Air Compressor Guide: Getting the Most for your Money
Contents
1. communications capability for remote monitoring and control Look for rigid piping with flexible connections to eliminate leaks Vibrations can loosen fluid and air fittings as well as electrical connections Some compres sors mount the motor and airend on vibration isolators to eliminate this source of stress Additional isolators under the compressor package offers another layer of vibration protection and for most rotary screw compressors these isolators eliminate the need for special foundations Look at the package efficiency Motor efficiency affects electrical Most reputable manufacturers report consumption Ensure your compressor performance and efficiency using the motor meets or exceeds EPAct Compressed Air and Gas Institute s standards TEFC motors offer much CAGI data sheet This reporting better protection from airborne dirt and standard helps end users make a one to dust than ODP motors one comparison between similar units A noise insulated Coolers and fans enclosure can reduce the compressor must be sized to provide low discharge noise emissions well below safety limits temperatures in high ambient tempera eliminating the need for a separate tures In air cooled units low noise radial compressor room This can save you fans generally provide better cooling thousands of dollars in site preparation while using less electricity than axial costs fans Also consider the ability to easily duct air in and out2. press air and sliding vane which uses radially moving vanes Select air compressors based on your plant needs Positive displacement compressors take in quantities of air and mechanically reduce the space occupied by the air to increase pressure Dynamic compressors use the mechanical action of rotating impellers to transfer pressure to the air Basic Operation of a Rotary Screw Compressor Aftercooler i Compressed air discharge 4 Visit our Website www kaeser com Fluid cooler Fluid Lector fl filter D Mixture L Separated fluid gy Compressed air Air intake filter Fluid separator Fluid E iii Selecting an Air Compressor he heart of the compressed advantages such as flexibility in air system is the air compres pressure selection Automatic belt sor itself When selecting an air tensioning devices are a must to ensure compressor the most important factors transmission efficiency and protect to consider are quality and reliability bearings from excess stress Reflected in quality and reliability are The control panel overall costs efficiency and ease of must be reliable user friendly and run maintenance The most cost effective the compressor efficiently It should unit may not be the lowest priced indicate operational status as well as Components to evaluate ina compressor offer maintenance interval reminders include diagnostic information and external
3. E E Control System Sequencer Separator lt Condensate Drain Optimized Compressed Air System Refrigerated Flow Controller Storage Condensate Air Receiver Air Dryer Treatment System This diagram depicts multiple compressors controlled by a system controller followed by clean air treatment and a storage air receiver with a flow controller This setup ensures optimal use of energy o evaluate a compressed air sys tem you must begin at the end What are your air requirements at the point of use Once you determine exactly what type and how much air you need you can begin to factor in design considerations costs and efficiencies Design Considerations Careful planning is essential for smooth operation System configuration should take into consideration both your requirements and the physical charac teristics of your installation Air cooled vs Water cooled Air cooled compressors have either integrally mounted or separate oil and air coolers These coolers require ade quate ventilation to perform reliably For water cooled compressors an adequate supply pressure and quality water must be available Full or Part Load Air compressors operate most efficiently at full load or off Depending on your usage profile it may be more cost effective to purchase multiple compressors to accommodate load variations In some cases variable frequency speed drive controlled units offer the best solutio
4. compressor that is difficult to maintain causes problems and costs money Some air compressors and air compres sor components are specially designed for easy maintenance 6 Visit our Website www kaeser com Noise and Other Site Requirements Air compressors with low sound enclosures and vibration isolators can save thousands of dollars in site preparation costs You may be able to eliminate the expense of a separate compressor room or special foundation What s the Warranty A warranty is the manufacturer s pledge to the customer Make sure you have a comprehensive warranty on your equip ment that is backed by solid manufac turer and distributor support Maintenance Checklist Compressor prefilters Check and clean or replace service frequency relates to condi tions in operating environment Compressor fluid level Should be at full mark change per manufacturer s recommen dation DO NOT OVERFILL Inlet filter cartridges Remove and clean or replace Drain traps Periodically check for proper operation Check for leaks throughout Piping and flexible joint packings control lines control line fittings clamps and connectors valves air pressure safety relief valves and pressure gauge connections Compressor cleanliness Maintain in a clean condition a compressor should never leak fluid Coolers Check water quality flow and temperature in water cooled units check inlet filters and coo
5. obtained from manufacturers Cost of Compressed Air You must go beyond initial cost when evaluating compressed air systems During the first year operating costs for compressed air can be 1 to 2 times the initial purchase price of the equip ment Efficiency of the compressor and the overall system efficiency are critical Electrical Expense As much as 70 of compressed air cost is electrical Cooling Cost lf you are consider ing air cooled compressors factor in the electricity used to run cooling fan motors If evaluating a water cooled system consider the quantity and required quality of the water as well as treatment electrical and disposal costs Maintenance Costs The easier the system is to maintain the more you save in the long run Leaks and Unnecessary Demand Any leaks in your system will add to your operating costs Unnecessary use of compressed air is wasteful and expensive Reliability An unreliable compressed air system can be disastrous to the bottom line A lost production day is never made up 70 of Your Long Term Compressor Cost is Electricity Maintenance Equipment Analyze the total cost of a compressed air system and you ll realize that power cost is significant In just one year it could exceed the cost of the compres sor itself Over a period of ten years this could consume 70 of your overall costs That s why it is important to investi gate energy efficiency when c
6. of the total expense in produc ing compressed air As electricity rates escalate across the nation and the cost of maintenance and repair increases selecting the most efficient and reliable compressor becomes critical Rotary screw compressors operate on the principle of positive displacement Filtered air enters the inlet of the airend where male and female rotors unmesh The air is trapped between the rotors and the airend housing This space is reduced as the rotors remesh on the opposite side of the airend Thus the air is compressed and moved to the discharge port Cooling fluid injected into the housing mixes with the air to seal lubricate and remove the heat gener ated by compression This fluid forms a thin film between the rotors that virtually eliminates metal to metal contact and wear The fluid is separated from the compressed air cooled filtered and returned to the injection point The compressed air passes through an aftercooler to reduce its temperature and is ready for the air treatment equipment Types of Air Compressors Air Compressors Dynamic Positive Placement l Centrifugal Axial Rotary Reciprocating Use a rotat Compress air Compress air ing impeller to through the through the impart velocity action of rotat use of a to the air which ing elements is converted to pressure reciprocating Most common piston types are rotary screw which uses rotating male and female rotors to com
7. 50 hp compressor rejects heat at approximately 126 000 Btu per hour Size air receivers for about 2 5 gallon capacity for each cfm of compressor capacity The water vapor content at 100 F of saturated compressed air equals about 6 gallons per day for each 100 cfm of compressor capacity Effects of Ambient Conditions on Compressor Ratings 120 5000 110 4000 100 3000 90 2000 80 1000 10 af 0 1 2 Altitude ft Ambient Temperature F Relative Humidity 5 6 7 scfm Reduction
8. Air Compressor Guide COMPRESSORS Built for a lifetime Getting the Most for Your Money How to Select and Protect Your Air Compressor Investment Troubleshooting Glossary and Reference Data Provided as a service by Kaeser Compressors Inc KAESER COMPRESSORS Built for a lifetime Engineering expertise With decades of combined experience in compressed air systems and design our entire team of qualified engineers is always at your service For specialized systems or unique requirements Kaeser s highly trained engineers provide expert applications assistance From complex installations and challenging environments to facilities with limited space Kaeser can design and lay out a system to meet the specified requirements for performance and reliability Using specialized tools such as our Power Cost Analysis and Air Demand Analysis we can provide an accurate assessment of the existing installation as well as a contrasting view of the proposed system s performance Kaeser uses state of the art CAD systems to lay out the proposed system and produce traditional two dimensional and three dimensional drawings for project execution Variables such as distance diameters equipment order location accessories and connections can be reviewed and modified if necessary prior to installation Ns wasawn Evaluating a Compressed Air System Control Air Line Control l a Receiver nite
9. cific conditions May be stated as acfm scfm or cfm FAD Cubic feet of air per minute cfm Volume delivery rate of air flow Cubic feet of air per minute free air cfm FAD cfm of air delivered to some specific point and converted back to ambient air free air conditions Actual cubic feet per minute acfm Flow rate of air measured at some reference point and based on actual conditions at that reference point Inlet cubic feet per minute icfm cfm flowing through the compressor inlet filter or inlet valve under rated conditions Standard cubic feet per minute scfm Flow of free air measured at a reference point and converted to a standard set of reference conditions e g 14 5 psia 68 F and 0 relative humidity Demand Flow of air under specific conditions required at a particular point Discharge pressure rated Air pressure produced at a reference point Discharge pressure required Air pressure required at the system inlet Displacement Amount of air in cfm displaced by the compressor piston under no load discharg ing directly to the atmosphere Dual control Load unload control system that maximizes compressor efficiency Compressor is normally operated at full load or idle and is Stopped and restarted automatically depending on demand Free air Air at ambient conditions of tempera ture humidity and atmospheric pressure at any specific location Inlet pressure The total pressure a
10. hould be included in the system plan Additionally most localities require that any oil be separated from condensate before the water can be disposed of in the municipal system Booster Compressors These com pressors efficiently increase plant air pressure for equipment or processes that require up to 650 psig Air Requirements Air Quality There are many key levels of compressed air quality ranging from shop air to breathing air The required air quality will determine the type of filtration and drying system Air Capacity Begin with capacity requirements and load factors for each tool and machine that will use com pressed air These compressed air requirements are generally available from the equipment manufacturers For an existing system a professional air system audit will provide valuable information Air Pressure Determine the pressure required at the point of use Pneumatic tool manufacturers rate tool capacities at specific pressure ratings The minimum required pressure can be determined by the equation Pr Pp PL where Pr Minimum required pressure psig Pp Pressure at point of use psig PL Total pressure loss psid Total pressure loss includes any losses at the dryers centrifugal separator particulate filter oil removal filter and oil vapor adsorber as well as piping and valves Once capacity and pressure requirements are known the air compressor size and input power requirements can be
11. ler surfaces on air cooled models Belt condition Check for wear or damage and re tension as required v Compressor temperature Should be within manufacturer s limits v Record service and load hours Systems that record both service and load hours are easier to maintain and troubleshoot Refer to the service manual for recommended maintenance schedule Accurate mainte nance and operating records are essential for smooth and trouble free operation Troubleshooting n a compressed air system as in any The troubleshooting chart below is plant system problems occur during not comprehensive but indicates some routine operation Most of these common problems that can develop in problems are minor and can be compressed air systems using positive corrected by simple adjustments clean displacement compressors ing or replacing a part or eliminating an adverse condition Any major problem that may develop is generally related to improper cooling or lubrication poor maintenance and operating practices or misapplying the system Problem Probable Cause Remedial Action Low pressure at Leaks in distribution piping Check lines connections and valves for leaks point of use Clogged filter elements Clean or replace filter elements Fouled dryer heat exchanger Clean heat exchanger Low pressure at compressor See below discharge Low pressure at For systems with modulating Follow manufacturer s recommendation for compressor dis load co
12. n for part load control operation Sequencers Sequencers improve the efficiency and reliability of multiple compressor systems With microproces sor controls they can stabilize system pressure and even track each unit s 2 Visit our Website www kaeser com service load and maintenance hours Heat Recovery Recovering and using the heat generated by an air compres sor conserves energy Waste heat has many applications including process use space heating and preheating boiler feedwater Aftercoolers These heat exchangers cool the compressed air and condense much of the moisture for easy removal This prepares the air for further treat ment Receiver Tank f you have widely vary ing compressed air loads consider a receiver tank to boost capacity during peak periods With a larger receiver tank you can meet occasional peak demand with a small compressor and avoid high electrical demand charges Dryers Removing moisture from compressed air is essential for virtually all applications Air quality requirements and ambient conditions will help determine the type of dryer required Piping Pipes must be carefully sized and arranged to minimize pressure drop and should be sloped to drain towards a drop leg or moisture trap Filters Regulators amp Lubricators These should be installed at the point of use Condensate Control Because con densate must be expelled from the system for reliable operation drain traps s
13. ntrols improper adjust adjustment of control charge ments of air capacity control Worn or broken valves Check valves and repair or replace as required Improper air pressure switch Follow manufacturers recommendations for setting setting air pressure switch Water in lines Faulty air oil separation Check air oil separation system change separator element Failed or undersized com Follow manufacturers recommendation for pressed air dryer proper oil level Dirt rust or scale In the absence of liquid water Install filters at the point of use in air lines normal aging of the air lines Excessive service System idling too much For multiple compressor systems consider to load hour ratio sequencing controls to minimize compressor idle time adjust idle time according to manufacturers recommendations Improper pressure switch Readjust according to manufacturer s setting recommendations Elevated compres Restricted air flow Clean cooler exterior and check inlet filter mats sor temperature Restricted water flow Check water flow pressure and quality clean heat exchanger as needed Restricted fluid flow Check compressor fluid level add fluid as required Low fluid level Remove restriction replace parts as required Excessive ambient Improper ventilation of compressor check with temperatures manufacturer to determine maximum operating temperature Kaeser Air Compressor Guide 7 Mission Statement We strive to earn our customers trust b
14. of the compressor package Topside exhaust often simplifies ducting for heat recovery and reduces footprint Efficiency and simplicity are important Direct coupled 1 to 1 drives offer the best efficiency with no loss in transmission efficiency and require no maintenance Belt drives require only simple maintenance and offer Kaeser Air Compressor Guide 5 KAESER COMPRESSORS Built for a lifetime Simple Service Kaeser compressors are designed for easy maintenance and serviceability The air filter oil filter and oil separator are all easy to reach check and replace Special inlet filter mats are readily accessible To facilitate oil changes each rotary screw compressor is fitted with an oil change pressurization valve and drain hose The doors and lid on the compressor cabinet allow immediate access to all maintenance points Maintenance o most people who select an air compressor the most important factors are overall cost efficien cy ease of maintenance and trouble shooting Who Can Fix It If an air compressor system can be serviced by in house personnel overall operating costs will be less and down time will be reduced The more complex the compressor and compressor controls the more difficult repairs will be Selecting the simplest system will save you money Easy to Maintain Proper maintenance adds to the reliabil ity and efficiency of the air compressor A
15. onsidering a new compressor Kaeser Air Compressor Guide 3 Global Standards ISO 8573 1 was developed in 1991 by ISO International Organization for Standardization to help facility engineers specify compressed air quality globally with Quality Classes for solid particulates humidity and oil Quality classes provide an internationally accepted unit of measure A typical pharmaceutical plant for example would have a compressed air specification of ISO Quality Class 1 2 1 This is equiva lent to 0 01 micron particulate filtration 40 F 40 C dew point and 0 008 ppm 0 01 mg m oil filtration SOLIDS Maximum Particle Size microns Quality Classes as specified 0 1 1 5 15 Quality Classes Quality Classes Liquid and Gas mg m PPMy jw as specified 0 01 0 008 0 1 0 08 0 8 4 21 KAESER COMPRESSORS Types of Air Compressors ompressed air is the fourth utility Along with gas electric ity and water it is essential to most modern industrial and commercial operations It runs tools and machinery provides power for material handling systems and ensures clean breathable air in contaminated environments It is used by virtually every industrial segment from aircraft and automobiles to dairies fish farming and textiles A plant s expense for its com pressed air is often viewed only in terms of the cost of the equipment Energy costs however represent as much as 70
16. t the inlet flange of the compressor Load factor Ratio of the average compressor load to the maximum rated compressor load during a given period of time Modulating control Control system which will run the compressor at reduced output to accommodate demand variations Running a compressor at less than full load results in a drop in compressor efficiency and thus an increase in operating costs Pressure Force per unit area Pounds per square inch psi Force per unit area exerted by compressed air Pounds per square inch absolute psia Absolute pressure above zero pressure Pounds per square inch gauge psig Pressure difference between absolute pressure psia and ambient pressure Pounds per square inch differential psid Pressure difference between two defined points in the system Pressure dew point Temperature at which water will begin to condense out of air at a given pressure Pressure drop Loss of pressure in a compressed air system due to friction or flow restriction Rules of Thumb Air compressors normally deliver 4 to 5 cfm per horsepower at 100 psig discharge pressure Depending on the size of the system compressed air costs about 25 to 30 cents per thousand cfm including operating and maintenance costs Every 2 psi pressure drop costs 1 of compressor horsepower in efficiency Power cost for each 1 horsepower operating constantly for one year at 10 cents per kwh is about 750 A
17. y supplying high quality Kaeser air compressors related compressed air equipment and premium blower systems Our products are designed for reliable performance easy maintenance and energy efficiency Prompt and dependable customer service quality assurance training and engineering support contribute to the value our customers have come to expect from Kaeser Our employees are committed to implementing and maintaining the highest standards of quality to merit customer satisfaction We aim for excellence in everything we do Our engineers continue to refine manufacturing techniques and take full advantage of the newest machining innovations Extensive commitment to research and development keeps our products on the leading edge of technology to benefit our customers KAESER COMPRESSORS Built for a lifetime Corporate Headquarters Kaeser Compressors Inc P O Box 946 Fredericksburg VA 22404 800 777 7873 Fax 540 898 5520 www kaeser com Certified Management Systems Member of o CAGI Cea www cagi org 2011 Kaeser Compressors Inc All rights reserved 05 11 USGUIDE1 Compressed Air System Glossary Absolute pressure Total pressure measured from absolute zero Aftercooler Heat exchanger for cooling air discharged from air compressor Atmospheric pressure Pressure above absolute zero at a specific location and altitude Capacity The amount of air flow delivered or required under some spe
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