Issues and Problems with Pressure Drop

 

Super Air Knife Install Sheet

Pressure drop comes in different forms, and it causes inefficiencies within your pneumatic system.  EXAIR writes statements in the installation manuals to help find the correct pipe sizes to supply the different products.  (Reference Super Air Knife Installation Manual above).   But there are other areas that can affect the performance.  These can be fittings, tubing, valves, and accessories.  In this blog, I will cover some pitfalls that can minimize the potential of your EXAIR products.

Pressure drop by definition is a difference or loss in pressure.  A properly sized Filter Separator will typically have a pressure drop of 5 PSID (0.3 bar) at the rated conditions.  So, if you start with 100 PSIG (6.9 bar), the air pressure after the filter separator will be 95 PSIG (6.6 bar).  But what happens when a filter separator is undersized or too small?  The pressure drop will be much higher.  So, if the pressure drop is 30 PSID (2 bar), then the downstream air pressure will only be 70 PSIG (4.8 bar).  At that pressure, you may not be able to get the performance that is required to do the job.

The first thing in determining these potential issues is what I like to call forensics.  If you can install a pressure gage at the inlet of any EXAIR product, then you can deduce if a potential problem is within your setup.   For example, if the Pressure Regulator is at 100 PSIG (6.9 bar), and the pressure gauge at the inlet is reading only 60 PSIG (4.1 bar), then there is a pressure drop of 40 PSID (2.8 bar) between these two points.  You can look in this area for the problem or problems.  If the gauge on the Pressure Regulator goes down as well when you are operating, then the problem area is upstream of the Pressure Regulator.  This can be from the pipe size or the air compressor.

The most common issues are fittings and tubing.  With fittings, small openings may not allow enough air to pass through.  Above is a photo of some typical fittings.  You notice that the right side of the chart has large enough openings to decrease pressure drop.  In some instances, quick connect fittings are commonly used to easily connect or disconnect pneumatic devices; but if you use too small or too many of these fittings, they can cause a large pressure drop.

The other problem is with the inner diameter of tubing, hoses, or pipes that are not properly sized.  Russ Bowman, a colleague, created a video showing the issues with improperly sized plumbing.  It is a very interesting video that shows the effect on a Super Air Knife.

If you want to get the most from your EXAIR products, you will need to reduce the amount of pressure drop in your system.  Pressure drop is wasted energy and can affect your pneumatic system.  You can follow my recommendations above.  Or if you would like to discuss your setup with an Application Engineer, we will be happy to assist.

John Ball
Application Engineer

Email: johnball@exair.com
Twitter: @EXAIR_jb

Preventative Maintenance for EXAIR Filters

Good engineering practice calls for point of use filtration and moisture removal, such as that provided by EXAIR Filter Separators.

I read a white paper from Parker Hannifin about compressed air filters.  The idea behind the paper was to remember your filter replacements.  Compressed air can be dirty with water, oil, pipe scale, etc.  As the filters capture the contamination, it will start to build pressure drop.  Remember, pressure drop is a waste of energy in your compressed air system.

Majority of EXAIR products use compressed air for cleaning, cooling, conveying, static elimination, coating and more.  To help keep them running efficiently, it is important to supply them with clean, dry, pressurized air.  EXAIR offers a line of Filter Separators and Oil Removal Filters to supply quality air to your equipment.  In this blog, I will explain the two types of filters that we carry and the maintenance requirements.  Filters and preventative measures can play an important part in your compressed air system.

Filter Separators are used to remove bulk liquid and contamination from the compressed air stream.  They utilize a 5-micron filter with a mechanical separation to help remove large amounts of dirt and water.  This type of filter would be considered the minimum requirement for filtration.  Most of the Filter Separators come with an auto-drain to automatically dispense the collection of oil and water.  EXAIR offers a variety of port sizes and flow ranges to meet your pneumatic flow requirement.  For maintenance, the filter elements should be changed once a year or when the pressure drop reaches 10 PSID (0.7 bar), whichever comes first.  I created a list in Table 1 below showing the correct replacement element kits for each model number.  And for any reason, if the bowl or internal components get damaged, we also have Rebuild Kits as well.  Just remember, the air quality is very important for longevity and functionality of your pneumatic systems and even for EXAIR products.

The Oil Removal Filters can make your compressed air even cleaner.  They work great at removing very small particles of dirt and oil.  They are made from glass fibers and can remove particles down to 0.03 micron.  They are designed to collect small particles and to coalesce the liquid particles into a large droplet for gravity to remove.  Because of the fine matrix, Oil Removal Filters are not great for bulk separation.  If you have a system with lots of oil and water, I would recommend to use the Filter Separator upstream of the Oil Removal Filter.  As with the Filter Separator, the filter element should be changed once a year or at a pressure drop of 10 PSID (0.7 bar).  EXAIR also offers a variety of port sizes and flow ranges.  Table 1 below shows the replacement Element Kits as well as the Rebuild Kits.  If the application requires very clean compressed air, the Oil Removal Filter should be used.

Table 1

By using EXAIR filters, they will clean your compressed air to prevent contamination on parts, performance issues, and premature failures.  As an ounce of prevention, you should add the replacement elements in stock and enter them in your preventative maintenance program.  With quality air, your pneumatic system and EXAIR products will provide you with effective, long-lasting performance without any maintenance downtime.  If you would like to discuss the correct type of filters to use in your application, you can speak with an Application Engineer.  We will be happy to help you.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

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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Video Blog: Importance of Point-of-Use Filtration

When operating any of your Intelligent Compressed Air Products, something that often gets overlooked is the importance of delivering clean, dry air to those point-of-use products. Many of our products have very tight orifices to help reduce the volume of compressed air they consume. In addition, most have no moving parts to wear out and require no maintenance. That is, unless you’re using unfiltered compressed air.

Rust and scale are commonly found within the distribution system inside your facility. Old iron pipe and receiver tanks are the common culprits. A common misconception is that the air is already filtered as it exits the compressor. While this may be true, there’s still places in the distribution system that can cause issues downstream.

To eliminate the hassle of taking things apart to periodically clean, EXAIR recommends installing a point-of-use filter for all of our Intelligent Compressed Air Products. Kits are available for purchase that come with a properly sized filter to ensure your air is sufficiently clean. To see how quickly debris can clog your products, check out my video below demonstrating the difference between dirty and clean air with a Model 110006 6″ Super Air Knife.

If you’ve already purchased and installed products without filters, it’s never to late to go back and install one. Contact an EXAIR Application Engineer today and we’ll be happy to help you determine the proper size for the volume of air you’re products need.

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