Kaeser Compressors


 Compressor Guide
Type of Compressors
Evaluating a Compressed Air System
Selecting an Air Compressor
Glossary and Reference Data
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Getting the Most for Your Money

How to Select and Protect Your Air Compressor Investment

Evaluating a Compressed Air System

     To evaluate a compressed air system, 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 of a compressed air system is essential for smooth operation. System configuration should take into consideration both your requirements and the physical characteristics of your installation.
Air-cooled vs. Water-cooled.
     Air-cooled compressors have either integrally-mounted or separate oil and air coolers. These coolers require adequate ventilation to perform reliably. For water-cooled compressors, a supply of adequate pressure and quality water must be available.
Single vs. Multiple Units.
     Air compressors operate most efficiently at full load. Depending on your usage profile, it may be more costeffective to purchase multiple compressors to accommodate load variations.
     Sequencers improve the efficiency and reliability of multiple compressor systems. With microprocessor controls, they can stabilize system pressure and even track each unit's service, load, and maintenance hours.
Heat Recovery.
     Recovering and using the heat generated by an air compressor conserves energy. Waste heat has many applications including process use, space heating, and preheating boiler feedwater.
     These heat exchangers cool the compressed air, thereby condensing much of the moisture for easy removal. This prepares the air for further treatment.
Receiver Tank.
     If you have widely varying compressed air loads, you should consider a receiver tank to boost capacity during peak periods. With a larger receiver tank, you can meet occasional peak demand with a smaller compressor and avoid high electrical demand charges.
     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.
     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, & Lubricators.
     These should be installed at the point-of-use.
Condensate Control.
     Because condensate must be expelled from the system for reliable operation, drain traps should 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 compressors will efficiently increase air pressure from the plant system for equipment or processes that require up to 500 psig or higher pressure.
Air Requirements
Air Quality.
     There are six key levels of compressed air quality ranging from shop air to breathing air. The quality of air required will determine which type of filtration and drying system is needed.
Air Capacity.
     Begin with capacity requirements and load factors for each tool and machine that will use compressed air. These compressed air requirements are generally available from the equipment manufacturers.
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 air receiver, 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 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 1/2 to 2 times the initial purchase price of the equipment. 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.
     If you are considering 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 and Repair Costs.
     The easier the system is to maintain, the more you save in the long run. Can the system be maintained and repaired by your in-house personnel, or does it require out-of-house assistance for most problems?
Leaks and Unnecessary Demand.
     Any leaks in your system will add to your operating costs. Unnecessary use of compressed air is wasteful and expensive.
     An unreliable compressed air system can be disastrous to the bottom line. A lost production day is never made up.
Six Levels of Compressed Air Quality
Application Level Air Treatment Components
Shop Air 1 Filtered Separator
Sir Tools, Sand Blasting, 
Pneumatic Control Systems
2 Refrigerated Compressed 
Air Dryer, Particulate Filter
Instrument Air, Paint 
Spraying, Powder 
Coating, Packing Machines
3 Refrigerated Compressed 
Air Dryer, Oil Removal Filter
Food Industry, Chemical 
and Pharmaceutical Industry 
4 Refrigerated Compressed 
Air Dryer, Oil Removal Filter, 
Oil Vapor Adsorber
Outdoor Pipelines, 
Pneumatic Transport of 
Hygroscopic Material, 
Breweries, Dairy Industry
5 Particulate Filter, 
Oil Removal Filter, 
Low Dew Point Desiccant 
Dryer, Particulate Filter, 
Oil Vapor Adsorber
Breathing Air 6 Breathing Air System (continuous or portable)

Types of Compressors / Selecting an Air Compressor / Maintenance / Troubleshooting / Glossary and Reference Data


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