Tag: venturi

Adjustable Air Amplifiers: Product Overview

Published on by John BallLeave a comment
Adjustable Air Amplifier

EXAIR manufactures two types of Air Amplifiers: Super Air Amplifier™ and Adjustable Air Amplifier™.  The Air Amplifiers can be used to cool, dry, clean, ventilate, exhaust and many other uses.  In this blog, I will focus on the features and benefits of the Adjustable Air Amplifiers.

The main difference between the Super Air Amplifier and the Adjustable Air Amplifier is the fact the Super Air Amplifier has a shim inside of it that sets the gap for the air flow.  Force and flow for the Adjustable Air Amplifier is changed by turning the exhaust plug with a pin wrench.  This will open or close the gap inside, changing the amount of vacuum and air flow.  When the desired performance has been found, we have a knurled lock ring to hold the flow at the desired level. This is great for changing environments where needs are regulated to different conditions.

The Adjustable Air Amplifiers come in either 303 Stainless Steel or Aluminum and are sized from ¾” to 4”.  We offer them in a kit which will add a filter separator and a pressure regulator to the mix.  The filter will clean the compressed air, and the regulator will control the amount of pressure to enable you to “dial it in”, so to say.  We also have a deluxe kit which will add another item, Electronic Flow Control, or EFC.  This unit has a photo-electric eye to control a timing circuit to turn on and off the Adjustable Air Amplifier.  This helps to save on compressed air usage. 

The maximum temperature rating for the Aluminum Adjustable Air Amplifier is 275oF (135oC) while the stainless-steel version is rated up to a maximum of 400oF (204oC).  The stainless steel version is also used for chemical resistance and food applications. 

They do not have any moving parts, so they will last a long time and require no maintenance. Since they do not employ a motor, they create a laminar airstream which makes them effective and quiet.  They use a Coanda profile to generate a low pressure on one side to entrain a large volume of ambient air along with the primary, compressed air flow.  The Air Amplifiers amplify the exhaust air up to 24:1, making them very efficient for the compressed air used to create the output flow.  They are designed to have hoses attached to the discharge or suction side if you wish to move the air to or from another location. 

EXAIR has many uses worldwide where our Air Amplifiers are being used.  If you have any questions or would like to discuss your application, you can contact the Application Engineers at EXAIR.  We would be happy to help. 

John Ball                                                                                     

Application Engineer

Email: johnball@exair.com

Twitter: @EXAIR_jb

Buy 1, Get 40 Free

Published on by Al WooffittLeave a comment

Buy one, get one free is a phrase many of us are familiar with. Most of the time it is a good thing; we all like free stuff. What would you say to buy one, get 30 free? Or even 40 free? That’s not far off how our Air Knives perform. They entrain large volumes of ambient air, so for every 1 SCFM of compressed air you are paying for, you are getting 30–40 SCFM of additional free ambient entrained air.

So how are our Air Knives able to do this? We explain this phenomenon in more detail in this blog here, but in summary, a Super Air Knife takes advantage of the Venturi Effect. Named after Giovanni Venturi, who found out that when you increase the speed of a fluid through an orifice, the surrounding fluid will move along with it. This creates a region of low pressure, and the faster the speed, the lower the pressure. With low pressure, the air around rushes in to fill that gap and join the airstream. The quantity of ambient air that gets ‘pulled’ into the airstream is entrained air, or free air.

The engineered surface of the Super Air Knife is designed to minimize as much loss in air speed as possible, which maximizes the amount of free air that is being entrained. The ratio between free air and compressed air used is called the amplification ratio. Super Air Knives have an amplification ratio of 40:1, with our Standard Air Knives having an amplification ratio of 30:1. For comparison, a pipe with holes drilled will have an amplification ratio of between 2:1 and 5:1. As you can see, with a Super Air Knife you are getting a much better deal on your compressed air usage.

This additional free air adds more mass, which allows the Super Air Knife to do more work. You will get a harder hitting force than a comparable product while using less compressed air. This makes Super Air Knives especially good for cooling and drying applications, where moving large volumes of air is ideal.

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.

It’s not just our Air Knives that take advantage of the Venturi effect to produce large amplification ratios. Many of our products are designed with efficiency in mind, including our Air Amplifiers, Air Wipes, and Air Nozzles and Jets, to name a few. If you would like to discuss how an EXAIR engineered compressed air product can amplify your process, then give us a call!

Al Wooffitt
Application Engineer

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Giovanni Battista Venturi: A Real Renaissance Man

Published on by Russ BowmanLeave a comment

Leonardo Da Vinci (1452-1519) was the quintessential Renaissance Man: artist, philosopher, scientist, mathematician, and an inventor ahead of his time. From the 15th to 18th Centuries, though, he was primarily known for his paintings. Then, in 1797, Giovanni Battista Venturi published his “Essai sur les ouvrages physico-mathématiques de Léonard de Vinci”, which brought to light Da Vinci’s immense volume of work in the scientific fields of fluid dynamics and aerodynamics. Curiously, he was only able to do this because of the access he gained to notebooks that had been looted by Napoleon’s troops during their occupation of Milan, Italy, and brought back to France.

To conclude that Venturi was just a writer, though, would be as bad as regrettable as calling Da Vinci just a painter. Born into a rich family in northern Italy, he was a star pupil at the Jesuit seminary in his hometown of Bibbiano. He was such a good student that in 1756 – at the age of ten – he started attending the seminary in Reggio Emilia, studying logic, metaphysics, and mathematics.

As a teenager, he enrolled in the university there, studying physics and biology before returning to the seminary, where he was ordained as a priest in 1769. He taught logic at the seminary for five years, and then went on to “the big city” of Modena to teach philosophy and geometry at the university there. He was 28 when he started there, and by age 30 he was teaching physics as well.

In addition to his service in the priesthood and at the university, he also held the office of official state engineer, mathematician, and auditor, appointed by the Duke of Modena. This meant he was responsible for the construction of bridges, draining of marsh land, and implementing regulations for the building of dams. And, in his spare time, it seems he also completed the town of Modena’s historical memoirs, a task that had been started by the town historian, but had remained dormant since his passing, some 56 years earlier.

All of this would have earned Venturi local, probably regional, and perhaps even national fame…especially the part about making Leonardo Da Vinci famous for more than just his art. But what really sealed his place in the annals of history was his discovery of a particular fluidic effect: namely, that a reduction in fluid pressure results when a fluid flows from one section of a pipe into a narrower section.

The Venturi effect, named after the real Renaissance man who discovered it, Giovanni Battista Venturi who published a paper on it in 1794.

Despite its discovery in the late 18th Century, it was not actually practically applied for almost 100 years, when an American hydraulic engineer named Clemens Herschel patented a water flow meter, in 1889. He named it the Venturi Meter, and they became prolific in water works around the turn of the century. Coincidentally, Mr. Herschel had a background in bridge building too.

Today, there are numerous machines that use the Venturi effect: fluid moving educator pumps, gas inspirators in grills, stoves, & Bunsen burners, paint atomizers, wine aerators, locomotive engine steam injectors, sandblasting nozzles, scuba diving regulators…and vacuum generators.

That last one is where EXAIR gets involved. We incorporate Venturis into our E-Vac Vacuum Generators, which are capable of vacuum levels up to 27″Hg. They’re used for material handling, pick & place systems, bag/package opening, label placement, vacuum forming, and workholding, just to name a few.

The wide throat diameter of the Adjustable E-Vac makes it suitable for applications where small amounts of particulate and/or liquid may be drawn through.

They’re also used in our Reversible Drum Vac and EasySwitch Wet-Dry Vac Systems. These are just two selections from our extensive line of compressed air operated Industrial Housekeeping Products.

EXAIR Reversible Drum Vacs (left) can fill a 55 gallon drum with water in 90 seconds, using a powerful Venturi. Our Chip Trapper Systems (middle) incorporate a Reversible Drum Vac to vacuum coolant from machine tool sumps for filtration. The EasySwitch Wet-Dry Vac uses a Venturi as well for dry and liquid cleanup applications.

Giovanni Battista Venturi retired in 1813, but continued writing a number of scientific and literary works, including a collection of Galileo’s manuscripts & letters. He died in 1822, at the age of 75.

Russ Bowman, CCASS

Application Engineer
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Boosting Ventilation With Air Amplifiers

Published on by Russ BowmanLeave a comment

Entering a confined space comes with a number of risks:

  • Physical hazards: mechanical equipment, falling objects, structural collapse, etc. Historically, these account for about 20% of fatalities associated with confined space entry.
  • Engulfment hazards: that’s a less horrific way to say “buried alive.” These are similar to some physical hazards, except the danger is from asphyxiation instead of being crushed. A prime example of this would be a farmworker falling into a grain silo in such a way that their head is submerged in the volume of grain. About 11% of confined space entry fatalities involve engulfment accidents. EXAIR Line Vacs are actually used in emergency responses to these.
  • Atmospheric hazards: Without adequate ventilation, carbon dioxide can build up, displacing the oxygen that workers need to breathe. Toxic and flammable gases are in this category as well, and whether workers are asphyxiated or poisoned, failure to provide a safe atmosphere accounts for almost 60% of confined space entry deaths.

Before workers enter a confined space, permits are oftentimes required. Atmospheric monitoring and ventilation are key aspects of such permits: Monitoring to ensure an adequate level of oxygen and the reduction of toxic & flammable gases to safe exposure limits, and ventilation to make sure that happens. It’s generally recommended to have ventilation/exhaust equipment capable of providing 20 air changes per hour.

EXAIR Air Amplifiers are an easy & reliable choice for providing the required ventilation. With no moving parts to break or electrical components to fail, all they need is a supply of compressed air. So, how do we choose the right one? Since we know we need 20 air changes an hour, the first step is to determine the volume of the space. Let’s say we need to enter a 10ft x 6ft x 6ft tank:

  • 10ft x 10ft x 12ft = 1,200 cubic feet
  • 1,200 cubic feet of air X 20 changes per hour = 24,000 cubic feet of air to change per hour
  • 24,000 cubic feet/hour ÷ 60 minutes/hour = 400 cubic feet per minute

In this case, we could specify a Model 6042 2″ Aluminum Adjustable Air Amplifier, which uses just 21.5 SCFM @80psig to generate a total developed flow of 430 SCFM (see table above). Minus the 21.5 SCFM of compressed air flow, that means it’s drawing 408.5 SCFM in from the tank.

If additional airflow is required, the ring gap of the Adjustable Air Amplifier can be easily increased by threading the plug out of the body until the needed flow is achieved. A Pressure Regulator can also be used to ‘fine tune’ the compressed air supply, and hence, the ventilation flow.

EXAIR Air Amplifiers are a simple, low-cost way to move air, smoke, fumes, and even light materials. If you’d like to find out more, or if you have a potential application to discuss, give me a call.

Russ Bowman, CCASS

Application Engineer
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