Compressed Air System Maintenance

When I was seventeen my grandfather took me to a used are dealership and helped me buy my first car. It wasn’t anything special, as it was a 1996  Chevrolet Lumina. It had its fair share of bumps and bruises, but the bones were solid. We took it home and he taught me how to do all the basics, we changed the oil, oil filter, air filter, brakes, pretty much every fluid we could, we changed.

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You see my grandfather retired from Ford Motor Company after 50+ years of service. And he always said, “If you treat it right, it will treat you right.”; and I’ve lived by that ever since.

Just like a car, air compressors require regular maintenance to run at peak performance and minimize unscheduled downtime. Inadequate maintenance can have a significant impact on energy consumption via lower compression efficiency, air leakage, or pressure variability. It can also lead to high operating temperatures, poor moisture control, and excessive contamination.

Most problems are minor and can be corrected by simple adjustments, cleaning, part replacement, or the elimination of adverse conditions. This maintenance is very similar to the car maintenance mentioned above, replace filters, fluids, checking cooling systems, check belts and identify any leaks and address.

All equipment in the compressed air system should be maintained in accordance with the manufacturers specifications. Manufacturers provide inspection, maintenance, and service schedules that should be followed strictly. In many cases, it makes sense from efficiency and economic stand-points to maintain equipment more frequently than the intervals recommended by the manufactures, which are primarily designed to protect equipment.

One way to tell if your system is being maintained well and is operating properly is to periodically baseline the system by tracking power, pressure, flow (EXAIR Digital Flowmeter), and temperature. If power use at a given pressure and flow rate goes up, the systems efficiency is degrading.

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Air Compressor

Types Of Maintenance

Maintaining a compressed air system requires caring for the equipment, paying attention to changes and trends, and responding promptly to maintain operating reliability and efficiency. Types of maintenance include;

  1. Poor Maintenance – Sadly, some plants still operate on the philosophy, “If it isn’t broke, don’t fix it.” Due to the lack of routine preventative maintenance, this practice may result in complete replacement of an expensive air compressor as well as unscheduled and costly production interruptions.
  2. Preventive  Maintenance – This type of maintenance can be done by plant personnel or by an outside service provider. Usually, it includes regularly scheduled monitoring of operating conditions. Replacement of air and lubricant filters, lubricant sampling and replacement, minor repairs and adjustments, and an overview of compressor and accessory equipment operation.
  3. Predictive  Maintenance – Predictive maintenance involves monitoring compressor conditions and trends , including operating parameters such as power use, pressure drops, operating temperatures, and vibration levels. The Right combination of preventive and predictive maintenance generally will minimize repair and maintenance costs.
  4. Proactive Maintenance – If a defect is detected, proactive maintenance involves looking for the cause and determining how to prevent a recurrence.

Unfortunately, even the best maintenance procedures cannot eliminate the possibility of an unexpected breakdown. Provisions should be made for standby equipment to allow maintenance with out interrupting production.

If you would like to discuss improving your compressed air efficiency or any of EXAIR’s engineered solutions, I would enjoy hearing from you…give me a call.

Jordan Shouse
Application Engineer
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Images Courtesy of Tampere Hacklab

Oil Removal Filters – Keeping Compressed Air Clean

Compressed air filters help to keep the air clean and condensate free to protect equipment from dust, dirt, pipe scale, oil and water. Even though the compressed air system will typically have a main dryer, additional treatment is often necessary. For this discussion, we will focus on the oil removal process and filter type.

After the compressed air has passed through a particulate filter, the dirt, dust and water droplets have been removed.  Oil that is present is much smaller in size, and mostly passes though the particulate filter.  The installation of a coalescing filter will provide for the removal of the majority of the fine oil aerosols that remain. The coalescing filter works differently than the particulate filters. The compressed air flows from inside to outside through the coalescing filter media. The term ‘coalesce’ means to ‘come together’ or ‘form one mass.’  The process of coalescing filtration is a continuous process where the small aerosols of oil come in contact with fibers of the filter media. As other aerosols are collected, they will join up and ‘come together’ and grow to become an oil droplet, on the downstream or outside surface of the media.  Gravity will then cause the droplet to drain away and fall off the filter element.

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Example of a 0.03 Micron Coalescing Oil Removal Filter

Some important information to keep in mind –

  • Change the filter regularly, not just when the differential pressures exceeds recommended limits, typically 5 PSI
  • Coalescing filters will remove solids too, at a higher capture rate due to the fine level of filtration, using a pre-filter for solids will extend the life
  • Oil free compressors do not provide oil free air, as the atmospheric air drawn in for compression contains oil vapors that will cool and condense in the compressed air system.

If you would like to talk about oil removal filters or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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The Importance Of Air Compressor System Maintenance

It should go without saying, but proper operation of anything that has moving parts will depend on how well it’s maintained.  Compressed air systems are certainly no exception; in fact; they’re a critical example of the importance of proper maintenance, for two big reasons:

*Cost: compressed air, “the fourth utility,” is expensive to generate.  And it’s more expensive if it’s generated by a system that’s not operating as efficiently as it could.

*Reliability: Many industrial processes rely on clean or clean & dry air, at the right pressure, being readily available:

  • When a CNC machine trips offline in the middle of making a part because it loses air pressure, it has to be reset.  That means time that tight schedules may not afford, and maybe a wasted part.
  • The speed of pneumatic cylinders and tools are proportional to supply pressure.  Lower pressure means processes take longer.  Loss of pressure means they stop.
  • Dirt & debris in the supply lines will clog tight passages in air operated products.  It’ll foul and scratch cylinder bores.  And if you’re blowing off products to clean them, anything in your air flow is going to get on your products too.

Good news is, the preventive maintenance necessary to ensure optimal performance isn’t all that hard to perform.  If you drive a car, you’re already familiar with most of the basics:

*Filtration: air compressors don’t “make” compressed air, they compress air that already exists…this is called the atmosphere, and, technically, your air compressor is drawing from the very bottom of the “ocean” of air that blankets the planet.  Scientifically speaking, it’s filthy down here.  That’s why your compressor has an inlet/intake filter, and this is your first line of defense. If it’s dirty, your compressor is running harder, and costs you more to operate it.  If it’s damaged, you’re not only letting dirt into your system; you’re letting it foul & damage your compressor.  Just like a car’s intake air filter (which I replace every other time I change the oil,) you need to clean or replace your compressor’s intake air filter on a regular basis as well.

*Moisture removal: another common “impurity” here on the floor of the atmospheric “ocean” is water vapor, or humidity.  This causes rust in iron pipe supply lines (which is why we preach the importance of point-of-use filtration) and will also impact the operation of your compressed air tools & products.

  • Most industrial compressed air systems have a dryer to address this…refrigerated and desiccant are the two most popular types.  Refrigerant systems have coils & filters that need to be kept clean, and leaks are bad news not only for the dryer’s operation, but for the environment.  Desiccant systems almost always have some sort of regeneration cycle, but it’ll have to be replaced sooner or later.  Follow the manufacturer’s recommendations on these.
  • Drain traps in your system collect trace amounts of moisture that even the best dryer systems miss.  These are typically float-operated, and work just fine until one sticks open (which…good news…you can usually hear quite well) or sticks closed (which…bad news…won’t make a sound.)  Check these regularly and, in conjunction with your dryers, will keep your air supply dry.

*Lubrication: the number one cause of rotating equipment failure is loss of lubrication.  Don’t let this happen to you:

  • A lot of today’s electric motors have sealed bearings.  If yours has grease fittings, though, use them per the manufacturer’s directions.  Either way, the first symptom of impending bearing failure is heat.  This is a GREAT way to use an infrared heat gun.  You’re still going to have to fix it, but if you know it’s coming, you at least get to say when.
  • Oil-free compressors have been around for years, and are very popular in industries where oil contamination is an unacceptable risk (paint makers, I’m looking at you.)  In oiled compressors, though, the oil not only lubricates the moving parts; it also serves as a seal, and heat removal medium for the compression cycle.  Change the oil as directed, with the exact type of oil the manufacturer calls out.  This is not only key to proper operation, but the validity of your warranty as well.

*Cooling:  the larger the system, the more likely there’s a cooler installed.  For systems with water-cooled heat exchangers, the water quality…and chemistry…is critical.  pH and TDS (Total Dissolved Solids) should be checked regularly to determine if chemical additives, or flushing, are necessary.

*Belts & couplings: these transmit the power of the motor to the compressor, and you will not have compressed air without them, period.  Check their alignment, condition, and tension (belts only) as specified by the manufacturer.  Keeping spares on hand isn’t a bad idea either.

Optimal performance of your compressed air products literally starts with your compressor system.  Proper preventive maintenance is key to maximizing it.  Sooner or later, you’re going to have to shut down any system to replace a moving (or wear) part.  With a sound preventive maintenance plan in place, you have a good chance of getting to say when.

If you’d like to talk about other ways to optimize the performance of your compressed air system,  give me a call.

Russ Bowman
Application Engineer
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Image courtesy of U.S. Naval Forces Central Command/U.S. Fifth Fleet, Creative Commons License 

Compressed Air Filtration – Particulate, Coalescing, and Adsorption Types

Compressed air systems will contain contaminants that can lead to issues and increased costs through contamination of product, damage to the air operated devices, and air line clogging and restriction. Proper air preparation is critical to optimizing performance throughout the plant operations.

Because there are different types of contaminants, including solid particles, liquid water, and vapors of water and oil, there are different methods of filtration, each best suited for maximum efficiency in contaminant removal.

Particulate Filters – The compressed air flows from outside to inside of the filter element. The compressed air first passes through a baffle arrangement which causes centrifugal separation of the largest particles and liquid drops (but not liquid vapors), and then the air passes through the filter element.  The filter element is usually a sintered material such as bronze.  The filter elements are inexpensive and easy to replace. Filtration down to 40-5 micron is possible.

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Particulate Type Filter with Sintered Bronze Element

Coalescing Filters – This type operates differently from the particulate type.  The compressed air flows from inside to outside through a coalescing media. The very fine water and oil aerosols come into contact with fibers in the filter media, and as they collect, they coalesce (combine) to form larger droplets towards the outside of the filter element. When the droplet size is enough the drops fall off and collect at the bottom of the filter housing.  The filter element is typically made up of some type glass fibers.  The coalescing filter elements are also relatively inexpensive and easy to replace. Filtration down to 0.01 micron at 99.999% efficiency is possible.

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Coalescing Type Filter with Borosilicate Glass Fiber Element

Adsorption Filters – In this type of filtration, activated carbon is typically used, and the finest oil vapors, hydrocarbon residues, and odors can be be removed.  The mechanism of filtration is that the molecules of the gas or liquid adhere to the surface of the activated carbon.  This is usually the final stage of filtration, and is only required for certain applications where the product would be affected such as blow molding or food processing.

When you work with us in selecting an EXAIR product, such as a Super Air Knife, Super Air Amplifier, or Vortex Tube, your application engineer can recommend the appropriate type of filtration needed to keep the EXAIR product operating at maximum efficiency with minimal disruption due to contaminant build up and unnecessary cleaning.

If you have questions regarding compressed air filtration or any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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