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.

9001
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.

9005
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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Compressed Air Accessories – Filters and Regulators – The Rest of the Solution

IMG_5696
EXAIR Regulator with gauge and Filter/Separator

Many times in the stories that are written in our daily blogs, we espouse the many benefits of installing and using EXAIR made products into our many customers’ compressed air-based applications. From the guy who has a small shop in his home garage using our Atto Super Air Nozzle to much larger applications where customers use our 84” Long Super Air Knives to do such things as drying cast Acrylic Sheets used in tub and shower surrounds, the message is a very consistent one. Customers benefit by saving money, increasing the safety level of an application, reducing sound levels and improving productivity.  There’s no doubt that our customers will excel in these areas.

Knowing there is much more to a compressed air system than just point of use products, lets shed a little light on the other “parts” of a typical system set-up. Those would be the compressed air filter / separators and the pressure regulators that are a highly recommended part of a good installation. But why are they so highly recommended? What exactly is their role and why would anyone want or need to install them?

First, the blunt realities of compressed air and its relative “un-clean” condition once it arrives at the point of use. Since compressed air a utility that is produced in-house, the quality and quantity available will vary widely from facility to facility. And since it is not a regulated utility such as gas or electricity are, there are no universal minimums of quality that compressed air must meet before sent out to the distribution system. Yes, of course, companies are all the time getting better at this part, but many still operate with older, iron pipe systems that produce rust and scale which wreak havoc on the components within mechanical products that use compressed air as their power source. The point is that you are never sure of the quality of the air you will get at the point of use, so install a compressed air filter near that point to keep the debris out of your Air Knife, Nozzle, Line Vac or even other components like solenoid valves, air motors and the like. Believe me when I say it is much easier to un-screw a bowl from a filter housing and change an element than it is to disassemble an air motor or an 84” long Super Air Knife because rust migrated in from the pipes. So it is quite safe to say that an ounce of prevention in this case is worth a pound of cure!

Second, the discussion turns to the Regulator part of the equation. As many know, our products and those of other pneumatic product manufacturers have a certain set of specifications regarding performance at stated input pressures. But what if your application doesn’t require that “full, rated performance”? Maybe instead of needing two pounds of force, you only need one pound? In fact, if you provided two pounds of blowing force, you would end up “over-blowing” your target. By that, I mean you cause damage to the target or other surrounding items in the application. Or, perhaps blowing to hard (or sucking too hard in the case of a Line Vac or E-vac) might cause the vessel or the material you are picking up to collapse or deform (due to too much power).  There is also the concern about using more energy than one really needs to in order to achieve the desired effect in an application. In other words, if you can achieve your goals with only 40 PSIG, then why would you ever use 80 PSIG to accomplish the goal? By reducing your compressed air from 80 down to 40 PSIG, you can easily reduce the air consumption of the “engineered” solution by another 40% + …………that’s the cherry on top of the cake when you compare the benefits of simply “bolting on” the solution of an engineered air nozzle vs. an open pipe in the first place. Then there is the issue of taking advantage of the pressure differential (from 80 down to 40 PSIG) that creates a little bit more air volume capacity. At 80 PSIG, your compressed air to free air volume ratio is 6.4:1. At 40 PSIG, it is only 3.7:1. The net effect is you effectively have an overall larger volume of air at the disposal of the application which is always a good thing.

Regulating pressure is definitely warranted given the benefits that compliment the operation of the core EXAIR products.

If you need a deeper understanding about how EXAIR’s products can help your application, feel free to contact us and we will do our best to give you a clear understanding of all the benefits that can be had by our products’ use as well as proper implementation of accessory items such as compressed air filters and regulators.

Neal Raker, International Sales Manager
nealraker@exair.com
@EXAIR_NR
www.EXAIR.com 

Video Blog: Repairing Automatic Drain Floats In EXAIR Compressed Air Filters

If you have an Automatic Drain Filter Separator, or Oil Removal Filter, with a float drain that’s blowing by, then this video is for you. As always, though, give us a call if you have any questions.

Russ Bowman
Application Engineer
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Regulators and Filters for Compressed Air

I would like to dive into the realm of filters and regulators. Majority of EXAIR products use compressed air to coat, conserve, cool, convey or clean. So, to keep the product running efficiently, we need to supply them with clean, dry, pressurized air. We offer a line of filter separators, oil removal filters, and regulators that can supply enough pressure and flow to keep the EXAIR products performing for a very long time. If we look at each individual item, we can see how they can play an important part in your compressed air system.

Regulators are used to control the amount of air pressure being supplied to your EXAIR products. This is important if you are trying to control the flow, force, and/or conveyance rate. One issue with regulators is “droop”. Droop is the amount of pressure drop when you flow through a regulator. If you set the pressure of a regulator with no flow, to let’s say 80 psig (5.5 barg). Once you start flowing, you will see the downstream pressure fall. This is dependent on the size of the regulator and the valve inside. This is very important because if you need 80 psig (5.5 barg) downstream of the regulator feeding an EXAIR product and the droop brings it to 30 psig (2 barg), you will not have enough flow for your EXAIR product, losing performance. EXAIR recommends a specific regulator for each of our products. We tested our products with the recommended regulators to make sure that you are able to get the best performance. If you do use another manufacturer’s regulator, make sure you are able to flow the correct amount of air at the pressure you need. Not all ¼” regulators flow the same.

Pressure Regulator
Pressure Regulator

Filter separators are used to remove liquid condensate and contamination from the compressed air stream. They have a 5 micron filter and work very well if you get a slug of water or oil into your compressed air system. They use mechanical separation to remove the large particles of dirt and water from the air stream. Most facilities have some type of compressed air dryer in their system. This will dry the compressed air. But, if a system failure occurs, then water, oil, and dirt are pushed into the compressed air lines and perhaps into your EXAIR products. Even if you have good quality air, it is important to keep your products protected. An ounce of prevention ….

Oil Removal Filter
Oil Removal Filter

 

The oil removal filters are used to keep the compressed air even cleaner yet. They work great at removing very small particles of dirt and oil. Without an oil removal filter, dirt particles and oil particles can collect in “dead” zones within the compressed air lines. Over time, a tacky glob forms. As it grows, it can break off and get into the air stream affecting pneumatic devices. The oil removal filter will be able to help eliminate the long term effects in your compressed air system. As a note, oil removal filters are not great for bulk separation. If you have a system with lots of water, you will need a filter separator in front of the oil removal filter to optimize the filtration. With the oil removal filters, the media is a barrier to collect the small particles of dirt and oil. If a slug of water or oil tries to go through, it will block a portion of the element off until it is forced through. This will increase the velocity and pressure drop of the element. With the high velocity, as the slug makes its way through the media, it can spray, re-entraining the liquid particles.

Now that we went through our pneumatic products, how do we use them together to get the best supply of compressed air? With both types of filters, we always want them to be upstream of the regulator. This is because the velocity is lower at higher pressures. Lower velocities mean smaller pressure drops which is good in filtration. If we can analyze the compressed air systems, I would like to categorize it into a good and premium quality. To supply a good quality of compressed air, you can have the compressed air run through the filter separator then a regulator. To produce the premium quality of compressed air, you can have your compressed air run through the filter separator, the oil removal filter, and then the regulator. With clean quality air, your EXAIR products will provide you with effective, long-lasting performance without maintenance downtime.

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

Why 5 PSIG Matters

Last week I pointed out the important locations for measuring your compressed air system pressure throughout your compressed air system.   One of the critical points to measure system pressure was before and after each filter.  This leads into another question that I receive every once in a while, “How do I tell when the filter needs to be changed?”  The answer to this is easy, when you see more than a 5 PSIG pressure drop across the filter.  This means that the element within the filter has become clogged with sediment or debris and is restricting the volume available to your downstream products.

Filter
EXAIR 5 micron Auto Drain Filter Separator

 

This can lead to decreased performance, downtime, and even the possibility of passing contaminants through the filter to downstream point of use components.  In order to maintain an optimal performance when using EXAIR filter separators and oil removal filters, monitoring the compressed air pressure before and after the unit is ideal.

Replacement filter elements are readily available from stock, as well as complete rebuild kits for the filter units. Changing the filters out can be done fairly easily and we even offer a video of how to do it.

The life expectancy of a filter element on the compressed air is directly related to the quality of air and the frequency of use, meaning it can vary greatly.  If you tie a new filter onto the end of a compressed air drop that has not been used in years, you may get a surprise by the filter clogging rather quickly.   However, if you maintain your compressor and your piping system properly then the filters should last a long time. Generally we recommend checking your filters every 6 months.

If you have questions about where and why to filter your compressed air contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

Keep Your Air Clean

I have been reading Kyle Thill’s blog over at Toyota Forklift, and he often speaks about the benefits of preventative maintenance and service schedule. With our products preventative maintenance can be the last thing on anyone’s mind, but it is important work to keep your compressed air systems clean and dry. Today I received a reminder of this.

We received a Heavy Duty Line Vac back from a customer today, who had taken us up on our offer of a 30 day Unconditional Guarantee.  It was no problem for us to take the unit back, but as we were taking it apart, we received a gentle reminder how important it is to use clean dry air with our products and to use compressed air filters on your compressed air lines.

IMG_3652             IMG_3655

On the right, we have a photo for Heavy Duty Line Vac for reference.  As you can see, a new Heavy Duty Line Vac will have clean metal surface inside the inlet.  When our quality department inspected the used unit returned from the customer, we found this pile of rust particles that had been deposited inside the unit, right at the air inlet position.  One of the reasons filters are so important with new equipment is that the increased load can dislodge contaminants that may have been building up inside old compressed air lines.  The other reason we always recommend compressed air filtration is because filters prevent debris from ending up on anything you blow off, cool, move or coat with our products.  Compressed air lines can carry oxidized metal, water or oil contaminants, which can be easily removed to ensure your products and ours are kept clean.

Dave Woerner
Application Engineer
Davewoerner@EXAIR.com
@EXAIR_DW

Compressed Air and Dew Point

Today’s discussion is on dew point of air as it has a significant impact on a compressed air system. The dew point is the temperature at which the water vapor in the air  can no longer stay in a vapor form, and condenses from a vapor into a liquid. The amount of water vapor contained in air is directly proportional to its temperature. The warmer the air the more space there is between molecules thus it is able to hold more water vapor.Capture

It is when air temperature drops below the dew point that issues develop in a compressed air system. Let’s take the example of a warm summer day at 90 F and 50% relative humidity. From the chart we see the dew point temperature to be 70 F. So at night, when all the equipment is shut down and the temperatures drop into the 60’s, water will condensate throughout the entire system. In the morning when the equipment is turned on, water blows through sensitive valving.

Compressing air will increase the dew point. Hot compressed air exiting the compressor and cooling while it makes its way through distribution systems is one reason for condensate in compressed air lines. Drying the compressed air is recommended to reduce or eliminate water condensate problems in a compressed air system.

There are several methods to dry out your compressed air. Each have their advantages and disadvantages. The following short review of the various options will help you decide which is best for your application.

After-coolers

The compressor’s after-cooler  which looks similar to a car’s radiator or the condenser in an air conditioner, is the first step to dryer air. It is placed at the compressor’s air outlet and uses either ambient air or water to cool the compressed air and condense some of the water vapor into a liquid that can be removed with a water separator.

The simplicity of design is a positive. The negative is that it can never cool below ambient but something above ambient depending on its capacity. After-cooler performance is rated by approach temperature, which is how closely the compressed air leaving the after-cooler will approach the temperature of the cooling medium used.

For example, if an air-cooled after-cooler is rated for a 10°F approach temperature, and the temperature of the ambient air is 90°F, the temperature of the air leaving the after-cooler will be 100°F. Assuming 50% relative humidity day the dew point will be 80 F.

Mechanical Water Separators

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Wet compressed air enters the separator and passes through a set of vanes that spins it in a vortex. Centrifugal force causes liquid to fly out of the compressed air stream and run down the inside of the filter bowl, where it can be drained off. These are installed at the point of use as a final defense before entering sensitive compressed air equipment. They are an inexpensive assurance of quality air. The ones EXAIR has also include a sintered bronze filter element to remove dirt and scale as well as water.

Deliquescent Dryer

A deliquescent dryer is basically a tank full of salt tablets. As the compressed air passes through the salt, the salt attracts water and dissolves into a brine that can be drained off. These are the least expensive dryers to purchase and maintain because they have no moving parts and require no power to run. The operating cost consists of the cost of more salt tablets.

Desiccant Air Dryers

These are similar to the deliquescent driers except they use a desiccant that attracts water but holds it. When they have reached their saturation limit they are either replaced or regenerated in one of three methods.

Operating cost of these dryers varies with the method used to remove water from or regenerate the desiccant.

Heatless regenerative dryers take a portion (about 15%) of the dry compressed air leaving the dryer and passes it through the desiccant to absorb the moisture out of it. Purchase cost economical but operational costs are high because if all the compressed air used to dry out the desiccant.

Heated purge regenerative dryers take advantage of the fact that hot air can hold more water than cold air. These dryers take about 5% of the dry compressed air leaving the dryer and pass it through an electric heater and then sends it through the wet desiccant bed. This dryer cost more than the heat less dryer but is offset by using half the compressed of that used by the heat less dryer.

Blower Purge Dryers

These are similar in concept to the had dryers found in restrooms but on a larger scale. Heated air is sent trough the desiccant with a blower. These are not quite as efficient because they are heating up ambient air which would not be as dry as compressed air.

Membrane Air Dryers

These dryers use pass the compressed air through a membrane with pores large enough to allow air molecules through but not large enough to allow water molecules through. The lower a dew point is needed, the more purge air is required. These

Refrigerated Air Dryers

Is an A/C system that refrigerate  the compressed air as close to freezing as possible in order to condense out as much water as possible then use a mechanical water separators to remove the condensed water. They require electricity to operate along with the associated cost of operation and maintenance.

Hopefully this gives you a better understanding on how to qualify your compressed air.

Feel free to contact me at any time with questions or concerns, or if I can be of any further assistance. I genuinely appreciate the opportunity! 1-800-903-9247 or click on the live chat icon in the upper left hand corner.

Joe Panfalone

Application Engineer
Phone (513) 671-3322
Fax (513) 671-3363
Web: http://www.exair.com
Twitter: http://www.twitter.com/exair_jp
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