4Pneumatic Power Pneumatics The 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.Air is most commonly used in pneumatic systems, although some systems use nitrogen. Pure nitrogen may be used if there is a danger of combustion in a work environment.
5Pneumatics vs. Hydraulics Pneumatic Systems . . .Use a compressible gasPossess a quicker, jumpier motionAre not as preciseRequire a lubricantAre generally cleanerOften operate at pressures around 100 psiGenerally produce less power
6Early Pneumatic Uses Otto von Guericke Showed that a vacuum can be createdCreated hemispheres held together by atmospheric pressureVon Guericke held public demonstrations in Germany during the 1660s where teams of horses tried to pull apart hemispheres held together by atmospheric pressure created using a pump.
7Early Pneumatic Uses America’s First Subway Designed by Alfred Beach Built in New York CityCompleted in 1870312 feet long, 8 feet in diameterClosed in 1873
8Properties of Gases Gases are affected by 3 variables Temperature (T) Pressure (p)Volume (V)Gases have no definite volumeGases are highly compressibleGases are lighter than liquids
9Pascal’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 surfaceSymbolDefinitionExample UnitpPressurelb/in.2FForcelbAAreain.2The area of a cylinder will be the surface area of the piston.
10Pascal’s Law ExampleHow 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 = ?
11Ideal Gas Law Manipulation The perfect gas laws describe the behavior of pneumatic systemsBoyle’s LawCharles’ LawGay-Lussac’s Law
12Boyle’s LawThe volume of a gas at constant temperature varies inversely with the pressure exerted on it.NASAp1 (V1) = p2 (V2)SymbolDefinitionExample UnitVVolumein.3
13Boyle’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.3p2 = ? V2 = 10. in.3Convert p1 to absolute pressure.p1 = 60. lb/in lb/in.2 = 74.7 lb/in.2
14Charles’ LawVolume of gas increases or decreases as the temperature increases or decreases, provided the amount of gas and pressure remain constant.NASANote: T1 and T2 refer to absolute temperature.
15Charles' 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.3V2 = ?T1 = 32°FT2 = 200.°FConvert T to absolute temperature.T1 = 32°F °F =492°RT2 = 200.°F °F =660°RThe temperature readings must be converted to absolute temperature in order for the equation to work.
16Charles' 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.3V2 = ?T1 = 32°FT2 = 200.°F
17Gay-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: T1 and T2 refer to absolute temperature.p1 and p2 refer to absolute pressure.
18Gay-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?
19Gay-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 lb/in.2, what is the pressure reading at the gauge?141.9 lb/in.2 – 14.7 lb/in.2 = lb/in.2= 130 lb/in.2
20Pneumatic Power Pneumatic power Pneumatics vs. hydraulics Early pneumatic usesProperties of gasesPascal’s LawPerfect gas lawsBoyle’s LawCharles’ LawGay-Lussac’s LawCommon pneumatic system componentsCompressor typesFuture pneumatic possibilities
21Future Pneumatic Possibilities What possibilities may be on the horizon for pneumatic power?Could it be human transport?zapatopi.net
23Hydraulic Power Hydraulics The use of a liquid flowing under pressure to transmit power from one location to anotherLiquid in a hydraulic system behaves like a solid since it compresses very littleOil is most often used in hydraulic systems, although other systems also may use synthetic oils or water.
24Hydraulic PowerAt least two examples of hydraulic power are visible on the fire truck.
25Early Hydraulic Uses Water Wheels Create rotational motion Descriptions exist as early as 1st century BCSeveral examples in ancient ChinaGrist mill is picturedModern turbines in hydro-powered dams are a sophisticated version of the water wheel used to create electricity.
26Most common in industrial settings Hydrostatic SystemsFluid is at restFluid is pressurizedPressure creates force and energyMost common in industrial settingsNational Fluid Power Association & Fluid Power Distributors AssociationPneumatic systems can also be referred to as hydrostatic since such systems are often pressurized.
27Hydrostatic SystemsPascal’s Law Pressure exerted by a confined fluid acts undiminished equally in all directionsClick the arrows to activate the hydraulic press.
28Mechanical Advantage Example A force of 100. lb is applied to the input cylinder of the hydraulic press seen below. What is the pressure in the system? How much force can the output cylinder lift? What is the mechanical advantage of the system?din = 4.0 in.Fin = 100. lbFin = 100. lb Fout = ?din = 4.0 in dout = 12.0 in.Ain = ? Aout = ?p = ? MA = ?dout = 12.0 in
29Mechanical Advantage Example Find the area of each cylinder.Fin=100. lb Fout=? Rin=2.0 in. Rout =6.00 in.Ain=? Aout=? p=? MA=?
30Mechanical Advantage Example Find the pressure in the system.Fin=100. lb Fout=? Rin=2.0 in. Rout=6.00 in.Ain=12.57 in Aout= in p=? MA=?
31Mechanical Advantage Example Find the force that the output cylinder can lift.Fin=100. lb Fout=? Rin=2.0 in. Rout =6.00 in.Ain=12.57 in.2 Aout= in p=7.955 lb/in MA=?
32Mechanical Advantage Example Find the mechanical advantage of the system.Fin=100. lb Fout= lb Rin=2.0 in. Rout =6.00 in.Ain=12.57 in.2 Aout= in p=7.955 lb/in MA=?
33Emerging Hydraulic Application Example Hydraulic Hybrid VehiclesBraking provides stored energy that is used to propel the vehicle forward.UPS™ expects 60-70% better fuel economy and 40% reduction in CO2 emissions.Although this technology is being explored for other purposes, delivery trucks can benefit from such technology because of frequent stops and starts.This hybrid allows for a smaller engine, resulting in better gas mileage and lower emissions. During braking a hydraulic hybrid converts the potential energy of the vehicle in motion to hydraulic pressure stored in the fluid power equivalent of a battery, which is called an accumulator. This stored energy can then be reused during the acceleration process.For more information visitUPS