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 

Intelligent Compressed Air: SCFM, ACFM, ICFM, CFM – What do these terms mean?

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An old Ingersoll-Rand air compressor

Air compressors have come a long way over the years. When sizing a new system, a few terms are commonly used: CFM, SCFM, ACFM, and ICFM. The term CFM, simply put, stands for Cubic Feet per Minute. This term can often be confusing and impossible to define for just one condition. One definition will not satisfy the conditions that will be experienced in many of your applications due to a number of variables (altitude, temperature, pressure, etc.). Air by nature is a compressible fluid. The properties of this fluid are constantly changing due to the ambient conditions of the surrounding environment.

This makes it difficult to describe the volumetric flow rate of the compressed air. Imagine you have a cubic foot of air, at standard conditions (14.696 psia, 60°F, 0% Relative Humidity), right in front of you. Then, you take that same cubic foot, pressurize it to 100 psig and place it inside of a pipe. You still have one cubic foot, but it is taking up significantly less volume. You have probably heard the terms SCFM, ACFM, and ICFM when used to define the total capacity of a compressor system. Understanding these terms, and using them correctly, will allow you to properly size your system and understand your total compressed air consumption.

SCFM is used as a reference to the standard conditions for flow rate. This term is used to create an “apples to apples” comparison when discussing compressed air volume as the conditions will change. EXAIR publishes the consumption of all products in SCFM for this reason. You will always notice that an inlet pressure is specified as well. This allows us to say that, at standard conditions and at a given inlet pressure, the product will consume a given amount of compressed air. It would be nearly impossible, not to mention impractical, to publish the ACFM of any product due to the wide range of environmental conditions possible.

ACFM stands for Actual Cubic Feet per Minute. If the conditions in the environment are “standard”, then the ACFM and SCFM will be the same. In most cases, however, that is not the case. The formula for converting SCFM to ACFM is as follows:

ACFM = SCFM [Pstd / (Pact – Psat Φ)](Tact / Tstd)

Where:

ACFM = Actual Cubic Feet per Minute
SCFM = Standard Cubic Feet per Minute
Pstd = standard absolute air pressure (psia)
Pact = absolute pressure at the actual level (psia)
Psat = saturation pressure at the actual temperature (psi)
Φ = Actual relative humidity
Tact = Actual ambient air temperature (oR)
Tstd = Standard temperature (oR)

Let’s run through an example of a compressor operating at a “non-standard” condition:

Elevation – 5000 ft.

Temperature – 80°F (80+460=540) – 540°R

Saturation Pressure – .5069psia

Relative humidity – 80%

demand – 100 SCFM

ACFM = (100 SCFM) [(14.7 psia)/((12.23psia) – (0.5069 psia)(80/100))] ((540°R)/(520°R))

=129.1 ACFM

In this example, the actual flow is greater. To determine the total ACFM consumption of any of our products with your system, take the published total consumption of the product and plug in the values for your compressed air system along with the standard variables.

The last term that you’ll see floating around to describe compressed air flow is ICFM (Inlet Cubic Feet per Minute). This term describes the conditions at the inlet of the compressor, in front of the filter, dryer, blower, etc. Because several definitions for Standard Air exist, some compressor manufacturers have adopted this simpler unit of measure when sizing a compressor system. This volume is used to determine the impeller design, nozzle diameter, and casing size for the most efficient compressor system to be used. Because the ICFM is measured before the air has passed through the filter and other components, you must account for a pressure drop.

The inlet pressure is determined by taking the barometric pressure and subtracting a reasonable loss for the inlet air filter and piping. According to the Compressed Air Handbook by the Compressed Air and Gas Institute, a typical value for filter and piping loss is 0.3 psig. The need to determine inlet pressure becomes especially critical when considering applications in high-altitudes. A change in altitude of more than a few hundred feet can greatly reduce the overall capacity of the compressor. Because of this pressure loss, it is important to assess the consumption of your compressor system in ACFM. To convert ICFM to ACFM use the following formula:

ACFM = ICFM (Pact / Pf) (Tf / Tact)

Where:

ICFM = Inlet Cubic Feet Per Minute

Pf  = Pressure after filter or inlet equipment (psia)

Tf = Temperature after filter or inlet equipment (°R)

For this example, let’s say that we’re in Denver, Colorado. The barometric pressure, as of today, is 14.85 psi with current ambient temperature at 71°F. The compressor system in this example does not have any blower or device installed before the inlet, so there will be no temperature differential after filter or inlet equipment. The ICFM rating for the system is 1,000 ICFM.

ACFM = 1,000 (14.85/14.55)(530.67/530.67)

ACFM = 1,020

In order to maintain the 1,000 ICFM rating of the system, the ACFM is 1,020, about a 2% increase.

If you’re looking into a new project utilizing EXAIR equipment and need help determining how much compressed air you’ll need, give us a call. An Application Engineer will be able to assess the application, determine the overall consumption, and help recommend a suitably sized air compressor.

Tyler Daniel
Application Engineer

E-mail: TylerDaniel@exair.com
Twitter: @EXAIR_TD

 

Compressor photo courtesy of David Pearcy via Creative Commons license.

Compressed Air Uses In Industry

From pneumatic hand tools like impact wrenches or nail guns to larger scale industrial applications like stamping presses, the use of compressed air can be found in almost any industry. In fact, it is often referred to as a “fourth utility” next to water, gas and electric.

Compressed air is used in virtually every industry!

 

Take for example in construction, workers will use a pneumatic riveter to join steel framing because of the power generated by the tool over an electrically powered device, not to mention it provides for a safer operation by removing an electrical hazard. Many companies use compressed air operated diaphragm pumps or air motor driven pumps to move expensive or viscous liquid from one location to another. These types of pumps are self priming drawing the liquid in and provide positive displacement meaning they fill and empty the liquid chamber with the same amount of liquid through a common inlet and outlet.

Amusement parks have used compressed air in some capacity in the operation of thrill rides like roller coasters or to enhance the effect of certain attractions. Compressed air can be found in hospitals where it is used for specialized breathing treatments or to power surgical instruments in an operating room. Educational facilities use compressed air for laboratory testing. You can even find compressed air in the tires on your car. Basically, when you think about it, compressed air is being used just about anywhere.

Here at EXAIR, we manufacture Intelligent Compressed Air Products to help improve the efficiency in a wide variety of industrial operations. Whether you are looking to coat a surface with an atomized mist of liquid, conserve compressed air use and energy, cool an electrical enclosure, convey parts or dry material from one location to another or clean a conveyor belt or web, chances are we have a product that will fit your specific need.

EXAIR has been providing engineered solutions since 1983.

 

To discuss your particular application or for help selecting the best product, contact an application engineer at 800-903-9247 for assistance.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

Compressed Air Valves image courtesy of Shane Gorski via creative commons license.

What Size Air Compressor Do I Need?

This is a common question from callers who are inquiring about the use of our products. Oftentimes, they’re going to be using significantly less air than they’re using right now, considering the low compressed air consumption rates of our engineered Intelligent Compressed Air Products. Sometimes, though, we have the opportunity to talk to someone at a small commercial or home operation, where they may have limitations on compressed air supply. While a Model 6084 2″ Aluminum Line Vac would do GREAT at conveying wood pellets from a storage bin to the furnace room (this is a very common call from folks who are taking advantage of high efficiency wood burning stoves for home heating,) they won’t convey more than a few pounds at a time with the compressed air being generated & stored by a typical home-use air compressor.

Limitations, of course, aren’t always a “stopper.” I just had the pleasure of talking to a Reversible Drum Vac user who simply needed some guidance on refurbishing his unit…it wasn’t performing as well as when it was new. Luckily, we have a solution for that, and it won’t cost you anything but about 10 minutes and some dish soap (or mild degreasing agent of your choice.)  Here’s a short video that shows you how it’s done:

https://blog.exair.com/2011/07/05/how-to-rebuild-your-reversible-drum-vac/

So, this got my caller “back in business” – conservation business, that is.  He operates a small garage, and recycles his waste oil.  The Reversible Drum Vac is used to clean up spills and empty drain pans into a central drum, which he then transfers to his main recycling tank.

This is all done with his shop’s small air compressor.  Even though it only produces about 8 SCFM @100psig, it has a 60 gallon tank, which allows the Reversible Drum Vac to operate for about 2 minutes…plenty of time to empty a drain pan or vacuum up some spills, and just enough to pump out the drum, even if it’s full to the top!

Sometimes a small air compressor is a “stopper;” sometimes it’s not.  If you’d like to discuss a potential compressed air product application, give me a call.

Russ Bowman
Application Engineer
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Oil And Water Don’t Mix, But Oil And Air Sure Do

Do you have oil in your compressed air system? It may be there on purpose…air operated tools require it, and there are a number of devices on the market that provide a precise amount of oil to keep the moving parts in these tools well lubricated and properly operating.

If it’s not there on purpose, it’s not necessarily a problem, though, and it’s hardly uncommon. Many air compressors are oil lubricated, which means there’s oil being pumped at a constant rate, directly towards the piston rings, and a little bit is always going to end up in the air. As the rings wear, even more makes it past…this is impossible to prevent, but, with proper maintenance, it’s kept to a very minimal amount. There are, of course, oil-less compressor designs, which can eliminate this entirely, but they’ve been known to carry a little heavier price tag. Some situations, though, make them worth every penny.

Trace amounts of oil like this don’t affect a lot of compressed air applications, including the performance of most of our products. There are times, however, when oil needs to be addressed…for instance:

*Blow off prior to painting or coating. Even trace amounts of oil on a surface to be painted can cause big problems.
*Electrical enclosure cooling. Oil won’t affect the heat removal performance of an EXAIR Cabinet Cooler System, but it can indeed cause serious issues with electrical/electronic components and devices if it’s present in the cold air that’s blowing on them.
*Air operated conveyors. Likewise, oil won’t hurt the performance of a Line Vac, but keep in mind that anything in the air supply will get on the material or product you’re conveying.
*Static Eliminators. Here’s a situation where oil in the air WILL have an effect on product performance…the emitter points of your EXAIR Static Eliminator need to be kept clean (including oil free) for proper operation. And, again, anything in your air is going to get onto your product.

This is where proper filtration comes in: properly installed downstream of a Filter Separator, EXAIR’s coalescing Oil Removal Filters take out even trace amounts of oil from the air flow, ensuring your process doesn’t see anything but clean, dry air.

EXAIR Model 9027 Oil Removal Filter, installed between Model 9004 Filter Separator and 9008 Pressure Regulator, using our Modular Coupling Kits

EXAIR Model 9027 Oil Removal Filter, installed between Model 9004 Automatic Drain Filter Separator and 9008 Pressure Regulator, using our Modular Coupling Kits.

Again, oil in your air isn’t always a problem. If you have questions about your application, though, give us a call…if it IS a problem, we’ve got a solution.

Russ Bowman
Application Engineer
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The Compressor Whisperer

(Whisperer, Whisperer, Whisperer…)

Professor Penurious is determined to break into television…we hope you enjoy the following trailer for his latest attempt.

Russ Bowman
Application Engineer
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What Type of Compressor Is Right for EXAIR Products?

Decisions

A frequent question (and rightfully so) for compressed air products is “How much compressed air does it use?”  Fortunately for EXAIR, we can provide these values with confidence, knowing the research and development, testing, and quality control that goes into the products we make.

For many applications, this question is cut and dry.  For others, particularly those that do not currently have compressed air on site, the question leads to further conversation.  One of the questions that is often asked, is “What type of compressor should we use with these products?”

While the end-use products (EXAIR products) will operate regardless of the compressor type, there are benefits and advantages to various compressor types in different applications.

For short-term or intermittent use, a reciprocating compressor can be an excellent choice.  The size and weight, maintenance requirement (relatively low), and ease of procurement make them very suitable for small demand applications.  They are also suitable for high pressures. Keep in mind that reciprocating compressors typically have higher noise levels and higher cost of compression when compared to screw compressors.

When the compressed air need is high volume, and the demand requires a continuous supply of compressed air, a rotary screw compressor can be a better choice.  Rotary screw compressors are designed for more regular use in industrial applications, are (generally) more maintenance intensive, feature partial load capability allowing to align supply and demand, and can be found in a variety of sizes. You can expect to pay more for these models than the reciprocating compressors.

From an engineering standpoint, reciprocating compressors are dynamic devices, and screw compressors are positive displacement devices.  Click here for a more in depth look at screw compressor operation.

EXAIR manufactures many, many compressed air driven devices with a concentration on solving problems, conserving compressed air and making it safe by meeting OSHA standards.  And, although we do not supply or support any specific compressor manufacturer, our Application Engineers are well versed in compressed air generation and suited to discuss those needs with our customers.

If you have a compressed air related question, contact an EXAIR Application Engineer.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

 

Image courtesy of Vic. Creative Commons License

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