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Forging new generations of engineers

Forging new generations of engineers. Pneumatics. Properties of Compressed Air. Components have long working life resulting in longer system reliability Environmentally friendly

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Forging new generations of engineers

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  1. Forging new generations of engineers

  2. Pneumatics

  3. Properties of Compressed Air • Components have long working life resulting in longer system reliability • Environmentally friendly • Safety issues are minimized (but not eliminated) e.g.. Fire hazards; unaffected by overloads (hydraulic actuators stall or slip when overloaded) • Pneumatic actuators in a system do not produce heat (except for friction)

  4. 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

  5. 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.

  6. Bellows Tool used by blacksmiths and smelters for working iron and other metals EarlyPneumaticUses

  7. Otto von Guericke Showed that a vacuum can be created Created hemispheres held together by atmospheric pressure EarlyPneumaticUses

  8. 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 EarlyPneumaticUses

  9. Properties of Gases • Gases are affected by 3 important variables • 1. Temperature, T • 2. Pressure, P • 3. Volume, V • Gas laws describe relationships between these variables

  10. Pneumatic Power

  11. 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

  12. Properties of Gases Absolute Pressure Pressure (P) is measured in pounds per square inch - lb/in.2 or psi Standard atmospheric pressure - 14.7 lb/in.2 Example: 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

  13. Properties of Gases Absolute Temperature 0°F and 0°C don’t represent TRUE ZERO° Absolute Zero = -460°F or -273°C Absolute Temperature is measured in degrees Rankine (°R = °F + 460 °) <- English/Std. degrees Kelvin (°K= °C + 273 °) <- Metric Example: If the air temperature in a system is 65 °F what is the absolute temperature? 65 °F + 460. = 525 °R

  14. Properties of GasesBoyle’s Law The pressure of a given mass of gas is inversely proportional to its volume (providing the gas remains at constant temperature) Isothermic (equal temperature)

  15. Properties of GasesBoyle’s Law continued

  16. Properties of GasesCharles’s Law When the pressure of a confined gas remains constant, the volume of the gas is directly proportional to the absolute temperature. • A given mass of gas increases in volume by: • 1/273 of its volume per degree Celsius rise • 1/459.7 of its volume per degree Fahrenheit rise

  17. Properties of GasesCharles’s Law continued Isobaric - equal pressure V1= V2 T1 T2 Where: V1 = initial volume V2 = resulting volume T1 = initial absolute temperature T2 = resulting absolute temperature A volume of air in an accumulator is submerged in a bucket of ice water (32 degrees F). If you remove the accumulator from the ice water and place it in a bucket of boiling water what would the resulting volume be. Fahrenheit Absolute is 460 + Fahrenheit V2 = V1x 672 492 V2 = V1 x T2 T1 = 1.36 V1

  18. Properties of Gases Gay-Lussac's Law When the volume of a confined gas remains constant, the pressure of the gas is inversely proportional to the absolute temperature. P1= P2 T1 T2 __ __

  19. Properties of Gases Ideal Gas Law P1V1= P2V2 T1 T2 ___ ___ Combining the work of Charles, Gay-Lussac, and Boyle we obtain: Which was the main precursor to the modern day ideal gas Law: PV=nRT

  20. Properties of Gases 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

  21. Properties of Gases Pascal’s Law 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 = ?

  22. Transmission Lines Regulator Filter Directional Control Valve Drain ReceiverTank Cylinder Pressure Relief Valve Compressor Common Pneumatic System Components National Fluid Power Association & Fluid Power Distributors Association

  23. Future Pneumatic Possibilities What possibilities may be on the horizon for pneumatic power? Could it be human transport? zapatopi.net

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