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Pneumatic Power. Pneumatic Power. 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. Pneumatics vs. Hydraulics. Pneumatic Systems . . .

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## Pneumatic Power

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**PneumaticPower**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.**Pneumaticsvs.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**EarlyPneumaticUses**Bellows Tool used by blacksmiths and smelters for working iron and other metals**EarlyPneumaticUses**Otto von Guericke Showed that a vacuum can be created Created hemispheres held together by atmospheric pressure**EarlyPneumaticUses**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**PropertiesofGases**Gases 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**Properties of Gases**Absolute Pressure Gauge 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**Properties of Gases**Absolute Pressure Pressure (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.2**Properties of Gases**Absolute Temperature 0°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**Pascal’s Law**Pressure exerted by a confined fluid acts undiminished equally in all directions. Pressure: The force per unit area exerted by a fluid against a surface**Pascal’s Law Example**How much pressure can be produced with a 3 in. diameter (d) cylinder and 50 lb of force? d = 3 in. p = ? F = 50 lb A = ?**Perfect Gas Laws**The perfect gas laws describe the behavior of pneumatic systems Boyle’s Law Charles’ Law Gay-Lussac’s Law**Boyle’s Law**NASA The volume of a gas at constant temperature varies inversely with the pressure exerted on it. p1 (V1) = p2 (V2)**Boyle’s Law Example**A 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**Charles’ Law**NASA Volume 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.**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.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**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.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**Gay-Lussac’sLaw**Absolute pressure of a gas increases or decreases as the temperature increases or decreases, provided the amount of gas and the volume remain constant. Note: T1 and T2 refer to absolute temperature. p1 and p2 refer to absolute pressure.**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°F p1 = 120. lb/in.2 T2 = 90.°F p2 = ? 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°R T2 = 90.°F + 460.°F = 550.°R**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/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 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**Common Pneumatic System Components**Transmission Lines Regulator Filter Drain Directional Control Valve Receiver Tank Cylinder Pressure Relief Valve Compressor National Fluid Power Association & Fluid Power Distributors Association**Compressor Types**Compair Reciprocating Piston Compressor**Compressor Types**Compair Rotary Screw Compressor**Compressor Types**Compair Rotary Vane**Future Pneumatic Possibilities**What possibilities may be on the horizon for pneumatic power? Could it be human transport? zapatopi.net**Image Resources**Compair. (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.aspx National 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.asp National 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/

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