E-Vacs: Shrinking Foam Packages

In-Line E-Vac Family

A foam manufacturer was looking for a way to reduce the size of their shipping packages.  The type of product was a polyurethane open-cell foam that they would place inside plastic bags to ship.  With shipping charges, the dimensional weight, not actual weight, is used, and it can be very costly.  Since it was open-cell foam, they wanted to evacuate the air from the plastic bags.  This would decrease the package volume and reduce shipping costs dramatically.

The company gave me some details on the product and their process.  The polyurethane foam had a density of 1.1 lb./ft3 (18 Kg/M3), and they were bagging pieces of the foam in plastic bags with the dimensions of 30” long by 10” diameter (0.75m long by 0.25m diameter).  They attempted to use a shop vac to reduce the volume; but, it was too loud and too cumbersome for their process.  They also noticed that the vacuum level was not enough to maximize the shrinkage.  They searched the internet for a better way, and they found the E-Vac™ Vacuum Generators.  They contacted EXAIR to get more information.

The EXAIR E-Vacs use compressed air to create a vacuum by a venturi method.  It can reach vacuum levels up to 27” Hg (91 kPa).  They are very compact and lightweight, and they do not have any moving parts to wear.  So, they are very durable and long lasting in systems with cycling or continuous operations.  In comparison, a typical electric vacuum has a vacuum pressure near 6” Hg (20 kPa).  With the EXAIR E-Vac having a vacuum level 27” Hg (91 kPa), we can draw out much more air to reduce the volume.

At EXAIR, we pride ourselves on customer service.  With this application, I was able to setup a representative sample for testing.  I shot a short video to show the power of our smallest E-Vac.  The video shows a representative sample with a smaller bag.  You can see the volume change with polyurethane foam.

In addition to the video, I was able to calculate the time to evacuate the package to 27” Hg (91 kPa).  EXAIR manufactures seven different sizes of High Vacuum E-Vac Generators with different flow ranges.  The above customer requested an evacuation time in about 30 second.  With Equation 1, I can determine the correct E-Vac size to meet the requirement.

Equation 1:  q = V * ln(p0 / p1)  / t
q = Vacuum flow rate (SCFM)

V = enclosed volume (ft^3)

p0 = atmospheric pressure (“Hg)

p1 = end vacuum pressure (“Hg)

t = evacuation time (min)

Details:
Volume of cylindrical plastic bag: V = 1.36 ft3

Atmospheric air pressure: p0 = 29.92” Hg

Final absolute air pressure: p1 = (29.92” Hg – 27” Hg) = 2.92” Hg

Time to evacuation: t = 0.5 min.

Thus,

q = V * ln(p0 / p1) / t

q = 1.36 ft3 * ln(29.92” Hg / 2.92” Hg) / 0.5 min

q = 6.3 ft3/min or 6.3 SCFM

From the specification on our E-Vac, I was able to recommend the model 810013M.  At 80 PSIG, this model has a vacuum flow rate of 6.85 SCFM; plenty enough to hit the target time.  After installing the E-Vac in their packaging process, they were able to reduce the size by almost 70%.  This was very helpful in reducing the dimensional weight for each shipment; saving the company and their customers much money.

If you would like to send samples in for vacuum test or need calculations for performance improvements, EXAIR Application Engineers will be happy to assist you.  EXAIR always likes to go that extra mile for our customers.

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

The Case For The Adjustable E-Vac Vacuum Generator

Vacuum generation is vital to many industrial processes:

*Pick-and-place. Vacuum cup systems are used to move metal sheets onto laser & plasma cutting beds, precisely place parts for assembly using end-of-arm robotic tooling, or moving awkward objects, like plates of glass, by hand.

The same Adjustable E-Vac Vacuum Generator can be used for a range of products, from the cinder bloc (left) to small pavers (right.)

*Bag/package opening.  When plastic bags come off a roll and are fed through an automated filler, vacuum cups can make quick work of opening them up, immediately before the filling operation.

*Vacuum filling.  A closed container can be easily filled, without a pump, by simply drawing a vacuum on it.  Same mechanism (and simplicity) as when you drink a beverage through a straw.

These are just a few of the typical uses for an EXAIR E-Vac Vacuum Generator…I’ve written before about how this is our most versatile product line (by number of different applications) but these in particular are the ones I want to use to make the case for the Adjustable E-Vacs.

EXAIR Adjustable E-Vac Vacuum Generators are available in four distinct models, depending on the needs of your application.  Performance is variable not only by regulating the air supply pressure (like any compressed air product) but also by threading the plug into the body, which changes the size of the annular gap that feeds the Venturi, changing the vacuum and flow levels.  This can be used to overcome vacuum loss due to material porosity or vacuum cup leakage in a pick-and place application, to accommodate different bag sizes or types in an opening application, or to change the rate at which a liquid is moved in a vacuum filling operation.

With four to choose from, EXAIR has an Adjustable E-Vac that will fit your vacuum generating needs.

Because of their larger throat diameter, they’re also better suited for situations where particulates or moisture may be entrained…they won’t clog or ‘stall out’ as is common with other Venturi-type products.  This is especially useful in vacuum chucking/clamping, or when contaminants from dirty environments can make their way into the system.

EXAIR E-Vacs provide instantaneous vacuum response, and are engineered for high efficiency to minimize air consumption.

Like EXAIR In-Line Vacuum Generators, they instantly develop rated vacuum as soon as compressed air is supplied, so they’re well suited for fast moving operations.  With no moving parts, they’re durable, effective, and if you feed them with clean, dry air, they’ll operate a good long time, virtually maintenance free.

If you have a vacuum generating application you’d like to discuss, please give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Person of Interest: Giovanni Battista Venturi

Giovanni Battista Venturi was an Italian physicist that was born in Bibbiano, Italy on March 15, 1746.  He died at the age of 76 on April 24, 1822.  During his early life, Giovanni was ordained as a priest at the age of 23; and, he became a professor of geometry and philosophy at the University of Modena at the age of 28.    He moved to Paris France where he worked with other scholars to expand his knowledge of physics and chemistry.  In 1797, he wrote a dissertation on the now famous “Venturi effect”.  However, an actual device was never created or applied until 1888 where Clemens Herschel was awarded the patent for the first Venturi tube.

Venturi Tube

The Venturi effect is a decrease in fluid pressure when fluid flows through a constricted area of a pipe.  In other words, as the diameter becomes smaller, the fluid velocity becomes faster.  This increase in velocity will create a lower pressure just past the constricted area.  when designed correctly, you can create a strong vacuum or a large negative pressure.

E-Vac design

The EXAIR E-Vac® Vacuum Generators use this phenomenon founded by Giovanni Venturi by using compressed air as the fluid.  This type of Venturi tube restricts the internal area to generate a fast velocity through the body creating a vacuum pressure for suction.  EXAIR offers three types of Venturi tubes; low vacuum, high vacuum and adjustable.  The high vacuum generators can create a vacuum level as high as 27” Hg (71 KPa).  The Adjustable E-Vacs can alter the internal air velocities by turning the body and getting different vacuum pressures.  Without any moving parts or electric motors to wear, the EXAIR E-Vacs are a simple design that is very durable, effective and long-lasting.  A great product for applications like pick and place, clamping, lifting and vacuum forming,

The Venturi effect was discovered in 1797, brought into existence in 1888, and is still used in vacuum applications to this very day.  If you have an application where a Venturi tube could help you, please contact an Application Engineer.  We will be happy to assist you.

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

 

Photo: Venturi Tube with labels by ComputerGeezer an Geof.  GNU Free Documentation License

EXAIR’s E-Vac Vacuum Generators & Accessories

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EXAIR’s In-Line and Adjustable E-Vacs are powerful compressed air powered vacuum generators. They’re a low-cost way to create a vacuum for a variety of different applications: pick and place, clamping, chucking, lifting, surface mounting, and vacuum forming are just some of the possibilities. Both the In-Line and Adjustable E-Vacs are available in a variety of different sizes and flows and can accommodate a wide range of applications.

In addition to the vacuum generators themselves, EXAIR offers a variety of different accessories to help you build a complete system. To minimize the sound level and ensure you’re adhering to OSHA 29CFR 1910.95, we have Standard Mufflers as well as Straight Through Mufflers. The Straight Through Mufflers offer the best level of sound reduction, up to 26 dBA!!

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Straight through mufflers are available from 1/4″-1″ MNPS

With no moving parts to wear out, EXAIR’s E-Vacs are virtually maintenance free when supplied with clean, dry compressed air. To maintain proper operation of your E-Vac, installation of an Automatic Drain Filter to remove any particulate and moisture from the air supply is necessary. In addition, oil removal filters are also available if your compressed air supply contains any oil as is common in many compressed air systems.

For pick and place or lifting applications, vacuum cups will be necessary. With a wide variety of different vacuum cups available: small round, large round, oval, and bellows, we can accommodate nearly any size or shape material. For heavier materials, round cups with cleats provide rigidity and ensure that the load remains stable. For applications on textured or uneven surfaces, bellows style cups have convolutions that allow for the cup to quickly decompress when it touches the surface of an uneven part or material.

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EXAIR’s family of vacuum cups

The vacuum port of the E-Vac has an NPT thread, vacuum cups can be installed directly in this inlet. For applications where the vacuum cup(s) are remotely located, we offer polyurethane vacuum tubing as well as a variety of different fittings to connect them. Both 1/4” and 3/8” O.D. sizes are available in 10’ lengths up to 50’. Simply indicate the model number of the tubing and add the length with a “-“ at the suffix. For example, a 900795-30 would be 30′ of 1/4″ O.D. tubing. In addition to fittings and tubing, vacuum check valves are also available. These can be beneficial if there is potential for fluctuations in the compressed air pressure or supply. In the event that there is a significant drop in pressure or loss of compressed air supply, the check valve will ensure that the load remains held.

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Push-in Swivel Tee Connector

With all of the different options making a selection can seem like a daunting task. A highly trained EXAIR Application Engineer is ready and available to help you!! With just a few quick details, we can help advise you about the proper size E-Vac generator for your application as well as recommend the most suitable cup and accessories. Give us a call, shoot us an e-mail, or reach out to us online via chat and we’ll make sure you have a complete vacuum solution ASAP with all parts ready to ship from stock!

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@Exair.com
Twitter: @EXAIR_TD

Intelligent Compressed Air: Bernoulli’s Principle

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Daniel Bernoulli was a Swiss mathematician and physicist born in 1700. He is most known for the Bernoulli principle, published in his book Hydrodynamica in 1739. The Bernoulli’s principle states that an increase in speed of a fluid will result in a decrease in pressure. As a fluid moves from a wider pipe to a narrow one, the fluid begins to move faster. The given volume of the fluid moving from one point to another over a set amount of time will not change. In order for the same amount of fluid to pass through a smaller orifice, it must speed up. This is displayed quite well in the flow of a river. At wide, open spaces the river flows slowly. In areas that become narrow, for example by a canyon wall, the speed of the river’s flow increases dramatically.

The Bernoulli principle also provides an explanation for the lift that is created on an airplane wing. When air encounters an obstacle (in this case an airplane wing), its path will narrow as it flows around the object. As this stream of air speeds up, some of the energy from the random motion of the air molecules must be converted into energy of the stream’s forward flow. Pressure is created by the random motion of these air molecules. Transferring this energy into the stream flow then results in a drop in the air pressure. An airplane wing is shaped so that the air must move faster over it than under it. This causes the slower moving air underneath to exert more pressure on the wing than the air moving across the top. This is referred to as lift and is what allows an airplane to fly.

Temperatures are beginning to creep back up here in Cincinnati and just last week pitchers and catchers for the Cincinnati Reds reported for Spring Training. They’ll also be watching Bernoulli’s principle in action. The oft-dreaded (for batters, anyway) 12-6 curveball occurs due to the way the pitcher forces the ball to spin. Due to way he grips the ball across the laces and imparts this spinning motion, more air pressure forms on the top of the ball. This causes the bottom of the ball to accelerate downwards, resulting in the phenomenon that drives many baseball players crazy as they swing and miss due to a miscalculation of the ball’s position.

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Some of EXAIR’s products also utilize the Bernoulli Principle. As the high-velocity air exits the nozzle of a Super Air Knife, a low pressure area is created that draws in surrounding ambient air at a rate of 40:1. The same also occurs with the Super Air Amplifiers, Adjustable Air Amplifiers, and Air Nozzles. If you’d like to discuss the application of any of our Intelligent Compressed Air Products, give an Application Engineer a call today.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@exair.com
Twitter: @EXAIR_TD

 

River image courtesy of Sasori33 via Creative Commons License
Reds image courtesy of Lisa via Creative Commons License

Custom Solution From Stock For A Pick And Place Application

Even if you’re just a casual, infrequent reader of our blogs, you likely know that EXAIR Corporation is proud of our abilities to customize solutions for “out of the box” compressed air product applications. Oftentimes, this is offered as a custom engineered product, developed from a user’s specifications when one of our stock products just won’t work for one reason or another. For instance, when an exotic material of construction is required for heat or corrosion concerns, a special length or size is needed for space constraints, etc.

An Air Amplifier with a PTFE plug (left,) a curved Super Air Knife (center,) and a flanged Line Vac are just a few ways EXAIR has provided custom solutions.

Other times, though, we can use a stock product for something other than what everyone else uses it for.  We’ve sold Air Amplifiers for use in vacuum chucking, and pick-and-place applications – those are normally the realm of our E-Vac Vacuum Generators.  Speaking of E-Vacs, they’ve been used to deflate basketballs.

And speaking of E-Vacs (still,) I had the pleasure of helping a long-time customer solve a new problem in their growing manufacturing business.  They put their consumer products in blister packages, and recently converted one of the lines that picks & places the plastic “blister” onto the cardboard “backer” from two at a time, to six at a time.  They were using a Model 810003M E-Vac High Vacuum Generator, which worked fine, every time, with two Model 900762 1″ x 1/2″ Oval Vacuum Cups, but when they put four more of those Vacuum Cups on, they weren’t able to pick all six “blisters” every time.

These plastic blisters are smooth and non-porous, so this a “textbook” application for a High Vacuum Generator.  They’re also VERY lightweight, and were picked in a horizontal motion, so the 27″Hg that the Model 810003M can generate wasn’t actually necessary.  By replacing it with a Model 800003M E-Vac Low Vacuum Generator, the extra vacuum flow solved the problem, with no increase in compressed air consumption, which was critical for this area of their operation.

EXAIR E-Vac Vacuum Generators and Vacuum Cups are a reliable, low cost solution for most any pick & place application.

EXAIR Intelligent Compressed Air Products can solve many of your industrial/commercial challenges.  Our catalog documents the ones they’re aimed at.  Others need to be addressed by knowledge and experience…and maybe a little theory to practice.  If that’s the case, call an EXAIR Application Engineer.  We’re here to help, and we’re pretty good at it.

How Versatile Are EXAIR Compressed Air Products?

I wish I could quantify that, but we keep finding more and more applications for them:

Vortex Tubes are used all the time for cooling applications, down to MINUS 40 degrees (Fahrenheit OR Celsius…that’s the point where they’re both the same; no math required.) They also produce a HOT air flow, which we usually call “exhaust,” but some users actually use IT for heating, and call the COLD flow the “exhaust.”

The EXAIR Vortex Tube. Cold air from one end; hot air from the other. Fully adjustable. You can use either...it's fine with us; whatever you need.
The EXAIR Vortex Tube. Cold air from one end; hot air from the other.  You can use either…it’s fine with us; whatever you need.

Our E-Vac Vacuum Generators are popular for “pick-and-place” jobs…hook one up to a Vacuum Cup and you can move parts around all day long. One time, though, I helped a

customer who needed to “pick-and-place” individual small pieces of woven fabric, a lot like a coffee filter. Even our smallest E-Vac, supplied from a Pressure Regulator cranked all the way down, was too much…it would still pick up most of the stack. We found they could use a Model 120020 3/4″ Super Air Amplifier just fine…the Pressure Regulator was still cranked all the way down, and it picked them up one at a time.

No matter what you need to pick-and-place, we've got you covered.
No matter what you need to pick-and-place, we’ve got you covered.

Our Super Air Knives are perfect for blow off, drying, and cooling applications…whether you’re trying to rid your product of dirt/debris, water, or heat, a laminar curtain of adjustable air flow is a “textbook” solution. But I recently had the pleasure of helping a customer who needed to KEEP SOMETHING IN PLACE and called to ask about an Air Knife. They had small cups running single-file down a conveyor belt, with an overhead brush roller pushing down on them at one point so they could be treated on one side. Without something holding them in place, the tooling would simply push them off the side of the conveyor. It required frequent adjustment because they run different sized cups…and they almost always lost some cups when they switched to a different size, while “dialing in” the brush tension. By installing a Model 110036 36″ Aluminum Super Air Knife in place of the brush, they can hold any size cup in place with the downward air flow “curtain.” No more lost product when they don’t get the brush adjustment just right!

Continuous, even, fully adjustable curtain of air...EXAIR Super Air Knives come in lengths from 3 inches to 9 feet.
Continuous, even, fully adjustable curtain of air…EXAIR Super Air Knives come in lengths from 3 inches to 9 feet, in stock.

If you have a compressed air application you’d like to discuss, give me a call.  Perhaps we’ll find the next level of versatility!

Russ Bowman
Application Engineer
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