Don’t let compressed air problems cost your facility energy and productivity

The true cost of common compressed air problems

Dec. 19, 2023
“Good things happen when you measure stuff.”

Ron Marshall is the founder of Marshall Compressed Air Consulting, a compressed air energy efficiency consulting firm, where he provides technical advice, system auditing, and training. He first developed his skills as an industrial compressed air systems expert at Manitoba Hydro, where he worked for 38 years, supporting more than 600 energy efficiency projects. Ron is a level 2 instructor with Compressed Air Challenge and conducts training internationally. Ron recently spoke with Plant Services editor in chief Thomas Wilk about his most recent cover story, "8 ways to justify upgrades to your compressed air system," as well as how to persuade teams to invest in the compressed air equipment they need.

Listen to Ron Marshall on The Tool Belt Podcast

PS: You spent the second half of your article outlining and blocking out some of the common problem areas that you encountered, you bucketed the problems you encountered in two or three groups. I’d like to spend the rest of our time together today talking about those groups. I think the first one was the one that caught my attention the quickest, which was maintenance and repair cost and reliability. Long story short, I think a lot of our listeners may have seen this. Often times the cost to repair a legacy asset like a compressor, like a motor ends up being more than the cost to replace, and yet those repairs happen so sporadically or once in a while, or the reports aren't being tracked that often that once people do see the overall cost of repair, they realize, oh my gosh, we actually spent more to repair this thing five times than it would have to replace with a new upgraded model. 

RM: Yeah, there's other things to look at other than energy efficiency that can save money. The compressors, they don't live forever, right, they're just like automobiles and they only last so many hours. They're running in a big plant, those compressors are running 24/7, 8,760 hours a year, so they need replacing and need repairing, and they'll just wear out. So yeah, I talked about in the article, this one paper mill, they had really old oil-free compressors, 1965 I think they were installed and they're still there actually, running. But they're so old that there's no parts available, so they had to have custom parts, custom rings, they had Teflon rings in them. They had to send their compressors away to some other province, and it turned out the repair costs each year was much more than the electrical costs. There was only going to be a slight decrease in energy costs if they changed to new types of compressors. But that repair cost, that was really significant. and that was definitely something that they took interest in, the repair cost.

PS: For anyone who's now wondering, how much did it cost to repair your compressed air storage tank or that compressor itself? Take a look at your CMMS or your business intelligence system and try and find out what those repair numbers actually are. Because if you don't know it, it might surprise you.

RM: When I'm doing audits, I always ask for some sort of printout maybe over the last five years, how much it cost to repair the compressors. I'm in another plant just now, monitoring a 100 hp compressor. I asked for those numbers, and I saw repair costs of $14,000. It only cost $12,000 in electrical costs to run that compressor, but $14,000! So I identified, okay, this is why they called me in, this big repair cost. They're trying to figure out what to do about that compressor. It's old, and they don't want to incur another cost like that. Turned out, once you measure the system, I could see that compressor is four times too large. All they need is a 20 hp compressor, not 100 hp. So yeah, good things happen when you actually measure stuff.

PS: We have that put on a bumper sticker or an event ribbon: “Good things happen when you measure stuff.” There's a second category, I sort of lumped in two different topics in one, but I wanted to talk about the quality of the air in the line itself, so I put air quality and pressure stability together. You alluded to, say, oil in the compressed air line, and you also mentioned that water in the line is a common issue as well, or something that's easy to troubleshoot.

RM: Yeah, that's right. When I go do measurements, I always try to put a dewpoint meter on to see if the air dryers are working. But yeah, that's a big thing, especially in food products companies, where sometimes the compressed air gets close, or sometimes contacts the product. You don't want water in the line. That's an oxygen rich environment in water, and there's organic dust and scale and all that stuff that are in the wetter regions of the compressed air. If you've ever had the misfortune of spraying some condensate on your hand in a compressed air system and you smell it, it smells like an old gym sock. That's because there's microbes growing in there. 

One of the main things to prevent the growth of micro-organisms inside the system is to keep the system dry. Dryness is very important to air quality in a food grade plant. And that water carries rust and by the time it gets to the end of the line, it's black gunk that comes out and it'll spray on product and discolor it. It’s very important to keep that air quality. Very nice and clean and dry, and the pressure very stable. That's a production variable, and if it's going up and down 30 psi, it can take machines down. It’s very hard to troubleshoot because people are not usually blaming the compressed air pressure for machine breakdown, so that's something that you should measure as well.

PS: You know, I've not had the pleasure of having compressor condensate spray into my hand like that. However, we have boys that are 10 and 12, and when they got back into their school activities in September, I know exactly the smell you're talking about because they would come home and suddenly our back porch smelled like dirty gym shoes. It wasn't cool enough in the house or outside to really get rid of that with a little bit of help.

RM: Yeah, you don't want to be spraying that on your buns, you know, in a in a bakery or something like that.

PS: I did a webinar just yesterday on predictive maintenance technologies, and one of the PdM cases was an automated lubrication system for an oven industrial oven chain. What was happening was the delivered the applicator wheel was designed to deliver grease and not oil. The oil was lower viscosity, and it started running over the product and pooling on the floor. The team didn't know what the problem was but they had a specialist in lubrication come in and identify, “wait a second, this technology is meant to deliver something which is a lot thicker, not a whole lot thinner.” So you know, oil in the product, this wasn't a compressed air story, but I hear you loud and clear where, you walk into a plant and that's one of the trouble spots to look at right away even if you are looking at the compressor system, is product quality. What is affecting the end product? Is it a bad paint job? Is it oil on the buns?

RM: Yeah, very important, the quality of air and pressure stability is important. And, you know, you identified a misapplication of a maintenance item, and there's sometimes misapplications that are found when you start digging into things. Equipment is being used incorrectly. I just ran across the other day a desiccant dryer feeding a laser cutter, and they had a double dryer system – they had a membrane dryer on a desiccant dryer, right in series. One of them is redundant, and this particular plant had a very high load during non-production, and it was all due to this dryer system. A membrane dryer consumes air constantly, and so does a desiccant dryer if it's not controlled properly. That was more than 50% of the total consumption in the place, just this dryer only used eight hours a day, yet the compressed air system was pressurized 100% of the time. The rest of it was mostly leaks. When I did my calculations, I found that 98% of the demand was due to the air dryer and leaks, and the rest of it was production!

PS: Wow. Wow. That leak example is going to resonate with our asset management listeners here,  there never seems to be enough time in the day to stamp them all out. Let’s go the last category, the heating and cooling costs. You had a couple of good examples in your article of how those were the presenting problem in the plant, the primary problem you were looking at.

RM: Heat recovery is something that is important in a compressed air system, especially when you live where you and I live, where it gets cold in the winter. That's one extra way you can justify a project. Not only maybe is maintenance reduced, the energy consumption is reduced, but also you can take some of that heat and most of the energy that goes into an air compressor comes out as heat, and do something with it. Also the displaced fuel could be natural gas or oil or electricity in heating something in the plant, and it can save you money as well and help justify the change to the compressed air system.

PS: That reminds me of something Wayne Perry once said, is that you didn't just buy yourself a new compressor, you bought yourself a heater which happens to make compressed air.

RM: Yeah. It's easy to take the heat and route it somewhere where there needs to be heat in the winter. But it's even better if you take that heat, if there's something that needs heat 100% of the time, like a boiler or something like that. I think I talked about in the article where a potato processing plant, they ran all the water from the air compressors into their boiler, because they weren't recovering their condensate, the steam was going to peel potatoes, really. That's what they were using the majority of it for, so they had to replace that water, and most of it went into the boiler, and pre-heating the water going into the boiler saved them natural gas costs. 

There's all kinds of other examples. I did an audit in Malaysia, an Asian country, right around the world from us. There, it never gets cold, right? I think the coolest it ever gets his 25ºC, or was that 70ºF, yet they were using the heat from their compressors for something. They were making solar cells, they had all kinds of chemical vats where they would dip the solar cell substrates in to process. So they took the heat off their compressors, and sent it to these chemical vats to heat it up; it didn't totally heat it up, but it was most of the input energy for it. Doing that we calculated it reduced their compressed air system costs quite substantially. It was down to maybe 11 kW / 100 cfm instead of 20 kW / 100 cfm for a normal system, because they're using the heat for something.

PS: You've got that money back to reinvest then in whatever kinds of equipment upgrades you need, just to draw the direct connection that we're talking about. Ron, we're almost the end of our time for the podcast today. Any final thoughts on this topic, where you’re looking at energy efficiency as something on top of everyone's mind, but oddly enough, when it comes to these decisions, there might be other problems, which are more critical to fix?

RM: I think we covered most of them. It's very common to see overheating happening in compressed air systems, so that's a common problem. When you're upgrading their system, you have to make sure that your system is sized properly, especially the air drying system, so in the hottest, moist, humid summer day after a rainstorm when it's super humid out that your air dryer can handle all that excess heat. That goes to easily maintain the air quality, and it reduces the pressure drop across the air dryers if you have it upsized for a worst case scenario. 

One other thing that is very common to see is the lack of backup capacity. A well-designed system will have enough backup capacity to withstand the loss of the biggest compressor. So your biggest compressor goes down, a backup starts automatically and maintains the pressure, nothing goes down. Production doesn't go down. You don't have thousands of people sitting there twiddling their thumbs, because you have backup capacity. I would say a very high percentage of my customers have no backup capacity, so when the compressor goes down own, then disaster happens. Production shuts down, they have to bring in an expensive diesel compressor. That is definitely something that should be on top of mind when you're upgrading a system: have enough backup capacity to handle the failure of the largest compressor. 

And it reduces maintenance costs too, because I've got customers who only shut down on holidays, right? They have no backup capacity, so when they call in their maintenance people to change the oil or do repairs on the compressors or something like that, they have to do it on a statutory holiday, and it costs an arm and a leg to get people there. So have enough backup capacity! That's very important and that has to be designed in.

PS: Wow, that's a great point, and thank you for mentioning that. It reminds me of a practitioner I once knew who said that one of the first problems he would look at when he arrived a new plant was how many rental compressors are in the yard, either being used or unused. And he used that an index into whether the plant was actually proactive about maintenance tasks and operations tasks or whether they were simply flying by the seat of their pants.

RM: That's right. Yeah, the problem is, you know, the maintenance dollars keep shrinking, the budgets keep shrinking, and it's tough for maintenance people to properly maintain their compressors because they don't have the staff very often, and don't have the money available to do full maintenance. But it’s very, very important to do it with air compressors. They need to be maintained, especially the lubricants inside them, because those lubricants are in an aggressive environment. You're mixing it with compressed air, heating it, exposing it to water and all that stuff. So it’s very aggressive environment for lubricants, so you have to change the lubricants on a proper schedule, and test it right to make sure that it's got the proper properties.

PS: Thanks for being on the podcast today, Ron. I'll make sure that there's a link to your article in the transcript and in the podcast notes and also a link to Compressed Air Challenge which, if you're looking to have your team trained up on compressed air technologies and best practices, look no further than It's a great site, a great resource, they have both training materials and trainers themselves you can work with, right Ron?

RM: Yeah, that's right. I'm a trainer as well, and we've got quite a few trainers available who could even come to your plant and do Compressed Air Challenge training, or there could be other regularly scheduled trainings nearby, or even webinars that are available.

About the Author

Thomas Wilk | editor in chief

Thomas Wilk joined Plant Services as editor in chief in 2014. Previously, Wilk was content strategist / mobile media manager at Panduit. Prior to Panduit, Tom was lead editor for Battelle Memorial Institute's Environmental Restoration team, and taught business and technical writing at Ohio State University for eight years. Tom holds a BA from the University of Illinois and an MA from Ohio State University

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