Shop Management: Control the Current

Is Your Compressor Inflating the Electric Bill?

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CLEVELAND – When it comes to air compressors and saving energy, size matters. But so does a good maintenance program. While officials at the Compressed Air and Gas Institute (CAGI) (https://www.cagi.org) won’t claim the machines are the biggest energy hog in the plant, they do estimate that poorly maintained and designed compressed air systems account for up to $3.2 billion in wasted energy annually in the United States. Over time, though, that’s likely to change, according to Rob Haseley, a CAGI technical consultant with more than 40 years in the compressed air industry. “With the Biden administration, the federal Department of Energy is continuing to investigate compressor efficiency,” he says. “Mandated performance levels go into effect in 2025. It will be just like when you buy a washing machine or a refrigerator. There’s the big yellow sticker telling you the amount of power you will consume over the course of one year.” The European Union was considering doing the same thing, he adds, and California has already instituted a mandate for their efficiency that mirrors the DOE efforts. In the meantime, though, the average compressed air system owner is wondering about the system doing its job in the facility every day. If it’s too small, the problems are obvious. If it’s too large, however, the result can be waste. Of course, each piece of equipment comes with specs on both the air consumption and the air pressure needed. One option is to add that all together and compare it against your compressor’s output. It’s important to remember that as the number of machines using a compressor grows, the tank size will need to do so, as well. Or you can hire an auditor to come in and do the calculations. Haseley says there is a growing body of Certified Compressed Air System Specialists certified by CAGI who can come in and look at your consumption and make recommendations. “Once you size the compressor, then you would size the storage tank,” he says, “If you don’t have constant demand, then you can use bigger receiver tanks.” However, he says in terms of energy savings, a positive innovation that has happened to the industry is the development of variable speed drives (VSD), similar to what’s in home appliances from washing machines to pool pumps. “It changes as the demands differ during the day,” Haseley explains. “It turns itself on and off, and changes to the different demands during the day. Say that everybody breaks for lunch at 11:30. Nobody needs the air at that point, so the compressor should either slow down or turn itself off. And then, when the lunch is over and people are back at work, it turns itself back on and speeds up.” Even if you aren’t in the market for a new air compressor, CAGI provides the following recommendations to save money: • Turn it off when not in use; • Fix existing leaks; • Prevent new leaks – look at piping system, check filter(s), check for sludge in the pipes; • Run at the required pressure, no more; • Check drains; • Change filters regularly; • Emphasize proper maintenance, and; • Identify and eliminate inappropriate uses of compressed air. With stone fabrication, regular maintenance can be critical. Consider adding filters and building a separate space for the compressor. On the other hand, a facility can save some money if the compressor system is designed for heat recovery which can be directed either to supplement winter heating or to heat water. The bottom line, Haseley says, is to remember that, from an energy consumption point of view, a compressor is nothing more than a box. “You put kilowatts of power in, and you get air out.”

-- K. Schipper