Green is good

Environmental awareness has become part of the fabric of our society. And while we still have a very long way to go, there's more of an effort than ever to make the products we use and consume more environmentally friendly. Compressors and generators supply much of the power on today's jobsites, so manufacturers' efforts to design and build greener machines go a long way toward ensuring cleaner and greener jobsites.

"Manufacturers are putting a great deal of effort into making equipment more environmentally friendly - and with compressors, that focus is primarily on noise reduction and fuel efficiency," says Chance Chartters, direct accounts manager, Mobilair, Kaeser Compressors.

As most are aware, EPA regulations for diesel engines have gotten much more strict over the past decade and are due to get tighter still in 2008 as Tier III/Tier IV interim regulations go into effect. According to Todd Howe, product marketing manager for generators at Ingersoll Rand, this presents a formidable challenge to manufacturers who aim to build energy-efficient, quiet and compact compressors and generators.

For example, Howe says, new EPA-compliant engines are not usually "drop-in" replacements for their predecessors. Often, the new engines mount differently and require different plumbing and wiring. As a result, the entire product can require a redesign to incorporate the new engine.

With each [EPA] Tier change, the engines run hotter, so the cooling systems in the machines get bigger, the machines themselves get louder and so on. Balancing all the various design objectives keeps engineers very busy, Howe says.

What's more, he says, is that the electronic controls in the new engines have increased in complexity, making it more difficult to interface them with the machine's electronic controls which the customer uses.

Marc James, product marketing manager for compressors at Ingersoll Rand, notes that the complexity of engine controls is a challenge but comes with some positive side effects too. Since engines have become more electronic, it allows manufacturers to develop the potential for better diagnostic and troubleshooting features.

Fuel for thought
Unfortunately, cleaner-burning engines are not necessarily more fuel efficient. In fact, OEMs say that between Tier I and Tier II, fuel efficiency actually went down rather significantly. Engine designers have worked hard to maintain fuel efficiency while reducing emissions, but haven't been able to improve it.

"For manufacturers, cleaner-burning engines have reduced NOx and particulates, but they run hotter and use more fuel," says Marc Leupi, product manager, utility equipment at Wacker Corp. "Then the challenge becomes how to quiet the unit but keep enough cooling air, because now we have to cool a hotter-running engine in the same tight enclosure. The effect is it increases the manufacturing cost. There's a lot more complexity to the equipment, but it's the same product."

Structurally speaking
The way compressor and generator enclosures are designed and built has a large effect on the machines' environmental friendliness.

"Noise is the most important customer attribute with regard to generators," says Howe at Ingersoll Rand. "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," explains Chartters. "Our [compressor] enclosure includes not only a solid-steel floor, but 2.5 inches 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."