Henri Coanda: June 7, 1886 – November 25, 1972

Henri Coanda was a Romanian aeronautical engineer best known for his work on the fluid dynamic principle with his namesake, the Coanda effect. Before this, Henri patented what he labeled as a jet engine.

Jet Engine 1
Jet Engine

Henri’s patent (French patent No. 416,54, dated October 22, 1910) gives more information into how he envisioned the motor working. When air entered the front, it passed through different cavities that caused the air stream to first contract and then expand. In Henri’s opinion this contraction and expansion converted the air’s kinetic energy into potential energy.  The air ultimately was channeled to a diffuser where it was discharged.

Henri stated that the efficiency of this engine could be improved by heating the air in the cavities, Henri’s logic was that this would increase the pressure of the air passing through.

What is obviously lacking in the patent (including identical ones taken out in England and the United States) is any mention of injecting fuel, which in a true jet engine would combust with the incoming air. Judging only by Henri’s patent, it was little more than a large ducted fan and it could not have flown.  Throughout Henri’s career he changed his story many times on whether this plane actually flew or not.

Not to cast too much shade on Henri’s accomplishments he did discover the Coanda effect.  The Coanda effect states that a fluid will adhere to the surface of a curved shape that it is flowing over.  One might think that a stream of fluid would continue in a straight line as it flows over a surface, however the opposite is true.  A moving stream of fluid will follow the curvature of the surface it is flowing over and not continue in a straight line. This effect is what causes an airplane wing to produce lift, and enhance lift when the ailerons are extended while at lower air speeds such as occurs during takeoff and landing.

plane-1043635_1920
Ailerons positioned for cruising speed

EXAIR uses the Coanda effect to offer you highly engineered, intelligent and very efficient compressed air products.  Our designs take a small amount of compressed air and actually entrain the surrounding ambient air with the high velocity exiting compressed air stream to amplify the volume of air hitting a surface.

nozzle_anim_twit800x320
Surrounding Air Captured (Entrained) In Exiting Compressed Air Stream
How Air Knife Works
1). Compressed Air Inlet, 2). Compressed Air Exiting EXAIR Super Air Knife 3). Surrounding Air Being Entrained With Exiting Compressed Air Stream
Super Air Amplifier
EXAIR Super Air Amplifier Entraiment

When you are looking for expert advice on safe, quiet and efficient point of use compressed air products give us a call.   We would enjoy hearing from you.

Steve Harrison
Application Engineer
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Back Blow Nozzles Clean Inside Metal Tubes

A manufacturing plant EXAIR worked with made cast aluminum tubes for the automotive industry.  After the parts were cast, a machining operation would clean the ends.  This left coolant and metal shavings inside the tube.  Before going to assembly, they had to clean the part.  They created a two-tube fixture (reference picture above) to fit the 25mm tubes in place.

Two home-made nozzles were used to fit inside the tubes to blow compressed air.  The nozzles were attached to the ends of two 17mm pipes which supplied the compressed air.  A cylinder was used to push the nozzles from the top of the aluminum tube to the bottom then back up again.  The liquid emulsion and debris would be pushed downward into a collection drum.  When they started operating their system, the inside of the tubes still had contamination inside.  They wanted to improve their process, so they looked for an expert in nozzle designs, EXAIR.

Back Blow Air Nozzle Family

EXAIR designed and manufactures a nozzle for just this type of operation, the Back Blow Air Nozzles.  We offer three different sizes to fit inside a wide variety of diameters from ¼” (6.3mm) to 16” (406mm).  They are designed to clean tubing, pipes, hoses, and channels.  The 360o rear airflow pattern can “wipe” the entire internal surface from coolant, chips, and debris.  For the application above, I recommended the model 1006SS Back Blow Air Nozzle.  This 316SS robust design would fit inside the tubes above.  The range for this Back Blow Air Nozzle is from 7/8” (22mm) to 4” (102mm) diameters.  The customer did have to modify the function of the equipment by placing the cylinder and the rods under the aluminum tubes.  The reverse airflow would still push the contamination into the collection drum that was placed underneath the tubes.

After installing the model 1006SS onto the rods, the cleaning operation became more efficient.  Not only was the entire internal diameter getting clean, they were able to turn off the compressed air until they reached the top of the tube.  With the model 1006SS, they only needed one pass to clean.  This cut the air consumption in half, saving them much money by using less compressed air.  In addition, they were able to speed up their operation by 20%.  Cleaner tubes, less time, cost savings; they were happy that they contacted EXAIR for our expertise.

Reverse Air Flow

If you need to clean the inside of tubes, hoses, pipes, etc., EXAIR has the perfect nozzle for you, the Back Blow Air Nozzles.  EXAIR can also offer these nozzles on our VariBlast, Soft Grip and Heavy Duty Air Guns for manual operations.  They come with Chip Shields and extensions that can reach as far as 72” (1829mm).  Or like the customer above, automate the system to get a great non-contact cleaning.

If you require any more details, you can contact an Application Engineer at EXAIR.  We will be happy to help.

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

What’s In My Air, And Why Is It Important?

Everyone knows there’s oxygen in our air – if there wasn’t oxygen in the air you’re breathing right now, reading this blog would be the least of your concerns. Most people know that oxygen, in fact, makes up about 20% of the earth’s atmosphere at sea level, and that almost all the rest is nitrogen. There’s an impressive list of other gases in the air we breathe, but what’s more impressive (to me, anyway) is the technology behind the instrumentation needed to measure some of these values:

Reference: CRC Handbook of Chemistry and Physics, edited by David R. Lide, 1997.

We can consider, for practical purposes, that air is made up of five gases: nitrogen, oxygen, argon, carbon dioxide, and water vapor (more on that in a minute.)  The other gases are so low in concentration that there is over 10 times as much carbon dioxide as all the others below it, combined.

About the water vapor: because it’s a variable, this table omits it, water vapor generally makes up 1-3% of atmospheric air, by volume, and can be as high as 5%.  Which means that, even on a ‘dry’ day, it pushes argon out of the #3 slot.

There are numerous reasons why the volumetric concentrations of these gases are important.  If oxygen level drops in the air we’re breathing, human activity is impaired.  Exhaustion without physical exertion will occur at 12-15%.  Your lips turn blue at 10%.  Exposure to oxygen levels of 8% or below are fatal within minutes.

Likewise, too much of other gases can be bad.  Carbon monoxide, for example, is a lethal poison.  It’ll kill you at concentrations as low as 0.04%…about the normal amount of carbon dioxide in the atmosphere.

For the purposes of this blog, and how the makeup of our air is important to the function of EXAIR Intelligent Compressed Air Products, we’re going to stick with the top three: nitrogen, oxygen, and water vapor.

Any of our products are capable of discharging a fluid, but they’re specifically designed for use with compressed air – in basic grade school science terms, they convert the potential energy of air under compression into kinetic energy in such a way as to entrain a large amount of air from the surrounding environment.  This is important to consider for a couple of reasons:

  • Anything that’s in your compressed air supply is going to get on the part you’re blowing off with that Super Air Nozzle, the material you’re conveying with that Line Vac, or the electronics you’re cooling with that Cabinet Cooler System.  That includes water…which can condense from the water vapor at several points along the way from your compressor’s intake, through its filtration and drying systems, to the discharge from the product itself.
  • Sometimes, a user is interested in blowing a purge gas (commonly nitrogen or argon) –  but unless it’s in a isolated environment (like a closed chamber) purged with the same gas, most of the developed flow will simply be room air.

Another consideration of air make up involves EXAIR Gen4 Static Eliminators.  They work on the Corona discharge principle: a high voltage is applied to a sharp point, and any gas in the vicinity of that point is subject to ionization – loss or gain of electrons in their molecules’ outer valences, resulting in a charged particle.  The charge is positive if they lose an electron, and negative if they gain one.  Of the two gases that make up almost all of our air, oxygen has the lowest ionization energy in its outer valence, making it the easier of the two to ionize.  You can certainly supply a Gen4 Static Eliminator with pure nitrogen if you wish, but the static dissipation rate may be hampered to a finite (although probably very small) degree.

At EXAIR Corporation, we want to be the ones you think of when you think of compressed air.  If you’ve got questions about it, give us a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Air photo courtesy of Bruno Creative Commons License

Great Stuff About Jets

There are a number of fascinating facts about jets…both the aircraft engines and the EXAIR Intelligent Compressed Air Products:

  • Because they don’t require dense air to engage spinning blades (like their propeller driven counterparts,) they can operate at much higher altitudes. (Jet aircraft engines only)
  • They provide a high thrust, directed airstream, which makes them great for part ejection, chip removal, and part drying. (EXAIR Air Jets only)
  • With few or no moving parts, they are extremely reliable, durable, and safe. (Both jet aircraft engines and EXAIR Air Jets)
  • They use the Coanda effect (a principle of fluidics whereby a fluid flow tends to attach itself to a nearby surface, and follow that surface regardless of the flow’s initial direction) to do what they do.
    • EXAIR Air Jets use this principle to generate a vacuum in their throat, pulling in a large amount of “free” air from the surround environment, making their use of compressed air very, very efficient.
    • Jet (and propeller driven) aircraft wings employ the Coanda effect to create aerodynamic lift, enabling the plane to fly.

Now, since I’m not a pilot, nor do I particularly like to fly, but I AM a fluid dynamics nerd, the rest of this blog will be about the Air Jets that EXAIR makes.

All of our Air Jet products operate on the same principle…using the Coanda effect (as described above) to generate a high volume air flow while minimizing compressed air consumption:

(1) Compressed air enters and is distributed through an annular ring, and directed towards the discharge via the Coanda effect.
(2) This causes entrainment of surrounding air, both through the throat, and at the discharge.
(3) The total developed flow has tremendous force and velocity, for a minimal consumption of valuable compressed air.(1) Compressed air enters and is distributed through an annular ring, and directed towards the discharge via the Coanda effect.
(2) This causes entrainment of surrounding air, both through the throat, and at the discharge.
(3) The total developed flow has tremendous force and velocity, for a minimal consumption of valuable compressed air.

There are four distinct models of the EXAIR Air Jet:

  • Model 6013 High Velocity Air Jet is made of brass for economy and durability.  The annular ring gap (see 1, above) is fixed by a 0.015″ thick shim.  Performance can be modified by changing to a 0.006″ or 0.009″ thick shim, which come in the Model 6313 Shim Set.
  • Model 6013SS is a Type 303 Stainless Steel version, for higher temperatures – good to 400°F (204°C) – and superior corrosion resistance.
  • Model 6019 Adjustable Air Jet is brass construction, and dimensionally identical to the Model 6103.  Instead of a shim that sets the annular ring gap, though, it has a threaded plug, with a micrometer-style indicator, to “fine tune” the gap.
  • Model 6019SS is the Type 303 Stainless Steel version…fine tuning adjustability, good for high heat and/or corrosive elements.
Four distinct models to meet the needs of your air blowing application.

If you’d like to find out more about EXAIR’s quiet, efficient, and safe Air Jets, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Video Blog: How To Calculate Air Consumption At A Pressure Other Than Published Values

The below video shows how to calculate the air consumption when operating at any pressure.

If you want to discuss efficient compressed air use or any of EXAIR’s engineered compressed air products, give us a call or email.  We would enjoy hearing from you!

Steve Harrison
Application Engineer
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How to Calculate SCFM (Volume) When Operating at Any Pressure

If you need to operate at a different pressure because you require less or more force or simply operate at a different line pressure, this formula will allow you to determine the volume of air being consumed by any device.

Volume Formula

Using the EXAIR 1100 Super Air Nozzle as our example:

1100

Lets first consider the volume of the 1100 Super Air Nozzle at a higher than published pressure.  As shown in the formula and calculations it is simply the ratio of gauge pressure + atmospheric divided by the published pressure + atmospheric and then multiply the dividend by the published volume.  So as we do the math we solve for 17.69 SCFM @ 105 PSIG from a device that was  shown consume 14 SCFM @ 80 PSIG.

higher

Now lets consider the volume at a lower than published pressure.  As shown it is simply the ratio of gauge pressure + atmospheric divided by the published pressure + atmospheric and then multiply the dividend by the published volume.  So as we do the math we solve for 11.04 SCFM @ 60 PSIG from a device that was shown to consume 14 SCFM @ 80 PSIG.

lower

When you are looking for expert advice on safe, quiet and efficient point of use compressed air products give us a call.  Experience the EXAIR difference first hand and receive the great customer service, products and attention you deserve!  We would enjoy hearing from you.

Steve Harrison
Application Engineer
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Experience The EXAIR Difference For Yourself!

The other day I received a call from the Corporate Director of a manufacturing company with multiple locations across the country.  He had grown frustrated with the service and quality he was receiving from his current Air Gun & Nozzle supplier.  He explained that he was unable to buy the individual components to make repairs to the air guns and described the overall quality as “disposable”.

I asked him for model air gun he had been purchasing so that I could make an accurate comparison and recommendation for the equivalent or better EXAIR offering.  As I researched this competitive air gun I was surprised to find out that the specifications were vague at best.  What I mean by that is EXAIR clearly publishes air consumption @ 80 PSI, force which is specified @ 12″ from the nozzle and the sound level in dBA @ 3′ from the nozzle.

I recommended the EXAIR 1699-24 (1699-12 pictured) which is the VariBlast Compact Safety Air Gun, 24″ Extension Pipe & the 1102 Mini Super Air Nozzle.

Final Image
1699-12

The 1699-24 (supplied with the 1102 Mini Super Air Nozzle) specifications are: 10 SCFM @ 80 PSI compressed air consumption, 9 ounces force @ 12″ from nozzle and 71 dBA @ 3′ from the nozzle.  The 1102 1/8 FNPT is available in Zinc Aluminum, 316 SS or PEEK plastic.

1102 Mini Super Air Nozzle

The customer reported an average noise reduction of over 15 dBA which looks considerable, however it is a greater gain than the number would indicate. An increase of 10 dB is required before sound is perceived to be twice as loud, therefore EXAIR lowered the perceived sound by over 150%!

While this customer did not add the optional EXAIR Chip Shield you certainly can.  Simply add -CS to the end of any Safety Air Gun part number.  The part number for the featured VariBlast Safety Air Gun would become 1699-24-CS.  Chip Shields are made from durable poly-carbonate that protect operators from flying debris often associated with blowing chips off machined parts.  Chip Shields are also great for keeping coolant from spreading everywhere during drying operations.  They are available for the VariBlast Safety Air Gun, Soft Grip Safety Air Gun and Heavy Duty Safety Air Gun.  Also Chip Shields can be used on Safety Air Guns with or without the aluminum extension!

When you are looking for OSHA safe, quiet and efficient point of use compressed air products give us a call.  Experience the EXAIR difference first hand and receive the great customer service, products and attention you deserve!  We would enjoy hearing from you.

Steve Harrison
Application Engineer
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