AirCell has unveiled the Modular Outdoor Air Compressor Room, which makes outdoor remote usage of electric air-cooled compressors, dryers and related equipment "a new standard for plant installations." Each unit features electronic thermal controls to ensure a constant minimum room temperature of 70ºF; over-sized filter bank to maintain internal cleanliness; high-density insulation to keep the room warm during winter months; and secured equipment placement to make the AirCell completely mobile. The room offers a simple process to move the compressed-air package outside the plant, reducing noise, decreasing breakdowns and freeing-up floor space.
www.aircell.ca

Compressed air systems are rarely installed with instrumentation that can provide a baseline to monitor system energy performance and associated cost. Operators usually run these systems blind to the real operating costs and perhaps unaware of the consequences of the problems plaguing their systems and associated compressed air powered machinery. Studies have show that a few hours of basic awareness training can go a long way in increasing system efficiency. This “efficiency” training often proves to have significant side benefits of a more productive and reliable system due to more stable pressure, improved compressed air system reliability and increased plant productivity.

So, how about the question? How much is your compressed air system costing your company?

Odds are that your management information system can track and control your pencil and paper clip purchases down to the penny, but to put an exact number on the cost of your compressed air, well that’s another story.

If you go to your compressor room and look around, you may understand the reason for the lack of information. The room will often be a noisy, hot and dirty place. The equipment within will have various instrumentation options to observe your system temperatures, pressures and operating hours, but missing will be any indication of flow and power consumption.

Track down your operators and ask about their operating strategy and compressor control coordination plan. More times than not the question will receive a blank stare, the reality of the situation will be that the plan and coordination strategy will be left to the default settings of the compressor manufacturer, or well meaning, but untrained operator.

But Isn’t Air Free?
Many end users think so — and don’t know what it costs to operate their air compressors, nor can they assess the cost of using 10, 50, or 100 cubic feet per minute. Many are surprised to discover that the operating costs throughout the life of compressed air equipment greatly exceed the initial purchase price. In fact, in most cases, the annual energy cost alone will exceed the purchase price in the first year of operation. It’s essential to determine the current annual costs in dollars and communicate this to all involved. In this way, better decisions can be made on new equipment selection and mode of operation of existing equipment.

Compressed Air Versus Other Energy Sources
Compressed air is a necessary part of most plant operations, but is not the most efficient source of energy in a plant. To operate a one-horsepower (HP) air motor, you need seven to eight HP of electrical power into the compressor. At higher than typical pressures, even more power is needed. The overall efficiency of a typical compressed air system can be as low as 10 to 15 percent.

Annual energy costs for a one-HP air motor versus a one-HP electric motor five days per week for a two-shift operation at $0.05/kWh is $1,164 (compressed air) vs. $194 (electric). This means the compressed air powered motor can cost six times as much for the same power output — more if plant pressures are higher than the estimated level of 90 psi.

Cost of Poor Performance
Systems with leaks waste money. The diagram shows the cost of leaks through a perfect orifice in a compressed air system.

Costs calculated using electricity rate of only $0.05 per kWh, assuming constant operation, 100 psig and a typical compressor.

Leaks make an air system less efficient and increase the cost per unit produced.

Why Use Compressed Air At All?
Compressed air systems are used in almost every sector of the economy, and there are thousands of different uses for compressed air. Uses in the manufacturing sector include powering pneumatic tools, packaging, automation equipment, conveyors, controls systems and others. Although they have many advantages, pneumatic tools are generally much less energy-efficient than electric tools. Many manufacturing industries also use compressed air and gas for combustion and process operations such as oxidation, fractionation, cryogenics, refrigeration, filtration, dehydration and aeration.

There are many applications where compressed air is the best solution. However, if there are other, more cost-effective sources of power, compressed air may be used inappropriately. Air may be free, but compressed air is expensive: when it is needed to make a product, it should be used wisely.

The Systems Approach
Compressed air systems consist of a supply side, which includes compressors and air treatment, and a demand side, which includes distribution and storage systems and end-use equipment. A properly managed supply side will result in clean, dry, stable air being delivered at the appropriate pressure in a dependable, cost-effective manner. A properly managed demand side minimizes wasted air and uses compressed air for appropriate applications. Improving and maintaining peak compressed air system performance requires addressing both the supply and demand sides of the system and how the two interact.

Hundreds of manufacturers produce the various pieces of equipment that are used in a compressed air system, from the compressor packages to the end use tools. There are generally many different options for accomplishing a given task with compressed air, and it is important to apply the equipment properly. Often, if a system is performing poorly, it is not because the equipment is faulty, but because it has been applied improperly or poorly maintained. Almost every compressed air system has room for performance improvement, from a modern system in a two-year old plant to one that has been modified and updated over the last forty years.

Improving and maintaining peak compressed air system performance requires not only addressing individual components but also analyzing both the supply and demand sides of the system and how they interact. This practice is often referred to as taking a “systems approach” because the focus is shifted away from components to total system performance. Applying the systems approach usually involves the following:

• Developing a basic block diagram of your system.
• Measuring your baseline (kW, pressures, and leak load) and determining costs, with available tools.
• Working with your compressed air system specialist to implement an appropriate compressor control strategy.
• Once controls are adjusted, re-measuring to get more accurate readings of kW and pressures, and to determine leak load.
• Walking through to check for obvious preventive maintenance items and other opportunities to reduce costs and improve performance.
• Identifying and fixing leaks and correcting inappropriate uses — knowing costs, re-measuring, and adjusting controls as above.

Understanding Your System
System operators need be able to understand their system problems and what to do about them. One of the ways to solve this need is efficiency-awareness training. The Compressed Air Challenge has developed two levels of training to aid in awareness: “Fundamentals of Compressed Air Systems” and “Advanced Management of Compressed Air Systems.”

A very high portion of end-users reported using materials directly from the training to make efficiency improvements to their compressed air systems. As a point of reference, compressed air system efficiency experts find that, for the typical compressed air system, 30 percent of system energy usage can be saved through cost-effective measures.

As well, studies also showed that end-users who implemented compressed air system efficiency measures also experienced significant non-energy benefits. End-users reported experiencing benefits such as: reduced downtime, improved system reliability, reduced moisture and contamination in the system air, more consistent system pressure, and restored delivery of adequate pressure to all system components.

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Ron Marshall is an industrial systems officer with Manitoba Hydro and Bill Scales is CEO of Scales Industrial Technologies Inc. For more information about the Compressed Air Challenge, visit www.compressedairchallenge.org.

Introducing the newest member to round out the family: the AS series from Rexroth is now available in a smaller version for lower flows with thread connection G1/4.

With its smallest version, Rexroth has expanded the AS line for compressed air preparation. The system, which provides excellent compressed air quality in a wide variety of applications and work environments, now includes the AS1 series for use in the low flow range.

With a width of 43 mm and connection thread G1/4, the AS1 series is virtually predestined for applications with flow requirements up to 1000 std l/min. Like the larger members of the AS series, the AS1 also stands for reliable, safe, and economical operation on a continuous basis.

These maintenance units not only perform the standard functions of filtering, regulation and lubrication, their modular and compact design further allows for the integration of all specific functions. Precision controllers, distributors, 3/2-way shut-off valves and filling valves round out the product range of maintenance units. This allows an optimum customized solution for each application. Modular construction makes it possible for individual components to be disassembled or subsequent extensions to be carried out as needed, even in the installed state.
www.boschrexroth.ca

Compressed air can comprise up to 20 percent of the costs of underground mining, according to the Ontario Mining Association (OMA), and 20 to 40 percent of energy costs at mines can be attributed to compressed air systems. Given that up to 70 percent of that air is wasted through leaks, the problem of leaks in compressed air lines is one of the most costly and inefficient draws on the bottom line.

The numbers are staggering. The OMA’s compressed air leak management program report, “Implementing a Sustainable Compressed Air Leak Program,” demonstrates just how costly leaks can be: a single 1/2-inch-diameter leak, assuming energy costs of $0.10/kWh, can total to $12,820 throughout the course of a year for a one-shift operation and as much as $47,850 for a three-shift operation. Even the tiniest of leaks can add up: a single 1/16-inch-diameter leak can cost up to $200 over a year for a one-shift operation and up to $750 for a three-shift operation.

In a typical mining operation, leaks in compressed air lines can number into the hundreds, resulting in wasted energy costs upwards of $100,000 a year. The costs alone should be enough to consider a leak management program, but leaks also create other problems. Fluctuating system pressure can lead to inconsistent performance of the tools and equipment that operate on compressed air. Operation time may need to be increased to make up for the lower pressure, which can increase maintenance costs and reduce the service life of compressors due to excess load.

Problem Areas
Leaks can occur at any point in a compressed air system and are blamed on a number of factors. Through regular mining activities, compressed air piping is exposed to vibration, impact and harsh materials, all of which could lead to leaks. Compressed air lines in the mining industry are typically joined using grooved mechanical piping due to the joining method’s ease of installation and maintenance, strength and ability to quickly adapt to changing mine geography. If the joints of a grooved system aren’t properly assembled, however, the gasket contained within the coupling housings can be a leak source. During its study, the OMA determined that pipe couplings are the most common source of leaks; approximately 60 to 80 percent of the air loss can be attributed to couplings.

Fortunately, the solution isn’t as drastic as replacing grooved piping systems, which mines rely upon to decrease installation and maintenance downtime and reduce total installed costs. The two primary causes of couplings as a leak source, pinched gaskets and incompatible gasket material, are easily fixed.

During coupling installation, a gasket can pinch, creating a leak path, if it’s not properly lubricated. Lubricating a gasket takes only a few seconds, but this step is often skipped to save time. If coupling gaskets are not pre-lubricated, personnel should take the time to lubricate the gaskets prior to installation, and managers should educate pipe installers as to the importance of doing so and the economic ramifications that result from leaks.

Mine maintenance personnel will try just about anything to save time, so adding a step to the pipe installation process may not be a welcomed idea. Installation-ready couplings, an alternative to traditional couplings, require fewer installation steps and decrease installation time compared to traditional couplings; they also reduce the chances of pinching a gasket upon assembly. Installation-ready couplings do not require disassembly prior to installation. The pre-assembled coupling is simply “stabbed” onto the pipe ends, and the bolts are tightened, like typical couplings, until the housing bolt pads meet metal-to-metal. Installation-ready couplings are offered in flexible and rigid styles in sizes up to 8 inches/200 millimeters.

The benefit of installation-ready couplings is twofold. First, they can reduce pinched gaskets during installation because the coupling is kept assembled and installed as a single unit, rather than piece-by-piece. Second, they can be installed in as little as half the time it would take to install traditional pipe couplings. As a result, installation-ready couplings meet owners’ goal to reduce costs and miners’ goal to save time.

Another cause of leaks at pipe couplings is gasket deterioration, which can occur when the gasket material is incompatible with, and not approved for the piping service. For example, when grade “E,” or EPDM, gaskets are used on compressed air lines, oil vapors present in the system can degrade the compound, eventually leading to a leak. EPDM is a commonly specified gasket grade, and is suitable for water services, but using this grade on air services can be problematic.

Oil separating filters are generally not used on compressed air systems, so the lines may carry oil vapors. As a result, grade “T,” or nitrile, gaskets should be used. This gasket grade is designed to stand up to air with oil vapors and will not degrade with exposure over time. Nitrile gaskets should not be used on water services, however, so mines will need to use two types of gaskets: EPDM for water services and nitrile for air services.

Replacing EPDM gaskets with nitrile gaskets on compressed air lines is not a quick maintenance procedure, but the cost savings that can be achieved through this method is significant. The OMA suggests conducting gasket replacement during maintenance to repair existing gasket leaks, and during installation of new compressed air systems.

Study Outcome
Three mines participated in the OMA’s air leak management project as pilot sites. The mines saw almost immediate results in energy savings. In fact, two of the mines saved about $100,000 in annual operating costs just by fixing major air leaks. The project report, which includes lessons learned and best practices, is a must-read for every mine.

Fixing leaks attributed to gaskets within pipe couplings will not solve all challenges involving compressed air systems. After all, leaks can occur at multiple points along the line, and a big-picture leak management program is necessary to ensure long-term commitment to locating and repairing leaks. Such a plan, according to the OMA, should include recognition of the role of people and leadership, uses of equipment and instrumentation, and the development of new procedures and processes.

Nevertheless, proper selection and installation of pipe couplings play a major role in reducing downtime associated with leaks. Repairing leaks can reduce air loss to less than 10 percent of the mine’s compressed air output, resulting in immediate and significant cost savings.

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Marc Carrière is the global mining market manager with Victaulic, a producer of mechanical pipe joining systems. For more information, visit www.victaulic.com.

Atlas Copco introduces the next generation in compressor controls across its oil-injected screw compressors range 11-90 kW GA/GA+/GA VSD. The new Elektronikon Graphic and the integrated Energy Saving (ES) Systems ES4/6i, are significant contributors to further increasing compressed air efficiency, resulting in lower operating costs. In addition, free online visualization enables remote monitoring, allowing for anticipation of operating and maintenance needs.