Category: Air Knife

Customizing Blow-off Applications

Published on by codybiehleLeave a comment

EXAIR Blowoff Systems are a combination of EXAIR air Nozzles, mag bases and Stay Set hoses. They are available in single or dual outlets and can change the length of the Stay Set Hose and/or the type of nozzle. The flexibility of this product comes in handy when an application require multiple point blowoff or requires different force values from each nozzle. Customizing allows you to fit the nozzles directly to the need of the application.

Example of an EXAIR Blowoff System – these can be customized with different nozzles or length of hose to suit your application best.

One example of this came from a customer who was running a 1950’s era Benchmaster OBI press to stamp out copper lamination and spring steel. There current set-up which can be seen bellow was not really that effective, was loose/floppy, and had been glued together. All of this made it hard for the Technician to line everything up to eject the parts. The technician reached out to us to see if we could substitute some nozzles on our dual Blow-off system with the stay set hose and dual port magnetic base (as seen above). We were able to piece together a special kit for them to swap out one of the 1103 Mini Super Air Nozzles with a 1126 1″ Flat Super Air Nozzle to match the current set-up.

The Customer’s current ejection set-up in the punch press

Customizing the nozzles in Blow-off systems can allow for better coverage on awkwardly shaped parts that might have a mix of both smooth surfaces and crevices. Also changing out the length of the Stay Set hoses that come with the kits can allow you to reach all sides when centrally located mounting is not applicable. Using two different length stay set hoses can also allow for two different blow off points to share the same mounting and air line; this means your maintenance team wont have to bring in multiple drops which I’m sure they will appreciate.

Not only can we customize blowoff systems for you, since we manufacture the products here in Cincinnati, OH, we can provide custom features and performance characteristics for you. Our wonderful team of Engineers (just don’t tell them I said that) can design special air knives, nozzles, and even air amplifiers to fit your needs. The image below shows custom Air Amplifiers (with customer specified flanges) that we have built. We can customize our products to fit your needs.

Custom Stainless Steel Sanitary Flange Air Amplifier
Special Curved Super Air Knife

If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Cooling With Compressed Air: Air Knife vs. Vortex Tube Products

Published on by Russ BowmanLeave a comment

One of the popular applications for the EXAIR Super Air Knife is cooling. When mounted so that the air flow sweeps across the surface of a product, the laminar nature of the air flow works to maximize the contact time with the surface, which also maximizes the heat transfer…which means better product cooling than, say the turbulent air flow from a fan or blower.

Still, it’s common for us to get questions about how to provide even faster cooling.  Well, the two main variables in heat transfer are the time the air is in contact with the product, and the difference in temperature between the product surface and the air.

We’ve already touched on “time in contact”…sweeping the laminar flow across the surface at as low of an angle as you can, against the direction of travel, is ideal.  Combine that with the extraordinarily high air flow due to the entrainment level of the Super Air Knife, and you get an awful lot of air in contact with the surface, for a (relatively) long time.

Super Air Knives cool steel casting from 1,725°F (940°C) to 200°F (93°C) in under 20 minutes.

The difference in temperature, though, is a little trickier to deal with.  Because the developed flow from the Super Air Knife is mostly entrained ambient temperature air from the surrounding environment, you’re at the mercy of that ambient temperature.  One of the most common question – of the common questions about faster cooling – is, can you feed a Super Air Knife with cold air from a Vortex Tube?  The answer is no, for two big reasons:

  • The Vortex Tube’s cold flow can’t be back pressured, which would happen if you fed it through the plenum of a Super Air Knife and tried to make it come out the 0.002″ gap.
  • Even if it did work, the entrained air which, remember, makes up most of the flow, is still room temperature…meaning the total developed flow is a lot closer to room temperature than however cold the air you fed the Super Air Knife would be.

If the surface area to be blown on, to effect the desired cooling, is suitably sized, a Vortex Tube can be installed at a low angle to sweep its flow across.  The cold air flow from a Vortex Tube can also be distributed to more than one point, to cover more surface area.  That’s exactly what we do with our Dual Point Hose Kits for our Adjustable Spot Coolers, Mini Coolers, and Cold Gun Aircoolant Systems:

Dual Point Hose Kits can distribute air to both sides of a part, or onto a wider surface, than a single point discharge.

In fact, both the Single and Dual Point Hose Kits have a variety of tips they can be fitted with for tighter, or broader, flow patterns:

In some cases, multiple Vortex Tube products can be used, and, in other situations, the cold air can be directed through a manifold of some sort:

There are numerous methods to distribute the cold air flow from a lone, or a series of, Vortex Tubes.

Applications like the two on the right above (setting molten chocolate in molds, and keeping those white plastic parts during ultrasonic welding, respectively,) commonly start out as Air Knife inquiries, but the need for refrigerated air leads to creative Vortex Tube solutions.

If you’d like to discuss whether your application is best served by a Super Air Knife or a Vortex Tube Spot Cooling Product, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Video Blog: Importance of Point-of-Use Filtration

Published on by Tyler DanielLeave a comment

When operating any of your Intelligent Compressed Air Products, something that often gets overlooked is the importance of delivering clean, dry air to those point-of-use products. Many of our products have very tight orifices to help reduce the volume of compressed air they consume. In addition, most have no moving parts to wear out and require no maintenance. That is, unless you’re using unfiltered compressed air.

Rust and scale are commonly found within the distribution system inside your facility. Old iron pipe and receiver tanks are the common culprits. A common misconception is that the air is already filtered as it exits the compressor. While this may be true, there’s still places in the distribution system that can cause issues downstream.

To eliminate the hassle of taking things apart to periodically clean, EXAIR recommends installing a point-of-use filter for all of our Intelligent Compressed Air Products. Kits are available for purchase that come with a properly sized filter to ensure your air is sufficiently clean. To see how quickly debris can clog your products, check out my video below demonstrating the difference between dirty and clean air with a Model 110006 6″ Super Air Knife.

If you’ve already purchased and installed products without filters, it’s never to late to go back and install one. Contact an EXAIR Application Engineer today and we’ll be happy to help you determine the proper size for the volume of air you’re products need.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD

Usefulness of a Coanda Profile

Published on by John BallLeave a comment

How did a past inventor help generate efficient compressed air products for EXAIR?  In the early 20th century, Henri Coanda who was a Romanian aeronautical engineer that built an experimental Coanda-1910 airplane.  There are some debates if the airplane actually flew, but he invented a curved surface for a wing to generate a Coanda effect. The Coanda effect is the “tendency of a fluid jet to stay attached to a convex surface”1.   Thus, a moving stream of fluid will follow the curvature of the surface rather than continuing to travel in a straight line.  The Wright Brothers who flew the first airplane in the state where EXAIR is located, Ohio, used the Coanda effect to create lift.  With a curved profile, the air will adhere to the surface, causing a low pressure which makes the airplane fly.

Standard Air Knife

Super Air Amplifier with shims

EXAIR uses this Coanda profile to make some of our Intelligent Compressed Air Products™.   Like the airplane wing, our curved surface will also create a low pressure.  How does this help?  Well, high pressure will always travel to low pressure.  Instead of lift, we use the low air pressure to entrain ambient air.  This ratio is what we call the amplification ratio.  The higher the amplification ratio, the higher the efficiency for a blowing device. Two main compressed air products that EXAIR manufactures use this type of profile; Air Knives and Air Amplifiers.  I will cover both below.

Compressed air flows through the inlet (1) to the Standard 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 optimize entrainment of air (4) from the surrounding environment.

The Air Knives that use the Coanda profile blows air along the length of the knife at a 90o angle from the exit.  We offer two types; the Standard Air Knife and the Full Flow Air Knife.  The Standard Air Knives are made in Aluminum or Stainless Steel with blowing widths up to 48” (1219mm).  The inlet ports are at each end; so, the overall length is 1” (25mm) longer.  The Full Flow Air Knives have the port or ports on the back.  The air blows out the entire length of the air knife.  The maximum length is 36” (914mm).

Both types of air knives use the Coanda profile to generate a low pressure as the air exits the gap and “hugs” the curve (reference photo above).  This low pressure draws ambient air into the air stream at a 30:1 amplification ratio for both the Standard Air Knife and Full Flow Air Knife.  So, for every one part of compressed air, we entrain 30 parts of ambient air.  Besides efficiency, it also adds mass to the air stream for a hard-hitting force.  With this engineered profile, the air stream is laminar which gives a consistent force across the entire length and reduces noise levels.  Not only will they save you money,  but they are also OSHA safe.

Air Amplifiers use the Coanda Effect to generate high flow with low consumption.

The Air Amplifiers use the Coanda profile in a circular form to pull in dramatic amounts of free surrounding air.  The Coanda effect is able to generate a low pressure to blow air for cooling, cleaning or removing smoke and debris efficiently and quietly.  The Air Knives above blow a flat stream of air while the Air Amplifiers will blow a conical air stream.  They can reach amplification ratios up to 25:1. The Super Air Amplifiers use a patented shim to increase efficiency.

Unlike fans, they blow a laminar air stream for quick cooling.  They do not have any moving parts or motors to wear, so they are very quiet.  EXAIR manufactures five different sizes from ¾” (19mm) to 8” (203mm).  The Adjustable Air Amplifiers have a plug that can be adjusted to control the blowing force from a breeze to a blast.  For cleaning surfaces, this is a nice feature to “dial” in to exactly what you need.  We also manufacture five different sizes in aluminum and stainless steel ranging from ¾” (19mm) to 4” (102mm).  Both Air Amplifiers can be attached to ducts to remove debris, heat or smoke from the area.

Utilizing the Coanda effect allows for massive compressed air savings. Whether it is a flat or round air stream, EXAIR can do this with high amplification ratios.  If you would like to discuss further how our Air Knives or Air Amplifiers can help you in your applications, please contact us. An Application Engineer will be happy to help you.  History has shown us a way to increase efficiency when using compressed air.  And you can take advantage of it with the Coanda profile.  Thank you Mr. Henri Coanda.

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

 

1note – Wikipedia – Coanda effect