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Advantages and Disadvantages of Each Compressor Type * By taking the estimated fullload bhp requirement of each compressor type at 100 psig discharge pressure at the compressor, a maindrive motor with a typical efficiency of 92 percent and 0.746 kW/bhp, the approximate efficiencies are obtained. © 2011 Schneider Electric. All rights reserved. All trademarks provided are the property of their respective owners. Advantages and disadvantages of any compressor are based on its characteristics and application. Advantages and disadvantages listed below are for a typical compressed air system in an industrial plant. The estimated fullload bhp requirement of each compressor type at 100 psig discharge pressure at the compressor, a main drive motor typical efficiency of 92 percent and 0.746 kilowatts (kW)/bhp, the approximate operating costs of operation are obtained. SingleActing, AirCooled Reciprocating Air Compressors Advantages include: • Small size and weight • Generally can be located close to pointofuse avoiding lengthy piping runs and pressure drops • Do not require separate cooling systems • Simple maintenance procedures. Disadvantages include: • Lubricant carryover as piston rings wear, which should be avoided • Relatively high noise • Relatively high cost of compression • Generally are designed to run not more than 50 percent of the time, although some can be at 80 percent • Generally compress and store the air in a receiver at a pressure higher than required at the pointof use. The pressure then is reduced to the required operating pressure but without recovery of the energy used to compress to the higher pressure. Operating Efficiency: 22 to 24 kW/100 cfm* DoubleActing,WaterCooled Reciprocating Air Compressors Advantages include: • Efficient compression, particularly with multistage compressors • Threestep (050100 percent) or fivestep (0255075100 percent) capacity controls, allowing efficient partload operation • Relatively routine maintenance procedures. Disadvantages include: • Relatively high first cost compared with equivalent rotary air compressors • Relatively high space requirements • Lubricant carryover on lubricant cooled units Relatively high vibrations require high foundation costs Seldom sold as complete independent packages Require flywheel mass to overcome torque and current pulsations in motor driver • Repair procedures require some training and skills. Operating Efficiency: 15 to 16 kW/100 cfm* LubricantInjected Rotary Screw Compressors Advantages include: • Compact size and complete package • Economic first cost • Vibrationfree operation does not require special foundation • Partload capacity control systems can match system demand

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 Advantages and Disadvantages of Each Compressor Type 

 

 * By taking the estimated full‐load bhp requirement of each compressor type at 100 psig discharge pressure at the compressor, a main‐drive motor with a typical efficiency of 92 percent and 0.746 kW/bhp, the approximate efficiencies are obtained.  © 2011 Schneider Electric. All rights reserved. All trademarks provided are the property of their respective owners. 

Advantages and disadvantages of any compressor are based on its characteristics and application. Advantages and disadvantages listed below are for a typical compressed air system in an industrial plant. The estimated full‐load bhp requirement of each compressor type at 100 psig discharge pressure at the compressor, a main drive motor typical efficiency of 92 percent and 0.746 kilowatts (kW)/bhp, the approximate operating costs of operation are obtained.  Single‐Acting, Air‐Cooled Reciprocating Air Compressors Advantages include: • Small size and weight • Generally can be located close to point‐of‐use avoiding lengthy piping runs and pressure drops • Do not require separate cooling systems • Simple maintenance procedures. Disadvantages include: • Lubricant carryover as piston rings wear, which should be avoided • Relatively high noise • Relatively high cost of compression • Generally are designed to run not more than 50 percent of the time, although some can be at 80 percent • Generally compress and store the air in a receiver at a pressure higher than required at the point‐of use. The pressure then is reduced to the required operating pressure but without recovery of the energy used to compress to the higher pressure.  Operating Efficiency: 22 to 24 kW/100 cfm*  Double‐Acting,Water‐Cooled Reciprocating Air Compressors Advantages include: • Efficient compression, particularly with multi‐stage compressors • Three‐step (0‐50‐100 percent) or five‐step (0‐25‐50‐ 75‐100 percent) capacity controls, allowing efficient part‐load operation • Relatively routine maintenance procedures. Disadvantages include: • Relatively high first cost compared with equivalent rotary air compressors • Relatively high space requirements • Lubricant carryover on lubricant cooled units Relatively high vibrations require high foundation costs Seldom sold as complete independent packages Require flywheel mass to overcome torque and current pulsations in motor driver • Repair procedures require some training and skills. Operating Efficiency: 15 to 16 kW/100 cfm*  Lubricant‐Injected Rotary Screw Compressors Advantages include: • Compact size and complete package • Economic first cost • Vibration‐free operation does not require special foundation • Part‐load capacity control systems can match system demand 

 Advantages and Disadvantages of Each Compressor Type 

 

 * By taking the estimated full‐load bhp requirement of each compressor type at 100 psig discharge pressure at the compressor, a main‐drive motor with a typical efficiency of 92 percent and 0.746 kW/bhp, the approximate efficiencies are obtained.  © 2011 Schneider Electric. All rights reserved. All trademarks provided are the property of their respective owners. 

• Routine maintenance includes lubricant and filter changes. Disadvantages include: • Less efficient full‐ and part‐load operation compared with water‐cooled reciprocating air compressors • Lubricant carryover into delivered air requires proper maintenance of air/lubricant separator and the lubricant itself. Operating Efficiency: 18 to 19 kW/100 cfm, single‐stage* 16 to 17 kW/100 cfm, two‐stage*  Lubricant‐Free Rotary Screw Air Compressors Advantages include: • Completely packaged • Designed to deliver lubricant‐free air • Do not require any special foundations. Disadvantages include: • Significant premium over lubricant‐injected type • Less efficient than lubricant‐injected type • Limited to load/unload capacity control and VSD • Higher maintenance costs than lubricant‐injected type over the life of the machine. Operating Efficiency: 18 to 22 kW/100 cfm*  Centrifugal Air Compressors Advantages include: • Completely packaged for plant or instrument air up through 500 hp • Relative first cost improves as size increases • Designed to deliver lubricant‐free air • Do not require any special foundations. Disadvantages include: • Limited capacity control modulation, requiring unloading for reduced capacities • High rotational speeds require special bearings, sophisticated monitoring of vibrations and clearances • Specialized maintenance considerations. Operating Efficiency: 16 to 20 kW/100 cfm*