Industrial Utility Efficiency    


It is becoming a “best practice” to install a variable frequency drive (VFD) air compressor whenever one is replacing an old air compressor.  As a result, real systems have fixed-speed and VFD air compressors, mixed.  I have observed several VFD compressor sizing methods.  In my last article, I referred to a common method: size one VFD compressor for the whole system.  This can work.  However, if it doesn’t meet a higher peak demand, one or more of the old compressors will be started, and a mixed system results.   Another method is to replace a compressor with the same size, but with a VFD.  If the compressor that was replaced is large, a big VFD is installed.  If small, a small one.

Air Compressors

Knowing when to overhaul a unit is important, and there are certain signs indicating a unit needs attention. Performing routine fluid checks, taking oil samples and routinely checking for bearing vibration can unveil indicators suggesting an upcoming failure. Oil contamination with metal fragments usually indicates parts are wearing. It’s also important to take notice of airend temperature increases. If internal air compressor temperatures go up, it’s a good indicator the cooler may be failing.

Air Treatment

Compressed air is dried to prevent condensation and corrosion which can disrupt manufacturing processes and contaminate products. Water is the primary promotor of chemical reactions and physical erosion in compressed air systems. A myriad of desiccant dryer designs have been devised to provide “commercially dry” air, air having a dew point of -40°F or less, to prevent corrosion.  Desiccant dryers use solid adsorbents in granule form to reduce the moisture content of compressed air.


High speed bearing technology is applicable for aeration blowers operating at much higher speeds than the typical 60Hz, 3600RPM for cast multistage units. High Speed Turbo (HST) units are usually single stage (though some utilize multiple cores) and rotate from 15,000 to 50,000RPM. At such high speeds, standard roller bearings cannot offer the industry standard L10 bearing life. Two types of bearing technologies have come to dominate the wastewater treatment market for these types of machines: airfoil and magnetically levitated. Often the two technologies are compared as equals, however, in many significant ways they are not.

Compressor Controls

When a system has the right combination of VFD and base-load air compressors, how do you coordinate their control? What tells the air compressors to run and load, to have just enough (or no) base-load air compressors and a VFD running, all the time air is needed? Appropriate master controls are needed. These controls are often called “sequencers” or “master control systems”.


Compressed Air Best Practices® Magazine interviewed Mr. Warwick Rampley, the National Sales Manager for Sydney (Australia) based, Basil V.R. Greatrex Pty Ltd. It’s not every day one is asked to deliver a system able to provide both a reliable compressed air dew point of -80°C (-112°F) and high purity nitrogen.  We work with some excellent technology suppliers and have engineered a rather interesting system.  Although our firm was founded in 1919, this application is one of the most demanding we’ve encountered. Basil V.R. Greatrex is a unique company as we focus only on compressed air measurement, compressed air quality and compressed air efficiency.


The design of wastewater treatment plants is changing, and it has something to do with LEGO® bricks. More specifically, it has to do with how large and complex LEGO structures are built. If you follow the instructions carefully, you build module after module, eventually piecing them together to create a fully functional and cohesive unit.


It’s one thing to move materials during the production process, but when it’s a finished product on the packaging line, choosing the right material handling system is essential. Getting it wrong results in squandered production time when product loss occurs, and wasted raw materials.

Cooling Systems

As a result of compressed air awareness training and a focus on energy management, two facilities in different parts of the world have reduced their compressed air demand substantially by removing vortex style cabinet coolers from some of their electrical panels and reworking the cooling systems.  These facilities were previously unaware of the high cost of compressed air and how much could be saved if other methods of cooling were used. This article describes some of their efforts in demand reduction.
Pressure regulators are everywhere compressed air is used. These simple devices, essential for safe and steady equipment operation, can be a big waster of compressed air. This article shows how with proper regulator selection, installation and setting management you can save compressed air and lower system pressures. This article looks at regulators on production equipment not central regulators or Process Flow Controllers.
Technology is available which enables a compressed air flow meter to measure not only the magnitude of the flow, but also the direction. Why is this important? In this article we will describe two case studies where bi-directional compressed air flow measurement plays a key role to come to the right conclusions. In the first case study, we will describe an electronics manufacturing plant, which has a large interconnected ring network with two air compressor rooms located in different buildings. The two air compressor rooms are about five hundred feet apart. In the second case study, the effect of compressed air flow measurement upstream of a local receiver tank is described.
The objective of this project is to help the building automation industry develop novel products that more cost-effectively identify faults (unwanted conditions) and inefficiencies in the operation of the compressed air plants of industrial facilities.  More cost-effective fault detection and diagnostics (FDD) products can come to the building automation marketplace only after that industry makes very significant advances in the state-of-the-art of its FDD software tools from what it currently offers.  Those advances require making common practice of rules-based artificial intelligence (AI) methods that the building automation industry has shown little to no familiarity with in its technology so far.  This project will utilize, under controlled conditions, the compressed air plant of the NIST campus as a facility for test and development of an embedded rules-based FDD tool based upon NIST expertise.
Rotary screw air compressor that makes its own lubricant from the surrounding air delivers oil-free compressed air to an environmental laboratory in Stuttgart, Germany - Many sensitive sectors of industry require oil-free compressed air. However, meeting this demand is often not as simple as it sounds. One way is to use oil-injected air compressors with downstream air treatment to meet the demand. A second option is oil-free air compressors, which operate without lubricants. Both versions have their own advantages as well as risks. Another alternative is to use rotary screw air compressors that use water as a lubricant.
When some people think about compressed air, they imagine the big, loud, dirty, unreliable machine in the back corner of their facility. Many businesses around the world rely on compressed air, and an unreliable air compressor can mean stopping an entire facility, costing thousands of dollars in lost productivity and repair labor. Additionally, that loud machine in the back corner is also a major energy consumer. So much so that many industry professionals refer to it as the “fourth utility.”
Figuring out the energy savings for the switch from pneumatic to electric tools requires an estimate of energy use for each case. The effect of replacing a few tools in a large compressed air system may be too small to detect using power monitoring on the air compressors. However, it is still a good practice, and when part of a larger program to reduce air consumption, the combined efforts will amount to something measureable. Another positive aspect may be that reduced compressed air use frees up needed air compressor capacity.
Compressed Air Best Practices® Magazine spoke with Mark Shedd, Head of Oil-free Air, Aggreko Rental Solutions - There are two distinct compressed air systems in a refinery or petrochemical environment: plant air and instrument air systems. Instrument air systems are almost always 100% oil-free air compressors on both the permanent and temporary systems. The demand for compressed air purity, in instrument air systems, is so high that the permanent install back-up system is usually nitrogen.
A Canadian chemical plant installed a large heated blower-purge style compressed air dryer, years ago, to condition the instrument air system against freezing temperatures.  The dryer selected was oversized for the connected air compressors and had unused on-board energy savings features.  A compressed air assessment revealed the site air compressors and compressed air dryers were running inefficiently and causing in-plant pressure problems.  Repairs to a compressed air dryer and the replacement of aging air compressors and dryers has reduced compressed air energy costs by 31 percent.
Compressed Air Best Practices® (CABP) Magazine and the Compressed Air and Gas Institute (CAGI) cooperate to provide readers with educational materials, updates on standards and information on other CAGI initiatives. CABP recently caught up with Rick Stasyshan, Technical Director for the Compressed Air and Gas Institute (CAGI) to provide readers with some insights into the benefits of CAGI’s Verified Performance Program for refrigerated compressed air dryers.
Atlas Copco has a long history serving the Houston-based energy and chemical industries with custom-engineered packages. The objective of this article is to show just a few examples of the custom applications typically engineered and manufactured in the Atlas Copco Houston operation. Opened in 2012, Atlas Copco Houston produces standard compressed air dryers as well as completely engineered air dryers for all markets. The air flow capacity of the dryers, produced at this location, vary from 5 to 12,750 scfm. This capacity range covers heatless, heated purge and blower purge air dryers.