Air Compressor - CAGI
Air CompressorSelection & Application¼ through 30 HPYEARS OFINDUSTRYLEADERSHIP
PrefaceThe purpose of this publication is to help users understand the basics of compressed air as a powersource and to provide initial technical guidance for selecting the right air compressor for specificapplications. The central focus is on packaged complete unit air compressors, most commonly used insizes 30 horsepower and below as measured according to standards for continuous duty compressors.Content has been provided by members of the Reciprocating Compressor and Rotary PositiveCompressor Sections. Products within the scope of these sections are most frequently used for generalpurpose industrial air supply, but they also find use in off-shore drilling, construction jobs, locomotives,ships, mining and other specialized applications.Membership of the Reciprocating Compressor and Rotary PositiveCompressor Sections:ALMiG USA CorporationAtlas Copco Compressors LLCBOGE AmericaChicago PneumaticELGi Compressors USA, Inc.FS-CurtisDV SystemsGardner DenverIngersoll RandKaeser Compressors, Inc.Mattei CompressorsQuincy CompressorSaylor-Beall Manufacturing Co.Sullair CorporationSullivan-PalatekVisit www.cagi.org for the most up-to-date listing of members.If you require additional information that is not contained in this document, contact a compressormanufacturer of your choice for additional information and instructions.
ContentsCompressed Air. 3a. How Can Air Generate Power?b. Where is Compressed Air Used?Advantages of Air Power. 4a. Air Power versus Electric Powerb. Air Power versus Hydraulic PowerTypes of Compressors. 5a. Reciprocating Type1. Single-Stage2. Two-Stage3. Rocking Piston Type4. Diaphragm Typeb. Rotary Type1. Rotary Sliding Vane Type2. Rotary Helical Screw Type3. Scroll TypeTypes of Controls. 7.Types of Drives. 8.a. V-Belt Drivesb. Gear Drivesc. Direct Drivesd. Engine DrivesAir Compressor Packaged Units. 8Air Compressor Performance.11a. Deliveryb. DisplacementAccessories.11a. Air Receiverb. Air Treatment Productsc. Belt Guardd. Diagnostic Controlse. Intake Filterf. Magnetic Motor Startersg. Variable Speed DrivesAir Compressor Installation.12Air Compressor System.13How to Select an Air Compressor.16a. Industrial Type Toolsb. Automotive Service Shopsc. For Use with Air Cylindersd. Air Flow Through OrificesCompressor Selector Chart.19Useful Formulae. 24Glossary. 252
Compressed AirHow Can Air Generate Power?When air is compressed, it is under pressure greater than thatof the normal atmospheric pressure and it characteristicallyattempts to return to its normal state. Since energy is requiredto compress the air, energy is released as the air expands andreturns to atmospheric pressure.Air compressors were designed to compress air to higherpressures and harness this potential energy source. Unlike othersources of power, no conversion from another form of energysuch as heat is involved at the point of application. Compressedair or pneumatic devices are therefore characterized by a highpower-to-weight or power-to-volume ratio.Not as fast as electricity or as slow as hydraulics, compressedair finds a broad field of applications for which its responseand speed make it ideally suited. Where there is an overlap, thechoice often depends on cost and efficiency and air is likely tohold the advantage.It is a utility that is generated in-house, so owners have morecontrol over it than any other utility. In addition, air does notpossess the potential shock hazard of electricity or the potentialfire hazard of oils. However, compressed air is under pressureand can cause harm and bodily damage if not respected. Safetycodes and regulations should be followed when working withcompressed air. The advantages of air power will be discussedfurther in the proceeding pages.Where is Compressed Air Used?Equally common are devices producing lateral motion and directforce, either steady or intermittent. Common examples areclamps, presses and automatic feeds. Air pressure can also beused to accelerate a mass, which then exerts an impact upon ananvil, as in paving breakers and pile drivers.Common applications in industrial plants and on constructionsites are air-powered nail guns, staplers, torque wrenches,screwdrivers, paint spraying and conveying of material. In paintspraying and in air conveying, the dynamic pressure of the airimparts motion.Compressed air powers many different kinds of devices. It canbe used to push a piston, as in a jackhammer; it can go througha small air turbine to turn a shaft, as in a dental drill; or it can beexpanded through a nozzle to produce a high-speed jet, as in apaint sprayer.Compressed air provides torque and rotation power forpneumatic tools, such as drills, brushes, nut runners, rivetingguns and screwdrivers. Such tools are generally powered bysome form of rotary air motor such as the vane or lobe typeor by an air turbine.3
Advantages of Air PowerWhen there are a dozen or more forms of energy to choosefrom, what advantages does air power offer? Here,compressed air stacks up against two of its competitors –electricity and hydraulics.Air Power versus Electric PowerFlexibility: Compressed air systems offer simpler installationthan hydraulics, particularly where tools are frequentlyinterchanged. Compressed air systems also offer betteradaptability for automation and flexibility for changing orexpanding operations.Cost: Air tools have fewer moving parts and are simplerin design, providing lower cost maintenance and operationthan electric tools.Flexibility: Air tools can be operated in areas where otherpower sources are unavailable, since engine-driven portablecompressors are their source of air power. Electric powerrequires a stationary source.Safety: Air-powered equipment eliminates the dangers ofelectric shock and fire hazard. Air tools also run cooler thanelectric tools and have the advantage of not being damagedfrom overload or stalling.Weight: Air tools are lighter in weight than electric tools,allowing for a higher rate of production per man-hour with lessworker fatigue.Maintenance: Air systems have less downtime than hydraulicsystems because they have less complex controls. Lesspreventive maintenance is required with air, whereas hydraulicfluids must be monitored and replaced periodically.Safety: Hydraulic devices operating near open flame or hightemperatures present fire hazards, unless fire-resistant fluids areused. Leakage in hydraulic systems can result in the presence ofdangerous hydraulic fluids and even complete system shutdown.In contrast, compressed air devices operate with lower systempressures and accidental air leaks release no contaminants.Weight: Lighter weight air tools contribute to a lower operatingfatigue as compared to heavier hydraulic tools.Air Power versus Hydraulic PowerCost: An air system has fewer parts than a hydraulic system,lowering service and maintenance costs. Also, the use of a singlecompressed air supply permits operation of many separatesystems at once. Hydraulic systems require more complex andcostly controls.4
Types of CompressorsAir compressors in sizes 30 horsepower and below include bothreciprocating and rotary compressors, which compress air indifferent ways. Major types of reciprocating compressors includereciprocating single acting, reciprocating diaphragm andreciprocating rocking piston type. Major types of rotary aircompressors include rotary sliding vane, rotary helical screw androtary scroll air compressors.Reciprocating Two-stage, Four CylinderFly WheelAir InletAir InletHeadHigh-PressurePiston CylinderLow-PressurePiston CylinderReciprocating Single Acting CompressorsReciprocating single acting compressors are generally ofone-stage or two-stage design. Compressors can be of alubricated, non-lubricated or oil-less design.In the single-stage compressor, air is drawn in from theatmosphere and compressed to final pressure in a single stroke.The single-stage reciprocating compressor is illustrated in(Figure 1). Single-stage compressors are generally used forpressures of 70 psi (pounds per square inch) to 135 psi.Air DischargeInterstage CoolerAir Intake FilterHeadPistonCrankcaseIntercoolerHeadPiston PinsLow-PressurePiston CylinderFly ing RodConnectingRodReciprocating Two-stage, Two CylinderInlet &Discharge ValvesReciprocating Single StageValve PlateInterstageCoolerHigh-PressurePiston CylinderCrankshaftIn the two-stage compressor, air is drawn in from theatmosphere and compressed to an intermediate pressure in thefirst stage. Most of the heat of compression is removed as thecompressed air then passes through the intercooler to thesecond stage, where it is compressed to final pressure.Two-stage compressors can include two cylinder designs.The two-stage reciprocating compressor is illustrated in(Figures 2a and 2b).Access PlateConnected RodsCrankcaseSingle and two-stage reciprocating compressors are frequentlyused in auto and truck repair shops, body shops, servicebusinesses and industrial plants. Although this type ofcompressor is usually oil lubricated, hospitals and laboratoriescan purchase oil-less versions of the compressors as illustratedin (Figure 3 ).5
Diaphragm TypeReciprocating Single Stage, Oil-lessHeadAir DischargeHeadAir InletPistonDiaphragmAir IntakeFilterConnecting RodCrankshaftCylinderOil-LessCrankshaftMotor ShaftRotary Sliding Vane TypeRocking Piston TypeRocking piston compressors are variations of reciprocatingpiston type compressors ( Figure 4). This type of compressordevelops pressure through a reciprocating action of a one-piececonnecting rod and piston. The piston head rocks as itreciprocates. These compressors utilize non-metallic, low frictionrings and do not require lubrication. The rocking piston typecompressors are generally of a smaller size and lowerpressure capability.Rocking Piston TypeHeadCupConnectingRodValve PlateCylinderMotor ShaftThe rotary vane compressor consists of a rotor mountedeccentrically in a housing ( Figure 6 ). As the rotor turns, the vanesslide out by centrifugal force until they seal against a thin filmof lubricant coating the stator wall. There is no metal-to-metalcontact as the blade tip glides on the surface of the lubricant.Air compression occurs when the volume of the spaces betweenthe sliding vanes is reduced as the rotor turns in the eccentriccylinder. Single-stage rotary vanes are oil injected and are mostcommon in industrial applications ranging in pressure from 60psi to 200 psi. Multi-stage versions range in pressure from 60 psito 150 psi, use flow-through lubrication that “consumes”lubricant and are most typically used in moving bulk materiali.e., concrete. While there are oil-free rotary vane blowers andvacuum pumps, rotary vane compressors are not oil free.Some of the advantages of rotary vane compressors are smoothand pulse-free air output, low noise, high output volume, lowvibrations, prolonged service intervals and long life.Rotary Sliding Vane TypeStatorDiaphragm TypeDiaphragm compressors ( Figure 5) are a variation ofreciprocating compressors. The diaphragm compressor developspressure through a reciprocating or oscillating action of a flexibledisc actuated by an eccentric. Since a sliding seal is not requiredbetween moving parts, this design is not lubricated. Diaphragmcompressors are often selected when no contamination isallowed in the output air or atmosphere, such as hospital andlaboratory applications. Diaphragm compressors are limited inoutput and pressure and they are used most often for light-dutyapplications.Slotted RotorOil Separation: Stage 1Bushing JournalBladeAir IntakeCompression CellInput Shaft6
Rotary Helical Screw TypeRotary Scroll TypeRotary helical screw compressors ( Figure 7) utilize twointermeshing helical rotors in a twin-bore case. In a single-stagedesign, the air inlet is usually located at the top of the cylindernear the drive shaft end. The discharge port is located at theopposite end of the cylinder. As the rotors unmesh at the air inletend of the cylinder, air is drawn into the cavity between the mainrotor lobes and the secondary rotor grooves. As rotationcontinues, the rotor tips pass the edges of the inlet ports,trapping air in a cell formed by the rotor cavities and the cylinderwall. Compression begins as further rotation causes the mainrotor lobes to roll into the secondary rotor grooves, reducing thevolume and raising cell pressure.Rotary Helical Screw TypeAir InletMale RotorAirDischargeThermalMixing ValveFemale RotorOil is injected after cell closing to seal clearances and removeheat of compression. Compression continues until the rotor tipspass the discharge porting and release of the compressed airand oil mixture is obtained. Single or multi-stage versions areavailable. This type of compressor can be oil lubricated, waterlubricated or oil-free. Some advantages of the rotary helicalscrew compressors are smooth and pulse-free air output,compact size, high output volume, low vibrations, prolongedservice intervals and long life.Rotary Scroll TypeAir compression within a scroll is accomplished by the interactionof a fixed and an orbiting helical element that progressivelycompresses inlet air ( Figure 8 ). This process is continuouslyrepeated, resulting in the delivery of pulsation-free compressedair. With fewer moving parts, reduced maintenance becomes anoperating advantage. Scroll compressors can be of lubricated oroil-free design.Cooling fan withintegral after-coolerAir intakeAir dischargeFixed ScrollOrbit ScrollTypes of ControlsControls are required for all compressors in order to regulatetheir operation in accordance with compressed air demand.Different controls should be chosen for different types ofcompressor applications and requirements.For continuous operation, when all or most of the airrequirements are of a steady nature, constant speedcontrols are required. Use constant speed controls wheneverthe air requirement is 75 percent or more of the free air deliveryof the air compressor or when motor starts per hour exceedmotor manufacturer recommendations. Constant speed controlsinclude load/unload control for all types of compressors andinlet valve modulation for rotary compressors.Start-stop controls are recommended for a compressor whenadequate air storage is provided and air requirement is less than75 percent of the compressor free air delivery.Variable speed controls are utilized when energy efficiency isan important criteria in selecting an air compressor. This type ofcontrol is most commonly found in rotary screw and rotary vanecompressor packages. A variable speed drive will control thespeed of the motor and dynamically adjust the speed (increaseor decrease) in order to meet the air demand required by theapplication.Dual controls allow for switching between constant speed andstart-stop operation by setting a switch. With dual controls, theoperator can select a different type of control to suit his or herspecific air requirements each time the compressor is used. Dualcontrols are helpful when a compressor is used for a variety ofapplications that vary between intermittent and continuous-duty.Sequencing controls provide alternate operation of eachcompressor at each operating cycle and dual operation duringpeak demands. Sequencing controls are ideal for operatingduplex air compressors or a group of compressors at peakefficiency levels or when 100 percent back-up air might berequired for critical applications.7
Types of DrivesAir Compressor Packaged UnitsMost compressors are driven by electric motors, internalcombustion engines or engine power takeoffs. Typically, poweris transmitted by one of these sources with V-Belt, gear or directdrive configurations. Alternatively, a compressor can have anengine drive. However, an engine drive must use one of thetraditional drive types to transmit power. Three common types ofdrives are used with these power sources.Air compressor packaged units are fully assembled aircompressor systems, complete with air compressor, electricmotor, belt, direct or gear drive and automatic controls. Optionalequipment includes air receiver, dryer, aftercoolers, automaticmoisture drain, low oil safety control, magnetic starter, waterseparator and particulate filters and pressure reducing valve.V-Belt Drives are most commonly used with electric motorsand internal combustion engines. V-Belt drives provide greatflexibility in matching compressor load to power source load andspeed at minimum cost. Belts must be properly shieldedfor safety.Gear Drives are commonly used with electric motors andprovide a reduction of the axial load on the compressed airproducing element, extending the operational lifetime. Moreworking points in the optimal working range provide areduction in shear force.Direct Drives provide compactness and minimum drivemaintenance. Compressors can be flange-mounted ordirect-coupled to the power source. Couplings must be properlyshielded for safety. Lower horsepower compressors also are builtas integral assemblies with electric motors.Air compressor units also come with a variety of configurations:gasoline or diesel engines, optional direct drive, optionalseparate mounted air receivers and more.Common types of packaged unit compressors include basemount, tank mount, tank mount duplex and tank mount withintegrated or mounted dryer. Electric motors or gas engines drivethe compressors. Typical examples of the packages are shown inFigures 9 through 12.Most compressors available in this horsepower range are aircooled. Installation is convenient because the unit requires onlya connection to electrical power and a connection to thecompressed air system.Engine Drives gasoline or diesel engine or power takeoff drivesare used primarily for portability reasons. A gearbox, V-Belt ordirect drive is used to transmit power from the sourceto the compressor.8
Base Mounted PackagesReciprocating BaseMount PackageRotary Screw BaseMount PackageRotary Vane BaseMount PackageBase Mounted/Tank Mounted Package UnitsBase MountedPackage UnitsTank MountedPackage UnitsFigure 9Base Mounted / Tank Mounted Package Units are Available with Integrated Dryers or Separate Dryer Options.9
Tank Mounted Simplex PackageReciprocating Tank Mount PackagesRotary Screw TankMount Package withIntegrated Dryer!Figure 10Tank Mounted Duplex PackageRotary ScrewDuplex PackageReciprocatingDuplex PackageRotary VaneDuplex PackageFigure 11Gasoline Engine Drive PackageFigure 121
Quincy Compressor Saylor-Beall Manufacturing Co. Sullair Corporation Sullivan-Palatek Visit www.cagi.org for the most up-to-date listing of members. If you require additional information that is not contained in this document, contact a compressor manufacturer of your choice for additional information and instructions.
I4 Compressor 2 ready I5 Compressor 3 ready I6 Compressor 4 ready I7 MOS activated Q1 Turn on compressor 1 Q2 Turn on compressor 2 Q3 Turn on compressor 3 Q4 Turn on compressor 4 Q6 Turn off compressor 1 Q2 Turn off compressor 2 Q7 Turn off compressor 3 Q8 Turn off compr
Compressed Air & Gas Institute s 1300 Sumner Avenue s Cleveland, OH 44115 Phone: 216/241-7333 s Fax: 216/241-0105 s E-mail: cagi@cagi.org 204 Compressed Air Distribution (Systems) CHAPTER 4 4 Compressed Air Distribution (Systems) CompreSSeD Air DiStribution SyStemS When a compressed air distribution system is properly designed, installed, operated
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CAGI's Centrifugal Compressor Section members: Atlas Copco, FS Elliott and Ingersoll Rand have trained engineers to assist and guide users through selecting the right size compressor for their operation. A compressor system assessment is recommended when upgrading and/or replacing existing systems to assure that system performance is maximized.
Hand Carry Electric Air Compressor Manual 9 AIR COMPRESSOR FEATURES Electric Motor: Device which provides the rotational force necessary to operate the compressor pump. Air Compressor Pump: To compress air, the pistons move up and down in the cylinders. On the downstroke, air is drawn in through the air intake valves while the exhaust valves .
compressor system efficiency and optimize the system energy usage. Since the capacity controls on a centrifugal compressor are a bit more complex than positive displacement types of compressors, consulting a factory-trained technician is always recommended. The members of the Centrifugal Compressor Section of CAGI can provide that assistance.
The compressed air directly from your compressor is not safe for breathing. The air stream may contain carbon monoxide, toxic vapors, or solid particles from the air tank. Breathing these contaminants can cause serious injury or death. Never use air obtained directly from the compressor to supply air for human consumption. The compressor is .
Why the AMC’s are Trivial Brandon Jiang January 24, 2016 1 How to Use this Document This could possibly be used as a sort of study guide, but its main intent is to of- fer students some direction to prepare for this contest other than just doing past problems. Note that it is assumed that the reader is mathematically capable of understanding the standard curriculum at school. If not, the .
