The Bernoulli Principle

What do baseball, airplanes, and your favorite singer have in common? If you guessed that it has something to do with the title of this blog, dear reader, you are correct.  We’ll unpack all that, but first, let’s talk about this Bernoulli guy:

Jacob Bernoulli was a prominent mathematician in the late 17th century.  We can blame calculus on him to some degree; he worked closely with Gottfried Wilhelm Leibniz who (despite vicious accusations of plagiarism from Isaac Newton) appears to have developed the same mathematical methods independently from the more famous Newton.  He also developed the mathematical constant e (base of the natural logarithm) and a law of large numbers which was foundational to the field of statistics, especially probability theory.  But he’s not the Bernoulli we’re talking about.

Johann Bernoulli was Jacob’s younger brother.  He shared his brother’s passion for the advancement of calculus, and was among the first to demonstrate practical applications in various fields.  So for engineers especially, he can share the blame for calculus with his brother.  But he’s not the Bernoulli we’re talking about either.

Johann’s son, Daniel, clearly got his father’s math smarts as well as his enthusiasm for practical applications, especially in the field of fluid mechanics.  His kinetic theory of gases is widely known as the textbook (literally) explanation of Boyle’s law.  And the principle that bears his name (yes, THIS is the Bernoulli we’re talking about) is central to our understanding of curveballs, airplane wings, and vocal range.

Bernoulli’s Principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure (e.g., the fluid’s potential energy.)

  • In baseball, pitchers love it, and batters hate it.  When the ball is thrown, friction (mainly from the particular stitched pattern of a baseball) causes a thin layer of air to surround the ball, and the spin that a skilled pitcher puts on it creates higher air pressure on one side and lower air pressure on the other.  According to Bernoulli, that increases the air speed on the lower pressure side, and the baseball moves in that direction.  Since a well-thrown curveball’s axis of rotation is parallel to the ground, that means the ball drops as it approaches the plate, leaving the batter swinging above it, or awkwardly trying to “dig it out” of the plate.
  • The particular shape of an airplane wing (flat on the bottom, curved on the top) means that when the wing (along with the rest of the plane) is in motion, the air travelling over the curved top has to move faster than the air moving under the flat bottom.  This means the air pressure is lower on top, allowing the wing (again, along with the rest of the plane) to rise.
  • The anatomy inside your neck that facilitates speech is often called a voice box or vocal chords.  It’s actually a set of folds of tissue that vibrate and make sound when air (being expelled by the lungs when your diaphragm contracts) passes through.  When you sing different notes, you’re actually manipulating the area of air passage.  If you narrow that area, the air speed increases, making the pressure drop, skewing the shape of those folds so that they vibrate at a higher frequency, creating the high notes.  Opening up that area lowers the air speed, and the resultant increase in pressure lowers the vocal folds’ vibration frequency, making the low notes.
  • Bonus (because I work for EXAIR) Bernoulli’s Principle application: many EXAIR Intelligent Compressed Air Products are engineered to take advantage of this phenomenon to optimize efficiency:
The high speed of the air exiting the (left to right) the Air Wipe, Super Air Knife, Super Air Nozzle, and Air Amplifier creates a low pressure (just like Daniel Bernoulli said) that causes entrainment of an enormous amount of air from the surrounding environment.  This maximizes flow while minimizing consumption of your compressed air.

If you’d like to discuss Bernoulli, baseball, singing, or a potential compressed air application, give me a call.  If you want to talk airplane stuff, perhaps one of the other Application Engineers can help…I don’t really like to fly, but that’s a subject for another blog.

Russ Bowman
Application Engineer
EXAIR Corporation
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People of Interest: Daniel Bernoulli (2/8/1700-3/17/1782)

Daniel BernoulliDaniel Bernoulli was born in the Netherlands in February of 1700. Mathematics was in his bloodline as the son of renowned Swiss mathematician, Johann Bernoulli. He and Johann’s brother, Jakob, both took jobs as professors at a university in Basel, Switzerland. Fittingly, Johann taught Daniel mathematics at a very young age. Daniel Bernoulli spent some time studying a variety of topics including philosophy, logic, and medicine. Daniel obtained his Bachelor’s Degree at the age of just 15, earning his Master’s Degree just one year later.

Daniel was well-known and was highly regarded among scholars throughout Europe. After spending some time teaching Botany, he switched to physiology topics in 1743. This continued for several years when in 1750 he was appointed to the chair of physics where he taught at Basel for 26 years. During this time, he also received a total of 10 grand prizes from the Paris Academy of Sciences for work he completed in astronomy, a variety of nautical topics, and magnetism.

Daniel is most commonly known for his work in developing what is now called Bernoulli’s Principle, which discusses the relationship between fluid speed and pressure. An increase in the speed of a fluid will occur simultaneously with a decrease in the fluid’s pressure or potential energy.

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.

The air entrainment properties of some of EXAIR’s Intelligent Compressed Air Products can be explained through Bernoulli’s Principle. As high-velocity air exits the nozzle of a Super Air Knife, for example, a low-pressure area is created that speeds up and draws in ambient air at an astonishing rate of 40:1. The same also occurs with the Super Air AmplifiersAdjustable Air Amplifiers, and Air Nozzles. To find out how you can utilize this advantage to save compressed air in your processes, give us a call. An Application Engineer will be happy to help assist you in determining the most suitable products for your application.

Tyler Daniel
Application Engineer
Twitter: @EXAIR_TD


Air Entrainment & EXAIR’s Intelligent Compressed Air Products

Air entrainment is a term that we bring up quite often here at EXAIR. It’s this concept that allows many of our products to dramatically reduce compressed air consumption. The energy costs associated with producing compressed air make it an expensive utility for manufacturers. Utilizing engineered compressed air products that will entrain ambient air from the environment allow you to reduce the compressed air consumption without sacrificing force or flow.

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.

Products such as the Super Air Knife, Super Air Nozzle, Air Amplifier, and Super Air Wipe all take advantage of “free” air that is entrained into the primary supplied airstream. This air entrainment occurs due to what is known as the Coanda effect. Named after renowned Romanian physicist, Henri Coanda, the Coanda effect is used in the design of airplane wings to produce lift. As air comes across the convex surface on the top, it slows down creating a higher pressure on the underside of the wing. This creates lift and is what allows an airplane to fly.

EXAIR Super Air Nozzle entrainment

This is also the same principle which is allowing us to entrain ambient air. As the compressed air is ejected through a small orifice, a low-pressure area is created that draws in additional air. Our products are engineered to maximize this entrained air, creating greater force and flow without additional compressed air. Super Air Amplifiers and Super Air Nozzles are capable of up to a 25:1 air entrainment ratio, with just 1 part being the supplied air and up to 25 times entrained air for free!! The greatest air entrainment is achieved with the Super Air Knife at an incredible ratio of 40:1!

This air entrainment principle allows you to utilize any of these products efficiently for a wide variety of cooling, drying, cleaning, or general blowoff applications. In addition to reducing your compressed air consumption, replacing inefficient devices with engineered products will also dramatically lower your sound level in the plant. Sound level in some applications can even be reduced down to a point that would eliminate the need for hearing protection with the OSHA maximum allowable exposure limits set at 90 dBA for an 8-hour shift.

If you have inefficient blowoff devices in your facility, give us a call. An Application Engineer will be happy to help you select a product that will “quietly” reduce your compressed air consumption!

Tyler Daniel
Application Engineer
Twitter: @EXAIR_TD

Types of Air Amplifiers: Amplify Volume or Amplify Pressure

EXAIR Air Amplifiers use a small amount of compressed air to create a tremendous amount of air flow.

As Application Engineers, we help many customers with finding solutions with effective, safe, and efficient EXAIR products.  But, in some instances, we get a request for an air amplifier to increase line pressures.  EXAIR does not manufacture this type of Air Amplifier.  In doing some research on the internet, I was able to find two different types of air amplifiers.  In this blog, I will describe the difference between the pressure-type and volume-type.

The EXAIR Super Air Amplifiers are defined as a volume-type of an amplifier.  They use compressed air to generate a large volume of air flow.  The amplification ratio is the comparison between the inlet air flow and the outlet air flow.  With the EXAIR Super Air Amplifiers, we can reach an amplification ratio of 25 to 1.  They use a Coanda profile with a patented shim to create a low pressure to draw in a large volume of the surrounding air.  EXAIR manufactures a variety of different sizes, materials, and types.  But they all do the same thing, amplify the volume of air.  To give an example, model 120024 Super Air Amplifier has a 25:1 amplification ratio.  It uses 29.2 SCFM (826 SLPM) of compressed air at 80 PSIG (5.5 bar).  So, the outlet air flow is amplified from 29.2 SCFM to 730 SCFM (20,659 SLPM) of air.  This large volume of air works great for cooling, exhausting, and transferring.  But, with any type of amplification, you have to lose something.  With the volume type Air Amplifiers, the outlet pressure is reduced dramatically.

The pressure-type air amplifiers are different from the Super Air Amplifiers as this device will amplify the outlet air pressure, not the volume.  It is an air pump that has a direct dual piston that uses two different diameters.  The larger diameter uses the drive inlet pressure while the smaller diameter is used for the boost pressure.  The amplification ratio is determined by the difference in volume from the drive piston to the boost piston.  They also come in a variety of ranges and sizes.  As an example, an amplification ratio of 15:1 will increase an inlet pressure from 100 PSI (7 bar) to an outlet pressure of 1,500 PSI (103 bar).  Since the pressure-type air amplifier is an air pump, the system has to cycle.  To do this, they use pilot valves to either add the inlet compressed air to the drive piston or to relieve the air pressure from the drive piston.  This cycling portion of the operation does reduce the efficiency of the air amplifier.  The pressure-type air amplifiers are used to generate high pressure for a specific application or area and eliminate the purchase of a high-pressure air compressor.  The applications include air clamps and presses, pressure testing, air brakes, and also blow molding.  Like stated above about losing something with amplifications, the volume of air is reduced dramatically.  Generally, a reservoir tank and over-sizing will be needed for a good system.

The Application Engineers at EXAIR enjoy talking to customers about compressed air applications.  If you need more information about Air Amplifiers, you can contact us directly.  We can explain the volume-type that we manufacture or refer you to a company that makes the pressure-type.  Either way, we will be happy to hear from you.

John Ball
Application Engineer
Twitter: @EXAIR_jb

Custom Air Amplifiers for Special Applications from EXAIR

The EXAIR Super Air Amplifiers and Adjustable Air Amplifiers are used in 100’s if not 1000’s of applications and locations across the world.  For cooling, drying, and cleaning of parts as well as venting and exhausting of smokes and fumes, or dust collection – the Air Amplifiers are sure to get the job done.

The Super Air Amplifiers are made of aluminum and are sized from 3/4″ to 8″ to cover a wide range of applications. Compact and lightweight, no electricity, no moving parts, and instant on/off are just a few of the features.

The Adjustable Air Amplifiers are made of aluminum or type 303 stainless steel and are sized from 3/4″ to 4″, and with adjustable output, provide a wide spectrum of performance.  They have the same great features of the Super Air Amplifier with the added benefit of varying force and flow.

2″ Super Air Amplifier and 2″ Stainless Steel Adjustable Air Amplifier

Even with the wide variety of types, sizes, and materials of construction, a customer may have a special need and there are numerous ways that EXAIR can customize the Air Amplifiers.  I’ll touch on several from the basics to the most complex.

  • The Super Air Amplifiers come with a stock shim that sets the performance seen in the catalog. There are other shim thicknesses available if more or less flow is preferred, and they can be installed at the factory if desired.
  • The Adjustable Air Amplifiers are designed for varying output by turning the plug further in to or out of the body. If there is a performance setting that is preferred, we can test, adjust and set it to meet that performance, allowing to be installed and ready for optimum results.
  • If the use of a special material will increase the benefit of the Air Amplifier, we can explore several options with you. One customer needed an Adjustable Air Amplifier with a PTFE plug to help draw a sticky material through a process and prevent the material from adhering to the surface of the Air Amplifier.
  • For those applications where the Air Amplifier is to be installed into a piping system, custom design with flanged ends can be done. Recent designs include stainless steel Adjustable Air Amplifiers with class 150 raised face flanges, and another with sanitary Tri-Clamp style.

Adjustable Air Amplifier with PTFE Plug, Class 150 Raised Face and Sanitary Tri-Clamp Flanges

  • A special High Temperature version was developed for moving hot air to surfaces requiring uniform heating while in a furnace or oven. This special design is rated for environments up to 700°F and its surface is protected from heat stress by a mil-spec coating process.  This special High Temperature Air Air Amplifier was so popular, it became a standard offering and is in stock!

high temp air amplifier1-1/4″ High Temperature Air Amplifier

For over 35 years, EXAIR has been designing and manufacturing the best performing and highest quality products in the marketplace. If you have a special requirement and in need of a custom solution, we’ve got the experience and history to solve most problems.

If you have questions about Air Amplifiers, custom Air Amplifiers, or any of the 15 different EXAIR Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer
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EXAIR’s Huge Variety of Air Nozzles is Like an Equalizer for your Application

MCS 3035 Final

Many of us are familiar with what an equalizer (EQ) looks like and what it does. Unfortunately, sometimes they get a bad rap from so-called audiophiles, which in my opinion are defined individuals who spent so much money on their equipment they can’t afford to buy any music to play!  Typically, they insist that tone controls must be set to flat because the sound recording engineers mastering the music have already equalized the recording to perfection and if you need to attenuate or cut certain frequencies it is an indicator of poor-quality equipment, and that is simply is not true!

Let’s consider some of the reasons why an equalizer makes sense and, in my opinion, an absolute necessity. The objects and materials in the room will change the sound reproduction characteristics of any speaker system.  If you have large floor standing speakers positioned in the corners of the room, sitting directly on wood floors the speakers are now “acoustically coupled” with the floor and the walls.   On the other hand, if you move the speakers away from the wall and/or place them on spikes or stands (isolating them for the floor) you would have “acoustically de-coupled” the speakers from the walls and floor, which will reduce the bass or low-frequency loudness. This all affects the perceived loudness and/or quality of the music we want to listen too.

This is where the graphic equalizer shines, no need to move the speakers around or use speaker stands or spikes.  An equalizer will allow you to increase or decrease the loudness of multiple frequencies.  You can completely customize your sound to suit your tastes, overcome issues with your listening room acoustics, the speakers you are listening with or even anomalies with the music recording.

Like adjusting an equalizer to suit your room acoustics, speaker size and/or speaker frequency response, EXAIR understands that the need for many different options gives you the necessary adjustments for a successful application.  A few sizes of Air Nozzle, Air Jet or High Force Air Nozzles will not solve every application with the highest efficiency or effectiveness.  EXAIR’s air nozzle variety allows you to produce maximum effectiveness based upon the air pressure and air volume you have available.  Whether you need a strong blast or a gentle breeze, if you have tricky mounting positions or remote applications, EXAIR has the largest selection to choose from and solve your production problem.

We clearly state compressed air volume requirements in SCFM (Standard Cubic Feet per Minute) at a given operating pressure in PSI (Pounds per Square Inch), force at 12” from the compressed air outlet and the sound loudness in dBA at 3′ from the nozzle. These details provide the starting point for selecting the best air nozzle.

When you are looking for expert advice on safe, quiet, efficient, and engineered point of use compressed air products give us a call.   We would enjoy hearing from you!

Steve Harrison
Application Engineer
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Super Air Amplifier Overview – Vent, Exhaust, Cool, Dry, Clean

Vent, exhaust, cool, dry, clean -with no moving parts!  That tag line from the catalog section pretty much says it all about the EXAIR Air Amplifiers, both the Super Air Amplifier and the Adjustable Air Amplifiers. I want to share some more information about the Super Air Amplifiers.

In general, the air amplifiers employ the Coanda effect – a basic principle of fluid flow – to create air motion in their surrounding.  Through intelligent design, this surrounding fluid flow can be manipulated and exploited, creating an amplification of a small amount of compressed air.

Super Air Amplifier

How do they work? In the figure below – a small amount of compressed air flows into the unit (1) to an annular chamber (2). The air is then throttled through a small ring nozzle (3) at high velocity. This primary air stream adheres to the Coanda profile (4), which directs it towards the outlet. A low pressure area is created at the center (5), inducing a high volume flow of the surrounding air into the primary stream. At the exit, you have the combination of flows, resulting in a high volume, high velocity flow.

How Air Amplifiers Work
Super Air Amplifier Coanda Profile
Close Up of the Coanda Profile

The amplification ratio – the outlet airflow compared to the compressed air flow is dependent upon the cross sectional area of the inlet, and the 3/4″ Super Air Amplifiers have 12:1 amplification ratios all the way up to the 4″ and 8″ Super Air Amplifiers with 25:1 amplification ratios! That is a lot of ‘free air’ to use for cooling, drying and cleaning.  And a lot of air or smoke that can be drawn at the inlet and vented away from the area. For more on the amplification ratios, see this -blog-

Each Super Air Amplifier has a patented shim (patent#5402938) that precisely sets the compressed air flow, and shim sets are available to install to increase the force and flow as needed.

Super Air Amplifier Shims
Patented Shims for the Super Air Amplifier

The balanced outflow of air minimizes wind shear to produce a very quiet, powerful flow at sound levels up to three (3) times quieter than other air movers.  A 4″ Super Air Amplifier operated at 80 PSIG will have a Sound Level of just 73 dBA.

The video below shows the power of the Super Air Amplifier in inducing a high volume flow of surrounding air (for venting) into the primary air stream (for cooling/drying/cleaning)

Typical applications include venting weld smoke, cooling hot parts, drying wet parts, cleaning machined parts, distributing heat in mold & ovens, dust collection, and exhausting vent fumes.

If you have questions about the Super Air Amplifier or any of the 16 different EXAIR Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer
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