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 

A Digital Flowmeter can Help Improve Your Monthly Electric Bill

No one likes paying their bills at the end of the month.  But, if you can save yourself some money, it helps to make it a little easier.  For this customer, he received a monthly bill for his compressed air.

Monthly Bill

An industrial facility consisting of four separate manufacturing plants and a power company that supplied all of them with utilities, i.e. hot water, natural gas, electricity, and compressed air.  The parent company decided to reorganize and sell the entities.  At the end of it, the power company was controlled by a different organization than the manufacturing plants.  The power plant was contracted to still supply the utilities to the individual plants, but now they would be charged individually on a monthly basis.

Being that compressed air is one of the most expensive utilities, the general manager of a solid-state electronic plant really noticed the charge on his bill.  He did an estimate on the amount of air that his equipment was using, and he compared it to the charges.  There was roughly a 20% difference in the figures.  Because of the excessive amount of money, he contacted EXAIR to see what we could offer.

In discussing their system, the compressed air was supplied through one 6” schedule 40 black pipe.  The pipe came into the facility in the ceiling and it branched off to supply the entire shop with compressed air.  He was looking for something to measure the compressed air flow with the ability to measure a cumulative amount.  He could use this amount to compare to his monthly usage.  He was also concerned about cutting into his compressed air line as this could cause him much downtime and additional costs.  He needed something easy to install, accurate, and versatile.

EXAIR Digital Flowmeter

I suggested our 6” Digital Flowmeter with the Model 9150 Summing Remote Display.  EXAIR Digital Flowmeters are designed to measure flow continuously and accurately.  You do not need to weld, cut, or disassemble pipe lines to install.  With a drill guide, the Digital Flowmeter can be easily mounted onto the 6” black pipe by drilling two small holes.  After that, they just had to insert the Digital Flowmeter into the holes, and tighten the clamp around the pipe.  The total procedure took less than 30 minutes, so downtime was minimal.  The EXAIR Digital Flowmeter measures flow by comparative analysis with thermal dispersion; so, the accuracy is very high and recalibration is not required.

EXAIR Summing Remote

With the option of the Summing Remote Display, they could attach it to the Digital Flowmeter and display the flow remotely up to 50 feet away.  They mounted it on the wall next to his office for the operational functions.  With a simple press of a button, it can show the current flow rates, daily flow rates, and cumulative flow rates.  So, during the billing cycle, he was able to get the cumulative measurement to compare the results, and reset the counter to zero for the next month.

Believe it or not, the power company was correct in their measurements.  But, not to waste an entire blog, I did have him turn the compressed air supply off after business hours to watch the flow rate.  He did find his 20% difference in compressed air leakage.  The Digital Flowmeter was able to measure low flows to target other problem areas in your compressed air system.  Now he had another chore in leak detecting and pipe fixing.

EXAIR Optimization line has different products that can help you to get the most out of your compressed air system.  With the customer above, he was able to measure his compressed air flow with the Digital Flowmeter, as well as detecting other issues.  I will now have to talk to him about our Ultrasonic Leak Detector.


John Ball
Application Engineer

Twitter: @EXAIR_jb


Picture: Calculator Calculation Insurance by stevepb.  Creative Commons CC0 Public Domain

Professor Penurious, Mystery Solver!

ZOINKS! What have Professor Penurious and the gang gotten into this time? Enjoy viewing this video – we sure do enjoy making them…And recognizing that some day the Oscar committee will be calling.

Russ Bowman
Application Engineer
(513)671-3322 local
(800)923-9247 toll free
(513)671-3363 fax
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Compressed Air Calculations, Optimization, and Tips

EXAIR uses our blog platform to communicate everything from new product announcements to personal interests to safe and efficient use of compressed air. We have recently passed our 5 year anniversary of posting blogs (hard for us to believe) and I thought it appropriate to share a few of the entries which explain some more of the technical aspects of compressed air.

Here is a good blog explaining EXAIR’s 6 steps to optimization, a useful process for improving your compressed air efficiency:

One of the Above 6 steps is to provide secondary storage, a receiver tank, to eliminate pressure drops from high use intermittent applications. This blog entry addresses how to size a receiver tank properly:

Here are 5 things everyone should know about compressed air, including how to calculate the cost of compressed air:

These next few entries address a common issue we regularly assist customers with, compressed air plumbing:

In a recent blog post we discuss how to improve the efficiency of your point of use applications:

Thanks for supporting our blog over the past 5 years, we appreciate it. If you need any support with your sustainability or safety initiatives, or with your compressed air applications please contact us.  

Have a great day,
Kirk Edwards

Advanced Management of Compressed Air – Storage and Capacitance

Receiver Tank Drawing

Last week I attended the Advanced Management of Compressed Air Systems seminar put on by the Compressed Air Challenge.  For those unfamiliar with the Compressed Air Challenge, it’s an organization focused on delivering reliable and sustainable compressed air that has maximized efficiency.  Many of the industry’s best practices are preached, if not mandated, and the ultimate goal is to reduce compressed air use as much as possible.  This fits in line with EXAIR products, their design for maximum efficiency, and the recurring ability of our customers to reduce their compressed air use by using our products.

The “advanced” seminar dives into compressed air system profiles, explores the math and theory behind system design, explains the various types of system controls, and shows how to balance compressed air supply and demand.  These things are great not only on their inherent value, but also because when Brian Farno, Russ Bowman, and I attended the Fundamentals of Compressed Air Systems seminar, we kept raising our hands asking questions that were “too advanced”.  The material presented here answered many of those questions, and sparked a few new ones.

One of the questions that came to me during the training had to do with the capacitance of a compressed air system.  When storing the energy of a compressed air system in a receiver tank, there has to be a pressure gradient in order for there to be energy storage.  If a receiver tank has the same inlet and outlet pressure, it is merely part of the system plumbing and provides no benefit to the system when demand peaks.  So I thought to myself, “if a pressure drop is needed across a receiver tank to achieve system capacitance, and the capacitance of the system is related to the value of that differential, a system could theoretically be supplied enough compressed air volume with the right pressure specs”.

So, I looked to the formula used for sizing a receiver tank.

V = (T x (C – R) x Pa)/P1-P2


V = Receiver volume in cubic feet

T = Time of the event in minutes (amount of time for which the receiver tank must be able to provide compressed air at the needed rate)

C = Intermittent demand amount (how much flow or “Q”) in CFM

R = Flow into tank during event (through needle valve, spare air in system, etc.) in CFM

Pa = Absolute atmospheric pressure (14.7 PSIA)

P1 = Initial receiver tank pressure (in PSI)

P2 = Final receiver tank pressure (in PSI)

Ok, nothing new there.  First grade stuff.  Plugging in some theoretical values we could say:

T = 1 minute

C = 50 cubic feet per minute

R = 0 cubic feet per minute.  In this example we’ll assume there is no residual compressed air flow and that the receiver tank must deliver all the airflow for the duration of the event.

Pa = 14.7

P1 = 100 PSIG

P2 = 90 PSIG

Using these values, the volume calculates to be 73.5 cubic feet.  But, most receiver tanks are sized in gallons so we can multiply by 7.48 to get the figure in gallons.  (7.48 gallons = 1 cubic foot)  This yields an approximate value of 550 gallons.  In plain terms, for the application above, we would need a 550 gallon receiver tank with an inlet pressure of 100 PSIG and an outlet pressure of 90 PSIG to provide compressed airflow over the needed (1) minute duration.

That’s a big tank.

Now, back to my thought on pressure differentials – if we increase the ΔP, we can decrease the size of the receiver tank.  Let’s say the inlet pressure to the receiver tank can be as high as 130 PSIG (a wet tank, in line before any filters or dryers).  This will quadruple the pressure differential and reduce the size of the tank by 75% to 138 gallons.  Great!

Well, great for a new system, but what about one already in place?  What if the application needs 50 CFM of compressed air flow for 1 minute, and the shop already has a 175 gallon tank.  We can work the equation in reverse to determine the necessary pressure differential that will ensure the system has enough capacitance to sustain the event (approximately 32 PSI).  It’s good to know the math.

As a whole, the seminar was a great success and the presenters proved why they’re experts in the field of compressed air.  We’re not too shabby here at EXAIR either.  If you have an application need, give us a call.

Lee Evans
Application Engineer

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