Efficiency under pressure
An industrial facility is much more than a building. The machines inside can often use even more energy than the building itself.

In Co-Motion’s case, pneumatic tools play an important role in nearly every stage of production. The owners want the 40-horsepower compressor that drives those tools to use energy as efficiently as their building.

The first step toward energy savings is specifying a premium efficiency motor. These may cost slightly more, but even for a single-shift operation, the energy savings will pay for itself. During its lifetime, the energy required to operate a motor costs about 50 times the purchase price. Eugene Water & Electric Board offers a motor rebate to make the decision to purchase a premium, energy efficient motor even easier.

Controls are important, too. A low unload control isolates the compressor from the distribution system when it reaches a maximum set point. The compressor idles until the system pressure drops to the point where a boost is needed. The pressure difference between the cut-in and cut-out points is set as large as possible without increasing the maximum pressure setting.

For greatest savings, the difference should be 20 pounds per square inch (psi) of pressure, although a 10 psi difference would be acceptable. The system pressure should be set as low as possible without affecting the performance of the tools.

Changes to the air distribution system are critical to the performance of the compressor. Increasing the system’s capacity allows it to hold pressure longer between compressor cycles. At Co-Motion, the size of distribution lines was increased to 2-inch diameter. The distribution system was laid out in a loop and a large receiver was installed.

Finally, good leak maintenance makes sure that air pressure is available for production work and not wasted by escaping to the atmosphere. EWEB is available to help with leak detection.

The long-term benefits of a compressed air system that is both efficient and well-maintained appear in better production efficiency and lower operating costs. There was also a short term benefit: the compressor system qualified for an incentive from EWEB’s Energy Smart Design program.

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This article originally appeared in Efficiency By Design, Fall 2000