Archive | Compressed Air


7:30 pm
August 3, 2017
Print Friendly

Adjustable Red-and-Green-Zone Dial Gauges

1708mtprod01pGauges with adjustable red-and-green-zone dial faces standardize the visual cues for compressed-air systems and offer maximum visibility of red-zone pressure or vacuum conditions. Red indicator bands on the high and low end of the green zone are said to be easily adjusted to delineate the upper and lower boundaries of safe operation for each pressure or vacuum system to which the gauge is applied. The visually impactful red band, covering the entire out-of-specification zone on the dial face, makes deviations from acceptable conditions easy to see. This type of simple-to-understand monitoring/warning system aids all personnel. Gauges feature dual displays: Psi/bar for pressure, bar/InHg for vacuum. Various pressure-range gauges are available with the maximum pressure at 150 psi/10 bar.
Festo Corp.
Hauppauge, NY


4:28 pm
July 12, 2017
Print Friendly

Untangle Compressed Air Misconceptions

Where air compressors are concerned, what you believe may not be rooted in fact and could be costing your operation.

 Leaks waste between 20% and 30% of all compressed air produced in industrial plants.

Leaks waste between 20% and 30% of all compressed air produced in industrial plants.

By Jane Alexander, Managing Editor

Compressed-air systems are often misunderstood. That’s why so many seem to be inefficient. The problem, according to compressed-air expert Ron Marshall, is that inefficiency constantly gnaws away at your bottom line through extra operating costs and, in some cases, reduced production-output capabilities. He knows what he’s talking about—and has been writing about it in Maintenance Technology’s pages for several years (see Learn More Box at the end of this article).

Marshall’s background includes, among other things, having been the first Canadian participant to qualify as a U.S. Department of Energy (USDOE) AIRMaster+ specialist and long-time involvement as a committee member and instructor with USDOE’s Compressed Air Challenge initiative ( He discusses several of the most widespread (and troubling) compressed-air misconceptions here.

Misconception: Compressed air is free.

“This one,” Marshall noted, “is a common belief among personnel who don’t have to pay a plant’s electrical bill.” In reality, using compressed air to drive any continuous mechanical operation can be very costly and inefficient. It takes about 7 to 8 hp of electrical power at the compressor to produce an equivalent of about 1 hp of mechanical output at a compressed-air-driven device, making it one of the most expensive energy consumers in your plant. Most of the energy ends up as heat in the compressor room, and often is simply blown into the atmosphere, warming the globe. Frequently, problems with the compressor control system, pressure restrictions, and extensive leakage make the 8:1 power ratio even worse.

When it comes to using compressed air to blow dust, turn an air motor, or agitate liquid, Marshall said it’s important to calculate energy-related costs associated with the operation. While it’s important to understand these costs yourself, it’s also important to educate others in your plant that compressed air is a very costly utility—and one that shouldn’t be wasted through inappropriate use.

Misconception: Fixing leaks saves big money.

According to Marshall, studies have shown that leaks waste between 20% and 30% of all the compressed air produced in industrial plants. Some plants with no leakage-detection-and-repair programs have even higher levels. Wasting 50% is not unheard of and, in some extreme cases, it can approach 80%.

“Considering the high cost of compressed air, leakage-reduction efforts have a high potential to reduce operating costs, Marshall stated, “but there’s a catch.” The energy savings you gain through leakage reduction is not always directly proportional to the flow reduction, but, rather, depends on the compressor control method. A very well-controlled system will turn the compressor energy down for every percent drop in leakage that is repaired. This would be a system with a good central compressor controller with multiple load/unload compressors, or a system with a properly sized and coordinated variable-speed-drive compressor.

“Some compressor control modes,” Marshall cautioned, “have less than optimum power-turndown capabilities, such as those running in blow-off or inefficient modulation mode, where the inlet flow to the compressor is choked off to control the output.” These compressors might only save 3% power for every 10% reduction in flow. Furthermore, this control mode causes an increase in pressure as the flow reduces, which causes the remaining compressed-air demand to consume more.

Jacking up pressure can make users happy, but cause problems in compressor rooms.

Jacking up pressure can make users happy, but cause problems in compressor rooms.

Misconception: Large pipe adds storage volume.

Adding storage volume to a compressed-air system can make it run more efficiently. Rather than clearing space for a large receiver tank in the compressor room, some people think they can install extra storage by upsizing their compressed-air lines. As Marshall noted, best-practice storage volume for load/unload compressors is between 5 and 10 gal./cfm of your trim compressor (the one that takes partial load). As an example, the recommended system storage for a100-hp compressor that puts out about 400 cfm would be between 2,000 and 4,000 gal.

Perhaps you want to upsize from 2-in. pipe to 3 in. to provide storage capacity. You should be aware that 3-in. pipe contains a volume of 38.7 gal./100 ft. To install the equivalent of a 2,000-gal. storage tank, you would need about 5,200 ft. of 3-in. pipe—about a mile of piping. So, should you upsize your piping? Marshall says yes, “but not to act as system storage.” Larger sized piping, he explained, reduces pressure loss in your system and that can allow a compressor to run at lower pressure, saving energy. If you do upsize piping, install a large receiver as well.

Misconception: Increasing pressure solves problems.

Marshall described what seems to be a common low-pressure-detecting instrument in many plants—a phone. “If compressed-air pressure gets low,” he said, “production will call and complain, and the compressor operators will jack up the pressure.” This may solve production issues, but it also causes a problem in the compressor room. That’s because, for every 2 psi of additional compressor discharge pressure, power input per unit of flow increases by about 1%. This manifests as higher power bills for the same amount of compressed air, and produces more heat inside the compressor, which can lead to shutdown, extra maintenance costs, and air-dryer problems.

“Many times,” Marshall said, “pressure problems are only temporary, often caused by production areas doing something strange with compressed air. They can also be caused by poorly sized piping, connectors, and hoses at the end use.”

Another problem with extra pressure is that all unregulated compressed-air consumers, i.e., leaks, will use almost 1% more air for every 1 psi in extra discharge pressure. This increases a compressor’s load, leading to more energy consumption.

Increasing pressure adds to a compressor’s load and increases energy consumption.

Increasing pressure adds to a compressor’s load and increases energy consumption.

Misconception: Change filters only if differential reads high.

Filter-pressure differential is one of the most common and largest single pressure restrictions found in compressed-air systems. According to Marshall, plant personnel often wait to replace filters until the differential-gauge needle (if there is one) points to a high level (often there are red and green indicators). Or, they simply ignore filter replacement.

“Replacing filters based solely on pressure differential,” he explained, “is problematic because most filters aren’t running at rated flow where the differential gauge is calibrated.” This means an occasional glance at a filter during average loads won’t reveal any problems. At high flows, though, the filter may develop excessive pressure differentials, causing low-pressure problems in the plant.

Misconception: Air dryers don’t improve efficiency.

Air dryers are another often-forgotten part of compressed-air systems with regard to energy efficiency. Marshall stressed that it’s important to choose air dryers that turn themselves down under light load conditions.

The choice of air dryer can save significant extra power, especially if your system has periods of light loading.

Misconception: Use VSD compressors anywhere, any way.

Marshall described variable-speed-drive controlled compressors (aka VSD or VFD compressors) as game changers for plants. “Where VSD compressors are applied properly,” he said, “the savings are substantially greater than with fixed-speed units, especially for single-compressor systems with significant periods of light load.” In fact, use of such units can often double the savings gained by other efficiency measures. Problems, though, can occur when these advanced technologies are misapplied or installed in poor locations.

It’s important to properly size and control VSD compressors when using them in multiple-compressor systems. The required pressure settings are different fixed-speed-compressor systems. Use of VSD units in applications with high temperatures, large amounts of ambient dust, and/or poor power quality is not recommended. In such cases, savings can be realized with fixed-speed compressors, using other types of capacity controls or with sequencing control. MT

Ron Marshall has spent more than 22 years working with compressed-air systems, first as an industrial systems officer with Manitoba Hydro, and since his retirement, as owner of a compressed-air consulting company. Contact him at

Rethink Your Purchasing Approach

When purchasing compressors, these questions are at the top of everyone’s list. The “obvious” answer is not always correct:

Can our plant save money by purchasing one large air compressor instead of two or three smaller ones? Not really. This approach may save on the initial purchase and ongoing maintenance costs, but these costs are typically only about 20% to 30% of the total life-cycle costs of running an air compressor. Over-sizing an air compressor will likely cost much more on the largest component of the lifetime operating costs: electricity input. For example, a single 200-hp load/unload compressor running full time at half capacity with a small receiver tank might consume $130,000/yr. of energy at $0.10/kWh. A well-designed system using two 100-hp units at the same average load would consume about $74,500/yr. in energy. Over 10 years the savings for choosing the two-compressor system would be worth more than half a million dollars.

Since all compressors are the same, can’t we just go with the least expensive? Not necessarily. The energy characteristics of air compressors vary with make and model. It’s wise to check out these numbers before purchasing a new compressor because the energy savings from choosing an efficient compressor can quickly offset any higher initial cost. Most large manufacturers have data sheets that show the power-versus-flow characteristics using a data format developed by the Compressed Air and Gas Institute ( Look up the numbers before you buy any new compressor to ensure you are purchasing the most efficient unit. All CAGI members are required to publish their numbers. The effort could save you a bundle.

learnmore2— “Who Cares About Compressed Air?”

— “How Much Is Your Air System Really Costing?”

— “Re-commission Your Compressed Air System”

— “Show Me the Money”

“Don’t Ignore Compressed Air Filters”


7:42 pm
April 13, 2017
Print Friendly

Top Tips For Maintaining Air Compressors

Use these tips to improve air-compressor performance and increase uptime.

Use these tips to improve air-compressor performance and increase uptime.

Air compressors and their output are valuable assets on which countless plants depend for efficient daily operations. Regular attention to and proper management of the health of these critical equipment systems can save time and money in all manufacturing systems.

John Skalka, service manager for Sullair (Chicago) offers several tips for maintaining your site’s air compressors. According to Skalka, following these procedures to help monitor and maintain air-compressor performance can result in reliable equipment and reduced downtime.

—Jane Alexander, Managing Editor

Maintain filters and separators.

Proper maintenance of a compressor’s consumable filters and separator elements will not only help to ensure maximum unit uptime, but also maximize its efficiency and performance.

Air intake and oil-filter maintenance should be conducted every 2,000 hr. Monitor the oil filter for contamination and wear metals, leading indicators that air-end maintenance is required.

Air/oil separator elements should be changed every 8,000 hr., along with compressor fluid. Proper air/oil separator maintenance will ensure oil carryover stays within the manufacturer’s specifications.

Remember that use of OEM service parts and lubricants in compressor maintenance will help ensure optimal equipment performance.

randmSample oil.

Regularly acquiring and analyzing oil samples helps monitor the condition of the compressor lubricant, as well as the unit itself. A robust oil-sampling and monitoring program will alert the user to fluid degradation resulting from increased viscosity, ingestion of chemicals or particulate, and high water content. It can also identify the presence of wear metals, which is a sign of bearing degradation, prior to catastrophic failure.

Oil-condition monitoring makes it possible to change the lubricant only when necessary to maintain peak performance. Samples should be drawn quarterly, during routine service maintenance on a compressor.

Remember to always draw your samples through a clean oil-sample port or from the center of the oil sump. Doing so will ensure that the results are free from particulate contamination.

Keep variable-speed drives clean.

Many of today’s compressors are equipped with a variable-speed drive (VSD) that increases efficiency and reduces energy consumption. While VSDs are electrical components, they are not completely maintenance free.

Most VSDs contain cooling fans and heat sinks that can accumulate dust and dirt during regular operation. Maintenance activities will help them run cooler and prolong their service life.

Eliminate the guesswork.

For plants that are unable to ensure regular compressor maintenance with in-house resources, outside support is available. Check with your local air-compressor sales and service center about plans that allow skilled, factory-trained technicians to routinely service your compressor(s) and related air-system equipment.

Finally, keep in mind that proper maintenance will help you realize years of reliable service from your compressor. MT

Sullair, part of Accudyne Industries (Luxembourg and Dallas, has been developing and manufacturing air compressors since 1965. For more information, visit


9:28 pm
February 9, 2017
Print Friendly

Ensure Clean, Dry Compressed Air

randmWhen it comes to compressed-air systems, equipment performance is only as good as the quality of the air itself. Unfortunately, the high-pressure air that these systems produce is wet and dirty. Air dryers and filters keep a compressed-air system operating efficiently, but only if they are properly maintained.

All atmospheric air contains some moisture and dirt. No matter how small the amount of contaminants initially, they are concentrated when the air is compressed. As the air heats up, its ability to hold water vapor increases. When the air begins to cool as it travels downstream, the vapor condenses into liquid.

Possible consequences of that condensation include, among other things, leaking seals, rusty or scaling pipelines, premature wear of moving components, and similar problems that can lead to subpar operation, equipment failure, and even damaged finished product. Plant personnel can prevent many of these headaches by selecting the right types of air dryers and filters to remove the liquid and particles and by performing regular maintenance on these

Compressed-air experts at Mazeppa, MN-based La-Man Corp. ( offer several tips regarding air dryers and filters. Keep them in mind.

—Jane Alexander, Managing Editor

Types of dryers

Most compressors incorporate an aftercooler to reduce the temperature of the compressed air. Air dryers are often installed to further reduce the moisture content. There are four major types of air dryers:

• refrigerated

• chemical or deliquescent

• regenerative or desiccant

• membrane or mechanical.

Condensation in compressed-air systems can lead to a multitude of ills, including equipment failure and damaged finished product.

Condensation in compressed-air systems can lead to a multitude of ills, including equipment failure and damaged finished product.

The simplest, most economical dryer is the membrane or mechanical type. It uses a textile filter made up of thousands of individual fibers to trap large particles and cause moisture to form large droplets (coalesce). These particles and droplets collect at the filter’s base and are drained off. Water vapor passes through the filter to a sweep chamber, where it is vented.

Mechanical systems are typically installed at the point of use (unlike desiccant-type dryers that are placed near the air compressor to capture water vapor). At this point, air temperature has cooled sufficiently to permit water droplets to form and be captured by the system.

Impact of air filters

Mechanical filters work with compressed-air dryers to remove water and other contaminants from the compressed air and prevent component contamination. Three types of filters are typically used:

• particulate

• coalescing

• adsorption.

Particulate filters are typically made of a fine mesh glass fiber, plastic fiber, or woven wire cloth. They remove large particles using centrifugal force, while smaller particles are strained out. The filter is rated by the largest-size particle it will allow to pass. These types of filters work hand in hand with coalescing filters.

Coalescing filters are high-efficiency filters that use a fine stainless-steel mesh or woven fiber cloth (such as a cotton co-knit) to remove water and lubricants from the compressed air. They are often installed downstream of a particulate filter.

Adsorption filters use activated carbon to remove gaseous contaminants from compressed air. They adsorb the oil vapor into the pores of the carbon granules and must be replaced once saturated with collected oil. They are point-of-use filters, which should be supported upstream by a coalescing filter. Typical uses for adsorption filters include sanitary environments, such as paint spray booths, clean rooms, and food and beverage manufacturing.

Bottom line: Using—and maintaining—filters dramatically improves the performance and extends the life of compressed air systems. MT

For more information on solutions that remove water, oil, and contaminates from compressed air systems, visit La-Man Corp. at


3:39 pm
December 2, 2016
Print Friendly

FS-Elliott Expands Distribution

elliotFS-Elliott Co., LLC, Export, PA, a manufacturer of oil-free, centrifugal compressors, has reached new distribution agreements with Dynamic Compressor Services, Rockwood, MI, CDA Systems, Livermore, CA, Power Equipment Co., Memphis, TN, and Rasmussen Air & Gas Energy, Waterloo, NE.

Joining a network of more than 75 distributors and representatives worldwide, the four new distributors are staffed with factory-trained sales representatives and service technicians, providing full support for local FS-Elliott customers. Services include installation and startup assistance, maintenance training, operator training, and remote or on-site technical support. These distributors maintain extensive inventories, providing immediate access to quality OEM parts for emergency or planned repairs.

“The caliber of distributors that we have added this year will allow us to reinforce our commitment to delivering quality products and services to our valued customers,” stated Will Collett, Director of Global Industrial Sales. “Delivering this level of quality to customers is something we are known for, and we are thrilled to bring our newest distributors on board to continue that strong reputation together.”

To locate your nearest FS-Elliott distributor, please visit


2:30 pm
August 10, 2016
Print Friendly

Who Cares About Compressed Air?

gun for compressed airBy Ron Marshall, For the Compressed Air Challenge

Compressed air is one of the most expensive sources of energy in an industrial facility. Consider the amount of energy that goes into air compressors, compared with the actual useful work returned at the compressed-air tool or machine.

Training courses on the fundamentals of compressed air include details on the high cost of producing this valuable resource for a point of use. Participants in such classes are usually amazed when they learn about the inefficiency of the energy transfer. The realization that compressed air isn’t free and, in fact, is quite pricey compared with other forms of energy, can mark a turning point in the attitudes of many users—and, for the health of their companies, they finally start to care.

randmHuman nature is a funny thing. If we don’t know the cost of something, it’s easy not to care about it—which results in waste. For example, people in my Canadian hometown are quite familiar with effective means for staying warm in cold weather. Yet, in the dead of winter, it’s not unusual for us to see wide-open windows in occupied apartment buildings around the community. To my eye, this is a sign of poor temperature control caused by faulty heating systems. In an attempt to keep their living spaces from becoming overheated, the residents resort to controlling the temperatures by the brute-force method of opening windows. After all, they don’t have to pay the heating bill; the building owner does. In short, it’s evidently easier for these apartment dwellers to continue wasting heat than to pick up the phone and call the building superintendent to fix a problematic thermostat.

A similar situation persists in industry when it comes to compressed air. Those of us who have spent much of our careers preaching about energy efficiency continue to see it time and again: a lack of caring from the plant floor on up. That can be changed, though. A good way to do it is to make people aware that what they are doing (or not doing) reduces their sites’ profitability, and could ultimately affect their job security.

Since compressed-air systems typically aren’t equipped with electricity meters, it’s easy for users to believe their compressed-air utility comes at no charge. This misconception leads to all types of inappropriate applications, i.e., using compressed air for cooling, mixing liquids, or cleaning dust. Proper training for all personnel is required to drive home the fact that what users are doing may be costing the plant a fortune in lost profits.

Installation of permanent power- and flow-measuring instruments on compressed-air systems is another way to make operators of this equipment aware of the actual costs. It also proves to them the positive effect of energy-efficiency measures that are implemented to save costs. Measuring, in turn, leads to effective management of a costly resource. These instruments can then be used to assist a company in setting up systems such as those described in the ISO 50001 Energy Management Standard. MT

For more information on compressed-air topics and related training through the Compressed Air Challenge (CAC), visit, or contact Ron Marshall directly at


4:07 pm
May 16, 2016
Print Friendly

Don’t Ignore Compressed Air Filters

Men during precision work on production line

By Ron Marshall, Compressed Air Challenge (CAC)

Compressed air filters are often-forgotten items that can affect the quality of your air supply and—surprisingly—the efficiency of your overall system. You can’t afford to overlook them.

Screen Shot 2016-05-16 at 11.02.07 AMAir compressors ingest atmospheric air from the compressor room, pass it through an inlet filter, and compress it to a space about 1/7th the original size. This process generates large amounts of heat that must be removed by some type of cooler. When this is done, moisture is squeezed and condensed out of the air and mostly eliminated by a water separator. While it’s inside the compressor, though, the air also picks up small amounts of the equipment’s lubricant. Any dust in the air as it passed the inlet filter remains, but in a denser form due to the reduction in volume.

Water, lubricant, and dust particles that aren’t filtered out before they reach the air dryer will travel to points unknown throughout the system. Among other things, such contaminants could then ruin your product or clog the internal pneumatic circuits of expensive production equipment. That’s why compressed air filtration is so important.

Fortunately, there are many different types and styles of filtering solutions in the marketplace, ranging from very coarse elements that remove large particles to very fine ones that remove tiny dust particles and minute traces of lubricant and water. Unfortunately, all filters present a restriction to the flow of air that leads to the development of pressure differential.

Contaminants, among other things, that aren’t filtered from your compressed air system could clog internal pneumatic circuits of expensive production equipment.

Contaminants, among other things, that aren’t filtered from your compressed air system could clog internal pneumatic circuits of expensive production equipment.

Pressure differential consumes energy in compressed air systems. About 1% of additional power is required for every 2 psi higher compressor-discharge pressure. Thus, filters need to be chosen wisely. Note, too, that there’s usually a balance between the need for clean air and the cost of compressor operation. In general, the finer your filtering, the higher your energy costs.

That said, who chooses your filters and why? Frequently it’s the compressor supplier—who might have somewhat of a vested interest in supplying your operations with filter elements for years to come. Often, you’ll find a train of multiple filters installed in a compressor room, from coarse to fine, sometimes in multiple groups before and after the air dryer. These types of units can represent the biggest pressure differential in a plant.

For more information on compressed air topics and related training through the Compressed Air Challenge (CAC), visit, or contact Ron Marshall directly at