A report card on compressed air knowledge: Part 2 By Michael Camber Missed part 1? Click here for the results of a recent quiz of automotive service shops about compressed air. The point least understood… More
By: Michael Camber
For decades, compressor manufacturers found creative ways to present their energy consumption in the most favorable light when up against competitors. Some were more scrupulous than others, but often the customer did not get the best value possible.
In the late 1990s— to forestall potentially cumbersome government regulations— the Compressed Air and Gas Institute and its compressor manufacturer members worked together to agree upon standards for measuring the energy efficiency of compressors and a format for publishing it so that buyers and specifiers could make fair comparisons when selecting compressors. The product of this effort is commonly known as the “CAGI datasheet” (see example below), and we’ve written about this before. The datasheets enable better apples-to-apples comparisons, and they can be helpful in providing documentation necessary for some utility rebate programs.
They further agreed to test protocols and developed a Performance Verification Program in which participating members’ products are periodically and randomly selected for testing by a third party to verify the performance data that manufacturers published in the CAGI datasheets format. Participation is voluntary and open to all manufacturers, whether they are CAGI members or not.
Participants may publish a decal on compressors as well as product literature, web pages, etc.
The key thing to be aware of is that manufacturers should not publish performance in the official format shown above or in any way present the Performance Verification logo unless they officially participate in the program and are in good standing. As of this writing, only 9 out of 21 members of CAGI’s Rotary Positive compressor section are currently participating in the Performance Verification Program. By the way, the CAGI program is the only one of its kind. I mention this because we’ve seen some creative marketing out there that implies government certification of product performance.
If a participating member’s products fail to measure up to published performance three times in a five year period, that manufacturer is suspended from the program for a minimum period of six months and should not present customers with CAGI datasheets or represent that they are participants in the Performance Verification Program.
If energy efficiency is important when selecting compressors, you owe it to yourself to get the product’s current CAGI datasheet and confirm the manufacturer is a current participant in the program (on the CAGI website).
Learn more about CAGI’s verification program in this video:
By: Wayne Perry
A flow controller is essentially a pressure regulator that reacts very quickly to changes in downstream demand, releasing volumes of stored compressed air with precision to maintain very stable system pressure. Given adequate storage upstream, they can maintain system pressures within +/- 1 psig of target pressure even with large swings in demand. Too often, system pressure is set higher than needed to allow for fluctuation. With the precision flow controls, the target pressure setting can be reduced to the minimum required for the end uses.
Flow controllers present several significant energy savings and operating benefits, especially in older existing plants that don’t have the capital budgets available for major compressed air system re-designs. In many of these cases, system capacity is no longer well-matched to production demands.
By lowering the system pressure to its minimum, artificial demand is reduced. Further, the volume of air the compressors must produce is also reduced, so that leaks and other unregulated uses will consume less air. This is especially advantageous for installations with older piping where it may not be feasible to repair or upgrade the air distribution system. Given that the average compressed air system will leak about one third of the total air volume and unregulated uses can account for another one third, or more of total volume, this reduction in pressure can affect more than half of the total air supply. For example, if the downstream pressure can be dropped from 100 psig to 80 psig, and half of the demand is unregulated, the volume required to support the system will drop by about 10%. In a system using 2500 cfm, the drop in artificial demand (250 cfm) is equal to a 50 hp compressor. This is a conservative number since it is common that more than half of the system demand is unregulated.
In addition to reducing artificial demand, a flow controller can be used to support large intermittent demand events (like bag house purges) that might otherwise draw down the system pressure and even cause an additional compressor to start in order to rebuild the pressure.
The chart below shows a compressed air system before and after installing a flow controller.
In this case, the plant was having problems with pressure swings and their supply was not quite able to meet demand. Their assumption was that a new air compressor was needed. Instead, a flow controller was installed and they were able to achieve a dramatic reduction in system pressure: from 82 psig to 69 psig, resulting in 6-1/2% power cost savings. This demand-side pressure reduction also reduced air loss due to leaks and unregulated usage by more than 13%—without fixing a leak. Adding the 6-1/2% savings from reducing the power, the 13% from the leaks, and an additional 3 – 4% for increased tool efficiency brings the total savings closer to 24%.
Another positive effect of using a flow controller to stabilize system pressure is an increase in productivity. With more stable system pressure, pneumatic devices operate more consistently, efficiently, and predictably. Nut runners, for example, will produce the same torque operation after operation with a stable pressure. Production machines will not alarm or stop due to fluctuations in system pressure. Product quality will improve. In some applications, stabilizing the air pressure has major production benefits that outweigh even large energy savings.
New installations, with today’s advanced electronic system controls, can achieve these benefits of pressure control without the use of flow controls. In many older systems, however, the flow controller offers stable system pressure without the need for advanced communications protocols—a huge benefit for systems that do not have the ability to easily connect with modern master system controllers.
This blog entry is an excerpt from our white paper, “The Proper Application of Pressure/Flow Controls”. To learn more, download the full version of the white paper here.
Register today for Plant Services magazine’s free webinar titled “Using Predictive Technologies with Compressed Air.”
Live webinar: Tuesday, August 28, 2018 | 2 pm ET
Compressed air has a major impact on production, with downtime a chief concern for industrial plants. The move towards IoT connectivity offers opportunities to better monitor and manage mission critical equipment, such as compressed air systems. Incorporating predictive technologies into day-to-day operations has the potential to improve reliability, increase uptime, and reduce maintenance costs.
Join compressed air experts Neil Mehltretter (Engineering Manager for Kaeser Compressors, Inc.) and Timothy Hitzges (Product Engineer for Kaeser Compressors, Inc) as they discuss ways to proactively improve compressed air system performance such as:
- Lubricant analysis
- Ultrasonic leak detection
- Data collection
Register here: https://info.plantservices.com/webinar-2018-compressed-air
Broadly speaking, industrial plants in the United States have been making great strides towards improving processes, reducing costs, and finding new ways to increase profit margins. The desire to reduce waste and better understand daily plant operations has spawned a number of strategies to accomplish these goals. One such strategy is Root Cause Analysis.
Root Cause Analysis (RCA) is a systematic approach to problem solving, commonly applied when there is a significant failure or issue with far-reaching impact. Its goal is to identify the factors of the negative event and determine what needs to change to prevent similar future occurrences. The spirit of RCA is investigative and collaborative in nature, whereby a team works together to discuss and carefully document the findings.
For compressed air, the common issue of wasted energy is a problem that warrants such analysis. According to a survey conducted by the US Department of Energy, approximately 10% of the electricity consumed at a typical industrial facility is for generating compressed air. In some facilities, this percentage can reach 30% or more. Much of this power is wasted in generation due to poor choices in compressor size and lack of controls. Additionally, it’s estimated that half of all compressed air generated is wasted. Despite the widespread waste of compressed air and the potential for optimizing a compressed air system, it is quite often neglected when plant efficiency initiatives are discussed.
In one example, a furniture manufacturer had grown its business and over the years, its compressed air system had grown into a 2400 hp system. Now, with a power bill for compressors over $1 million per year, management felt it was time to take a look at ways to improve the system. An in-depth assessment produced some eye-opening results. The total productive demand on the system could be satisfied with only half of the compressors currently being used. The manufacturer was losing about $500,000 per year on power, about $250,000 per year on maintenance, and had spent about $600,000 in capital for equipment that was not needed.
Unfortunately, this situation is all too common. The tendency in industrial plants is to throw equipment (and power) at compressed air system problems instead of trying to find the root cause of issues like pressure fluctuation. As it turned out for this furniture manufacturer, $500,000 of power costs could be eliminated for less money than they were spending every year on maintenance for equipment they did not need. Very few manufacturers would accept a 50% scrap rate for production inputs, yet it is quite common in compressed air.
This blog entry is an excerpt from our white paper, “Applying Root Cause Analysis to Compressed Air”. To learn more, download the full version of the white paper here.
By: Kaeser Compressors, Inc.
If you are looking for some quick tips to improve your compressed air system, consider starting with our most read blog posts from 2017.
#5 This is Why You Don’t Use PVC: Using PVC in a compressed air system poses significant safety risks. This post covers what you need to know if you are considering using it.
#4 Receiver Tanks for Small Compressed Air Systems: 2017 is the third year that this post has been in our top 5. It includes tips for where to install an air receiver tank in your compressed air system.
#3 Choosing Between an Air-cooled or Water-cooled Compressor: This post outlines four questions to answer when deciding between an air-cooled and water-cooled compressor.
#2 Some Like It Hot…Your Compressor Room Doesn’t: Last year’s top post has slipped to number two this year. If you are having problems with compressor room overheating, read this post for tips on better temperature regulation.
#1 The Art of Dryer Sizing: This post has been rising in popularity since it was published in 2015 and is the most viewed post from 2017. Read this post to understand how temperature and pressure impact water content and to learn how to make sure dryers are properly sized.
Do you have a topic you’d like us to cover in 2018? Let us know in the comments.