Given the technological age we live in, the preferences for a specific air compressor design might seem a bit argumentative. Yet, for businesses that are highly dependent on compressed air, especially those with demanding applications, choosing the right compressor technology may be crucial.
 In the automotive collision repair business, for example, the continuous availability of unfaltering, high-volume compressed air is vital to support various tools as well as the filtered breathing air system.
 “When the air goes down, we’re dead in the water,” says Sandy Muir, Vice President of Facility Management at Caliber Collision Centers, a chain of 64 shops located throughout Southern California and Texas specializing in automotive structural, mechanical body and refinish work. “Until we got the right compressor technology, I would get a call that one or two shops were down every day, waiting for service technicians to get them back up and running.”
 With first class operations running 24/7, having air compressor problems was unacceptable for Caliber. Ultimately, it was also unacceptable to customers, including car owners and insurance companies. Both wanted high quality but timely repairs, to get the cars restored to OEM standards and also avoid the costs and inconvenience of rental cars. Since collision work is a continuous flow, air system downtime often delayed deliveries of a whole chain of technicians, processes and cars.
 “This situation was intensified by our need for clean air, including providing a pure supply to our paint systems and tools as well as the breathing system that delivers fresh air via respiratory masks to our paint spray technicians,” explains Muir.
Choosing the right technology
 Over the years, Caliber had used or evaluated several types of air compressor systems, including piston-driven models and rotary screw designs.
 “Everybody is familiar with the old piston-style of compressor,” says Muir. “It’s a fairly simple concept, a piston running up and down and turning a crankshaft. But of course that motor also relies on intake and exhaust valves, which tend to wear and then leak. Once that happens, oil and sometimes fuel can get into the air system. That is definitely a drawback to the purity of the system and causes maintenance headaches.”
 Caliber has also used rotary screw compressors, but was disappointed with the inherent volumetric and efficiency problems due to the “blow hole” and air leakage (back to the intake) characteristics of those compressors. Moreover, in order to make up for inefficiencies and keep up air volume, designers of rotary screw compressors incorporate higher speed, which is detrimental to service life.
 “Also, the pressure buildup at the end of the screws is so high and so hot, it burns out the bearings,” says Muir. “Plus, they could never keep the back end of the screws together because of the axial thrust; so, they just kept adding more and bigger bearings. We have had screw compressors blow up because of the extreme pressure point at the end of the screws.”
 Most recently Caliber changed over to rotary vane compressors, a more sophisticated technology with one major moving part. The rotary vane design is far more efficient and cleaner than the piston or rotary screw technologies. Also the vanes (or blades) are held outwardly by centrifugal force. A film of oil between the blades and the stator (housing) wall forms a practically perfect seal. Importantly, the performance of a rotary vane compressor does not degrade over time because during rotation the vanes slide on an oil film preventing direct contact with the internal surface of the stator. This means there is virtually no wear on the vanes.
 Caliber purchased their rotary vane compressors from Lans Company (Glendora, CA), a major distributor of compressed air systems. While Lans provides a selection of compressor technologies, brands and accessories, when it comes to rotary vane compressors, the firm recommends the Mattei line.
 “One problem with rotary vane compressors was the use of Bakelite vanes,” explains Stuart Silverman, Lans Co. President. “But the Mattei models are cast iron, and because of the oil system, there is virtually no wear. I would say they last three times longer than the rotary screw models. Also, the Mattei rotary vane compressor uses no bearings, but instead uses a bushing, so they last much longer than other models.”
 Silverman adds that the volumetric efficiency of these compressors is approximately 90 percent, supplying a reliable continuous volume of air while also providing a substantial savings in energy, wear-life and maintenance costs.