Drop and give me 20!

By: Michael Camber

During a recent set up of a new controller installed to manage three compressors (two 40 hp and one 75 hp), our field rep mistakenly set the system pressure 20 psi lower than planned. A week or so later, during a system check, the technician discovered the error. Meanwhile, the plant equipment ran fine. Nobody in the plant noticed any production issues. So in addition to a 13% power reduction from better compressor management, the customer got another 10% power benefit by running at lower pressure.

We certainly don’t recommend this approach to finding your proper system pressure, but this incident highlights a very common mistake in compressed air systems: many compressed air systems are running at higher pressures than needed. A rule of thumb for typical plant air systems is that every 2 psig increase in pressure requires 1% more power. So turning up the compressors from 100 to 110 psig increases power consumption about 5%. This practice does not increase productivity. It just uses more energy— and often causes premature wear in pneumatic equipment.

If you have any doubts at all (or even if you don’t), we advise turning down the pressure to see if it affects production, but with a conservative approach. Try 1 psi per week until someone in production complains. This is a no-cost solution that immediately saves money. And the bigger the system and the higher your utility rates, the more you save. The added bonus is reducing the volume lost through leaks, and this also reduces flow demand and compressor run time.

If you are trying to overcome pressure drop between the compressor and points of use, the ideal solution is to minimize the source (s) of the pressure drop (e.g. replace clogged filters, make sure ball valves are fully open, replace undersized piping and fittings). And if it does become necessary to set pressure higher, do it incrementally. People tend to bump up the pressure 5 or 10 psi at a time without trying to adjust it back down.

This is a tip you can take to the bank.

For additional tips visit our website!

Compressed air ideas from the IMTS show floor

By Michael Camber

We spotted a good article in Plant Services this week by Ron Marshall, an independent consultant on compressed air efficiency.  Ron reported on some compressed air related innovations he saw at the big International Manufacturing Technology Show (IMTS) last fall.

In addition to covering some new controls and motor designs from compressor manufacturers, he noted some other items he saw that can save energy by reducing compressed air demands. 

Some plants divert compressed air into electrical cabinets for cooling effect.  Ron mentions some alternatives that are much more energy efficient. On a related note, he pointed out that food processors or other plants needing frequent wash down sometimes use compressed air to create positive pressure in electrical cabinets to prevent moisture infiltration.  This is effective but potentially wasteful unless the air is regulated to the minimum pressure required. Other items of interest were devices to detect leaks within pneumatic equipment and air saving nozzles for air knives. While we often emphasize methods to optimize the supply of compressed air, reducing demand-side inefficiencies is equally important.  

Check out his article here.  And while you are at it, if you are not familiar with Compressed Air Best Practices, you are missing out on a good source for ideas to improve your operations. 

CAGI: Helping you pick the good apples

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.

Sample CAGI datasheet for Kaeser's CSD 125 air compressor
Sample CAGI datasheet for Kaeser’s CSD 125 air compressor

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:

Additional resources:

  1. White paper: CAGI Data Sheets: An apples to apples comparison
  2. CAGI’s Performance Verification Program

What is a Flow Controller and What Does it Do?

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.

Figure 1a

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.

Compressed Air Webinar: Using Predictive Technologies with Compressed Air

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:

  1. Lubricant analysis
  2. Ultrasonic leak detection
  3. Data collection

Register here: https://info.plantservices.com/webinar-2018-compressed-air