Vibration isolation: Vibrations can loosen fluid and air fittings as well as electrical connections. Some compressors mount the motor and airend on vibration isolators to eliminate this source of stress. Additional isolators under the compressor package offer another layer of vibration protection, and for most rotary screw compressors, these isolators eliminate the need for special foundations.
Motor: Motor efficiency affects electrical consumption. Ensure your compressor motor meets or exceeds Energy Policy Act (EPAct) standards. TEFC motors offer much better protection from airborne dirt and dust than ODP motors.
Sound enclosures: An insulated enclosure can reduce the compressor noise emissions well below safety limits, eliminating the need for a separate compressor room. This can save you thousands of dollars in site preparation costs.
A warranty is the manufacturer's pledge to the customer. Make sure you have a comprehensive warranty on your equipment that is backed by solid manufacturer and distributor support.
Look for experience and expertise from the compressor supplier and service provider. A collaborative and consultative selling process is more likely to produce an efficient and reliable system. Consider whether the salesperson works to understand your facility's specific operational requirements and can clearly explain product features and relate their benefits to your needs.
Specific considerations for the aircraft maintenance industry
Without a consistent supply of compressed air, standard air tools and other pieces of vital shop equipment will not run. If the tools are not running, neither is the service shop. Productivity losses due to compressor reliability problems can mean real losses in hard dollars.
Determine pressure and flow needs
When designing a compressed air system, pressure and flow are the essential considerations. When asked about compressor size, many end users say they need 145 or 175 psig compressors. Compressor size is not determined by pressure requirements. It is determined by the compressor's output capacity in cubic feet per minute (cfm).
Consult the tool manufacturer's manual to determine pressure and flow requirements. Very few tools actually require pressures above 100 psig and over pressurizing will only cause premature wear. Most tool and compressor manufacturers publish charts with flow guidelines. Adding all of these together yields the total flow requirements. However, it does not take into account the percentage of time each tool is used. This requires some study of how the different parts of the facility shop operate throughout the day. To determine actual flow requirements, data logging devices are ideal for recording compressor usage over time.
Many users do not understand the inverse relationship between pressure and the volume of air delivered in a compressed air system. End users often complain about "not enough air" and will increase the pressure setting on a compressor to compensate. This actually reduces the volume of air delivered and increases the air consumption. In most cases, the problem is inadequate flow due to an undersized compressor, poor compressor performance, inadequate pipe size, and/or leaks. Increasing system pressure will increase the amount of air lost through leaks ? and everyone has leaks. Countless compressed air system studies have confirmed that as much as 35 percent of all compressed air produced is lost through leaks.
What air quality do you need?
Refrigerated dryers and particulate/oil removal filters provide the clean, dry air today's expensive tools and equipment require. Water or moisture in various forms causes excessive wear in tools or rust in iron pipes. It also accumulates in tanks, reducing the volume available for storage and causing the compressor (piston type only) to run beyond its recommended duty cycle.
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