at a given weight of a specified volume of a substance at a given
temperature and pressuretemperature and pressure
Specific gravity Specific gravity comparison of the weight of a substance to the weight of comparison of the weight of a substance to the weight of
an equal volume of wateran equal volume of water Float tube hydrometer is used to measure thisFloat tube hydrometer is used to measure this
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Fluid PropertiesFluid Properties
Force applied to a fluid divided by the area of the Force applied to a fluid divided by the area of the fluidfluid
P=F/AP=F/A Units are psi, psf, N/m squared, PaUnits are psi, psf, N/m squared, Pa
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PressurePressure
Gauge pressureGauge pressure Absolute pressureAbsolute pressure VacuumVacuum HeadHead AtmosphereAtmosphere
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Pressure Measurement Pressure 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
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Pressure Measurement in Pressure Measurement in FluidsFluids
At normal atmospheric pressure:At normal atmospheric pressure: If gauge scale reads 0 psi, then absolute scale reads If gauge scale reads 0 psi, then absolute scale reads
14.7 psi14.7 psi
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Pressure Measurement in Pressure Measurement in FluidsFluids
Barometer Instrument that measures atmospheric pressure Standard piece of meteorological data used by weather
forecasters to predict the future
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Pressure Measurement in Pressure Measurement in 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
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Pressure Measurement in Pressure Measurement in 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
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Pressure Measurement in Pressure Measurement in FluidsFluids
Pascal’s PrinciplePascal’s Principle
Pressure applied to a confined fluid is transmitted in Pressure applied to a confined fluid is transmitted in all directions to every portion of the fluidall directions 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 Neglects pressure variations within a fluid that may
be caused by the weights of standing columns of fluidbe caused by the weights of standing columns of fluid Valid for both liquids and gases, even though there Valid for both liquids and gases, even though there
are different compressibility and temperature factors are different compressibility and temperature factors to a gasto a gas© Permission granted to reproduce for educational purposes only
BernoulliBernoulli’’s Theorems Theorem
In a volume of flowing fluid, total energy is In a volume of flowing fluid, total energy is the same at every point in its path of flowthe same at every point in its path of flow
Simply put, when the fluid speed Simply put, when the fluid speed increases, the pressure decreasesincreases, the pressure decreases
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Gas Reactions to Pressure and Gas 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 relate how real gases react to pressure, temperature, and
volume changesvolume changes BoyleBoyle’’s laws law
constant temperatureconstant temperature CharlesCharles’’ law law
constant pressureconstant pressure Gay-LussacGay-Lussac’’s laws law
constant volume constant volume General gas law General gas law
Combination of all threeCombination of all three
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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
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Gas Reactions to Pressure and Gas 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
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Week 2 Lab Assignment1. 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