"Noise is the most important customer attribute with regard to generators," says Howe. "We keep the noise level down with design techniques that improve air flow through the packages without increasing the noise."

Both compressors and generators are generally kept quiet with the use of additional foam insulation and thicker sheet metal, but there is always room for improvement.

"Noise pollution can be significantly reduced by offering a fully enclosed package with a solid floor," says Chartters. "Our [compressor] enclosure includes not only a solid-steel floor, but 2.5 in. of sound-dampening foam for maximum sound attenuation."

He continues, "Having precision-machined airends also contributes to lower noise levels. Tighter tolerances and heavy-duty bearings designed for longevity provide smooth operation and lower vibrations in any compressor."

While noise levels on compressors and generators are not legislated at this time, quieter units do have a competitive advantage, Leupi states. "The quieter, the better," he says.