EXAIR Super Air Knife vs. Blower-type Air Knife

Super Air Knife Blower Air Knife

Super Air Knife                           Blower Air Knife

A plastic company was developing thin layered films in their laboratory on a miniature prototype machine. It was designed for trial runs to make 24” wide material from various plastics, blends, and thicknesses.  They would place the plastic pellets into a hopper, and the material would be melted and extruded into a flat sheet.  To harden the material, it would land onto a cold drum, a large cylinder that had chilled water running through it.  To keep the sheet on the surface of the cold drum, they had a blower air knife.  In addition to the blower air knife, they had to use two ¼” copper air lines blowing on the outside section of the film.  Whenever they decided to make a change to their process, change material runs, or even for clean up; they had to move the blower air knife from the cold drum.  This was a hassle as it had a 3” hose attached to a blower.  It was very cumbersome and awkward to handle.  They heard about the EXAIR Super Air Knives, and they wanted me to do a comparison to their current system.  I was glad to compare the EXAIR 110224 Super Air Knife to their blower-type air knife system.

 

  1. They were getting “stretch” marks on the plastic film.
    • Blower-type air knife – Hot air is generated by the blower system. When the hot air hits the cool surface, it will cause an uneven hardening of the material, causing stretch marks.
    • Super Air Knife – It has a 40:1 amplification ratio. That means that 40 parts of the ambient air is entrained with 1 part of compressed air. Being that the ambient air is much cooler than the hot air from the blower system, it actually aides in cooling. There is no thermal shock to the material, and hardening is better and faster.
  2. They required an even force across the surface of the plastic film to keep against the cold drum.
    • Blower-type air knife – Their design had one 4” line feeding into the side of the blower air knife. This would cause 2 issues for an even force. As the velocity of the air hits the opposite side of the knife, the closed end, a turbulent air flow is developed. Also, there would be a slight negative pressures at the entrance caused by the velocity of the air entering. This turbulent mayhem and slight negative pressure are very inconsistent in force and velocity. The reason that they had to add the additional two ¼” copper lines to blow compressed air on the outside edges.
    • Super Air Knife – The flow that is delivered from the Super Air Knife is laminar. This means that the force and velocity is consistent across the entire length, even on the outside. With this even force, the film is held evenly and securely onto the cold drum.
  3. They needed maneuverability for change overs and clean up.
    • Blower-type air knife – To keep the needed pressure on the film, they had to have the blower air knife ¼” from the surface of the cold drum. So, before a change over or clean up procedure is started, they had to remove the knife and attachments. This was time consuming, cumbersome, and a headache to move.
    • Super Air Knife – With the compact design, the Super Air Knife has a large force in a small package. It has a footprint of 1 ¾” X 1 ½” X 24” long with only two ¼” NPT compressed air lines feeding it. The force measurement is equivalent from 3” to 12” away from the surface. Now, they could mount the Super Air Knife far enough to not disrupt their cleaning or change-over procedures. This saved them much time in changing to different materials and clean up.
  4. They wondered about the compressed air usage.
    • Blower-type air knife – This device does not require any compressed air to operate, but because it could not keep the film against the cold drum on the outer edges, they did have to use compressed air. With the two ¼” copper tubing at 80 psig, they were using a total of 79 SCFM of compressed air.
    • Super Air Knife – As a direct comparison to their air usage, the Super Air Knife would use 70 SCFM of compressed air at 80 psig across the entire width of the film. But with the unique design to entrain 40 parts of ambient air, it gives the Super Air Knife a powerful force. They were able to reduce the air pressure to 40 PSIG to keep the film on the cold roll, which also cut the air consumption to 41 SCFM. This efficient design helped them to save on compressed air without the added cost of the electricity to run the blower motor.
  5. Any other comparisons between the two products
    • Blower-type air knife – With the sound of the blower and the turbulent air flow, the unit was very loud. It had a sound level over 90 dBA, and with the operators working around this system, they required PPE for hearing.
    • Super Air Knife – These units are very quiet. At 40 PSIG, the sound level is only 61 dBA. (Just as a reference, the sound level is 72 dBA at 100 PSIG). This was very nice for the operators as they did not need to wear the ear plugs to work around their machine all day.

When it comes to using the EXAIR Super Air Knife, it has many benefits over the blower-type air knife. We can even include the initial cost in which we would be about 1/10 the cost of a blower-type air knife system.  For this customer above, they were delighted to replace that system with the Super Air Knife, and start running plastic film effectively, efficiently, and quietly on their miniature prototype machine.

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

Super Air Knife Provides Tension with Fine Adjustment for a Lightweight Plastic Film

A company had a small converting machine that was winding a plastic film onto a roll. The width of the plastic film was only 3” across, and the amount of tension required for a consistent roll was small. The maximum amount of tension without damaging the plastic film was 16 ounces of force.  In converting media onto rolls, it is very important to control the tension on the web to reduce defects like wrinkles, out-of-round rolls, or stretching.

They explained the setup that they were trying. They had a 4” manifold with two 2” wide “duck-foot” nozzles attached.  They sent a hand drawing to better describe what they were using. (See below).  The issue that they were seeing was too much variation in the blowing force being applied to the film.  To get near the correct blowing force, they had to start at an air pressure of about 18 PSIG.  As they ran the process, the operator would have to adjust the pressure continuously to evenly roll the film onto the core.  The process was out of control, and they wondered if EXAIR had a better way to evenly exert this force.

Dual Flat Nozzle Manifold

Dual Flat Nozzle Manifold

In analyzing the drawing and their setup, I noticed a couple of things that could cause the variations. I modified his drawing to better explain the situation (Reference below).  As compressed air leaves the two flat nozzles, the center section will overlap.  This overlap will cause turbulence in the air flow pattern.  In order to get an even distribution of forces across the width of the product, turbulence cannot exist.  Turbulence is a mixing pattern where the velocity is not linear; thus, causing high and low pressure points on the target.  The other thing that I noticed was the low air pressure that they could not go above.  This limited the precision of the incremental forces.  Because of the fixed openings of the two nozzles, they had to have a ceiling with the air pressure at 18 PSIG for 16 ounces of force.  If they had to “bump” the force level, the change was difficult to hit exactly.  If we divided the 16 ounces of force between 0 – 18 PSIG, we would get roughly 0.9 ounce of force per PSIG.  You lose the accuracy to make fine adjustments.

Overlap of air flow pattern

Overlap of air flow pattern

I recommended our model 110003, 3” Super Air Knife and a model 110303 Shim Set. The Super Air Knife blows compressed air across the entire length.  Without any overlap, the flow is laminar, and the velocity profile is moving in the same direction.  Thus, an even force across the entire 3 inches.  The Shim Set comes with additional shim thicknesses of 0.001”, 0.003”, and 0.004” thick (the standard thickness of 0.002” is installed in the Super Air Knife). In working with such a precise force requirement, they needed additional options for more control.  They could change the shims as a coarse adjustment and adjust their pressure regulator as a fine adjustment.  This combination gave them the best results to accurately dial in the correct force and not damage the material.  With the maximum requirement of 16 ounces across 3 inches of film, they were able to change the shim to the 0.004” thickness.  For the model 110003 Super Air Knife, it put them at a maximum pressure of 86 PSIG, not 18 PSIG.  Thus the increment was now 0 – 86 PSIG for 16 ounces of force, or 0.19 ounces per PSIG.  There was much more resolution to make smaller changes to the force levels thus optimizing their adjustment range.

Super Air Knife with Shim Set

Super Air Knife with Shim Set

In replacing the competitor’s product with a Super Air Knife, our customer had all the necessary control to wrap rolls of film without issue. The setup with the nozzles on a manifold design resulted in turbulence, which was noisy and produced inconsistent results.  It also restricted their adjustment resolution in changing forces, as they do not use shims.  If you would like to exert a greater degree of precision blowing with products like the Super Air Knife, please contact us. We would be happy to discuss your application and help you meet such goals.

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

Super Air Knife Helps Make More Candy Bars

It’s known in various places as Beggar’s Night, Trick-or-Treat, or just good old Halloween.  Whatever you call it, many of us have fond memories of donning a costume and a mask and roaming the neighborhood in search of candy.  Most of the grownups we encountered were only too happy to oblige our requests, in exchange for the opportunity to spend some time on the porch, enjoying a brisk autumn evening.  We won’t talk about the times when it may have rained, snowed, or been unseasonably hot…like, in the 80F range (yes, I grew up in Ohio.)

As fond as those childhood memories are, I’ve built a solid arsenal of grownup memories too, both passing out candy to neighborhood kids, and escorting my own kids around the neighborhood…of course, I always “suited up” for the occasion…

My neighbors breathed a collective sigh of relief when my sons became old enough to go Trick-or-Treating without Dad.

My neighbors breathed a collective sigh of relief when my sons became old enough to go Trick-or-Treating without Dad.

It’s probably no great secret that candy manufacturers ramp up their production in preparation for the occasion.  I had the pleasure of discussing an application with one of them recently – in fact, it was for some of the bite-size candy bars that they were about to be “Job One.”  This particular treat is produced as a continuous “strand” of nougat that is extruded onto a conveyor.  It’s then covered in peanut pieces and cut to size before being coated in chocolate.  Now, because these are bite-size bars, they’re making 3-4 times as many cuts as their regular candy bars (you know…the ones you got at the “cool houses?”) there’s 3-4 times as many peanut pieces on the belt.

To recover these pieces, they got a Model 110254 54″ Aluminum Super Air Knife Kit, and installed it to blow a light “curtain” of air across the belt in the area where the cutting takes place.  The excess pieces are blown into a trough on the side of the conveyor, where they’re cleanly and neatly recovered & recycled.  They only need about 5psig of compressed air supply pressure to do this, and it’s timed to the indexing of the belt, so not only is it reliable & effective, it’s just about as efficient as they can get.

The EXAIR Super Air Knife – quiet, efficient, and infinitely adjustable to meet the needs of most any blow off situation.

If you’d like to talk about Super Air Knives, Trick or Treating, or Halloween candy, give me a call.  I know a LOT about all of those things.

Russ Bowman
Application Engineer
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A Tale Of Two Cooling Applications

There are many, many ways to cool something down. Which method works best will depend on a number of factors, but the biggies are:

*How hot is it?
*How cool do you need it?

If you call EXAIR to discuss a cooling application, these are most likely the first questions that’ll be asked. And the answers will determine which product line we start talking about. In the title of this blog, I promised you two tales…here’s the first:

A caller from a metal fabricating shop needed to cool down metal cylinders after they were heated to 400F, and was curious to know if this was a good application for one of our products. Now, he had already answered one of our questions, so the answer to the second would tell the rest of the tale.

Turns out, they only needed to get down to 120F or so, which made this an excellent application for our Super Air Knives…they’re going to blow a laminar, high volume flow of ambient temperature air onto the part. We knew this from a past application that was so well documented that we included it in our catalog…you can read all about it on page 21 (if you don’t have one, get one – it’s free.) But for now, here’s a graph of the cooling rate comparison with the Super Air Knife:

While the fans no doubt made for large volume air movement, the laminar flow of the Super Air Knife resulted in a much faster heat transfer rate.

While the fans no doubt made for high volume air movement, it was also very turbulent.  The laminar flow of the Super Air Knife resulted in a much faster heat transfer rate.

When I showed this to the caller, that was all the convincing it took…their goal was to reach 120F in about a minute and a half.  Which, as you can see, will be no problem for the Super Air Knife.

Tale #2 is a bit different.  This was from a firearms manufacturer who needed to cool small, but hot, parts quickly, and they needed to reach room temperature.  Looking at the graph above, we know that blowing room temperature air on a hot part will cool it rapidly, until the temperature of the part begins to approach room temperature.  The solution?  Colder air, of course!

Enter the EXAIR Vortex Tube…after some discussion of the part size, shape, and their compressed air capacity, we determined the Model 3215 Medium Vortex Tube should be suitable for their operation.  By generating a cold air flow of about 20F, this replicated the higher temperature differential we see in the left-hand side of the cooling graph above…where the cooling rate was the highest.

If you’d like to talk about how “cool” an EXAIR product can make your application, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Adjustability=Flexibility=Wide Ranging Performance

Recently, I moved into a new house, and it didn’t have bathroom vent fans.  In order to prevent mold and mildew growth from the humid shower air; we decided to install them ourselves.  Going to the local home goods store, we were faced with a wall of options, with factors such as noise level, CFM rating and of course price.  Going over the myriad of possibilities was headache inducing and of course, the bathroom size was borderline between a small and mid-size unit. The decision came down to – pay more and oversize it or risk installing an undersized unit.  If only they made a unit to cover a wide variety of conditions.

Here at EXAIR, we make many types of Intelligent Compressed Air Products.  Many times, when we are talking to customers, the right size or performance needed isn’t quite clear.  Fortunately, many of the products we make are flexible, and allow for adjustability and increased range of performance to best match the specific need of the application.

For example, The Super Air Knives and Super Air Wipes have available Shim Sets to increase or decrease the air gap and change the force and flow.  The shims are easily installed, and come in a wide choice of sizes. Super Air Knives are available, from stock, in aluminum, 303SS, 316SS, and PVDF. Super Air Wipes are made from aluminum or 303 SS.

The Super Air Amplifiers also have available patented Shim Sets to fix the air flow at a predetermined setting. Adjustable Air Amplifiers have an infinitely adjustable air gap which can easily be set to match the application needs if a predetermined flow is not preferred. Adjustable Air Amplifiers also have a smaller footprint than Super Air Amplifiers and can also use the aforementioned shims to preset the air flow in applications where space is limited. These are available in 303 stainless steel and aluminum. We also have a high temperature option.

adjustable Air Amplifier

Adjustable Air Amplifier

Within our already enormous and flexible Air Nozzles & Jets product line, the Flat Super Air Nozzles have available Shim Sets to provide the ability to adjust the force and flow for blowoff or cleaning operation.  The model 1009 Adjustable Air Nozzle has an adjustable gap setting, allowing you to “tune in” the force and flow to meet the application requirement.  Also, the Adjustable Air Jet provides an adjustable gap setting to control the air flow performance. Flexibility also comes from the available materials of zinc/aluminum, aluminum, 303SS, 316SS and PEEK thermoplastic.

For vacuum generation, the Adjustable E-Vac allows for the vacuum and flow rate to be easily adjusted.  With a simple turn of the unit, the vacuum and flow levels can be changed to overcome porosity and increase or decrease the lifting power.

Adjustable EVac

Adjustable E-Vac

There are several other Intelligent Compressed Air Products that EXAIR manufactures that offer the adjustability and flexibility, such as Vortex Tubes and Adjustable Spot Coolers.

If only EXAIR manufactured bathroom fans, I could have ensured making the right choice and be able to match the performance to exactly meet my application needs.

Brian Bergmann
Application Engineer
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The Super Air Knife: It’s Super Easy To Install

One of the more commonly asked questions about one of our more commonly asked-about products is:

“How do you install a Super Air Knife?”

Well, I’m glad you (or, in this case, “they,”) asked! There are several options, and they’re all pretty simple:

The Universal Air Knife Mounting System – right out of the box, the 9060 Universal Air Knife Mounting System is ready to go. It gives you a complete range of motion, so changes to the angle, direction, and distance of the air flow to the target are quick and easy. Multiple systems provide secure support for longer Air Knife lengths.

The 9060 Universal Air Knife Mounting Systems are perfect for simple, fast installation and positioning.

The 9060 Universal Air Knife Mounting Systems are perfect for simple, fast installation and positioning.

The Air Knife Plumbing Kit – Air Knives 24″ and longer need to be supplied at multiple inlets.  A Plumbing Kit comes with everything you need to get that down to just one (lengths to 54″) or two (lengths to 108″) 1/2 NPT connections, saving you from hunting down the fittings and hose or tube, while ensuring you get sufficient air flow for optimum performance.

Plumbing Kits

The Super Air Knife Itself (part 1) – because the Air Knife cap & body are held together with a series of Stainless Steel cap screws, there’s a 1/4″-20 tapped hole, about 3/8″ deep, every 2″ along the bottom of the body. These are commonly used to install the Air Knife to an acceptable mount.

If you've got something to hold it to, mounting a Super Air Knife with 1/4"-20 fasteners is a snap!

If your equipment already has rails or a frame, mounting a Super Air Knife with 1/4″-20 fasteners is a snap!

The Super Air Knife Itself (part 2) – like I said above, when they get longer than 24″, an Air Knife needs to be supplied at both ends to ensure proper air flow across the entire length. There are MANY Super Air Knives installed over conveyor belts (a “textbook” application) that are simply supported by hard piping to both ends. The Air Knife is, essentially, as well supported as the piping.

Use the supply piping to adequately support longer lengths of Super Air Knives

Use the supply piping to adequately support longer lengths of Super Air Knives.

The Super Air Knife Itself (part 3) – I saved “part 3″ to talk about the 3” Super Air Knife specifically…see what I did there? These short, compact units can actually be supported and plumbed properly, using a Magnetic Base and a Stay Set Hose.

Install and reposition a 3" Super Air Knife using any steel surface with a Mag Base & Stay Set Hose.

Install and reposition a 3″ Super Air Knife using any steel surface with a Mag Base & Stay Set Hose.

If you’ve got an application for a Super Air Knife, we can help you get in installed, in a snap. Call me; let’s talk!

Russ Bowman
Application Engineer
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A Great Application For…Something Else

Some applications just sound like textbook situations – a caller wants to remove static charge from, and blow off a large, flat surface. That’s PERFECT for the laminar, high velocity ionized air curtain produced by a Super Ion Air Knife. All you have to do is pick the length, and we have them from 3 inches to 9 feet long.

Large, flat surfaces - perfect for a Super Ion Air Knife, right?

Large, flat surfaces – perfect for a Super Ion Air Knife, right?

Twice in the past week, I’ve been interrupted in my zeal to present the Super Ion Air Knife in these ideal situations by:

“…but I can’t move the product – I need to have something portable.”

And that’s OK. This is where it’s good to have a variety of offerings, including the portable, versatile, high performance Ion Air Gun. It’s durable and lightweight, so, if you can’t move the part, you can easily move the Ion Air Gun AROUND the part.

While it might be a "perfect" application for a Super Ion Air Knife, the Ion Air Gun works better if the product is stationary.

While it might be a “perfect” application for a Super Ion Air Knife, the Ion Air Gun works better if the product is stationary.

EXAIR Application Engineers are trained, and focused on, providing solutions. Even when something sounds “textbook,” there’s usually another way (or several) to look at it. And we’re really good at that. If you’d like to find out how to fit an EXAIR product into your compressed air needs, give me a call.

Russ Bowman
Application Engineer
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