The Bigger the Badder

May 20, 2015

If you have a big compressed air system you are likely wasting more than most.

One observation I’ve made over the years is that it seems the bigger the compressed air system gets the worse the compressed air waste becomes.

Some of the smallest systems, such as compressors located in automotive shops or small industrial sites, tend to have very small leakage loads as a percentage of their average output.  Perhaps it is because the quiet surroundings during breaks and off hours leads the system owners to the noisy leaks and compressed air drainage and this causes them to take action.  For small systems with little capacity to spare the addition of a wasteful end use or two is immediately noticed, especially if it makes the compressor run longer or causes low pressure events that disturb production activities.

Some of the largest systems tend to be very wasteful, especially if a significant excess in capacity exists, perhaps due to a downsizing, or change in production technology that has reduced the productive air flow.  In these cases the compressed air production equipment tends to be somewhere in a locked room out of the way or in a special outbuilding.  When someone adds inappropriate uses of compressed air to the system, or where leakage levels have continued to climb over the years due to lack of attention, this additional load is rarely noticed.  Year after year this wasteful air load continues to build, causing the compressors to consume more and more energy, but because there is lots of capacity to spare the pressure continues to be at adequate levels, causing no concern.  Most of these systems have no system of monitoring and tracking, so the only way the operators know there is trouble is if the limit of compressor capacity is finally reached, and the pressure goes down impacting production.

Some recent examples I have seen:

  • A large mining facility with 6,000 cfm compressor capacity typically uses about 3,000 cfm of average air, but flow in the mine with no production is 2,000 cfm suggesting 66% leakage levels.  Recently the leakage load has climbed to 3,000 cfm but no pressure problems or repair activities are evident.

  • A cabinet making facility has 6 large compressors with total capacity of 5,000 cfm and an average flow of about 1,600 cfm.  Compressed air production on weekends with no production in the plant is about 1,000 cfm suggesting a level of 63% non-productive usage.

  • A manufacturer of large motor vehicles with 3,500 cfm of compressor capacity consumes an average flow of 750 cfm during their 8 hour production shift.  Previously plant production levels were higher and longer but there was an industry downturn. Leakage tests on weekends when no production activities are running show the flow is 500 cfm, suggesting a leakage percentage of 67%.

Do these large operators care, perhaps in some way, but not enough in these cases to spend the effort finding and fixing leaks.  They likely won’t do anything serious unless the pressure crashes low enough to affect production.  And due to their excess capacity they have a long way to go.

Learn about the cost of plant leakage at a Compressed Air Challenge Fundamentals of Compressed Air Systems seminar near you.  Our calendar of trainings is here.

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