Super Air Knife Shims & How They Affect Performance

To Shim or not to Shim… The Super Air Knife is a fabulous piece of equipment. Between the quiet laminar flow of air, and the intense 40 to 1 ratio of entraining the ambient air around it, this Knife is definitely cutting edge (pun intended). As you look at the front edge of the Super Air Knife, or as we call it “the place where the magic happens“, you will see that there is a very small slit or gap where the air flows. The gap in that metal is caused by the shim that is inside the Super Air Knife. We control the size of this gap with shims. Hark, what light through yonder air gap breaks?… Sorry, I get carried away sometimes.

The shims in the Aluminum Super Air Knives are made of a polyester plastic, the PVDF Super Air Knife Shims are made of PTFE, and I will give you two guesses what the Stainless Steel Super Air Knife Shims are made of, you guessed it… Flubber… Just kidding, they are stainless steel of course.

All of our Super Air Knives, regardless of material, ship standard with a 2 thou shim installed. 2 thou you ask? I did too. That is 2 thousandths of an inch, or 0.002″. This is the height of the gap where the Air Flows out. When you are looking at all of our published numbers in the catalogue or on the website, all of those performance numbers are based on this 2 thou shim. Here is the Super Air Knife performance table:

Pic by Conmongt, licensed by Pixabay

So, what if you need more or less air than what’s on this list? We can adjust the gap. We can add shims up to @ 0.01″ to increase the flow. Or we can go down to 0.001″ (1 thou). This poses the question of, what happens to performance? The good news with the shims is that the Air Consumption is a direct linear proportion to this performance table, and the force is very close to the same. So if you double to a 4 thou shim, you double the air consumption and force. Velocity and sound level will vary, but I do not have data to what degree.

As we size these, generally see people wanting more air, larger gaps (more shims), But conversely, we can decrease the air flow down to a 1 thou shim (1/2 of the published values above). Technically we can go smaller than 1 thou, but there is a limit to where a hole is no longer a hole. Here is a breakdown of our stock shims, with colors and sizes for the Super Air Knives:

The Super Air Knives are in a class of their own. As long as you feed the Super Air Knives enough air (SCFM) you can run them at most any psig to retrieve the desired air flow for you application. As an added means of flexibility, you can change the gap size with shims. I have put in a request to change the name of these to Super Flexible Air Knives, but I’m not holding my breath.

Public Domain Picture Licensed by Pixabay

One more thing about Shims. We can customize your shims!! Now I am not talking about putting your logo on them (but money talks!!), but we can customize your length. Let me give you an example. Let’s say that you need 58″ of airflow, no more no less. Our standard length Super Air Knives are 54″ and 60″. We can make you a custom knife, which is a great option, but for 1 or 2, this is probably not very cost-effective. But we can make you a custom shim. We can have the knife only push 58″ of air with a shim blocking the rest. Furthermore, you can decide if you want 58″ centered on the knife, or all 58″ starting from the left, or right side. It is a very cost-effective way to get a custom flow width.

Please let me know of you have any questions, or would like to discuss any of this further.

Thank you for stopping by,

Brian Wages

Application Engineer

EXAIR Corporation
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Super Air Knife’s Adjustability and Flexibility = Success

The EXAIR Super Air Knife is the most efficient compressed air 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.

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EXAIR Super Air Knife removing moisture after a rinse on anodized parts.

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. But the best thing about our Super Air Knives is how you can adjust the air pressure and flow to complete a wide variety of tasks. You can adjust them in two different ways, Replacing or adding Shims, or regulating the incoming air pressure.

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Shims for the aluminum, 303 Stainless Steel, and 316 Stainless Steel Super Air Knives

Changing out your shim!

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 blog with the video to show you how it’s done:

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Video Blog: How to Change a Shim in a Super Air Knife

Filter Regulator
Regulator and filter

Another advantage to having a Pressure Regulator at every point of use is the flexibility of making pressure adjustments to quickly change to varying production requirements.  Not every application will require a strong blast sometimes a gentle breeze will accomplish the task.  As an example one user of the EXAIR Super Air Knife employs it as an air curtain to prevent product contamination (strong blast) and another to dry different size parts (gentle breeze) coming down their conveyor. For Performance at different supply pressures see the chart below.

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Super Air Knife Performance Table

EXAIR products are highly engineered and are so efficient that they can be operated at lower pressures and still provide exceptional performance!  This save’s you money considering compressed air on the average cost’s .25 cents per 1000 SCFM.

If you’d like to discuss altering the performance of your Super Air Knife, give us a call.

Jordan Shouse
Application Engineer
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Many Air Knife Materials and Shim Options to Suit Your Application

The EXAIR Super Air Knives are used in many applications ranging from part drying, to web cleaning, to conveyor blowoff, and many other uses. For most processes, the aluminum models provide the performance required and withstand the environmental conditions present.

Ambient temperature limits for the aluminum models is 180°F (82°C). EXAIR also offers the air knives in types 303 and 316 Stainless Steel, which increase the temperature limit to 800°F (427°C) and provides a great degree of corrosion resistance. For the harshest, most corrosive environments, an air knife constructed of Polyvinylidene Fluoride (PVDF) with a temperature limit to 275°F (135°C) is available.

Super Air Knives
Aluminum, Stainless Steel and PVDF Super Air Knives

But what can we do about those applications where the increased corrosion resistance isn’t needed and the temperatures do not approach anywhere near to 800°F (427°C)?

The solution to this situation is an aluminum air knife with a custom stainless steel shim. The aluminum material is rated to 400°F (204°C) and the shim is good to 800°F (427°C) so this knife can be used in those hotter environments up to 400°F (204°C). This option helps to keep the cost of the knife low, by utilizing the lower cost aluminum for the body and cap.

The table below details the materials of construction options for the Super Air Knife – a wide array of material offerings to suit even the hottest, harshest conditions.

Air Knife Temperature Table

We recommend consulting with an Application Engineer to review the application, process, and environmental conditions, and we can present best options.

And don’t forget, the shims can be further customized for special blowoff requirements. See the blog that my colleague, Russ Bowman, posted here.

If you have questions about Super Air Knives or any of the 15 different EXAIR Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer
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Super and Adjustable Type Air Amplifiers

The EXAIR Air Amplifiers are a powerful, efficient and quiet air mover, whose power can be harnessed for blowoff, cooling and ventilation applications. Using a small amount of compressed air, air amplifiers pull in large amounts of surrounding air to produce a high volume, high velocity outlet flow.  Quiet and efficient, output flows with amplification ratios of up to 25 times are possible. There are two types, the Super Air Amplifier and the Adjustable Air Amplifier.

The Super Air Amplifier, with sizes ranging from 3/4″ to 8″, has a patented design (patent #5402938) that uses a special shim to maintain critical position of the components parts. It is through this critical gap setting that a precise amount of compressed air is passed at exact intervals controlled by the shim toward the center of the of the Super Air Amplifier.  The jets of air create a high velocity flow across the entire cross sectional area, which in turn pulls in large amounts surrounding air, resulting in the amplified outlet flow.  Because the outlet flow remains balanced and minimizes wind shear, sound levels are typically three times lower than other types of air movers. The shims are available in thicknesses of 0.003″ (supplied as standard), 0.006″ and 0.009″, and changing to a larger shim will increase the force and flow of the outlet air. The 8″ Super Air Amplifier is supplied with a 0.009″ shim, with a 0.015″ shim available.

2″ Super Air Amplifier and Patented Shim Design

For high temperature applications (up to 700°F/374°C) a special 1-1/4″ High Temperature Air Amplifier is available, with performance equal to the 1-1/4″ Super Air Amplifier. Its surfaces are protected from heat stress by a mil-spec coating process. The High Temperature Air Amplifier is highly effective at pushing large amounts of hot air to areas that typically remain cool.

The Adjustable Air Amplifier, with sizes ranging from 3/4″ to 4″, does not use a shim, and has an infinitely adjustable air gap, which regulates the air consumption and outlet flow from a light breeze to a powerful blast. A highly effective air mover, it can be tailored to meet the exact air flow and force of your specific application. They are available in aluminum and in stainless steel (Type 303) for food service, higher temperatures (400°F/204°C) and corrosive environments.

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2″ Adjustable Air Amplifier, in Aluminum or Stainless Steel

Force and flow of the Adjustable Air Amplifier is changed by loosening the knurled lock ring and turning the exhaust end to open or close the gap.  Once the desired force and flow is achieved, the knurled ring can be tightened to lock the device at the current setting. Typically, an air gap of 0.002″ to 0.004″ provides the required performance.

The table below summarizes the key features of the Super Air Amplifier and Adjustable Air Amplifier.  Please contact an Application Engineer if you need assistance in making a selection.

Air Amp Selection Chart

Note that EXAIR can manufacture special Air Amplifiers to your specification including special flanged mounting style or with a PTFE plug to avoid sticky material build up.

To discuss your application and how a Super or Adjustable Air Amplifier or any EXAIR Intelligent Compressed Air Product can improve your process, feel free to contact EXAIR, myself, or one of our other Application Engineers. We can help you determine the best solution!

Brian Bergmann
Application Engineer

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