Tag: entrainment

Venturi Effect in Use

Published on by jasonkirbyLeave a comment

The Venturi effect describes the phenomenon where a fluid, such as air or water, accelerates as it passes through a constricted section, resulting in a decrease in pressure. This occurs because the fluid is drawn into the narrower area, and the increase in velocity leads to a corresponding drop in pressure. The effect is named after Giovanni Battista Venturi, who first articulated this principle in 1797.

A perfect example of the Venturi Effect can be found in our Air Amplifiers. Compressed air enters through the air inlet and flows into an annular chamber, where it is accelerated through a small ring nozzle. This high-velocity primary airstream follows the Coanda effect, guiding it toward the outlet. As a result, a low-pressure zone forms at the center, drawing in a significant volume of surrounding air into the primary flow. The mixture of the primary airstream and the surrounding air is then expelled from the Air Amplifier at a high volume and velocity.

The Venturi Effect is represented in amplification ratios. A ratio represents the relationship between two quantities, indicating how many times one value is contained within another. In the case of the Super Air Knife, this ratio illustrates the volume of ambient air that is drawn in alongside the primary flow of compressed air. With an impressive amplification ratio of 40:1, the Super Air Knife incorporates 40 parts of ambient air for every single part of compressed air, making it one of the most efficient air-operated knives available. This addition of mass enhances the device’s ability to deliver a powerful force, enabling it to perform more effectively in various applications.

The Venturi effect is integral to various EXAIR products designed for cooling, drying, and cleaning, alongside our vacuum generators. If your facility has a process that could benefit from an Intelligent Compressed Air solution, please reach out to us. We would be pleased to discuss your specific application and develop a solution that not only lowers your compressed air expenses but also enhances worker safety.

Jason Kirby
Application Engineer
Email: jasonkirby@exair.com
Twitter: @EXAIR_jk

Amplification Ratio: Super Air Knives

Published on by John BallLeave a comment
Super Air Knife

Earlier, I wrote a blog about how entrainment works with EXAIR products by using two phenomena, Coanda Profile and the Venturi Effect.  You can find it here, “Entrainment: how it works and why EXAIR products use it.”  In this blog, I will cover the Super Air Knife specifically and how it uses the Venturi Effect to entrain the surrounding air. 

This Venturi Effect is named after Giovanni Venturi, who discovered that by increasing the velocity through an orifice, the surrounding fluid will move with it, generating a lower pressure.  The higher the velocity, the lower the pressure.  When you have a low pressure, the surrounding air will fill that void and move into the airstream.  The amount of ambient air that gets “pulled” into the airstream is the entrainment, and this amount as compared to the inlet flow is the Amplification Ratio. 

So, what does this mean?  The definition of a ratio is the relationship between two amounts showing the number of times one value is contained within the other.  For the Super Air Knife, it is a value that shows the amount of ambient air that is drawn in along with the primary, compressed air flow.  With an amplification ratio of 40:1, that means that there are 40 parts of ambient air for every 1 part of compressed air, which helps make them the most efficient compressed air operated Air Knives available on the market.  By adding mass, the Super Air Knife will give a hard-hitting force to do more “work”. 

Most people think that compressed air is free, but it is most certainly not.  Because of the amount of electricity required to produce compressed air, it is considered to be a fourth utility for manufacturing plants.  To save on utility costs, it is important to use compressed air as efficiently as possible.  So, the higher the amplification ratio, the more efficient the compressed air product.  Manufacturing plants that use open fittings, copper tubes, and drilled pipes for blowing are not efficient.  These types of products generally have a very low amplification ratio, somewhere between 2:1 to 5:1.  When EXAIR began manufacturing in 1983, we knew that there was a better way of saving compressed air by increasing the amplification ratios of our various air moving products.

I like to explain things in everyday terms.  For this analogy, we can use the amplification ratio as represented by gas mileage.  Like your car, you want to get the most distance from a gallon of gas.  With your compressed air system, you want to get the most utilization for the compressed air being expended.  With an EXAIR Super Air Knife, it has a 40:1 amplification ratio; or, in other words, you can get 40 MPG.  But, if you use drilled pipes, copper tubes, etc. for blowing, then you are only getting 2 to 5 MPG, so to say.  If you want to get the most “mileage” for the money you spend on creating compressed air, you want to check the “fuel efficiency” of your blow-off components.

EXAIR manufactures many blow-off items with high amplification ratios to save compressed air. EXAIR can help “tune up” your blow-off systems to make them efficient and safe by contacting an Application Engineer.  We will be happy to help you.  

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

Entrainment: How it Works and Why EXAIR Products are Engineered to Use it.

Published on by John BallLeave a comment
EXAIR Super Air Nozzle entrainment

Because of the large amount of energy required to run an air compressor, the pneumatic system is considered the fourth utility in a manufacturing plant.  And saving this commodity and using it as efficiently as you can, should be a priority.  EXAIR has many products that can save energy by using less compressed air.  And the story behind this is entrainment explained by Bernoulli’s equation. 

Bernoulli’s principle explains how a high velocity fluid can generate a low pressure.  (You can read more about Bernoulli’s principle HERE.)  Let’s start by looking at Equation 1.

Equation 1:

P + d * V2/2 = C 

P – pressure

d – density of the fluid

V – velocity

C – a constant

As you can see from Equation 1, when the velocity goes up, the pressure must go down.  When we have a lower pressure, then the surrounding fluid will fill that void.  Since air is a fluid, we can use high velocity to entrain the surrounding ambient air.  The free air will add to the compressed air to give the airstream mass for a hard-hitting force.  This ratio of ambient air to compressed air is called entrainment.  The higher the entrainment, the more efficient the product.  Bernoulli’s Principle can be applied in two ways; as a Coanda and as a Venturi.  EXAIR uses both methods in our products for creating low-pressure effects. 

Compressed air flows through the inlet (1) to the Full Flow (left) or Standard (right) 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.

The first way is from a Coanda profile.  Coanda, named after Henri Coanda, noticed that a fluid would “hug” a curved surface.  (You can read more about Henri Coanda HERE.)  The high velocity air going around the curved surface will generate a low pressure above it.  You can imagine an airplane wing generating that low pressure to fly.  We use this with our FullFlow and Standard Air Knives, our Air Wipes, and our Air Amplifiers.  With a Coanda profile, we can get an amplification ratio up to 30:1, which means that for every 1 part of compressed air, 30 parts of ambient air is entrained.  We are able to create an efficient blow-off device by using the Coada profile. 

To generate even lower pressure, this can be done by a Venturi.  This phenomenon is named after Giovanni Venturi, who discovered that by increasing the velocity through an orifice, the surrounding fluid will move with it, generating a lower pressure.  (You can read more about Giovanni Venturi HERE.)  Remember the higher the velocity, the lower the pressure from Equation 1 above.  We use the Venturi effect on our Super Air Knives, E-Vacs, Line Vacs, and Super Air Nozzles.  As compared to our FullFlow and Standard Air Knives, the Super Air Knives can generate an amplification ratio of 40:1.  As an engineered product, we were able to increase efficiency even further. 

EXAIR has been manufacturing Intelligent Compressed Air® products since 1983.  We can provide solutions that are efficient, effective, and safe for blow-off systems.  In comparison, the other blow-off devices are like incandescent light bulbs, while EXAIR products are like LED light bulbs.  Entrainment of free ambient air can save you a lot of money when using your compressed air system.  If you would like to discuss solutions to use less compressed air and improve your bottom dollar, an Application Engineer at EXAIR is available to help.   

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

EXAIR Super Air Knife Promotion

Published on by Jordan T ShouseLeave a comment

Starting in November through the end of the month, order any EXAIR Super Air Knife and receive a free 1210 Soft Grip Safety Air Gun. This applies to all stock Super Air Knifes. The Model 1210 is a top pick for many industrial applications. With the ideal combination of forceful air flow, quite noise level, and compressed air usage there’s not many applications that aren’t suited for this style of gun. All EXAIR’s Safety Air Guns are compliant with OSHA 1910.242 (b), relating to dead-end pressure, and can keep your personnel safe. 

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 industry, EXAIR did not want to stop there.  We were able to engineer a more efficient, more powerful, and much quieter air knife, the Super Air Knife.  In this blog, I will discuss the features and benefits that the Super Air Knives can offer.

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 that low pressure to entrain ambient air.   What does this mean for you?  It will save you money by using less compressed air.  The mass of the ambient air is added to the compressed air stream to give it a strong blowing force.  The Super Air Knife has an amplification ratio of 40:1, which means that for every 1 part of compressed air, 40 parts of ambient air are drawn into the air stream.  Ambient air is free. Compressed air is expensive.  EXAIR was able to engineer a design to use Bernoulli’s principle to make one of the most efficient air knives in the marketplace.

What else makes EXAIR unchallenged?  We manufacture and stock the widest range of lengths and materials.  To start, EXAIR has Super Air Knives ranging from 3” to 108” (76 mm to 2,743 mm) in three different materials; aluminum, 303 stainless steel, and 316/316L stainless steel.  EXAIR also offers Super Air Knives in PVDF material with Hastelloy hardware for chemical resistant applications from 3” to 54” (76 mm to 1,372 mm).  Depending on the temperature requirement, chemical resistance, OSHA and FDA regulations, or application details, 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.  You can read more about specials HERE. 


Air Knives are available in Super, Standard and Full-Flow styles, and all versions are able to be customized to a customer’s specific needs. For help solving any specific blowoff problems, please contact an Application Engineer. All Air Knives are CE compliant.

With today’s cost of making compressed air, it is important to use it as efficiently as possible.  The Standard and Full Flow Air Knives would be good options to use.  But the best way to conserve is with the Super Air Knife.  In the U.S. and Canada, EXAIR offers a 30-day unconditional guarantee on our cataloged items, so you can try them out.  You can see for yourself how effective these compressed air guns can be.  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.  And until December 31st, 2024, EXAIR is offering a free Soft Grip Safety Air Gun, a $115.00 value, as a complimentary gift for qualifying online Super Air Knife purchases. 

Jordan Shouse
Application Engineer
EXAIR Corporation
Visit us on the Web
Follow me on Twitter
Like us on Facebook