Pneumatic Power Pneumatics The use of a gas flowing under pressure to transmit power from one...
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Transcript of Pneumatic Power Pneumatics The use of a gas flowing under pressure to transmit power from one...
![Page 1: Pneumatic Power Pneumatics The use of a gas flowing under pressure to transmit power from one location to another Gas in a pneumatic system behaves like.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e8a5503460f94b8ff0c/html5/thumbnails/1.jpg)
Pneumatic Power
Pneumatics
The use of a gas flowing under pressure to transmit power from one location to another
Gas in a pneumatic system behaves like a spring since it is compressible.
![Page 2: Pneumatic Power Pneumatics The use of a gas flowing under pressure to transmit power from one location to another Gas in a pneumatic system behaves like.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e8a5503460f94b8ff0c/html5/thumbnails/2.jpg)
Pneumatics vs. Hydraulics
Pneumatic 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 power
![Page 3: Pneumatic Power Pneumatics The use of a gas flowing under pressure to transmit power from one location to another Gas in a pneumatic system behaves like.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e8a5503460f94b8ff0c/html5/thumbnails/3.jpg)
Early Pneumatic Uses
Bellows
Tool used by blacksmiths and smelters for working iron and other metals
America’s First Subway
• Designed by Alfred Beach
• Built in New York City
• Completed in 1870
• 312 feet long, 8 feet in diameter
• Closed in 1873
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Properties of GasesGases are affected by 3 variables
– Temperature (T)– Pressure (p)– Volume (V)
Gases have no definite volume
Gases are highly compressible
Gases are lighter than liquids
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Properties of Gases
Absolute PressureGauge Pressure: Pressure on a gauge
does not account for atmospheric pressure on all sides of the system
Absolute Pressure: Atmospheric pressure plus gauge pressure
Gauge Pressure + Atmospheric Pressure = Absolute Pressure
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Properties of Gases
Absolute 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?
![Page 7: Pneumatic Power Pneumatics The use of a gas flowing under pressure to transmit power from one location to another Gas in a pneumatic system behaves like.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e8a5503460f94b8ff0c/html5/thumbnails/7.jpg)
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
FA
p
Symbol Definition Example Unit
p Pressure lb/in.2
F Force lb
A Area in.2
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Fluid Power PrinciplesPascal’s Law
Relationship between force, pressure, and area
force=pressure area
forcepressure=
areaforce
area=pressure
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Pascal’s Law Example
How much pressure can be produced with a 3 in. diameter (d) cylinder and 50 lb of force?
p 2
lbFinal 7.0
in.
2Final A 7.1in.
2Sub/Solve A ( 1.5 )
2Formula A r
p 2
50lbSub/Solve
7.1in.
pF
FormulaA
d = 3 in. p = ?F = 50 lb A = ?
![Page 10: Pneumatic Power Pneumatics The use of a gas flowing under pressure to transmit power from one location to another Gas in a pneumatic system behaves like.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e8a5503460f94b8ff0c/html5/thumbnails/10.jpg)
Boyle’s Law
The volume of a gas at constant temperature varies inversely with the pressure exerted on it.
p1 (V1) = p2 (V2) NASA
Symbol Definition Example Unit
V Volume in.3
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An increase in velocity results in a decrease in pressure. Likewise, a decrease in velocity results in an increase in pressure.
Bernoulli’s Principle
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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 V1 = 40. in.3
p2 = ? V2 = 10. in.3
Convert p1 to absolute pressure.
p1 = 60. lb/in.2 + 14.7 lb/in.2 = 74.7 lb/in.2
1 1 2 2Formula ( V ) ( V )p p
p3 322
lbSub /Solve 74.7 ( 40.in. ) ( 10.in. )
in.2988 in
3
. lb
10.in.p22
p 22 2
lbFinal 3.0 10
in
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Charles’ Law
Volume of gas increases or decreases as the temperature increases or decreases, provided the amount of gas and pressure remain constant.
1 2
1 2
V VT T
Note: T1 and T2 refer to absolute temperature.
NASA
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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°F
T2 = 200.°F
Convert T to absolute temperature.
T1 = 32°F + 460.°F =492°R
T2 = 200.°F + 460.°F =660°R
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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.°F
Convert T to absolute temperatureT1 = 32°F + 460.°F = 492°RT2 = 200°F + 460.°F = 660°R
1 2
1 2
V VFormula
T T
32Final V 38in.
32
3
V28in.Sub /Solve
492 R 660. R18480in R
492 R 2V
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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.
p p1 2
1 2T T
Note: T1 and T2 refer to absolute temperature.
p1 and p2 refer to absolute pressure.
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Gay-Lussac’s Law Example
A 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.p1= 120. lb/in.2 + 14.7 lb/in.2 = 134.7 lb/in.2
Convert T to absolute temperature.T1 = 62°F + 460.°F = 522°RT2 = 90.°F + 460.°F = 550.°R
p p1 2
1 2
FormulaT T
p 22Final 140lb / in.
p22
2
134.7lb / in.Sub /Solve
522 R 550. R74085lb / in R
522 Rp2
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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?
p 22Final 141.9 lb / in.
If the absolute pressure is 141.9 lb/in.2, what is the pressure reading at the gauge?
141.9 lb/in.2 – 14.7 lb/in.2 = 127.2 lb/in.2
= 130 lb/in.2
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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
Drain
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Compressor Types
Reciprocating Piston Compressor
Compair
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Compressor Types
Rotary Screw Compressor
Compair
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Compressor Types
Rotary Vane
Compair
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Future Pneumatic Possibilities
What possibilities may be on the horizon for pneumatic power?
Could it be human transport?
zapatopi.net
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Properties of Gases
Absolute Temperature0°F does not represent a true 0°
Absolute Zero = -460.°F
Absolute 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 °R