Saving Compressed Air – The Fourth Utility

We all know the value of electric, water and gas but what about compressed air? Your compressed air system has an annual cost and deserves to be treated as a cost center. In my previous career, I was guilty of not having a budget for compressed air in my business plan and wish I knew then what I needed for a more efficient compressed air system. Compressed air carries a significant value and deserves to be a cost center with aggressive annual efficiency planning.

Unfortunately, several misconceptions about how to reduce energy costs through increased compressed air efficiencies have prevented many industrial operations from taking control of their compressed air energy costs. There are 2 main focuses about compressed air systems that can begin to reduce expenditures, improve the reliability of your systems and generate savings for future equipment improvements. First, you can look at energy savings in the compressor motors but this is a more complicated and more expensive endeavor that can be a next step when tackling compressed air savings head on. Second, the demand side of the compressed air system is where many efficiencies can be gained. A focus on leaks, storage, pressure and inefficient use are generally simple and inexpensive to address.

Increasing the pressure isn’t always the answer. In fact, frequently it is not. An efficient compressed air system is characterized by stable pressure levels. Steady pressure levels are achieved by addressing two things: air demand patterns and the minimum acceptable pressure level required for reliable production. Unfortunately, many operators who fail to properly diagnose the causes of system problems simply increase pressure to improve performance. Arbitrary increases to the pressure without understanding the root causes of performance issues can lead to increased energy costs. An audit completed by your compressed air specialist will reveal which aspects of your compressed system can be fine-tuned in order to reduce energy costs and increase reliability. Use of the “Six Steps to Optimizing Your Compressed Air System” will help achieve your goals for cost savings and efficiencies.

Begin with establishing a baseline for your system and learn what your typical air use looks like. This can be done with a flow meter installed at the compressor outlet. A flow meter is also useful at each machine or process demanding compressed air because they can (1) indicate if a machine or process is operating atypically and consuming more air than usual and (2) identify where high demand machines or processes are located in your facility.

It is estimated that up to 20% of compressed air produced by industrial air compressors is wasted due to leaks in typical facilities.¹ Approximately 20% of the air produced for industrial applications ends up being lost through leaks. The use of EXAIRs’ model 9061 Ultrasonic Leak Detector will enhance your efforts in finding leaks.

Choose engineered products to apply compressed air, these product have a focus on efficiency and outperform commercial products which do not concern themselves with air reduction.

When moving around your facility, look for applications of compressed air which can be turned off when personnel are on break or can be turned off in between parts. This step is very simple and can reap big savings.

Be sure to store compressed air close to high demand applications, this will prevent peaks and valleys in your compressed air demand which contributes toward less maintenance for your compressor.

Also lower your pressure at compressed air points of use. Keeping the pressure at the minimum pressure required for a successful application can also help keep system wide pressure to a minimum, which will increase lifetime of your compressor.

The good news is that, in most cases, lower energy costs are completely attainable for industrial operations that have not optimized their compressed air systems. To begin saving please contact EXAIR about compressed air products that can lower your compressed air costs today.

Eric Kuhnash
Application Engineer
E-mail: EricKuhnash@EXAIR.com
Twitter: @EXAIR_EK

  1. Best Practices for Compressed Air Systems, second edition. From The Compressed Air Challenge.

Air Compressor Motors and Controls, Working Together.

One of the most important aspect of an efficient compressed air delivery system is effective utilization of compressor controls. The proper use of compressor controls is critical to any efficient compressor system operation. In order to reduce operating costs, compressor controls strategies need to be developed starting with minimizing the discharge pressure. This should be set as low as possible to keep energy costs to a minimum.

The compressor system is designed with maximum air demand in mind. During periods of lower demand compressor controls are used to coordinate a reduction in output that matches the demand. There are six primary types of individual compressor controls:

  1. Start/Stop – This is the most basic control. The start/stop function will turn off the motor in response to a pressure signal.
  2. Load/Unload – The motor will run continuously, but the compressor unloads when a set pressure is reached. The compressor will then reload at a specified minimum pressure setting.
  3. Modulating – Restricts the air coming into the compressor to reduce compressor output to a specified minimum. This is also known as throttling or capacity control.
  4. Dual/Auto Dual – On small reciprocating compressors, this control allows the selection of either Start/Stop or Load/Unload.
  5. Variable Displacement – Gradually reduces the compressor displacement without reducing inlet pressure.
  6. Variable Speed – Controls the compressor capacity by adjusting the speed of the electric motor.

All of these controls then control the compressor motors and they have several different starting methods.

There are several types of modern motor starters:

Full Voltage Starters: The original, and simplest method.  These are similar in theory to the old knife switches, but the operator’s hands aren’t right on the connecting switch.  Full line voltage comes in, and amperage can peak at up to 8 times full load (normal operating) amperage during startup.  This can result in voltage dips…not only in the facility itself, but in the neighborhood.  Remember how the lights always dim in those movies when they throw the switch on the electric chair?  It’s kind of like that.

Reduced Voltage Starters: These are electro-mechanical starters.  Full line voltage is reduced, commonly to 50% initially, and steps up, usually in three increments, back to full.  This keeps the current from jumping so drastically during startup, and reduces the stress on mechanical components…like the motor shaft, bearings, and coupling to the compressor.

Solid State (or “Soft”) Starters: Like the Reduced Voltage types, these reduce the full line voltage coming in as well, but instead of increasing incrementally, they gradually and evenly increase the power to bring the motor to full speed over a set period of time.  They also are beneficial because of the reduced stress on mechanical components.

The Application Engineering team at EXAIR Corporation prides ourselves on our expertise of not only point-of-use compressed air application & products, but a good deal of overall system knowledge as well.  If you have questions about your compressed air system, give us a call.

Jordan Shouse
Application Engineer

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Compressor Photo Credits to Bryan Lee, Creative Commons License

Top Factors for Air Compressor & System Maintenance

Performing regular maintenance on your compressor system helps to keep everything operating in peak condition and ensures you’re not wasting unnecessary energy. Just as you perform regular routine maintenance on your vehicles, a compressed air system also needs a little TLC to keep things running smoothly. Neglected maintenance items can lead to increased energy costs, high operating temperatures, and coolant carryover. Much of these issues can be eliminated simply by performing routine maintenance on the components of the system.

According to the Best Practices for Compressed Air Systems by the Compressed Air Challenge (1), components within the system that need maintained include: the compressor, heat exchanger surfaces, lubricant, lubricant filter, air inlet filter, motors, belts, and air/oil separators.  

The compressor and all surfaces of the heat exchanger need to be kept clean and free of contaminants. When these components are dirty, compressor efficiency is greatly reduced. Any fans and water pumps should also be regularly inspected to ensure that they’re functioning properly. The air inlet filter and piping should also be cleaned. The quality of the air in the facility will impact the frequency, refer to the manufacturer’s specifications for ideal intervals for performing scheduled maintenance.

The lubricant and lubricant filter must also be changed per manufacturer’s specifications. Old coolant can become corrosive, impacting useful life and damaging other components while reducing efficiency. While synthetic lubricants are available that have an extended life compared to standard coolants, this does not extend the life of the lubricant filter itself.

Belts should be routinely checked for tension (every 400 hours is reasonable) to alleviate bearing wear. Belts will stretch and wear under normal operation and must be adjusted periodically. It’s a good practice to keep some spares on hand in the event of a failure.

End use filters, regulators, and lubricators should also be periodically inspected and filter elements replaced as needed. If left unchecked, a clogged filter will increase pressure drop. This can cause both a reduction of pressure at the point of use or an increase in the pressure supplied by the compressor, leading to increased energy costs.

Another often overlooked maintenance item is leak detection and repair. Leaks contribute to unnecessary air usage, pressure drop, and increased energy costs. EXAIR offers an Ultrasonic Leak Detector that can be used to identify the leaks in your system and allow you to make the necessary repairs.

EXAIR Ultrasonic Leak Detector

In order to keep your system running in peak condition, regular maintenance is critical. By paying close attention to the manufacture’s recommendations, and implementing a regular maintenance schedule, you can ensure you’re getting the most out of your system components.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD

(1) Scales, W. (2021). Best Practices for Compressed Air Systems : Second Edition (2nd ed.). The Compressed Air Challenge,.

Compressor system image courtesy of Compressor1 via Flickr Creative Commons License

Intelligent Compressed Air: Compressed Air System Components

In any manufacturing environment, compressed air is critical to the operation of many processes. You will often hear compressed air referred to as a “4th utility” in a manufacturing environment. The makeup of a compressed air system is usually divided into two primary parts: the supply side and the demand side. The supply side consists of components before and including the pressure/flow controller. The demand side then consists of all the components after the pressure/flow controller.

The first primary component in the system is the air compressor itself. There are two main categories of air compressors: positive-displacement and dynamic. In a positive-displacement type, a given quantity of air is trapped in a compression chamber. The volume of which it occupies is mechanically reduced (squished), causing a corresponding rise in pressure. In a dynamic compressor, velocity energy is imparted to continuously flowing air by a means of impellers rotating at a very high speed. The velocity energy is then converted into pressure energy.

Still on the supply side, but installed after the compressor, are aftercoolers, and compressed air dryers. An aftercooler is designed to cool the air down upon exiting from the compressor. During the compression, heat is generated that carries into the air supply. An aftercooler uses a fan to blow ambient air across coils to lower the compressed air temperature.

When air leaves the aftercooler, it is typically saturated since atmospheric air contains moisture. In higher temperatures, the air is capable of holding even more moisture. When this air is then cooled, it can no longer contain all of that moisture and is lost as condensation. The temperature at which the moisture can no longer be held is referred to as the dewpoint. Dryers are installed in the system to remove unwanted moisture from the air supply. Types of dryers available include: refrigerant dryers, desiccant dryers, and membrane dryers.

Also downstream of the compressor are filters used to remove particulate, condensate, and lubricant. Desiccant and deliquescent-type dryers require a pre-filter to protect the drying media from contamination that can quickly render it useless. A refrigerant-type dryer may not require a filter before/after, but any processes or components downstream can be impacted by contaminants in the compressed air system.

Moving on to the demand side, we have the distribution system made up of a network of compressed air piping, receiver tanks when necessary, and point of use filters/regulators. Compressed air piping is commonly available as schedule 40 steel pipe, copper pipe, and aluminum pipe. Some composite plastics are available as well, however PVC should NEVER be used for compressed air as some lubricants present in the air can act as a solvent and degrade the pipe over time.

Receiver tanks are installed in the distribution system to provide a source of compressed air close to the point of use, rather than relying on the output of the compressor. The receiver tank acts as a “battery” for the system, storing compressed air energy to be used in periods of peak demand. This helps to maintain a stable compressed air pressure. It improves the overall performance of the system and helps to prevent pressure drop.

Finally, we move on to the point-of-use. While particulate and oil removal filters may be installed at the compressor output, it is still often required to install secondary filtration immediately at the point-of-use to remove any residual debris, particulate, and oil. Receiver tanks and old piping are both notorious for delivering contaminants downstream, after the initial filters.

Regulator and filter

In any application necessitating the use of compressed air, pressure should be controlled to minimize the air consumption at the point of use. Pressure regulators are available to control the air pressure within the system and throttle the appropriate supply of air to any pneumatic device. While one advantage of a pressure regulator is certainly maintaining consistent pressure to your compressed air devices, using them to minimize your pressure can result in dramatic savings to your costs of compressed air. As pressure and flow are directly related, lowering the pressure supplied results in less compressed air usage.

EXAIR manufactures a wide variety of products utilizing this compressed air to help you with your process problems. If you’d like to discuss your compressed air system, or have an application that necessitates an Intelligent Compressed Air Product, give us a call.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD

Compressor Image courtesy of Compressor1 via Creative Commons License