2012 Project Lead The Way Inc Principles of Engineering Pneumatic Power Pneumatic power Pneumatics vs hydraulics Early pneumatic uses Properties of gases Pascal s Law Perfect gas laws ID: 487036
Download Presentation The PPT/PDF document "Pneumatic Power" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Pneumatic Power
© 2012 Project Lead The Way, Inc.
Principles
of
EngineeringSlide2
Pneumatic Power
Pneumatic power
Pneumatics vs. hydraulicsEarly pneumatic usesProperties of gasesPascal’s LawPerfect gas laws
Boyle
’
s Law
Charles
’
Law
Gay-Lussac
’
s Law
Common pneumatic system components
Compressor types
Future pneumatic possibilitiesSlide3
Pneumatic PowerPneumaticsThe use of a gas flowing under pressure to transmit power from one location to anotherGas in a pneumatic system behaves like a spring since it is compressible.Slide4
Pneumatics vs. HydraulicsPneumatic Systems . . . Use a compressible gas Possess a quicker, jumpier motion Are not as precise Require a lubricant Are generally cleaner Often operate at pressures around 100 psi Generally produce less powerSlide5
Early Pneumatic UsesBellowsTool used by blacksmiths and smelters for working iron and other metalsSlide6
Early Pneumatic UsesOtto von Guericke Showed that a vacuum can be createdCreated hemispheres held together by atmospheric pressureSlide7
Early Pneumatic UsesAmerica’s First SubwayDesigned by Alfred BeachBuilt in New York City
Completed in 1870312 feet long, 8 feet in diameter Closed in 1873Slide8
Properties of GasesGases are affected by 3 variablesTemperature (T)Pressure (p)Volume (V)Gases have no definite volumeGases are highly compressibleGases are lighter than liquidsSlide9
Properties of GasesAbsolute PressureGauge Pressure: Pressure on a gauge does not account for atmospheric pressure on all sides of the systemAbsolute Pressure: Atmospheric pressure plus gauge pressure
Gauge Pressure + Atmospheric Pressure = Absolute PressureSlide10
Properties of GasesAbsolute PressurePressure (p) is measured in pounds per square inch (lb/in.2 or psi)Standard atmospheric pressure equals 14.7 lb/in.2
If a gauge reads 120.0 psi, what is the absolute pressure?120.0 lb/in.
2 + 14.7 lb/in.2 = 134.7 lb/in.2Slide11
Properties of GasesAbsolute Temperature0°F does not represent a true 0°Absolute Zero = -460.°FAbsolute Temperature is measured in degrees Rankine (°R)°R = °F + 460.
If the temperature of the air in a system is 65 °F, what is the absolute temperature?
Answer:65 °F + 460. = 525 °RSlide12
Pascal’s LawPressure exerted by a confined fluid acts undiminished equally in all directions.Pressure: The force per unit area exerted by a fluid against a surface
Symbol
Definition
Example Unit
p
Pressure
lb/in.
2
F
Force
lb
A
Area
in.
2Slide13
Pascal’s Law Example
How much pressure can be produced with a 3.00 in. diameter (d) cylinder and 60.0 lb of force (F)?
d =
3.00
in.
p
=
?
F =
60.0
lb
A =
?
Formula
Sub / Solve
*
*Note: This intermediate value has been
rounded. The full stored value in your calculator should be utilized when substituted into the next step.
Formula
Sub / Solve
Sub / Solve
Slide14
Perfect Gas LawsThe perfect gas laws describe the behavior of pneumatic systemsBoyle’s LawCharles’ LawGay-Lussac’s LawSlide15
Boyle’s LawThe volume of a gas at constant temperature varies inversely with the pressure exerted on it.
p
1 (V1) = p2 (V2)
NASA
Symbol
Definition
Example Unit
V
Volume
in.
3Slide16
Boyle’s Law ExampleA cylinder is filled with 40. in.3 of air at a pressure of 60. psi. The cylinder is compressed to 10. in.3. What is the resulting absolute pressure?p1 = 60. lb/in.2 V
1 = 40. in.3 p
2 = ? V2 = 10. in.3Convert p1 to absolute pressure.p1 = 60. lb/in.2 + 14.7 lb/in.2 = 74.7 lb/in.
2Slide17
Charles’ LawVolume of gas increases or decreases as the temperature increases or decreases, provided the amount of gas and pressure remain constant.
Note:
T1 and T2 refer to absolute temperature.
NASASlide18
Charles' Law ExampleAn expandable container is filled with 28 in.3 of air and is sitting in ice water that is 32°F. The container is removed from the icy water and is heated to 200.°F. What is the resulting volume?
V1 = 28in.3
V2 = ?T1 = 32°FT2 = 200.°FConvert T to absolute temperature.
T
1
= 32
°
F + 460.
°
F =
492
°R
T
2
= 200.
°
F + 460.
°
F =
660
°RSlide19
Charles' Law Example
An expandable container is filled with 28 in.3 of air and is sitting in ice water that is 32°F. The container is removed from the icy water and is heated to 200°F.
What is the resulting volume?V1 = 28in.3V2 = ?T1 = 32°FT2 = 200.°FConvert T to absolute temperatureT1 = 32°F + 460.°F = 492°RT2 = 200°F + 460.°F = 660°RSlide20
Gay-Lussac’s LawAbsolute pressure of a gas increases or decreases as the temperature increases or decreases, provided the amount of gas and the volume remain constant.
Note:
T
1
and T
2
refer to absolute temperature.
p
1
and
p
2
refer to absolute pressure.Slide21
Gay-Lussac’s Law ExampleA 300. in.3 sealed air tank is sitting outside. In the morning the temperature inside the tank is 62°F, and the pressure gauge reads 120. lb/in.2. By afternoon the temperature inside the tank is expected to be close to 90.°F. What will the absolute pressure be at that point?
V =
300. in.3 T1 = 62°Fp1 = 120. lb/in.2 T2 = 90.°Fp2 =
?
Convert
p
to absolute pressure.
p
1
= 120. lb/in.
2
+ 14.7 lb/in.
2
=
134.
7
lb/in.
2
Convert T to absolute temperature.
T
1
= 62°F + 460.°F =
522°R
T
2
= 90.°F + 460.°F =
550.°RSlide22
Gay-Lussac’s Law ExampleA 300 in.3 sealed air tank is sitting outside. In the morning the temperature inside the tank is 62°F, and the pressure gauge reads 120 lb/in2. By afternoon the temperature inside the tank is expected to be closer to 90°F. What will the absolute pressure be at that point?
If the absolute pressure is 14
1.9
lb/in.
2
, what is the pressure reading at the gauge?
14
1.9
lb/in.
2
– 14.7 lb/in.
2
=
12
7.2
lb/in.
2
=
130 lb/in.
2Slide23
Common Pneumatic System Components
National Fluid Power Association & Fluid Power Distributors Association
Receiver Tank
Compressor
Transmission Lines
Cylinder
Pressure Relief Valve
Directional Control Valve
Filter
Regulator
DrainSlide24
Compressor Types
Reciprocating Piston Compressor
CompairSlide25
Compressor Types
Rotary Screw Compressor
CompairSlide26
Compressor Types
Rotary Vane
CompairSlide27
Future Pneumatic PossibilitiesWhat possibilities may be on the horizon for pneumatic power?Could it be human transport?
zapatopi.netSlide28
Image ResourcesCompair. (2008). Compressed air explained: The three types of compressors. Retrieved March 5, 2008, from http://www.compair.com/About_Us/Compressed_Air Explained--03The_three_types_of_compressors.aspx Johnson, J.L. (2002). Introduction to fluid power. United States: Thomson Learning, Inc.Microsoft, Inc. (2008). Clip Art. Retrieved January 10, 2008, from http://office.microsoft.com/en-us/clipart/default.aspxNational Aeronautics and Space Administration. (2008).
Boyle’s law. Retrieved February 3, 2008, from http://www.grc.nasa.gov/
National Fluid Power Association. (2008). What is fluid power. Retrieved February 15, 2008, from http://www.nfpa.com/OurIndustry/OurInd_AboutFP WhatIsFluidPower.aspNational Fluid Power Association & Fluid Power Distributors Association. (n.d.). Fluid power: The active partner in motion control technology. [Brochure]. Milwaukee, WI: Author.Zapato, L. (n.d.) The inteli-tube pneumatic transportation system. Retrieved February 29, 2008, from http://zapatopi.net/inteli-tube/