What Makes EXAIR’s Super Air Knife so Efficient

EXAIR Super Air Knives have been designed to improve upon performance characteristics of our original Standard Air Knife design, which was already a very good performer itself. The Super Air Knife design improves air consumption and noise exposure levels. Since they use less air, they cost less to operate. Because they operate quieter, they can contribute to a quieter environment and increase safety for your personnel. 

Compressed air is such a common utility in manufacturing environments (and more) that many of us take it for granted and may not be the best stewards of its use.  EXAIR Super Air Knives are the most efficient compressed air knife on the market today and help us all to use our compressed air more wisely.

If you have homemade air knives, pipe with drilled holes or manifolds with multiple nozzles, you are in a position to play the hero and save your company compressed air and money. 

Implementing a design which uses the free air surrounding us all, is a significant feature making the Super Air Knife efficient. This is done by utilizing entrainment to move the surrounding ambient air and amplify the blast of compressed air.

Diagram showing how the Super Air Knife works

Air Entrainment is the phenomenon that occurs when air/gas under pressure is released from a device in such a way that a low pressure is generated in the immediate area of the gas discharge.  Gas from the surrounding environment is then pulled into the discharged air stream, increasing its volumetric flow rate. Using this principle, a Super Air Knife increases the air flow without increasing the amount of compressed air used.

This phenomenon is prevalent in many of EXAIR’s products but shines the brightest with EXAIR’s Super Air Knife. The Super Air Knife Sports the highest entrainment ratio out of all of the products with a whopping 40:1 ratio, this makes for a very efficient use of compressed air. With an air consumption of only 2.9 SCFM per inch of air curtain at 80 psig then the air knife would be moving 116 SCFM per inch of air curtain. That’s a lot of air!

Also the fact that entraining ambient air is just moving the ambient air with the energy within compressed air makes process is extremely quiet. This is because the outer layers of the total developed flow are lower in velocity, and serve as a sound-attenuating boundary layer.  The sound level of a Super Air Knife at any length is only 69dBA.  That’s about as loud as someone talking at normal speech 3’ away from you.

Entrainment demonstration using a 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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EXAIR Super Air Knives Blast Away the Competition

When a wide area is in need of cleaning, cooling, or drying there isn’t a better option available on the market than EXAIR’s Super Air Knife. It’s laminar and even airflow across the length has solved process problems and provided manufacturing solutions for thousands of customers. We’ve been manufacturing Air Knives for over 30 years now, with the Super Air Knife making its first appearance back in 1997. Since then, the Super Air Knife has undergone a few enhancements over the years as we’re constantly trying to not only introduce new products but also improve on the ones we have. We’ve added new materials, longer single piece knives, as well as additional accessories.

What sets EXAIR’s Super Air Knife above the competition is the ability to maintain a consistent laminar flow across the full length of the knife, particularly when compared against blower operated knives or even fans. A fan “slaps” the air, resulting in a turbulent airflow where the airflow particles are irregular and will interfere with each other. A laminar airflow, by contrast, will maintain smooth paths that will never interfere with one another.

Blower Style air knife

Blower knives are commonly seen in industry that also cannot provide a laminar airflow. Additionally, they are expensive to purchase, produce a high sound level, and require periodic maintenance. Costly maintenance that results to downtime, as well as the physical space the system takes on the shop floor are all eliminated when using the Super Air Knife.

One of the simplest alternatives to the Super Air Knife is a homemade drilled pipe. While it’s quite easy to put together with materials that are likely already available to you, the true hidden cost here is the operating cost. The high energy use related to the total compressed air consumption makes this “seemingly economic” solution into an expensive one quickly. Not to mention, these devices are not considered to be safe per OSHA 1910.242(b).

The effectiveness of a laminar airflow vs turbulent airflow is particularly evident in the case of a cooling application. The chart below shows the time to cool computers to ambient temperatures for an automotive electronics manufacturer. They used a total of (32) 6” axial fans, (16) across the top and (16) across the bottom as the computers traveled along a conveyor. The computers needed to be cooled down before they could begin the testing process. By replacing the fans with just (3) Model 110012 Super Air Knives at a pressure of just 40 psig, the fans were cooled from 194°F down to 81° in just 90 seconds. The fans, even after 300 seconds still couldn’t remove enough heat to allow them to test.

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.

Utilizing a laminar airflow is also critical when the airflow is being used to carry static eliminating ions further to the surface. Static charges can be both positive or negative. In order to eliminate them, we need to deliver an ion of the opposite charge to neutralize it. Since opposite charges attract, having a product that produces a laminar airflow to carry the ions makes the net effect much more effective. As you can see from the graphic above showing a turbulent airflow pattern vs a laminar one, a turbulent airflow is going to cause these ions to come into contact with one another. This neutralizes them before they’re even delivered to the surface needing to be treated. With a product such as the Super Ion Air Knife, we’re using a laminar airflow pattern to deliver the positive and negative ions. Since the flow is laminar, the total quantity of ions that we’re able to deliver to the surface of the material becomes greater. This allows the charge to be neutralized quickly, rather than having to sit and “dwell” under the ionized airflow.

With lengths from 3”-108” and (4) four different materials all available from stock, EXAIR has the right Super Air Knife for your application. In addition to shipping from stock, it’ll also come with our unconditional 30-day guarantee. Test one out for yourself to see just how effective the Super Air Knife is on a wide variety of cooling, cleaning, or drying applications.

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

EXAIR Super Air Knives: Controlling the Force

EXAIR has been manufacturing Intelligent Compressed Air® products since 1983.  In the beginning, the Standard Air Knives and Full Flow Air Knives were very effective at that time.  But as leaders in this market, EXAIR did not want to stop there.  We were able to engineer a more efficient and more powerful air knife, the Super Air Knife.

Super Air Knife has 40:1 Amplification Ratio

Bernoulli’s principle explains how a high velocity fluid can generate a low pressure.  The EXAIR Super Air Knife creates a high velocity air stream to produce a low pressure to entrain ambient air.   What does this mean for you?  It will save you much money by using less compressed air.  The mass of the ambient air is added into the air stream to give a strong blowing force.  The Super Air Knife has an amplification ratio of 40:1. For every 1 part of compressed air, 40 parts of ambient air is drawn into the blowing air stream.  Ambient air is free, and compressed air is expensive.  EXAIR was able to engineer a design to use the Bernoulli’s principle to make one of the most efficient air knives in the market place.    In this blog, I will discuss how you can change the air usage and force of the EXAIR Super Air Knives.

We manufacture and stock the widest range in lengths and materials.  To start, EXAIR has Super Air Knives ranging from 3” to 108” (76mm to 2,743mm) in three different materials; aluminum, 303 stainless steel, and 316/316L stainless steel.  There is no-one else in this industry that can manufacture to those lengths.  EXAIR also offers Super Air Knives in PVDF material with Hastelloy hardware for chemical resistant applications from 3” to 54” (76mm to 1,372mm).  Depending on the application requirement, temperature, chemical resistance, and OSHA and FDA regulations, we probably will have one on the shelf for you.  If EXAIR does not have it, we can make special air knives in different lengths and materials to best fit your application.

Pressure Regulators

To adjust the force and air usage a Pressure Regulator is a very helpful tool. The regulator would be considered a fine adjustment for the Super Air Knife.  With the laminar flow, the force is very consistent across the entire length; so, you can “dial” in the exact force.  EXAIR always recommends to use the least amount of pressure to “do the job” because this will save you even more money.  For the coarse adjustment, EXAIR Super Air Knives have replaceable shims.  So, you can increase or decrease the gap to get a variety of force ratings.  The Aluminum version uses colored plastic shims for visual verification.  They come stock with a 0.002” (0.05mm) red shim installed.  We have other thicknesses in our Shim Sets which includes a 0.001” (0.03mm), 0.003” (0.08mm), and a 0.004” (0.10mm) colored as amber, green, and tan respectively.

The Stainless Steel Super Air Knives come with a stainless steel shim for higher temperatures and chemical resistance.  Stock units have the 0.002” (0.05mm) thickness as well.  The Shim Sets come with three additional 0.002” (0.05mm) shims to stack.  EXAIR does have the ability to manufacture other thicknesses in stainless steel.  Similarly, the PVDF Super Air Knives use a PTFE shim for maximum chemical resistance.  It is also 0.002” (0.05mm) thick, and there are three more shims in the Shim Set.

This unique feature of using shims allows for the most flexibility in creating forces for different applications ranging from a blast to remove rocks from a conveyor to a breeze for light duty work.

We can include the pressure regulator, filter, and Shim Sets in our standard kits.  It will make our Super Air Knives a more complete system that is properly sized.  With the today’s cost in making compressed air, it is important to do it as efficiently as possible.  And with the Pressure Regulator and Shim Sets available, you can control the blowing force and air usage.  From now until December 31st, EXAIR is having a promotion.  You will receive a model 1210 Safety Air Gun for free, a $91.00 value, with qualified purchases.  (Check it out HERE).  If you have any questions about the Super Air Knife or if you would like to discuss an application, you can contact an Application Engineer at EXAIR.   We will be glad to help you.

John Ball
Application Engineer

Email: johnball@exair.com
Twitter: @EXAIR_jb

Why You Should Replace Homemade Blowoffs with Engineered Solutions – ROI

 

The cheapest and easiest solution isn’t always necessarily the best. The best example I like to use to highlight this is the incandescent light bulb. They’re definitely the cheapest to buy, but over the useful life it will cost more in electricity to operate and it won’t last nearly as long as an LED light bulb. When you compare the costs of electricity as well as the lifespan of an incandescent bulb, it becomes quite clear that the initial price difference between the two will be quickly recouped over the lifetime of the LED bulb. Once it pays for itself, it doesn’t just stop saving you electricity. These savings continue to compound.

The same can be said when comparing the Super Air Knife to a commonly seen homemade alternative, drilled pipe. While it only takes a matter of minutes to drill a few holes into a section of pipe, the operating costs (electricity required to generate the compressed air) are significantly higher than that of the Super Air Knife. In addition, it’s not nearly as effective and is considered unsafe under OSHA 29 CFR 1910.242 (b) and depending on operating pressure is likely also considered dangerous due to the high sound levels as outlined in OSHA 29 CFR 1910.95(a).

Air exiting out of drilled holes in a pipe will create a turbulent airstream. This turbulence not only contributes to the high sound level but it’s ability to entrain surrounding ambient air is minuscule. The air entrainment ratio of a compressed air solution refers to the relationship between supplied compressed air and the free ambient air that is brought into the primary airstream. The higher the amplification ratio, the less compressed air necessary to complete a similar task. For a drilled pipe, the amplification ratio is generally around 3:1. With the Super Air Knife, this is dramatically increased with an amplification ratio of 40:1.

SAK vs drilled pipe

The Super Air Knife has a precisely set air gap across the full length of the knife, allowing for an efficient and quiet laminar airstream. When compared to a drilled pipe, the air consumption is dramatically reduced as is the sound level. For example, let’s take an 18” section of drilled pipe, with 1/16” diameter holes spaced out every ½”. At 80 PSIG, each hole consumes 3.8 SCFM. With a total of 37 holes, this equates to a total of 140.6 SCFM.

3.8 SCFM x 37 = 140.6 SCFM

A Super Air Knife, operated at 80 PSIG with .002” stock shim installed will consume a total of 2.9 SCFM per inch of knife. An 18” SAK would then consume just 52.2 SCFM.

2.9 SCFM x 18 = 52.2 SCFM

140.6 SCFM – 52.2 SCFM = 88.4 SCFM saved 

Replacing an 18” drilled pipe with a Super Air Knife represents a total reduction in compressed air consumption of 63%! How much does this equate to in $$$? A reasonable average of cost to generate compressed air is about $0.25/ 1000 SCF. Let’s assume just a 40hr workweek:

88.4 SCFM x 60 mins x $0.25/1000 SCF = $1.33/hr

$1.33 x 40hr workweek = $53.20 USD

$53.20 x 52 weeks/year = $2,766.40 USD in yearly savings

The 2019 list price on a Model 110018 Super Air Knife is $397.00. By replacing the homemade solution with an 18” Super Air Knife, the return on investment is just over 38 working days of an 8-hr shift. If your plant runs multiple shifts, or works on weekends, it pays for itself even quicker.

exairsak_colormedia_600x

Once the knife has paid for itself, it doesn’t just simply stop saving you money. That savings continues to compound and add to your bottom line. Don’t waste unnecessary air (and money) by using solutions that aren’t engineered to do the job in a safe and efficient manner. Reach out to an Application Engineer and get yourself an Intelligent Compressed Air Product that’s Built to Last.

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

 

Light bulb photo courtesy of Pixabay.