Unit I.pdf

UNIT.1
Chapter.1
Introduction to Fluid Power
JCOE,KURAN (Gorade N.B)

Fluid Power Basics
1. Prime mover
2. Pump
3. Control Volume
4. Actuator
5. Fluid Energy
6. Mechanical Energy

Layout of Fluid Power System

Components of FPS
• Major components
1. Prime mover
2. Pump or compressor
3. Control valves
4. Actuators
5. Piping system
6. Fluid

Components of FPS
• Supporting Components
1. Filters
2. Strainer
3. Storage tank
4. Heat Exchanger
5. Pressure Guages
6. Sensors
7. Protective Devices
8. Control Devices
9. Accumulators

Advantages
1. Easy of Conveyance
2. Large actuating force could be achieved
3. Absence of Linkages
4. Division of Energy much Easier
5. Self cushioning Effect
6. Self Lubricating
7. Smooth and jerky free operation
8. Multiplication of force
9. Reversibility
10.Compact and simple
11.Accuracy
12.Long linear motion
13.Heat transfer Characteristics
14.Monitoring is easy
15.Less noisy
•

Drawbacks of FPS
1. Leakage
2. Frictional Losses
3. Oil is fire Hazards
4. Variation of viscosity
5. Bursting of pipe lines

Comparison in HPS and PPS

Application of FPS
1.Machine tool and Production
2.Material Handling
3.Hydraulics Press
4.Mobile and stationary Machines
5.Clamping Devices

Hydraulic Transmission
1.Static or Hydrostatic Transmission
2.Dynamic or Hydrodynamic Transmission

Hydrostatic Transmission

Hydrodynamic Transmission

Pascal's Law
• In a body of equally dense fluid at rest the
pressure is the same for all points in the fluid
so long as those points are at same depth
below the fluid surface

Pascal`s Law

Hydraulic Press

Types of Fluid Power System
1.Hydraulic System
2.Pneumatic System
3.Open Circuit
4.Closed Circuit

Open and Closed Circuit

UNIT 1
Chapter 2
Fluids for Hydraulic System

Introduction
• Four Basic Functions
1. Transmitting power
2. Moving Parts
3. Sealing gaps
4. Cooling and dissipation heat

Classification
1.Petroleum based
2.Water based
3.Synthetic based

Essential Qualities of Fluid
1. Prevent Rust
2. Prevent formation of sludge
3. Depress foaming tendency
4. Stability
5. Uniform properties
6. Prevent corrosion
7. Avoid damaging of seals
8. Avoid mixing with water

Petroleum Based Fluid
1. Aircraft
2. Construction plants
3. Shock Absorber
4. Brakes

Advantages
• Protection against rust
• Better sealing property
• Better heat dissipating property
• Easy to keep clean system
• Low density and light weight

Disadvantages
1. High Cost
2. Low flash points and fire points
3. Highly inflammable

Synthetic based fluid
1. Laboratory prepared fluids
2. Not contain any water or volatile materials
3. Chemical stability very good and high
pressure and temperature working
• Eg. Phosphate Easters
• Halogenated hydrocarbons
• Silicon synthetic fluid

Advantages
• Less inflammable
• Can operate at high temperature
• Suitable for high pressure system

Disadvantages
1. Attack and spoil paints
2. Performance is poor at low temperature
3. VI is very low
4. Sp.gravity is high
5. Develop acidity during operation
6. Cost is very high

Water Based Fluid
• Advantages
• Disadvantages

High Water Based Fluid (HWBF)
• As per ANSI it is HWCF (American National
Standard Institute)
• Proportion of additives:
1. Water-90-95%
2. Additives-5-10%
a) First Generation-Soluble oil cutting fluids
b) Second Generation-High water content oil
c) Third Generation-Micro emulsion
d) Fourth Generation-Thickened micro emulsion

Advantages
1. High flash point
2. Good cooling characteristics
3. Biodegradable hence eco friendly
4. Cleanliness
5. Viscosity constant
6. Low cost
7. Ease to storage
8. Easy transportation

Disadvantages
• High density –contamination-difficult to filter
• Very high corrosion
• Foaming tendency
• High evaporation rate
• High rate of leakage

Types of HWCF
• Water glycol mixture
• Water glycol

Fire Resistant Fluids
• HF-A : >80%Water
• HF-B: 40:60
• HF-C : Water Glycols-40:60 pH at 9
• HF-D: Synthetic Fluid

Properties of Hydraulic Fluid
1. Viscosity
2. Viscosity Index (VI)
3. Lubricating Property (Lubricity)
4. Chemical Stability
5. Freedom from acidity
6. Flash Point
7. Fire Point
8. Toxicity
9. Density
10. Compressibility
11. Good Heat Dissipation
12. Foaming Tendency
13. Low Volatility
14. Low coefficient of expansion
15. Cleanliness
16. Rust Prevention Capability

Selection of Fluids
1. Speed and Accuracy
2. Surrounding conditions
3. Economic Consideration
4. Pressure Levels
5. Operating temp Level
6. Lubricity
7. Safety of operators
8. Expected service life

Additives and Inhibitors
1. Anti foaming
2. Corrosion inhibitors
3. Anti wear resistant chemicals
4. Biocide
5. Emulsifier
6. Lubrication agent
7. Deionisation agent
8. Oxidation agents

Effect of Temp.and Pressure on
Hydraulic Fluid

VI and Temp Vs Viscosity

UNIT 1
Chapter 3
Seal and Sealing Materials

Functions of Seal
• To avoid leakages

Basic Requirements of Seals
1. Effective Sealing
2. Durable
3. Compatible With any Fluids

Causes of Leakages
1. Irregularities in surface
2. Increase in clearance
3. Loosing of joints
4. Excessive operating pressure
5. Fluid contamination
6. Damaged or worn out seal

Classification of Seals
1. Static seals
2. Dynamic Seal

Static Seal
• When no relative motion between two moving
parts
• Also called gaskets

Dynamic Seal

Classification Based on methods of Sealing
1. Positive
2. Non-Positive

Based on working conditions
1. Pressure
2. Environmental conditions
3. Fluid Medium
4. Dynamic and static condition
5. Temperature of system
6. Functional reliability and expected life

Based on shapes
1. T seals
2. V
3. U cups
4. U-Packing

Properties
1. Hardness
2. Volume change-Swelling and Shrinkage
3. Compression Set
4. Tensile Strength
5. Permanent Set
6. Adhesion
7. Aniline Point
8. Squeeze

Sealing Material
1. Cork
2. Leather
3. Metal
4. Rubber
5. Asbestos
6. Elastomeric seal material

UNIT 1
Chapter 4
Types of Pipes and Hoses

Functions of Pipes and Hoses
1. To transport energy through closed conduits
2. Provide flexibility and strength to high
pressure system

Classification of Fluid Power Lines
Fluid Power
Lines
Pipe(Rigid)
Tubes(Semi
Rigid)
Hoses
(Flexible)

Properties of Fluid Power Conduits
1. Mechanical Strength
2. Supporting Strength
3. Terminal Points
4. Damping Capability
5. Smoothness of Surface

Pipe Materials
1. Steel
2. Copper
3. Brass
4. Aluminium
5. Stainless steel

Selection of Pipe Dimensions
Three important Dimensions
1. Outer Diameter (OD)
2. Inner Diameter (ID)
3. Wall Thickness
• Selection of ID
1. Flow rate of fluid
2. Permissible friction losses

Schedule of Pipes
• ANSI Specifies it
• It varies from 10 to 160
• Wall thickness is expressed as SCHEDULED
NUMBER

Tubes and Tubing
• More flexible as compared to pipes
• Manufacture by precision drawing
• Tubing Size :
• Designated by OD.Eg 5/8 Inch tube

Hoses
• Made up by flexible materials
• Permit relative motion between components

Constructions of Hoses

Hose Materials
• Inner Tube
1. Synthetic Rubber
2. Plastics
3. Nylon
4. Braided Nylon
5. Teflon
6. Homogeneous Synthetic Rubber
7. Neoprene
8. Butyl
9. Natural Rubber
• Hose Reinforcement Materials
1.Steel Wires
2.Nylon
3.Rayon
4.Synthetic Yarn
• Outer Protective Cover Materials
1.Neoprene
2.Cotton Yarn
3.Nylon

Tube Joints and Fittings
• 370 flare fitting/450 flare fitting
• Ferrule compression fitting
• Straight threaded connector
• O ring compression fittings
• Sleeve compression fitting

Flare Fittings

Ferrule Fittings

Straight Threaded Connectors

Sleeve Compression fitting

Quick Action Coupling

O Rings Compression Fittings

Pressure Drop in Hoses/Pipes
• Hydraulic energy loss due to friction and
leakages
1.Losses due to friction increase with increase in
viscosity
2.Losses due to leakages decrease with increase
in viscosity
• Head Loss,
• Hp= λ*(v/d*g*l/d)

UNIT 1
Chapter 5
Fluid Conditioning

Introduction
• For smooth, Efficient and trouble free function
• The method of maintaining the quality of fluid
is called fluid conditioning

Sources of Contamination
1. Manufacturing Related
2. System Generated
3. Maintenance Generated

Types of Contamination
• Particulate Contamination
1.Organic Contamination
2.Metallic Solid Contamination
3.Inorganic Solid Contamination
• Fluid Contamination
1.Water Contamination
2.Solvent Contamination
3.Foreign Liquid Contamination
4.Air Contamination

Causes of Contamination
1. Particles originally contained in the system
2. Particles introduced from outside source
3. Particles created within system
 Mechanical particles
 Chemical particles
4. Particles introduced by foreign liquids

Contamination Control
• Fluid maintained within permissible limit of
particulate matter
• Cleaning of all parts ,drying
• Hydraulic Fluid Sampling

Filters
• The devices which is used for trapping the
insoluble contaminants by some porous
medium
• Micron Rating- It indicates smallest size of
particles that filter can retained
• Strainer-Without depth ,Less efficiency as
compared to filters
• Fluid Cleaning Mechanism:
• Sedimentation and Settling tanks

Filter Materials
1.Metal Elements (Sintered Particles)
2.Edge Type
3.Mesh and Cloth Type
4.Non Metals Elements
• Felted
• Woven Cloth
• Wound Yarn

Location of Filters
1. Return Line Filter
2. Suction line filter
3. Pressure filter
4. Combination of suction and pressure filter

Return Line Filter

Suction Line Filter

Pressure Filter

Combination of Suction and
Pressure Line Filter

Filter Housing

Multipass Test Rig

Testing of Filter Contamination
Level and Standardisation
1. Necessity for filter rating
2. Filter Performance
3. Multi-pass test Rig

Beta Rating of Filters
• Degree of Separation
• βx=ni/no
• A system requires 10 micron level filtration
• ni=15000
• no=200

Types of Filter
1. Surface Filter
2. Depth Filter
3. Full Flow Filter
4. Bypass Filter

Full Flow Filter

Bypass Filter

End of Unit I
Thank You
PROF.Gorade Nishigandh B.
9970721118
nishigandh1992@gmail.com
Jaihind College of Engineering ,Kuran

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