Fluidics, Boundary Layers, And Engineered Compressed Air Products

Fluidics is an interesting discipline of physics.  Air, in particular, can be made to behave quite peculiarly by flowing it across a solid surface.  Consider the EXAIR Standard and Full Flow Air Knives:

Compressed air flows through the inlet (1) to the Full Flow (left) or Standard (right) Air Knife, into the internal plenum. It then discharges through a thin gap (2), adhering to the Coanda profile (3) which directs it down the face of the Air Knife. The precision engineered & finished surfaces serve to optimize the entrainment of air (4) from the surrounding environment.

If you’ve ever used a leaf blower, or rolled down the car window while traveling at highway speed, you’re familiar with the power of a high velocity air flow.  Now consider that the Coanda effect can cause such a drastic redirection of this kind of air flow, and that’s a prime example of just how interesting the science of fluidics can be.

EXAIR Air Amplifiers, Air Wipes, and Super Air Nozzles also employ the Coanda effect to entrain air, and the Super Air Knife employs similar precision engineered surfaces to optimize entrainment, resulting in a 40:1 amplification ratio:

EXAIR Intelligent Compressed Air Products such as (left to right) the Air Wipe, Super Air Knife, Super Air Nozzle, and Air Amplifier are engineered to entrain enormous amounts of air from the surrounding environment.

As fascinating as all that is, the entrainment of air that these products employ contributes to another principle of fluidics: the creation of a boundary layer.  In addition to the Coanda effect causing the fluid to follow the path of the surface it’s flowing past, the flow is also affected in direct proportion to its velocity, and inversely by its viscosity, in the formation of a boundary layer.

High velocity, low viscosity fluids (like air) are prone to develop a more laminar boundary layer, as depicted on the left.

This laminar, lower velocity boundary layer travels with the primary air stream as it discharges from the EXAIR products shown above.  In addition to amplifying the total developed flow, it also serves to attenuate the sound level of the higher velocity primary air stream.  This makes EXAIR Intelligent Compressed Air Products not only as efficient as possible in regard to their use of compressed air, but as quiet as possible as well.

If you’d like to find out more about how the science behind our products can improve your air consumption, give me a call.

The Case Is Mounting For Stay Set Hoses

So, you’ve selected a quiet, efficient, and safe EXAIR Super Air Nozzle for your blow off application – good call! – and now you’re thinking about how to install it.  Sometimes, it’s as simple as replacing whatever you’re using right now:

EXAIR Intelligent Compressed Air Products have common NPT (or BSP) connections, making for easy replacement of most any existing threaded device.

Or maybe you’re using an open end blow off…in which case, you’re just an adapter away:

EXAIR Super Air Nozzles are quick and easy to install on existing copper tube, via a simple compression fitting.

Perhaps, though, it’s a new installation, or the existing supply lines aren’t suitable for one reason or another.  In those cases, we’ve still got you covered…consider the EXAIR Stay Set Hose:

Precise aiming and location is a breeze with EXAIR Stay Set Hoses.

Available in a variety of lengths from 6″ to 36″, they’re positionable, and re-positionable with a simple bending action.  They won’t kink or easily fatigue like copper tubing.  The supply end is 1/4  MNPT, and you have your choice of 1/4 MNPT or 1/8 FNPT on the other end, depending on which Super Air Nozzle, Air Jet you need to use it with.

We also offer Blow Off Systems, which are a combination of a specific Air Nozzle (or Air Jet,) fitted to a Stay Set Hose:

Model 1126-9262, for example, is a Model 1126 1″ Flat Super Air Nozzle with a 9262 Stay Set Hose.

For added convenience and ease of installation, these products can also come with a Magnetic Base:

Mag Bases come with one or two outlets. Stay Set Hoses come in lengths from 6″ to 36″.

Stay Set Hoses are also available with a variety of our Soft Grip Safety Air Guns, and they make the GEN4 Stay Set Ion Air Jet one of our most popular Static Eliminator products.  They’ve even been successfully applied with small Air Amplifiers and Air Knives…with certain limitations (spoiler alert: trying this with a 108″ Super Air Knife is going to be a definite “no.”)

Model 110003 3″ Aluminum Super Air Knife with 6″ Stay Set Hose & Magnetic Base.

From the beginning in 1983, EXAIR’s focus has been on being easy to do business with, and that goes from our friendly customer service to our expert technical support to our 99.9% on-time shipments (22 years and running) to designing our engineered products and value-added accessories with efficiency, safety, and ease of installation in mind.  If you want to find out more, give me a call.

How To Make Compressed Air Get Cold…A Couple Of Different Ways

The Vortex Tube makes cold air for the same reason that a can of compressed air gets cold when I clean my computer keyboard, right?

That’s a common question, and since they both start with compress air and end up with cold(er) air, it’s not an unreasonable assumption.  But the answer is no; they’re not the same.   Both are curious physical phenomena, though:

Cans of compressed air get cold while they’re discharging because of a thermodynamic principle known as the adiabatic effect.  When you pressurize a gas by compressing it into a container, you’re putting all those molecules into a smaller volume of space…and you’re adding potential energy by the compression.  Then, when you release that gas back to atmospheric pressure, that energy has to go somewhere…so it’s given off in the form of heat – from the air inside the can, as the pressure inside the can decreases.  Now, the air that’s not under as much pressure as it was when you pushed the button on top of the can is going to start coming out of the can pretty soon.  I mean, there’s only so much air in there, right?  So, since it’s given off that energy immediately upon the drop in pressure, when it comes out of the can, it’s at a lower temperature than it was before you started spraying it out.

Vortex Tubes, on the other hand, generate a flow of cold air by a completely different phenomenon of physics called, maybe not so curiously, the Vortex Tube principle:

You can get a lot more cold air – and a much lower temperature – from a Vortex Tube than you can from a can of compressed air.

If you need a reliable and dependable flow of cold air, look no further than EXAIR’s comprehensive line of Vortex Tubes and Spot Cooling Equipment.  We’ve got 24 models of Vortex Tubes to choose from, as well as “out of the box” solutions for cooling applications like the Adjustable Spot Cooler, Mini CoolerCold Gun Aircoolant Systems. and, to protect your sensitive electrical and electronic enclosures from heat, Cabinet Cooler Systems.  If you’d like to find out more, give me a call.

Russ Bowman

Application Engineer
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Six Steps To Optimizing Your Compressed Air System – Step 1: Measure

“To measure is to know – if you cannot measure it, you cannot improve it.”
-Lord Kelvin, mathematical physicist, engineer,and pioneer in the field of thermodynamics.

This is true of most anything. If you want to lose weight, you’re going to need a good scale. If you want to improve your time in the 100 yard dash, you’re going to need a good stopwatch. And if you want to decrease compressed air consumption, you’ll need a good flowmeter. In fact, this is the first of six steps that we can use to help you optimize your compressed air system.

Six Steps To Optimizing Your Compressed Air System

There are various methods of measuring fluid flow, but the most popular for compressed air is thermal mass air flow.  This has the distinct advantage of accurate and instantaneous measurement of MASS flow rate…which is important, because measuring VOLUMETRIC flow rate would need to be corrected for pressure in order to determine the true compressed air consumption.  My colleague John Ball explains this in detail in a most excellent blog on Actual (volume) Vs. Standard (mass) Flows.

So, now we know how to measure the mass flow rate.  Now, what do we do with it?  Well, as in the weight loss and sprint time improvements mentioned earlier, you have to know what kind of shape you’re in right now to know how far you are from where you want to be.  Stepping on a scale, timing your run, or measuring your plant’s air flow right now is your “before” data, which represents Step One.  The next Five Steps are how you get to where you want to be (for compressed air optimization, that is – there may be a different amount of steps towards your fitness/athletic goals.)  So, compressed air-wise, EXAIR offers the following solutions for Step One:

Digital Flowmeter with wireless capability.  This is our latest offering, and it doesn’t get any simpler than this.  Imagine having a flowmeter installed in your compressed air system, and having its readings continually supplied to your computer.  You can record, analyze, manipulate, and share the data with ease.

Monitor your compressed air flow wirelessly over a ZigBee mesh network.

Digital Flowmeter with USB Data Logger.  We’ve been offering these, with great success, for almost seven years now.  The Data Logger plugs into the Digital Flowmeter and, depending on how you set it up, records the flow rate from once a second (for about nine hours of data) up to once every 12 hours (for over two years worth.)  Pull it from your Digital Flowmeter whenever you want to download the data to your computer, where you can view & save it in the software we supply, or export it directly into Microsoft Excel.

From the Digital Flowmeter, to your computer, to your screen, the USB Data Logger shows how much air you’re using…and when you’re using it!

Summing Remote Display.  This connects directly to the Digital Flowmeter and can be installed up to 50 feet away.  At the push of a button, you can change the reading from actual current air consumption to usage for the last 24 hours, or total cumulative usage.  It’s powered directly from the Digital Flowmeter, so you don’t even need an electrical outlet nearby.

Monitor compressed air consumption from a convenient location, as well as last 24 hours usage and cumulative usage.

Digital Flowmeter.  As a stand-alone product, it’ll show you actual current air consumption, and the display can also be manipulated to show daily or cumulative usage. It has milliamp & pulse outputs, as well as a Serial Communication option, if you can work with any of those to get your data where you want it.

With any of the above options, or stand-alone, EXAIR’s Digital Flowmeter is your best option for Step One to optimize your compressed air system.

Stay tuned for more information on the other five steps.  If you just can’t wait, though, you can always give me a call.  I can talk about compressed air efficiency all day long, and sometimes, I do!


The Case For The EXAIR Super Air Wipe

If you’ve ever used an air gun to blow something off, you’re familiar with the cleaning ability of compressed air.  If you can get the whole object blown off from where you’re standing, there really is no substitute…but what if you need to get to the other side…or sides?

Even if your product is not on fire, you probably wouldn’t want to “limbo” under it with an air gun…

This is where the EXAIR Super Air Wipe comes in…they allow you to blow a continuous, uniform 360° air stream, all around your product.  Consider their benefits:

*Sizes: the Super Air Wipe’s compact ring design means it won’t take up a lot of room; you just need a few inches, in any direction, to install one.  We stock them in eleven sizes, from 11″, all the way down to our brand-new 3/8″ diameter.

*Durability:  All EXAIR Super Air Wipes are assembled with stainless steel shims and hardware.  Models up to 4″ come with a rugged, stainless steel wire braided hose, connecting the two halves for compressed air supply.

The aluminum Super Air Wipe is available in 11 sizes; the stainless steel Super Air Wipe comes in 5 sizes…all from stock.

*Ease of installation:  Smaller sizes can be supported by the compressed air supply line, if a pipe is used and threaded into the connector hose’s 1/4 NPT port.  Larger sizes can likewise be adequately supported with pipe to both halves. All models have a bolt circle of 1/4″-20 tapped holes for more permanent and rigid mounting.  The split ring design is another key feature:

Simply open the two halves, and clamp them around your product…no threading!

*Corrosion resistance: Depending on the environment in which the Super Air Wipe will be installed, we offer them with aluminum (3/8″ – 11″ sizes) or stainless steel (3/8″ – 4″ sizes) bodies.

*Temperature rating: Aluminum Super Air Wipes are good to 400°F (204°C) and stainless steel models are good to 800°F (427°C.)

*Range of operation: We install a 0.002″ thick shim in all stock Super Air Wipes; this is suitable for a wide range of typical industrial/commercial blow off applications…a Pressure Regulator can then be used to “dial in” the air flow precisely to meet specific needs.  If a job calls for higher force & flow, additional 0.002″ shims can be installed.  Shim Sets come with the Super Air Wipe Kits, or individual shims can be ordered separately.

*Performance: Before the Super Air Wipe, a ring of nozzles was commonly used.  In fact, they still are, but we’re trying to fix that, at every opportunity we come across.  Problem with those is, it’s hard to get an even air flow all around, which leads to inconsistent blow off.  They can also be loud & inefficient, as we’ve found in numerous Efficiency Lab tests and Case Studies, like this one…

These wasteful and loud modular plastic tube blow offs…
…were replaced with EXAIR Super Air Wipes. 24 such replacements netted the customer an annual compressed air cost savings of over $13,000.00.

…and this one…

Implementing a Super Air Wipe salvaged a $30,000 job for this customer. Click on the picture to read all about it in our Case Study Library (registration required.)

Do you have a challenging blow off application that you need help with?  Call us to find out how an EXAIR Super Air Wipe (or another one of our Intelligent Compressed Air Products) can be a simple, quick & easy solution.

Custom Shims – Literally A Breeze For EXAIR

As proud as we are of being able to ship most any catalog product, same day, from stock (99.9831% of the time for on-time shipping in 2017…22 years straight for 99.9% or better,) we take a certain amount of pride in our ability to offer custom solutions for challenging applications as well. Our Engineering and Production teams have a deep well of resources (knowledge, experience, and capability) to draw from, which allows us to meet those challenging applications head-on, in short order.

The one I’m writing about today isn’t exactly one of those challenging ones…

A machine fabricator had a special need for an Air Knife. It had to be Stainless Steel, and it had to be 30″ long. No problem so far…that’s a Model 110030SS 30″ Stainless Steel Air Knife, and it’s on the shelf. Thing is, they only needed 26″ worth of air flow; a full 30″ width was going to disturb, and maybe damage, the edges of the sheet of material that the air was being blown onto.

So we made a custom shim for the Air Knife.  Now, we make these all the time, in all kinds of configurations…hence the term “custom.”  Since this one was blowing onto a web where they didn’t want to disturb the material on the far edges, we made this shim to provide 26″ of flow, on center.  We could just as easily made it to provide 26″ of flow starting at one end or the other, or a specified distance from one end or the other.  Or 13″ of flow on both ends, with 4″ of no flow in the middle, for a total of 26″.

If your application is more challenging than a custom shim, we’ve also made Air Knives with (left to right) curved radius, special material (glass filled PEEK shown here,) flat, double-sided, and even one with end-mount threaded holes.

Regardless of how challenging (or not) your compressed air product application is, we’re here to discuss, any time you’re ready.  Call us.


Custom Solution From Stock For A Pick And Place Application

Even if you’re just a casual, infrequent reader of our blogs, you likely know that EXAIR Corporation is proud of our abilities to customize solutions for “out of the box” compressed air product applications. Oftentimes, this is offered as a custom engineered product, developed from a user’s specifications when one of our stock products just won’t work for one reason or another. For instance, when an exotic material of construction is required for heat or corrosion concerns, a special length or size is needed for space constraints, etc.

An Air Amplifier with a PTFE plug (left,) a curved Super Air Knife (center,) and a flanged Line Vac are just a few ways EXAIR has provided custom solutions.

Other times, though, we can use a stock product for something other than what everyone else uses it for.  We’ve sold Air Amplifiers for use in vacuum chucking, and pick-and-place applications – those are normally the realm of our E-Vac Vacuum Generators.  Speaking of E-Vacs, they’ve been used to deflate basketballs.

And speaking of E-Vacs (still,) I had the pleasure of helping a long-time customer solve a new problem in their growing manufacturing business.  They put their consumer products in blister packages, and recently converted one of the lines that picks & places the plastic “blister” onto the cardboard “backer” from two at a time, to six at a time.  They were using a Model 810003M E-Vac High Vacuum Generator, which worked fine, every time, with two Model 900762 1″ x 1/2″ Oval Vacuum Cups, but when they put four more of those Vacuum Cups on, they weren’t able to pick all six “blisters” every time.

These plastic blisters are smooth and non-porous, so this a “textbook” application for a High Vacuum Generator.  They’re also VERY lightweight, and were picked in a horizontal motion, so the 27″Hg that the Model 810003M can generate wasn’t actually necessary.  By replacing it with a Model 800003M E-Vac Low Vacuum Generator, the extra vacuum flow solved the problem, with no increase in compressed air consumption, which was critical for this area of their operation.

EXAIR E-Vac Vacuum Generators and Vacuum Cups are a reliable, low cost solution for most any pick & place application.

EXAIR Intelligent Compressed Air Products can solve many of your industrial/commercial challenges.  Our catalog documents the ones they’re aimed at.  Others need to be addressed by knowledge and experience…and maybe a little theory to practice.  If that’s the case, call an EXAIR Application Engineer.  We’re here to help, and we’re pretty good at it.