Video Blog: Which EXAIR Air Knife Is Right For You?

The following short video explains the differences between the 3 styles of Air Knives offered by EXAIR – The Super, Standard and Full-Flow. All of these Models are IN STOCK, ready to ship, with orders received by 3:00 PM Eastern.

If you need additional assistance choosing your EXAIR Air Knife, please contact an application engineer at 800-903-9247.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

 

Super Air Knife Math – When 72 + 72 = 75

The Super Air Knife is the latest generation of EXAIR engineered air knife that dramatically reduces compressed air usage and noise when compared to other blowoffs.

Super Air Knife Data

From the chart above, the Super Air Knife when supplied with 100 PSIG of compressed air has a sound level of just 72 dBA (A-weighted decibel scale) when measured from 3′ away.  72 dBA is a moderate sound level, and some common comparisons are ‘normal speaking voice’ at 70 dBA and ‘living room music’ at 76 dBA.

For many processes, such as a bottling line drying operation, a pair of the air knives delivers the best performance. When asked, “what is the sound level for (2) of the knives,” a little Acoustic Engineering is in order. Because the decibel scale is logarithmic, the result is not as simple as adding 72 + 72 = 144.  144 dBA is in the range of a jet aircraft take off! Thankfully, both the actual sound level and the numerical value are determined another way.  I’ll spare you a lot of the math but the equation is as below.

Capture

… where SL1, SL2, SL3 are the sound levels in dBA of the each sound makers, for as many that are being combined.

In the case of (2) Super Air Knives operated 100 PSIG, the combined sound works out to be a quiet 75.0 dBA — a powerful, efficient and quiet product ideal for many applications and process within the manufacturing environment.

Super Air Knife

Super Air Knife

As a helpful rule of thumb- combining any (2) items will yield an increase of 3 dBA, combining (3) results in a rise of 4.8 dBA, and combining (4) results in a 6 dBA rise over just (1) of the items.

The Super Air Knives have been successfully used in a wide range of applications, including part drying, sheet and conveyor cleaning, web cooling, scrap removal, pre-paint dust blowoff, and many, many more.

To discuss your application and how an EXAIR Intelligent Compressed Air Product can make your process better and quieter, feel free to contact EXAIR and myself or one of our other Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Selecting An EXAIR Air Knife

Many times we receive a  call from a customer looking for an Air Knife but they are unsure which design is the best to suit their needs. With 3 options to choose from, the Super Air Knife, Standard Air Knife and Full-Flow, it can seem like a somewhat daunting task so lets take a look at some of the key differences between the units. We keep all of these models in stock and can ship same day on orders we receive by 3 pm.

Super Air Knife

EXAIR Super Air Knife

Let’s start with our most popular choice, the Super Air Knife. The Super Air Knife is our most efficient unit, using a 40:1 amplification rate of entrained surrounding air to compressed air, it consumes only 2.9 SCFM per inch @ 80 PSIG while maintaining a low sound level of 69 dbA. This unit produces a laminar airflow across the entire length of the knife and there are air inlets on each end, as well as on the bottom. We offer lengths from 3″ up to 108″ in aluminum, 303ss, or 316ss. Additionally we offer lengths up to 54″ in PVDF (Polyvinylidene Flouride) for applications requiring superior chemical resistance, like those associated to acids, solvents or aggressive chemicals. There are 1/4-20 tapped holes on the bottom of the knife which can be used for mounting. We recommend the Super Air Knife most often because it uses the least amount of compressed air and has the most even airflow from end to end.

Std Air Knife

Standard Air Knife

Secondly we offer our Standard Air Knife which provides a 30:1 amplification rate, consuming slightly more compressed air at 3.4 SCFM per inch @ 80 PSIG. These units are louder at 83 dBA and feature air inlets on each end. Lengths available from 3″ up to 48″ in aluminum or 303ss construction.  The airflow length is 1″ smaller than the length of the knife (1/2″ of no flow on each end), for example a 12″ Standard Air Knife has a 13″ physical length with a 12″ airflow length. This is the first knife we ever manufactured and is a solid choice with good performance.

Full-Flow

Full-Flow Air Knife

Lastly, the Full-Flow Air Knife. Again providing a 30:1 ratio of entrained ambient air to compressed air, has the smallest dimensional footprint. Air consumption is slightly less than the Standard Air Knife at 3.1 SCFM per inch @ 80 PSIG with an airflow length equal to the length of the knife. We offer lengths from 3″ up to 36″, again in aluminum and 303ss and the air inlets are on the back of these units. The Full Flow Air Knife fills the need for customers with limited mounting space and who cannot fit a Super Air Knife into the desired location.

Hopefully this information will help in making the best decision to fit your needs. Of course if you still need additional support, please don’t hesitate to contact one of our Application Engineers for assistance.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

Full-Flow Air Knife Dries Copper Strip

Last week I was working with a customer who was using our 36″ Full-Flow Air Knife to dry a flat copper strip as it exited the rinse cycle of their process. The customer chose the Full-Flow design due to it’s small profile, making it easier to fit into the tight space available to mount to their machine. The customer stated that they flow tested the knife before installation and the knife “worked great” but once mounted, the flow was reduced significantly. They were thinking of returning the unit under our Unconditional 30 Day Guarantee but I offered to help troubleshoot the unit to see if we couldn’t relieve their issue(s).

Full-Flow

The Full-Flow Air Knife is available up to 36″ in either aluminum or 303ss construction.

When they tested the unit external to the machine they were using 1″ hose (our recommendation for a 36″ Air Knife) running to a tee, which stepped down to 1/2″ ID hose going to both rear inlets on the back of the knife. But when they installed the knife, due to space limitations, they reduced the main supply to 3/8″ tubing and plumbed only 1 inlet using a quick disconnect. This explained some of the low output flow with the unit. Using undersized supply lines and quick disconnect cause significant pressure drops due to their small inside diameters. When this occurs, you aren’t able to flow enough volume of air (SCFM) to the knife, which results in reduced performance and uneven flow.

The second issue was how they had the unit mounted to the machine. Wanting to keep the air inlets easily accessible, they mounted the face of the knife (the surface the compressed air runs along) right up to the outside wall of the machine, leaving just a small gap for the output flow and built a protective shield around the unit. The Full-Flow Air Knife will entrain 30 parts of surrounding, ambient air for every 1 part (SCFM) of compressed air used. With the unit being unable to entrain any free air, the output flow is further diminished.

How the Standard Air Knife Works

Illustration showing how the Standard and Full-Flow Air Knives operate.

After increasing the supply line to both inlets, removing the quick disconnect and protective shield and moving the knife back to allow for the air entrainment, the customer called back to advise that the strip was now completely dry.

If you are experiencing reduced performance or need help with the installation of your EXAIR product, give us a call at 1-800-903-9247.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

Proper Plumbing Makes Full Flow Air Knives Operational

Full Flow Air Knives for plate drying

These EXAIR Full Flow Air Knives were in need of an EXAIR Application Engineer’s expertise

Sometimes we get calls or emails from our customers that need help.  Help can be in the form of product selection, heat load calculation, or proper installation.  I had one such interaction with an end user of our Full Flow Air Knives, using them in the manner shown above.

The problem they were having was poor flow and low force from the blow off.  We originally discussed the application over the phone, and after suspecting a plumbing issue may be at play, I asked for a photo.  I received a quick photo of their setup and immediately saw the two knives were poorly plumbed.  The clear/light blue hose, and the dark blue hoses in the photo just aren’t big enough for two knives of this size.

When installing any compressed air driven product, pressure and flow are the name of the game.  Sometimes, as in this case, there was good pressure at the gauge (which, if checked at the inlet of the knife would have shown a significant pressure drop), but there just wasn’t enough flow.  The root cause was diameter of the piping used to deliver the air from the main line to the point of use.

Once the compressed air line sizes were increased, the knives worked flawlessly and the end user could use them as intended – which was blowing debris off of a plate fed through the middle of the two knives.

If you have an application that you think may have a plumbing concern, or any other need for EXAIR products, contact an EXAIR Application Engineer.  We’ll be happy to help.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

How To Choose An Air Knife

The EXAIR Super Air Knife has a prominent place near the front of our catalog, and THIRTEEN pages of photos, application details, performance data & specifications. It’s the most efficient and quietest product of its kind on the market, and our most diverse product offering in terms of size range, operational adjustability, materials of construction, and accessories available. For almost any general industrial air blow off application, the EXAIR Super Air Knife is the superior choice in terms of air usage, sound level, and capability.

EXAIR Super Air Knives come in a wide range of lengths, for a wide range of possibilities.

EXAIR Super Air Knives come in a wide range of lengths, for a wide range of possibilities.

As tireless champions of the causes of reducing air consumption and noise, we’re always going to promote these benefits of the Super Air Knife. Still, a caller asked me the other day, “Well, why do you still make the others?”…meaning, of course, our Standard and Full Flow Air Knives. Why, indeed:

*Given the same air supply pressure, the Standard Air Knife generates the highest force of our three styles. The amount of force applied isn’t always a prime consideration…if you think about one of the more “textbook” applications for an Air Knife, it doesn’t take a great amount of force to blow off dust and light debris from a conveyor belt…certainly this is a case where efficiency factors in: the lower air consumption of a Super Air Knife can pay for the cost difference between it and a Standard Air Knife in as little as three months of operation.

The Standard Air Knife has the highest force, for when it's needed.

The Standard Air Knife has the highest force, for when it’s needed.

Of course, if you’re blowing stubborn debris out of tight spaces, like gummy, greasy dirt that’s accumulating in the recesses of a finned tube heat exchanger, that extra force can make all the difference. No; the Standard Air Knife isn’t as efficient or quiet as the Super Air Knife, but it’s still a far cry better than a drilled pipe.

*While the Super Air Knife is pretty compact – you only need a few square inches of profile area to successfully mount it – the Full Flow Air Knife is even smaller, requiring not much more than one square inch of profile for mounting. With ports on the rear face (instead of the ends & bottom for the Super Air Knife,) they can fit in very tight quarters.

Low profile and lightweight, the Full Flow Air Knives are a great fit for tight quarters.

Low profile and lightweight, the Full Flow Air Knives are a great fit for tight quarters.

The Full Flow Air Knife is also the lightest weight for a given length. A 36” Aluminum Super Air Knife, for instance, weighs about 8lbs. The 36” Aluminum Full Flow Air Knife weighs less than 4lbs. Most of the time, 8lbs is a very manageable amount of mass to support, but there are situations where every ounce matters, and if yours is one of them, you’re looking at the Full Flow Air Knife all the way.

*The biggest (in the most literal sense) factor in Air Knife selection is, well…size. We make the Standard Air Knives in lengths to 48”, and the Full Flow Air Knives come as long as 36”. The Super Air Knives, however, are stocked in lengths from 3” to 108”, and can be coupled together for as long of an uninterrupted, steady, laminar air flow as you need.

At the end of the day, a majority of blow off applications can be handled just fine with any of our Air Knives. If you’d like to discuss your application and see which one is best for you, give us a call.

Russ Bowman
Application Engineer
(513)671-3322 local
(800)923-9247 toll free
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Full Flow Air Knife Increases Airflow By 3000%

Condensor Housing

Inside of the housing of the photo above is an EXAIR Full Flow Air Knife. The housing serves as a shield to a condenser on a specially built machine for one of the Big Three U.S. auto manufacturers. The purpose of the air knife within the housing is to supplement heat removal by passing large volumes of ambient air over the condenser, thereby helping to return the gaseous fluid to a liquid state.

When compressed air was supplied to the air knife in this photo, there was very little airflow. Knowing that there was something amiss, and that an Application Engineer could offer potential solutions, the OEM called in to EXAIR.

Immediately upon seeing the photo, the root cause of the problem was evident. There was no ambient air available for the air knife to entrain. It looks like an attempt was made to open the housing *in the bent edges at the top of the housing), but it was not enough.

Removing the housing from the machine revealed the following internal installation.

Condensor Housing Internal

With such a setup, there was no entrainment of ambient air, and the total airflow was only a fraction of what it should be. Removing the current shield and fabricating an alternate design which allows ambient airflow solved the problem in this application. Compressed air use remained low, and total airflow was increased by 3000%.

EXAIR products keep compressed air use low and performance to a maximum. For help with your application, contact an EXAIR Application Engineer.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

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