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


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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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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Sound Power Vs Sound Pressure

EXAIR Intelligent Compressed Air Product dBA ratings as compared to other sounds

When trying to explain or state a number associated with how loud a sound or noise is it can be somewhat confusing or at the very least, ambiguous.  This blog will help to make it clear and easy to understand the difference between Sound Power and Sound Pressure.

Sound Power is defined as the speed at which sound energy is radiated or transmitted for a given period of time.  The SI unit of sound power is the watt. It is the power of the sound force on a surface of the medium of propagation of the sound wave.

Sound Pressure is the sound we hear and is defined as the atmospheric pressure disturbance that can vary by the conditions that the sound waves encounter such as furnishings in a room or if outdoors trees, buildings, etc.  The unit of measurement for Sound Pressure is the decibel and its abbreviation is the dB.

I know, the difference is still clear as mud!  Lets consider a simple analogy using a light bulb.  A light bulb uses electricity to make light so the power required (stated in Watts) to light the bulb would be the “Sound Power” and the light generated or more specific the brightness is the “Sound Pressure”.  Sound just as with the light emitting from the bulb diminishes as the distance increases from the source.  Skipping the math to do this, it works out that the sound decreases by 6 dB as the distance from the sound source is doubled.  A decrease of 3dB is half as loud (Sound Pressure) as the original source.  As an example sound measured at 90 dB @ 36″ from the source would be 87dB at 54″ from the sound source or 84dB at 72″.

We at EXAIR specialize in making quiet and efficient point of use compressed air products, in fact most of our products either meet or exceed OSHA noise standards seen below.

OSHA Noise Level

EXAIR also offers the model 9104 Digital Sound Level Meter.  It is an easy to use instrument for measuring and monitoring the sound level pressures in and around equipment and other manufacturing processes.

If you have questions about the Digital Sound Level Meter, or would like to talk about any of the quiet EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR or any Application Engineer.

Steve Harrison
Application Engineer

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Super and Adjustable Type Air Amplifiers

The EXAIR Air Amplifiers are a powerful, efficient and quiet air mover, whose power can be harnessed for blowoff, cooling and ventilation applications. Using a small amount of compressed air, air amplifiers pull in large amounts of surrounding air to produce a high volume, high velocity outlet flow.  Quiet and efficient, output flows with amplification ratios of up to 25 times are possible. There are two types, the Super Air Amplifier and the Adjustable Air Amplifier.

The Super Air Amplifier, with sizes ranging from 3/4″ to 8″, has a patented design (patent #5402938) that uses a special shim to maintain critical position of the components parts. It is through this critical gap setting that a precise amount of compressed air is passed at exact intervals controlled by the shim toward the center of the of the Super Air Amplifier.  The jets of air create a high velocity flow across the entire cross sectional area, which in turn pulls in large amounts surrounding air, resulting in the amplified outlet flow.  Because the outlet flow remains balanced and minimizes wind shear, sound levels are typically three times lower than other types of air movers. The shims are available in thicknesses of 0.003″ (supplied as standard), 0.006″ and 0.009″, and changing to a larger shim will increase the force and flow of the outlet air. The 8″ Super Air Amplifier is supplied with a 0.009″ shim, with a 0.015″ shim available.

2″ Super Air Amplifier and Patented Shim Design

For high temperature applications (up to 700°F/374°C) a special 1-1/4″ High Temperature Air Amplifier is available, with performance equal to the 1-1/4″ Super Air Amplifier. Its surfaces are protected from heat stress by a mil-spec coating process. The High Temperature Air Amplifier is highly effective at pushing large amounts of hot air to areas that typically remain cool.

The Adjustable Air Amplifier, with sizes ranging from 3/4″ to 4″, does not use a shim, and has an infinitely adjustable air gap, which regulates the air consumption and outlet flow from a light breeze to a powerful blast. A highly effective air mover, it can be tailored to meet the exact air flow and force of your specific application. They are available in aluminum and in stainless steel (Type 303) for food service, higher temperatures (400°F/204°C) and corrosive environments.

2″ Adjustable Air Amplifier, in Aluminum or Stainless Steel

Force and flow of the Adjustable Air Amplifier is changed by loosening the knurled lock ring and turning the exhaust end to open or close the gap.  Once the desired force and flow is achieved, the knurled ring can be tightened to lock the device at the current setting. Typically, an air gap of 0.002″ to 0.004″ provides the required performance.

The table below summarizes the key features of the Super Air Amplifier and Adjustable Air Amplifier.  Please contact an Application Engineer if you need assistance in making a selection.

Air Amp Selection Chart

Note that EXAIR can manufacture special Air Amplifiers to your specification including special flanged mounting style or with a PTFE plug to avoid sticky material build up.

To discuss your application and how a Super or Adjustable Air Amplifier or any EXAIR Intelligent Compressed Air Product can improve your process, feel free to contact EXAIR, myself, or one of our other Application Engineers. We can help you determine the best solution!

Brian Bergmann
Application Engineer

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Two Types of Air Amplifiers – Volume and Pressure

When the topic of Air Amplifiers comes up, there are two avenues to consider –  is it the air pressure or the air volume that you wish to amplify?  There exists technologies to amplify either parameter, and we will examine them both.

There may be equipment or processes within a facility that operate best at air pressures higher than can be delivered, due to air compressor limitations or the supply system. An Air Pressure Amplifier can take the existing compressed air supply, and boost the pressure allowing for the higher needed air pressure without requiring a dedicated compressor capable of operating at the higher pressure.

An Air Pressure Amplifier is basically an air pump, driven by a portion of the compressed air supply.  The pump cycles and compresses the remaining amount of compressed air to a higher outlet pressure. This higher output pressure can be used to operate the equipment or process that required the pressure levels that the base system could not supply. The drawback is that the pump system consumes a good amount of the compressed air volume, to power the pump which reduces the amount of air available for other equipment or processes.  This drives up the compressed air consumption for the system, and requires the extra capacity to operate.

The other type of Air Amplifier is the kind that amplifies the air flow volume. EXAIR manufactures this type of amplifier.


The air flow amplification works by taking compressed air (1) and directing into an annular chamber (2). It is then throttled through a small ring nozzle (3) at high velocity. This primary stream of air adheres to the Coanda profile (4) and is directed through the outlet. A low pressure area is created at the center, inducing a high volume flow (5) of surrounding air to be drawn in and added to the main air stream. The combined flow of primary and surrounding air exits as a high volume, high velocity flow.


EXAIR manufactures (2) types of Air Amplifiers, the Super Air Amplifier and the Adjustable Air Amplifier.  In addition, a special model for High Temperature applications is available.  Sizes range from 3/4″ (19mm) to 8″ (203mm) to meet most air flow requirements.  Air amplification ratios start at 12:1 for the 3/4″ model and increase to 25:1 for the 4″ and 8″ models.

Charts and tables are available to help determine the right Air Amplifier for the job.

If you have questions about the Air Amplifiers, or would like to talk about any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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