MRO Magazine

Compressed air technology boosts plant equipment


November 14, 2003
By PEM Magazine

The quality and consistency of compressed air delivered to machinery contribute to improved production. Today, many compressor manufacturers are striving to build better units, while investing in the development of new technologies. Since the introduction of variable-speed drive compressors, for example, power savings have been impressive.

"We recognized that with the continuous rise of electricity costs, whereas the electrical bill on average represented 70 percent of the total life-cycle cost of a compressor, that it was important to introduce compressors with integrated variable-speed technology," says Leo Di Bello, product manager for Montreal’s Atlas Copco Compressors Canada (

"An independent and official electrical laboratory measured and verified electrical bill savings as high as 35 percent. As a result, the market has been quick to acknowledge the benefits of variable-speed technology."

It should be noted that Atlas Copco has extended its variable-speed drive technology throughout its range of oil-free and oil-injected compressors.


Larry McNett, spokesperson for Quincy, IL-based Gardner Denver (, agrees that variable-speed drive is a hot topic in the compressor industry. Gardner Denver introduced its newest rotary screw package, the eXact RPM variable-speed air compressor.

"Using the latest in variable-speed technology, the eXact RPM is designed for saving money on energy bills during part load applications, up to 40 percent," says McNett. "It’s designed around the variable-speed concept from the top down."

The eXact RPM VS8740 model delivers 870 CFM at full capacity down to 118 CFM, approximately 14 percent of full capacity. "This broad airflow range best fits the needs of plants that experience large fluctuations in air demand within a shift or from one shift to another," says McNett.

Gardner Denver’s Digi- Pilot controller integrates the frequency drive and operation of the eXact RPM air compressor into a single interface control, allowing easy changes in setting the operational points, according to the company. The DigiPilot also features enhanced self-diagnostic and protective shutdown capabilities, full text operating status and service messaging and digital control for precise and instantaneous response to air system demands, says the company.

Gardner Denver’s other new product is the PureAir oil-free, two-stage compressor. PureAir offers a completely integrated air block that incorporates the gear housing, air-end and drive-motor mounting. The flow path for the compressed air is guided between stages, coolers and the crankcase. This integral design minimizes internal pressure drop, which saves on horsepower usage, say the company.

The design also helps to eliminate many complicated external pipeworks and flanged connections. In turn, this reduces noise transmission through internal flow paths, says the company.

"The convenient water-cooled heat exchanger has been integrated with interchangeable rack style, which minimizes leak-prone connections and simplifies cleaning," says McNett.

Mississauga, ON-based CompreVac Inc. ( carries a complete line of high-efficiency separators for oil removal from rotary screw, vane and refrigeration compressors, including the Rietschle Thomas Zephyr series. The company says its offering includes multi-claw vacuum pumps and compressors that are dry, frictionless and economical at high-pressure differentials.

"Contactless operation is now the preferred technology. Some of Zephyr’s features include the utilization of a highly evolved, optimized claw design for dry, efficient, frictionless compression," says Margit Schwarz, vice-president of marketing for CompreVac. "Compared to roots-type pumps, energy savings can be significant, making it cost effective to own."

"Zephyr is able to reach much higher pressure differentials than roots-type pumps, whether used in vacuum or pressure services. By using two non-contacting claw rotors, which operate without friction or lubrication, the Zephyr series offers reliability."

Zephyr units are also energy efficient, environmentally friendly without pollution or contamination and maintenance-free with fewer parts and seals. As well, they offer cool and quiet operation, says the company.

When selecting a new compressor, it’s also important to consider the associated maintenance that will enable smooth, long-term operation. Atlas Copco now includes built-in, refrigeration-type air dryers, desiccant-type dryers and heat-of-compression dryers along with filtration in its offering. As well, an integrated all-in-one box saves on space and reduces installation costs, says the company.

"Control and maintenance are facilitated with the lack of external components," says Atlas Copco’s Di Bello. "All this in a surprisingly compact package, which provides the quantity and quality of compressed air required."

Atlas Copco’s design and manufacturing procedures are compliant with ISO 9001 and ISO 14001 standards. The manufacturer’s goal is to also produce compressors that exceed OSHA standards, so that they can be installed close to where people are working. "With this type of performance, the compressor can replace the compressor room," says Di Bello. "We call it the work place concept."

Di Bello says the integrated design philosophy has eliminated lots of piping and inevitable leaks, which simplifies maintenance. He also says that regular service items are strategically grouped together.

CompreVac’s Zephyr units also save on compressor maintenance, since they have filters and separators for all makes of air compressors. "Compressed air is essential in many industries," says CompreVac’s Schwartz. "Clean, oil-free air is required to reduce maintenance costs."

To keep step, Gardner Denver has built all of its units with maintenance departments in mind. For example, the eXact RPM is designed with easy-to-reach maintenance points and a small footprint, which frees up valuable equipment room space and makes installation easier.

"Everything is located in convenient-to-reach areas, so that maintenance personnel aren’t hampered during servicing," says Gardner Denver’s McNett. "The easier it is to work on a unit of this nature, the quicker a production line can benefit from maximum uptime."

Tapping into its relationship with Keltec Technolab, CompreVac offers a complete line of filters and separators cross-referenced to all major compressor manufacturers. Keltec-Technolab builds a wide range of air-oil separators for air compressors and vacuum packages, as well as air inlet, oil and coalescing-type filters.

Peter Fretty is a freelance writer and frequent PEM contributor. You can reach him by email: