EXAIR’s Super Air Knife Replaces Blower-Driven Slotted Pipe

EXAIR’s Super Air Knives are the ideal fit for any application requiring a laminar “curtain” of air for blowoff purposes. The high-velocity airflow does an excellent job of cleaning off surfaces, cooling, and drying in a wide variety of applications throughout industry. These products are engineered to provide a consistent and reliable force across the full length of the knife, ensuring repeatable performance in any application.

I recently worked with a customer who manufactures a variety of bread products. In one application, they were using slotted pipes connected to a blower to clean sesame seeds off of trays after baking. The cut pipes seemed like a simple and economical solution since they had the materials there in the facility already, but the homemade blower-knives were lacking in force necessary to clean the trays.

Slotted pipes operating off of a blower didn’t quite pack the “punch” necessary to clean the trays.

When the tray wasn’t fully cleaned, residual seeds would stick to the bottom of the next loaves and burn leaving an unacceptable product for their customers. The solution was to implement a manual step of scraping off the trays which required a dedicated operator to perform this single operation. The plant runs 24/7, leading the customer to hire 3 new personnel strictly for cleaning the trays all day long.

Recent staffing difficulties due to COVID-19 led management to seek out areas where they could enhance their production efficiency and identified an opportunity in this application. EXAIR’s compressed air operated Super Air Knives provide a hard-hitting curtain of air that is very effective at cleaning. The (2) slotted pipes were replaced with (2) Model 110024SS stainless steel Super Air Knives and plumbed into their existing compressed air system.

Immediately, the higher force provided by the Super Air Knives displayed the ability to completely clean the trays and eliminate the need for dedicated operators for this part of the process. This allowed them to shift personnel to areas in the facility in desperate need of help, while still solving the problem of rejected bread loaves due to residual seeds.

If you have an application in your facility that is in need of an efficiency makeover, give us a call. Our team of experienced Application Engineers is ready to help evaluate your process and make any necessary recommendations.

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

Henri Coanda: June 7, 1886 – November 25, 1972

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.

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 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.

EXAIR also uses this Coanda profile to make some of our Intelligent Compressed Air Products™.  Like an airplane wing, our curved surface will create a low pressure.  How does this help?  Well, higher pressure will always travel to lower pressure.  Instead of lift, we use the low air pressure to entrain ambient air.  This ratio of entrained air to compressed air 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. 

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” (25.4mm) longer than the blowing length.  The Full Flow Air Knives have a port, or ports, on the backside.  Like the name states, the air blows out the entire length of the air knife.  The maximum length is 36” (914mm).  Both types 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 the engineered profile, the airstream is laminar which gives a consistent force across the entire length and makes them quiet.  Not only will they save you money by using less compressed air, but they are also OSHA safe.    

Super Air Amplifier – flow region

The Air Amplifiers use the Coanda profile in a circular form to pull in large amounts of free surrounding air.  The Coanda effect is able to generate a low pressure in the center to blow air for cooling, cleaning or removing welding smoke and debris efficiently and quietly.  The Air Knives above will 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 from a breeze to a blast.  For cleaning surfaces, this is a nice feature to “dial” in the correct amount of blowing force.  We also manufacture five different sizes ranging from ¾” (19mm) to 4” (102mm).  Both types can be ducted to remove debris, heat or smoke. 

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 application, please contact us. An Application Engineer will be happy to help you replace your inefficient blowing devices.  History has given us a way to increase efficiency for blowing compressed air.  Thank you, Henry Coanda. 

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

1note – Wikipedia – Coanda effect

Save Compressed Air with the EXAIR Electronic Flow Control

The best way to save compressed air is to simply turn it off when it’s not being used. This might seem pretty simple, but there may be processes in your facility where this couldn’t be achieved by just turning a valve. In applications where product is traveling along a conveyor, and must be dried, cooled, or blown off, there is likely some spacing in between the parts. It isn’t necessary to keep the blowoff running constantly if there’s periods of intermittent spacing. To help reduce the overall load on the air compressor, implementing a solution to shut the air off in between each part can have a dramatic impact. EXAIR’s Electronic Flow Control, or EFC, is designed to improve efficiency by reducing overall compressed air usage. It utilizes a photoelectric sensor that detects when the part is present. When it’s not, it triggers a solenoid valve to close and shut off the compressed air supply.

efcapp
EXAIR EFC

One way to use the Electronic Flow Control would be for Turning a Atomizing Spray nozzle on to coat your product.  For example see the photo below where you could use the EFC to sense the pants coming down the line. Then turn the air supply on to spray a bleach solution to get the weathered look you are after. Once the pants pass the EFC will turn the nozzle off, replacing a manual operation awhile saving compressed air and your liquid solution!

Another use would be to tell when a hopper that is being filled by a Line Vac is empty or over filled.  You can adjust the sensor and the control module to sense that the hopper is empty and it will turn the compressed air on to the Line Vac to then feed the hopper.  Then set the timer module so it will run for the length of time it takes to fill the hopper.  The other way would be to place the sensor at the top of the hopper and have it sense when the pile of media has reached the full level.

The EFC models available from stock can accommodate flows up to 350 SCFM. For applications requiring more compressed air, EFCs with dual solenoids are also available. If you have an application in one or more of your processes where intermittent compressed air use could help save you money, give us a call. We’d be happy to take a look at the application and help determine just how quickly the EFC could start paying YOU

Jordan Shouse
Application Engineer

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Twitter: @EXAIR_JS

Customer Saves Nearly $7000 by Installing Super Air Knives on Converting Machine

EXAIR proves often that we’re able to work with you to create a customized solution that best serves your application. Recently I had the pleasure of working with a customer who wanted a better solution on their tissue paper converting machine. What they currently had was too loud, too inefficient, and they knew there was a better way.

The machine was an old rewinder used to convert webs of tissue paper ranging from 99-115” in width. Installed on the old machine was a 115” drilled pipe with 1/16” drilled holes spaced out every ½” along the length of the pipe. This was using a substantial amount of compressed air and was significantly louder than they would’ve liked. They purchased a new machine that had an EXAIR Super Air Knife already installed and working great, so they reached out to us for some help.

The customer conducted some time studies to determine exactly how much air this application required. The air blast ran for 500 seconds per hour, equating to 8.3min/hr of air usage. The operation runs 24/7, but with time spent doing changeovers the actual run time is closer to 20hrs.

20hrs x 8.2min = 166 min/day of air usage

166min x 365 = 60,590 min per year

A 1/16” unpolished, drilled hole will consume 2.58 SCFM at a pressure of 60 PSIG. With a total of 228 holes across the full pipe, this is quite a bit of compressed air.

2.58 SCFM x 228 = 588 SCFM of compressed air

588 x 60,590 min = 35,626,920 SCF

Considering the lightweight nature of the material, we recommended that the customer use our .001” shim to cut the flow from our stock Super Air Knives to their minimum. We recommended our Model 110054-.001 and Model 110060-.001. At 60 PSIG, a Super Air Knife with .001 shim installed will consume 1.15 SCFM/inch of knife length.

114 x 1.15 SCFM = 131 SCFM of compressed air

131 x 60,590 min = 7,937,290 SCF

Installing the Super Air Knives with .001” shim reduced their air consumption by 77% for a total air savings of 27,689,630 SCF each year. But, what does this mean in terms of money? To determine the cost of compressed air, we use the approximate value of $0.25/1000 SCF.

27,689,630 SCF x $0.25/1000 = $6,922.41

In just one year, on this one single machine, this customer was able to save almost $7k per year. These knives quickly pay for themselves, then begin to contribute to your bottom line. All of this in addition to lowering the sound level and providing a safer working environment for their operators.

If you have areas in your facility that are using air inefficiently, contact an EXAIR Application Engineer today.

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