Compressed Air Filters: What They Are, And Why They Matter

The first time I ever bought a brand new car was in 1995…it was a Ford Escort Wagon. My plan was to pay it off quick and run the tires off it. Well, I DID actually put new tires on it several times over the 11 years and 200,000 miles I had it. But, aside from fuel & tires, that car cost me less than $2,000 in repairs over all that time…an achievement that my mechanic said was due largely to the aforementioned planned maintenance, which largely consisted of regular oil changes, which, of course, included a new oil filter, every 3,000 miles. For the record, I didn’t run the wheels off it; I sold it when I took a job that included a company vehicle. Also for the record, I found out the fellow I sold my car to was still driving it after I left that job (and company vehicle.) He, too, believed in regular oil changes, and he might still have that 1995 Escort on the road for all I know.

So, yeah, I’m a big believer in the importance of fluid filtration.  If you’re a regular reader of the EXAIR Blog page, you likely are too.  The two main culprits that cause the most problems in a compressed air system are solid particulates and water.  These are easily addressed with a Filter Separator, like EXAIR Model 9004 Automatic Drain Filter Separator.  It has a 5 micron particulate element, and a centrifugal element that imparts a spinning motion to the air flow.  Since water is denser than air, any droplets of moisture are “flung” to the inside wall of the bowl, while the moisture-free air continues on through the discharge.

 

The particulate element captures solids larger than 5 microns, and the centrifugal element eliminates moisture.

Another common impurity in compressed air is oil.  Since oil-less compressors came along, this is easy to eliminate at the source…literally.  However, for other types of compressors (piston types in particular,) as they age, the oil that lubricates the moving parts can seep by the piston rings and get to the air side.  Oil doesn’t carry the same wear and corrosion problems that dirt & water do, but it causes particular problems in air conveyance and blow off applications: anything in your air is going to get on your product.  Ask any paint booth operator, for example, what happens when a metal surface hasn’t been cleaned of all traces of oil.  It really does look a “fish eye.”

The most common type of oil removal filter uses a coalescing element.  Oil entrained in pressurized gas flow isn’t as dense as water – so centrifugal elements won’t remove it – and it tends to act like particulate…but very fine particulate – so typical sintered particulate elements won’t remove it.  Coalescing elements, however, are made of a tight fiber mesh.  This not only catches any trace of oil in the air flow, but also much finer particulate than those sintered elements.  EXAIR Oil Removal Filters, like the Model 9027 shown below, provide additional particulate filtration to 0.03 microns.  That’s some pretty clean air.

The coalescing element of an Oil Removal Filter catches oil and very fine particulate.

For best results, we recommend both the Filter Separator and Oil Removal Filter.  Make sure you install the Filter Separator upstream of the Oil Removal Filter…that way, its 5 micron element catches all the “big” particles that would quickly clog the very fine coalescing element, necessitating an element replacement.  In fact, this arrangement will allow the Oil Removal Filter to operate darn near indefinitely, maintenance free.

If you have questions about keeping your compressed air clean, moisture free, and oil free, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Exploring Optimization: Standards And Certifications For Compressed Air Audits

EXAIR Corporation has devoted almost 37 years to manufacturing engineered products aimed at the most efficient, quietest, and safest use of compressed air.  Sometimes, a caller has recognized that an open pipe blow off, for example, is loud, wasteful, and unsafe, and just wants to install an engineered product that they know will be an improvement.  They may not be interested in precisely quantifying the savings…they’ll just notice that their lone air compressor runs less, and their electric bill isn’t as high anymore.

Others, however, may have a compressed air system that comprises multiple compressors, with advanced controls, and they may have specific operational goals in regard to how the individual compressors are loaded and controlled, or maybe even eliminating the need to run particular compressors all the time…or at all.

The skills & knowledge necessary to handle such a task are within the confines of discipline of mechanical engineering, but oftentimes, specialized training is needed to effectively conduct an audit in order to formulate an execute such an optimization plan.  If you’re interested in pursuing this training, or working with trained personnel, here’s a brief description of the training that’s available, and how you can find people that have been through it:

  • The American Society of Mechanical Engineers (ASME) publication “Guidance for ASME EA-4, Energy Assessment for Compressed Air Systems” details the requirements for performing an audit.  Since there are so many configurations of compressed air systems, it’s not a “step by step” procedure, but it IS handy for developing one, if you know how.  Speaking of which…
  • The Compressed Air & Gas Institute (CAGI) offers training & certification in two categories:
    • Certified Compressed Air System Specialists (CCASS) – these are qualified experts who have demonstrated competence (by means of a comprehensive examination) in skills and abilities relating to the design, service, sales, and installation of compressed air systems & equipment.
    • Certified Compressed Air System Assessors (CCASA) – in addition to CCASS certification, these individuals has passed another comprehensive examination, verifying their knowledge and skills as practitioners performing assessments (audits) of compressed air systems.

Both of these certifications comply with the ISO 17024 Conformity Assessment standard, which governs General Requirements for Bodies Operating Certification of Persons in any field of endeavor.  This means that, not only have certified personnel all passed the same tests regardless of where they are, but the tests they’ve passed meet stringent standards for examining knowledge level and competence in these fields.

Bottom line: if you want an in-depth, accurate evaluation of the efficiency of your compressed air system, experts are available.  The Compressed Air & Gas Institute even publishes directories so you can find them in your area.

Russ Bowman
Application Engineer
EXAIR Corporation
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Tale Of The Tape: EXAIR Cabinet Cooler Systems vs. Air To Air Coolers

As summer heat continues to rise, so does the volume of inquiries we get for EXAIR Cabinet Cooler Systems.  Many callers want to know what differences they can expect in using our products versus other methods they’re considering…or even using…right now.

One very common method is the use of a fan to draw cooling air into the panel, from the surrounding environment.  This is the simplest, and least expensive option, but it has two main drawbacks:

  • Components inside the panel are now exposed (albeit in a controlled manner) to the very same environmental elements that putting them inside a panel was supposed to protect them from.
  • Since the air surrounding the panel is the cooling medium, the temperature inside the panel will never be lower than the temperature outside the panel.  Fan cooling in hot environments will still allow overheating.
If a computer’s fan in the family room can get this dusty, imagine how much worse a control panel on a factory floor can get.

Two key benefits of EXAIR Cabinet Cooler Systems take direct aim at these drawbacks:

  • Once properly installed on a sealed enclosure, all the air entering the enclosure comes from your compressed air supply.  It’s also been through the Automatic Drain Filter Separator that comes with every EXAIR Cabinet Cooler System, so it’s clean and moisture free.
  • The air generated by the Cabinet Cooler is refrigerated, thanks to the Vortex Tube phenomenon.  It doesn’t matter how hot it is in the area; the air going into the panel is about 50F colder than the compressed air supply.  
Cold air from your compressed air supply, with no openings to the environment, eliminates any environmental effects on cooling capabilities.

Fans are one of the two methods of “air to air” cooling – the other is a closed loop system commonly known as a heat pipe:

*Hot air (inside the panel) causes refrigerant in heat pipe to flash to a gas.
*Cold air (from the environment) causes the refrigerant to condense to a liquid.

While this eliminates the environmental contamination concerns of dirt & humidity, it’s still limited.  Just like fan cooling, this method cannot make it cooler inside the enclosure than the ambient temperature in the surrounding area.

Despite this limitation, heat pipes (first column, below) are generally quite cost effective.  But, considering a total cost of ownership difference of less than $15/year, it’s clear that EXAIR Cabinet Cooler Systems, which aren’t limited by ambient temperature, are a strong contender for favorite selection.

Reliable, durable, and cost effective: the EXAIR Cabinet Cooler System.

EXAIR Cabinet Cooler Systems provide up to 5,600 Btu/hr worth of cooling power.  Regardless of your environment (even Classified/Hazardous locations,) we’ve got a system to keep your electronic and electrical panels safe from heat, humidity, and contamination. If you’d like to discuss enclosure cooling and the benefits of EXAIR Cabinet Cooler Systems, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Computer Fan image courtesy of tico_24 Creative Commons License

The Importance Of Properly Sized Compressed Air Supply Lines

EXAIR Corporation manufactures a variety of engineered compressed air products that have been solving myriad applications in industry for almost 37 years now.  In order for them to function properly, though, they have to be supplied with enough compressed air flow, which means the compressed air supply lines have to be adequately sized.

A 20 foot length of 1/4″ pipe can handle a maximum flow capacity of 18 SCFM, so it’s good for a Model 1100 Super Air Nozzle (uses 14 SCFM @80psig) or a Model 110006 6″ Super Air Knife (uses 17.4 SCFM @80psig,) but it’s going to starve anything requiring much more air than those products.  Since compressed air consumption of devices like EXAIR Intelligent Compressed Air Products is directly proportional to inlet pressure, we can use the flow capacity of the pipe, the upstream air pressure, and the known consumption of the EXAIR product to calculate the inlet pressure of a starved product.  This will give us an idea of its performance as well.

Let’s use a 12″ Super Air Knife, with the 20 foot length of 1/4″ pipe as an example.  The ratio formula is:

(P2 ÷ P1) C1 = C2, where:

P2 – absolute pressure we’re solving for*

P1 – absolute pressure for our published compressed air consumption, or C1*

C1 – known value of compressed air consumption at supply pressure P1

C2 – compressed air consumption at supply pressure P2

*gauge pressure plus 14.7psi atmospheric pressure

This is the typical formula we use, since we’re normally solving for compressed air consumption at a certain supply pressure, but, rearranged to solve for inlet pressure assuming the consumption will be the capacity of the supply line in question:

(C2 P1) ÷ C1 = P2

[18 SCFM X (80psig + 14.7psia)] ÷ 34.8 SCFM = 49psia – 14.7psia = 34.3psig inlet pressure to the 12″ Super Air Knife.

From the Super Air Knife performance chart…

This table is found on page 22 of EXAIR Catalog #32.

…we can extrapolate that the performance of a 12″ Super Air Knife, supplied with a 20 foot length of 1/4″ pipe, will perform just under the parameters of one supplied at 40psig:

  • Air velocity less than 7,000 fpm, as compared to 11,800 fpm*
  • Force @6″ from target of 13.2oz total, instead of 30oz*
  • *Performance values for a 12″ length supplied with an adequately sized supply line, allowing for 80psig at the inlet to the Air Knife.

Qualitatively speaking, if you hold your hand in front of an adequately supplied Super Air Knife, it’ll feel an awful lot like sticking your hand out the window of a moving car at 50 miles an hour.  If it’s being supplied with the 20 foot length of 1/4″ pipe, though, it’s going to feel more like a desk fan on high speed.

The type of supply line is important too.  A 1/4″ pipe has an ID of about 3/8″ (0.363″, to be exact) but a 1/4″ hose has an ID of only…you guessed it…1/4″.  Let’s say you have 20 feet of 1/4″ hose instead, which will handle only 7 SCFM of compressed air flow capacity:

[7 SCFM X (80psig + 14.7psia)] ÷ 34.8 SCFM = 19psia – 14.7psia = 4.3psig inlet pressure to the 12″ Super Air Knife.

Our Super Air Knife performance chart doesn’t go that low, but, qualitatively, that’s going to generate a light breeze coming out of the Super Air Knife.  This is why, for good performance, it’s important to follow the recommendations in the Installation Guide:

This table comes directly from the Installation & Operation Instructions for the Super Air Knife.
All Installation Guides for EXAIR Intelligent Compressed Air Products contain recommended air supply line sizes for this very reason.  If you have any questions, though, about proper compressed air supply, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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