Thinking Outside of the Box

Over the years of working at EXAIR, I have spoken to thousands of customers. The applications we discuss can run the full range that is showcased in the Solutions section of our website. It is always fun to approach applications when we have to think outside of the box for a solution. Throughout the Application Engineering department, our level of experience here combined with the customer’s knowledge of their setup, sometimes results in a solution that is not straightforward. Sometimes, we have to think outside of the box.

What kind of application may we have encountered where the obvious solution wasn’t the one that worked? One of the best applications that came to mind for me is when a customer was attempting to lift/pick up a very porous piece of filter media like the pre-filter from a Heavy Duty HEPA Vac. This material is extremely lightweight and porous. When hearing from a customer, I want to pick this material up, my mind quickly goes to the E-Vac Vacuum generators which are used to generate vacuum to operate suction cups.

In-Line E Vac picking up a block of cut extrusion.

With this material however, the vacuum flow needed is quite extensive and there is another product which is going to be a more efficient use of compressed air. That product, the Super Air Amplifier. As you can see in the photo below, a 2″ Super Air Amplifier easily lifts the porous material and because the suction side is a nominal hose size a hose can easily be attached if needed. The image shows a single amplifier lifting a larger sheet from a bench, these could be organized in an array like suction cups to pick materials up.

Model 120022 – 2″ Super Air Amplifier picking up a porous pre-filter material.

The moral of the story is to keep an open mind for solutions, while one path will always work other paths may become a more efficient manner. These solutions don’t always fit inside a box nice and neat. The Super Air Amplifier fit this because the amount of air entrained is tremendous and can easily be utilized to pull low vacuum force/high flow applications. This is very similar to fume evacuation which would be a “normal” application for the Super Air Amplifier.

If you want to discuss any point of use compressed air application with us, contact an Application Engineer and let us help you determine the solution your job needs.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

EXAIR Line Vacs™: We can do specials…

Here is a question; what is an eductor?    Eductors are also called ejectors, Venturi jets, aspirators, jet mixers, or jet pumps.  Eductors use either compressed gas or liquid to generate a vacuum by a Venturi effect which is based on Bernoulli’s equation.  (You can read more about the person here, “People of Interest: Giovanni Battista Venturi March 15, 1746 – April 24, 1822 By Tyler Daniel”.)  They can be used for vessel evacuation, gas sampling, pump priming, venting, and blending.  EXAIR Line Vacs work on this same principle in creating a Venturi vacuum by using compressed gas.  In this blog, I will cover the design, verification, and testing that EXAIR provided for a customer’s special.    

For this customer, the design was based around our 2” and 1” 316SS Line Vacs.  They required ISO flanges on the vacuum and exhaust sides to match their piping connections for gas sampling.  They would supply nitrogen to the inlet port as a carrier gas to generate the venturi and to mix with the sample gas.  Since the accuracy of the test is dependent on the amount of each gas, we had to test the operations of the Line Vacs at different conditions. 

First, EXAIR designed these special Line Vacs to get approval.  Once the customer approved, EXAIR had to make a strong effort to meet the other criteria that was requested.  Generally, with our standard Line Vacs, we use our test data with estimated conveyance rates, inlet flow rates, and vacuum pressures measured at 80 PSIG (5.5 bar).  For these special Line Vacs, we had to do a bit more work because it was for gas sampling.  This was not a problem for us.  EXAIR has many calibrated instruments to accurately measure different conditions.  For this customer, we had to measure the inlet flow, suction pressure, velocity, and maximum back pressure at different inlet pressures.  We also had to create another chart showing the exhaust velocities with a back pressure present. 

From these details, the customer could calculate the amount of nitrogen that would be introduced to the gas sample at different pressures and backpressures.  And, as an added preference, they requested us to do a leak check after assembly.  We were willing to buy the flange blanks and add this test procedure to the router.  We looked for leaks between the cap and body of the special Line Vac, as well as the flanges to verify that gas was not escaping.  EXAIR tries to support our customers to the best of our abilities.  For this customer, we worked together to provide the needed information for their setup.    

The reason that I wrote this blog was to show that EXAIR has the capabilities to make special items for specific applications.  If we need to use different materials, design configurations, and even present test data, we can decide the best course of action.  With special products, they are unique to customers in fit, form and function as a solution, whether for end-users or OEMs.  For the special Line Vac above, we presented the data as related to an eductor for this customer’s decision to place the order.  If you would like to see if EXAIR can make a special product for you, please do not hesitate in contacting an Application Engineer at EXAIR.  We will be happy to work with you. 

John Ball
Application Engineer

Email: johnball@exair.com
Twitter: @EXAIR_jb

What Is A Coanda Profile?

The big thing that sets engineered products like EXAIR Intelligent Compressed Air Products apart from other devices is the engineering that goes into their design.  Several principles of fluidics are key to those designs:

The one I wanted to discuss today, though, is the Coanda Effect, what it means for our engineered compressed air products, and what they can do for you:

The Coanda effect is named after Henri Coandă, who was the first to use the phenomenon in a practical application…in his case, aircraft design.  He described it as “the tendency of a jet of fluid emerging from an orifice to follow an adjacent flat or curved surface and to entrain fluid from the surroundings so that a region of lower pressure develops.”  Put simply, if fluid flows past a solid object, it keeps flowing along that surface (even through curves or bends) and pulls surrounding fluid into its flow.  Here’s a demonstration, using an EXAIR Super Air Amplifier and a plastic ball:

What’s interesting here is that the Super Air Amplifier is not only DEMONSTRATING the Coanda effect, it’s also USING it:

Air Amplifiers use the Coanda Effect to generate high flow with low consumption.

EXAIR Standard and Full Flow Air Knives also have Coanda profiles that the primary (compressed air) flow follows, and uses, to entrain “free” air from the surrounding environment:

Compressed air flows through the inlet (1) to the Standard 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.

EXAIR Air Wipes can be thought of as “circular Air Knives” – instead of a Coanda profile along the length of an Air Knife, an Air Wipe’s Coanda profile is on the ring of the Air Wipe, which entrains surrounding air into a 360° ring of converging air flow:

Air Wipe – How it works

So that’s the science incorporated in the design of our products.  But what does it mean to the user?

  • Efficiency.  Pulling in a tremendous amount of “free” air from the surrounding environment means minimal consumption of compressed air, while still getting a hard hitting, high velocity air flow.
  • Sound reduction.  This air entrainment also creates a boundary layer in the air flow, resulting in a much quieter air flow than you get from a simple open-end blow off.

EXAIR Corporation is committed to helping you get the most out of your compressed air system, and thanks to Mr. Coandă, that includes reducing your compressed air consumption and noise levels.  If you’d like to find out more, give me a call.

Russ Bowman, CCASS

 

 

 

Application Engineer
EXAIR Corporation
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Carburetors and Venturi Tubes: Thank You Giovanni Battista Venturi

I know it has been a little while since I blogged about something with a motor so it should be no surprise that this one ties to something with a combustion chamber. This all starts with an Italian physicist, Giovanni Battista Venturi. His career was as a historian of science and a professor at the University of Modena. He gave Leonardo da Vinci’s creations a different perspective by crediting da Vinci to be a scientist with many of his creations rather than just an amazing artist. He then began to study fluid flow through tubes. This study became known as the Venturi Tube. The first patents in 1888 came to fruition long after Giovanni passed away. So what was this Venturi effect and how does it tie in to carburetors let alone compressed air?

The illustration below showcases the Venturi effect of a fluid within a pipe that has a constriction. The principle states that a fluid’s velocity must increase as it passes through a constricted pipe. As this occurs, the velocity increases while the static pressure decreases. The pressure drop that accompanies the increase in velocity is fundamental to the laws of physics. This is another principle we like to discuss known as Bernoulli’s principle.

1 – Venturi

Some of the first patents using Venturi’s began to appear in 1888. One of the key inventors for this was Karl Benz who founded Mercedes. This is how the Venturi principle ties into combustion engines for those that do not know the history. This patent is one of many that came out referencing the Venturi principle and carburetors. The carburetors can vary considerably in the complexity of their design. Many of the units all have a pipe that narrows in the center and expands back out, thus causing the pressure to fall and the velocity to increase. Yes, I just described a Venturi, this effect is what causes the fuel to be drawn into the carburetor. The higher velocity on the input (due to this narrowing restriction) results in higher volumes of fuel which results in higher engine rpms. The image below showcases Benz’s first patent using the Venturi.

2 – Venturi Patent

While carburetors slowly disappear and now can mainly be found in small engines such as weed eaters, lawn mowers, and leaf blowers, the Venturi principle continues to be found in industry and other items. Needless to say, I think Giovanni Battista Venturi would be proud of his findings and understanding how monumental they have been for technological advancements. For this, we will recognize the upcoming day of his passing 199 years ago on April 24, 1822.

Brian Farno
Application Engineer
BrianFarno@exair.com
@EXAIR_BF

1 – Thierry Dugnolle, CC0, Venturi.gif, retrieved via Wikimedia Commons https://upload.wikimedia.org/wikipedia/commons/1/16/Venturi.gif

2 – United States Patent and Trademark Office – Benz, Karl, Carburetor – Retrieved from https://pdfpiw.uspto.gov/.piw?Docid=00382585&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect1%3DPTO1%2526Sect2%3DHITOFF%2526d%3DPALL%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsrchnum.htm%2526r%3D1%2526f%3DG%2526l%3D50%2526s1%3D0382,585.PN.%2526OS%3DPN%2F0382,585%2526RS%3DPN%2F0382,585&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page