Extra Shims Give Super Air Knives A Boost

The EXAIR Super Air Knife is the most efficient and quietest compressed air blow off knife on the market. We know this because we’ve tested them, and our competitors’ offerings, for performance, using the same instruments, controls, and procedures. We’re not going to publish data that we can’t back up, and that’s a fact.

We will use the same precision calibrated equipment, by the way, to test your existing products for savings comparison in our Efficiency Lab service.

We will use the same precision calibrated equipment, by the way, to test your existing products for savings comparison in our Efficiency Lab service.

They’re also ideally suited to a wide variety of applications – they come in lengths from 3 inches to 9 feet long (and can actually be coupled together for uninterrupted air flows of even longer lengths,) a variety of materials for just about any environment, and changing performance is as easy as “dialing in” a regulator, or, for gross adjustments, installing a different (or additional) shim.

As the title of this blog suggests, a larger shim gap will give you higher flow and force from your Air Knife. Honestly, the 0.002″ shim that comes pre-installed in all of our Air Knives is perfectly suitable for most blow off applications, and appropriate air supply conditions are the first thing you should check for before going with thicker shims, but if you do indeed need a boost, a thicker shim will indeed give you one…here’s a video to show you how it’s done:

Keep in mind that appropriate air supply is going to be important here as well…by increasing the shim gap, you’re increasing the amount of compressed air flow required.  This means that you may need a larger diameter of infeed pipe to carry that much air, and/or you may have to plumb that air to additional ports on the Super Air Knife.

This is from the Installation & Operation Guide that ships with your Super Air Knife. It's also available from our PDF Library (registration required.)

This is from the Installation & Operation Guide that ships with your Super Air Knife. It’s also available from our PDF Library (registration required.)

For most cases, we can use the above data to determine how to properly supply a Super Air Knife with additional shims.  For example, let’s look at a 12″ Super Air Knife:

*With a 0.002″ shim, you’ll need a 3/8″ pipe, assuming infeed length of 10ft or less, to pass the 34.8 SCFM that this unit will consume when supplied @80psig.

*By installing a 0.004″ shim, you’re doubling the air consumption, which means it’ll consume the same amount as a unit twice this length…we can see from the chart, then, that a 24″ Super Air Knife will need a 1/2″ infeed pipe.

*Also, since you’re using the same amount of air as the 24″ Super Air Knife, the 12″ unit should be treated like the 24″ one, and plumbed to (2) inlets at opposite ends of the knife (see “Compressed Air Supply” notes above.)

This is just one simple case for a small unit. If you’d like to discuss altering the performance of your Super Air Knife, give us a call.

Russ Bowman
Application Engineer
Find us on the Web http://www.exair.com/28/home.htm
Follow me on Twitter
Like us on Facebook

Cooling Fabric with a Super Air Knife Increases Production Speed

Super Air Knife has 40:1 Amplification Ratio

Super Air Knife has 40:1 Amplification Ratio

I received a call from a customer in the textile industry. The customer was producing a fabric that ends up being used for furniture.  The fabric varied in width between 4 feet (1.2 meters) and 6 feet (1.8 meters) wide.  In one of the processes, the material went through an oven to be heated to 200 deg. F (93 deg. C).  This would “set” a fire retarding chemical compound in the fabric.  As the fabric web exited the oven, they needed to cool it to roughly 120 deg. F (49 deg. C) so it could be handled by the operators.

The customer tried their luck at designing a duct that was seven feet (2.1 meter) long by one foot wide (30.5 cm) by one foot tall (30.5 cm).  At the bottom of the duct, they cut one inch wide (2.5 cm) slots along the length in an attempt to create a wide airflow across their material.  The large metal box (ducting) was suspended across the fabric and oriented to blow air straight down onto the material.  On the open end of the metal box, they mounted a fan to blow air inside with the intention that the slits in the duct work would direct the air from the fan onto the fabric.

Their idea worked to some small degree, but the cooling results were simply too little to continue with this kind of solution. Fortunately, the customer knew about EXAIR Corporation and they contacted us to see if we could help. Because they needed to provide additional time for the fabric to cool, they slowed their line speeds down to 20 yards/min (18 meters/min). It was obvious that they wanted to increase the throughput if they could.

In order to increase throughput, we needed to figure a way to increase the cooling rate.  To increase the cooling rate, we can either use colder air or more air.  Given the wide format of the material, the best decision for this application would be to blow more air across the target material.  The Super Air Knife has a 40:1 amplification ratio.  For every 1 part of compressed air, it will entrain and move 40 parts of ambient air to the target surface.  The result is that a larger volume of air hitting the surface of the material.  More volume hitting the target means we can cool it quicker.  I suggested a model 110272, 72″ Super Air Knife Kit to span across the different width of fabrics.  It can be mounted across the width of the material and set at a 45 degree angle to the material in a counter flow orientation. The reason for the angle and the counter-flow orientation are to enhance the cooling effect provided by the Super Air Knife. Orienting the Super Air Knife at a low angle allows for the flow coming from it to stay in contact with the material web for a much longer period of time.

By removing the fan with the duct work and installing the Super Air Knife, they found they could increase throughput to 30 yards / min. (9.2 meters / min). A 50% increase. The customer was thrilled about the significant increase as this was a real bottleneck in their production process.

If you have any cooling issues, you can rely on EXAIR to determine the best product. If you have any questions or would like to discuss any of your applications, you can contact the Application Engineers at EXAIR.

John Ball, Application Engineer
Twitter: @EXAIR_jb

Helping A Customer Get Their Installation Setup Just Right


Staggered Super Air Knife setup used to solve blow off problem

With the amount of applications capable of benefiting from a Super Air Knife we tend to field a lot of questions about the product.  How much force does the Super Air Knife produce?  (2.5 oz of force for every inch of knife length.) What is the noise level at various operating pressures?  (57-69 dBA at operating pressures from 20-80 PSIG.)  Is an Air Knife right for my application?  (Possibly!  Our Application Engineers can help answer that question definitively.)

Another common question we have from existing customers and prospective customers alike, is in regards to the proper mounting of an Air Knife solution in a conveyor blowoff application.  As a standard practice we recommend to install the air knife/knives at a 45° angle of attack, opposite the direction of material travel.  (We refer to this as counterflow.)  And, if the knives are mounted vertically for a side-based blow off, we normally recommend to install the knives directly opposed to each other.  This type of setup creates a nice chevron pattern in the blow off, removing water, dirt, or whatever other undesirables are at play.

Recently, though, I went through a troubleshooting exercise with an end user unable to achieve adequate blow off with our go-to type of setup.  No matter the pressure or angle, we just couldn’t get the setup dialed in to remove the undesirable (in this case, water) while still allowing material flow.  In this application the force from the two knives hitting simultaneously was too great to allow the lighter products through the blow off curtain.  So I requested some sample product be sent in and ran some in-house tests.

What we found was identical to the results from the field, which were a bit puzzling.  We could blow off the water from the product, but not to the degree of dryness necessary.  This was because the weight of the product was too low to keep the product in place when in contact with the high force blow off from a set of two Super Air Knives.  We could force the product through by hand, but that wasn’t a real or repeatable option.

But, after trying various configurations we found the solution!  Two Super Air Knives mounted directly parallel produced too much force.  BUT, two Super Air Knives mounted in a staggered pattern separated our blow off air flows just a bit.  This setup allowed the product to pass through one air stream, then into the combined air stream of two knives, and then again through one air stream.


Another view of the staggered setup used in this application

This solution, show above, brought the level of dryness to the needed level and allowed our customer to get back on track.  Without a solution to this problem workflow slowed, production reduced, and defects increased.  With the combination of an EXAIR product and our product support, we were able to increase workflow and production while eliminating defects due to excess water o the product.

If you have an application with a similar need, contact an EXAIR Application Engineer.

Lee Evans
Application Engineer

Super Air Knife Keeps Saw Shavings Contained

A customer called me to help solve an issue with his dust collection system. They manufacture steel pipe in the range from ½” (13mm) to 6” (152mm) diameter.  An operation was to cut the pipes to length and blow out the shavings.  The pipe was laying flat, and they would slide one end of the pipe into an 8” (203mm) wide slot.  This slot was located on the side of a sheet metal plenum.  The plenum was the containment area and the entrance to their dust collection system.  An operator would blow compressed air into the opposite end of the pipe to remove all the small shavings from inside the pipe and into the containment area.  The slot had vinyl slats to help keep the metal shavings inside the plenum.  The issue occurred with the larger diameter pipes.  Because of the volume of air required to blow out the larger pipes, it would overcome the vacuum level and the metal shavings would migrate out.  Thus affecting the integrity of the dust collection system.

Super Air Knife

Super Air Knife

The slot was 60” (1.5 meters) long and 8” (203mm) wide. I suggested our Super Air Knife kit, model 110260.  The customer mounted the Super Air Knife above the slot to shoot air across the opening.  It was roughly 3″ (76mm) away from the side and aimed slightly back toward the bottom of the slot.  This would ensure any contamination to remain inside the plenum. When the customer had a batch of larger pipe, he would turn on the Super Air Knife.  The air curtain barrier had enough force to keep the debris inside the plenum.  The metal shavings remained inside the containment area, and it kept the area clean and safe.

Instead of purchasing a larger vacuum or dust collection system, a quick and simple solution was to use the EXAIR Super Air Knife. If you ever come across a situation where you need help with process challenges, you can always call EXAIR and speak to one of our Application Engineers.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: twitter.com/exair_jb

Use The Force…Or Not…It’s Up To You, Really

The month of May, in 1977, was a great time to be ten years old. I was finishing up my fifth grade year, a pivotal one, thanks to Miss Walker, who ended up being my favorite teacher ever. She had a pet rat named A.J. that we took turns taking home for the weekend. She rewarded us for class performance by taking us outside to play softball on warm & sunny spring afternoons. I trace my love for math (and hence, my inspiration for a career in engineering) to the excitement she instilled in me for the subject…I was among the first to master the multiplication tables.

And then there was Star Wars. There were commercials for the movie and the toys and the merchandise on TV; I swear they ran every five minutes. A fast food chain released a series of posters (free with purchase) and every time a new one came out, Miss Walker promptly hung it on the classroom wall. None of us, her included, could hardly wait until the premiere. I could go on (and on and on and on,) but suffice it to say (for the purposes of this blog,) I’ve been a BIG fan ever since.

Which brings us to today…opening day for “Star Wars, Episode VII: The Force Awakens.” The first time, by the way, a Star Wars movie hasn’t premiered in the month of May, but I digress. The 10 year old inside me wants to go see it RIGHT NOW, but the grownup I have to be has a company Christmas party, two Boy Scout events, and a pre-holiday “honey-do” list to attend to first.

Of course, the “other” epic space movie series couldn’t resist launching THEIR new trailer this week…

All this talk about The Force (capital “F”) and the fact that I write this blog on company time has me thinking about compressed air applications that involve force (lower case “f”) and how using force (unlike “The Force”) is not always prudent.

This is the case in just about any blow off application that uses air under pressure. Open ended copper tubing, drilled pipes, etc., are common and easy ways to discharge compressed air for debris removal, drying, or cooling a part. But the fact is, they waste a LOT of the energy devoted to compressing the air by simply turning it into brute force and noise.

This is where EXAIR Intelligent Compressed Air Products(r) come in: by using the energy of the compressed air to entrain air from the surrounding environment, the total air flow is amplified, resulting in a high velocity blast, at minimal consumption. No; it doesn’t have the same amount of force as an open ended discharge device, but most blow off applications don’t need all that much force anyway.

Of course, there ARE situations where you need to use the force, and we’ve got efficient and OSHA compliant ways to do that too: additional shims in Air Knives, Air Wipes & Air Amplifiers, or larger Super Air Nozzles.

“A long time ago, in a galaxy far, far away,” the continuing theme of the Star Wars saga is to use The Force properly. For the past 32 years, the continuing theme at EXAIR is to help you use the force (of your compressed air) properly. Let me know how we can help.

May The Force be with us all…this weekend, and always.

Russ Bowman
Application Engineer
Find us on the Web
Follow me on Twitter
Like us on Facebook

EXAIR PVDF Super Air Knife in a Harsh Environment

Sometimes at EXAIR, we are challenged with an aggressive environment, and in this application, we had a customer that manufactured tractor batteries.  He was concerned about the sulfuric acid leaving the filling station area, and he wondered if we could help him.  After the batteries would get filled with sulfuric acid, they would be capped and then conveyed to a wash system.  He wanted to remove any excess acid that may have been on the battery for safety reasons.

PVDF Super Air Knife

PVDF Super Air Knife

I recommended our PVDF Super Air Knives.  These Super Air Knives are made with Polyvinylidene Fluoride (PVDF) with Hastelloy® hardware and a PTFE shim.  These materials are very inert to acid and caustic solutions.   Also with its unique design, it is able to optimize the compressed air usage with a consistent, strong blowing force.  The customer purchased three pieces of a model 110012-PVDF.  He was able to keep the hazardous sulfuric acid contained in the filling station.  As a bonus, he was able to increase the life of his washing solution because less acid was entering into the wash station.  He was so impressed by the effectiveness of the PVDF Super Air Knives that he purchased three more pieces for after the washing system.  He was able to speed up the drying process for QC checks and packaging.

If you are faced with an extreme challenge, you can contact an Application Engineer at EXAIR to see if we may have a solution for you.

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


Hastelloy is a registered trademark of Union Carbide and Carbon Corporation.

Counter-flow – How to Mount Air Knives for Maximum Effect

counter flow

Example: Counter-flow arrangement

As with any tool, there can be a right way and a wrong way to use the tool. In this article I will explain the best way to mount a Super Air Knife in a blowing application so that you achieve the maximum force, time in contact and of course, effectiveness.

There is a term we use, “counter-flow”, to describe the opposing travel of target material/conveyor (red arrow) and the airflow coming from an Air Knife (yellow arrow). By having opposing flows, the Air Knife is able to blow the debris, contamination, water or other fluid back into the direction from which it came. Sometimes a catch pan can be used to collect and re-use the fluid. In the photo above, note that the air knife is oriented to blow from right to left and the parts are travelling on the conveyor belt from left to right. This is a simple example of how we set up counter-flow.

Also, with regard to effective Air Knife mounting strategies; the Super Air Knife in the photo is mounted using our Universal Air Knife Mounting System which allows for maximum flexibility for positioning and stability of the Air Knife once set. The Universal Air Knife Mounting System is another great accessory that you can recommend to clients to make the set up very easy. Of course a suitable compressed air filter and pressure regulator should be used for clean air and adjustability of force in the application.

Finally, in the photo above, note that the Super Air Knife is mounted up-side down. We generally recommend this kind of orientation with the cap of the Super Air Knife being closest to the material being blown off. This allows you to get the air knife a bit lower and closer to the target material. The lower the angle, the better. This allows for a longer time in contact between the Super Air Knife and the target material. When the target material spends more time in the high velocity flow, the more likely you are able to impart the desired effect whether that be drying, cooling, blowoff or static elimination. To find a good mounting angle to start, I recommend customers use the front, angled edge of the Super Air Knife cap as a guide for what part of the Super Air Knife to keep parallel to the moving surface. This is a great reference from which blowing angle can be optimized.

If you find yourself with an Air Knife application and are unsure about how to proceed with mounting it, the idea explained above is one of the core foundations we utilize for solid Air Knife mounting technique.

Neal Raker, International Sales Manager



Get every new post delivered to your Inbox.

Join 18,022 other followers

%d bloggers like this: