Henri Coanda: Founder of The Coanda Effect (1886-1972)

EXAIR uses the Coanda effect in many of our products. Henri Coanda is an important figure in the world of fluid dynamics and aerodynamics.

Henri Coanda was a prominent Romanian Inventor and aerodynamics pioneer is known for the creation of the Coanda-1910 experimental plane as well as discovering the Coanda effect. On June 7, 1886 Henri was born in Bucharest Romania to General Constantin Coanda and Aida Danet. In 1899 Henri’s father who desired him to have a military career had him transfer to a Military High School for additional years of schooling, where he graduated with the rank of Sergeant Major. Continuing his studies, he went on to technical school back in Bucharest for Artillery, Military, and Naval Engineering. In 1904 he was sent to an artillery regiment in Germany where he would enroll in Technische Hochshule. Henri did not give up on studying and in 1907 went to Montefiore Institute in Liege, Belgium, where he met Gianni Caproni.

In 1910 Henri and Gianni began a partnership to construct an experimental aircraft which was later called the Coanda-1910. The Coanda-1910 was unlike any other aircraft of its time as it had no propeller; instead it sported an oddly shaped front end with built-in rotary blades arranged in a swirl pattern. These blades were driven by an internal turbine screw that would suck air in through the turbine while exhausting the gases out of the rear, propelling the plane forward. This initial jet engine was quite impressive for the time, but sadly nobody believed it would ever fly and is believed that it never did achieve flight. Coanda is not credited with the invention of the jet engine, but his technology spurred the future of aviation into the future.

During World War 2 Henri spent his time developing the turbo-propeller drive system from his 1910 Biplane. After World War 2 had ended Henri began furthering his research on the Coanda Effect which would become the basis for several investigations into entrained and augmented flow of fluids. Later on in 1969 Henri would spend the last of his days in Romania serving as Director of the Institute for Scientific and Technical Creation. Coanda died on November 25, 1972 in his home town of Bucharest.

Here at EXAIR we have taken Henri Coanda’s, Coanda Effect and applied it to a number of our products to help amplify total airflow and save on compressed air.  The most notable product lines are our Air Amplifiers, Air Nozzles, and Air Knives – which are some of the most efficient products of their kind. These products can help lower your compressed air demand. 

If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Air Compressor Motors And Controls

Electric motors are by far the most popular drivers for industrial air compressors.  Indeed, they are the prime movers for a great many types of industrial rotating equipment.  In their simplest form of operation, rotary motion is induced when current flows through a conductor (the windings) in the presence of a magnetic field (usually by electricity inducing a magnetic field in the rotor.)  In the early days, you’d start one up by flipping a big lever called a knife switch.

Example of a knife switch

These are cumbersome and inherently dangerous…the operators literally have their hand(s) on the conductor.  If the insulation fails, if something mechanical breaks, if they fail to make full contact, electrocution is a very real risk.  Over time, motor starters came in to common use.  Early in their development, they were more popular with higher HP motors, but soon were made for smaller motors as well.

There are several types of modern motor starters:

Full Voltage Starters: The original, and simplest method.  These are similar in theory to the old knife switches, but the operator’s hands aren’t right on the connecting switch.  Full line voltage comes in, and amperage can peak at up to 8 times full load (normal operating) amperage during startup.  This can result in voltage dips…not only in the facility itself, but in the neighborhood.  Remember how the lights always dim in those movies when they throw the switch on the electric chair?  It’s kind of like that.

Reduced Voltage Starters: These are electro-mechanical starters.  Full line voltage is reduced, commonly to 50% initially, and steps up, usually in three increments, back to full.  This keeps the current from jumping so drastically during startup, and reduces the stress on mechanical components…like the motor shaft, bearings, and coupling to the compressor.

Solid State (or “Soft”) Starters: Like the Reduced Voltage types, these reduce the full line voltage coming in as well, but instead of increasing incrementally, they gradually and evenly increase the power to bring the motor to full speed over a set period of time.  They also are beneficial because of the reduced stress on mechanical components.

The Application Engineering team at EXAIR Corporation prides ourselves on our expertise of not only point-of-use compressed air application & products, but a good deal of overall system knowledge as well.  If you have questions about your compressed air system, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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How to Calculate the Cost of Leaks

Leaks are a hidden nuisance in a compressed air system that can cause thousands of dollars in electricity per year. These leaks on average can account for up to 30% of the operation cost of a compressed air system. A leak will usually occur at connection joints, unions, valves, and fittings. This not only is a huge waste of energy but it can also cause a system to lose pressure along with lowering the life span of the compressor since it will have to run more often to make up for the loss of air from the leak.

There are two common ways to calculate how much compressed air a system is losing due to leaks. The first way is to turn off all of the point of use compressed air devices; once this has been complete turn on the air compressor and record the average time that it takes the compressor to cycle on and off. With the average cycle time you can calculate out the total percentage of leakage using the following formula.

The second method is to calculate out the percentage lost using a pressure gauge downstream from a receiver tank. This method requires one to know the total volume in the system to accurately estimate the leakage from the system. Once the compressor turns on wait until the system reaches the normal operating pressure for the process and record how long it takes to drop to a lower operating pressure of your choosing. Once this has been completed you can use the following formula to calculate out the total percentage of leakage.

The total percentage of the compressor that is lost should be under 10% if the system is properly maintained.

Once the total percentage of leakage has been calculated you can start to look at the cost of a single leak assuming that the leak is equivalent to a 1/16” diameter hole. This means that at 80 psig the leak is going to expel 3.8 SCFM. The average industrial air compressor can produce 4 SCFM using 1 horsepower of energy. Adding in the average energy cost of $0.25 per 1000 SCF generated one can calculate out the price per hour the leak is costing using the following calculation.

If you base the cost per year for a typical 8000 hr. of operating time per year you are looking at $480 per year for one 1/16” hole leak. As you can see the more leaks in the system the more costly it gets. If you know how much SCFM your system is consuming in leaks then that value can be plugged into the equitation instead of the assumed 3.8 SCFM.

If you’d like to discuss how EXAIR products can help identify and locate costly leaks in your compressed air system, please contact one of our application engineers at 800-903-9247.

Cody Biehle
Application Engineer
EXAIR Corporation
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EXAIR Super Air Knives: Customized for You

In a recent blog “EXAIR Super Air Knives: Overview”, I shared the features and benefits that puts the “Super” in the Super Air Knives.  But, let’s not define ourselves by our widest range of lengths and materials that we stock.  EXAIR can also customize the Super Air Knives to fit your requirements.  Many manufacturers like to make their standard items and expect the customers to adapt to their design.  But at EXAIR, customer service is our primary focus.

EXAIR manufactures our products at one location in Cincinnati, Ohio.  So, this gives us the flexibility to do many things like making adaptive configurations with our Super Air Knives.  Here are some examples that our customers requested.

  • Special lengths: EXAIR stocks standard incremental lengths from 3” (76mm) up to 108” (2.74 meters) in aluminum, 303SS, and 316SS materials; or 3” (76mm) to 54” (1,372mm) for PDVF Super Air Knives. But sometimes, the Super Air Knife has to fit into a specific area where a standard length will not work.  This is where EXAIR exceeds, and we can make any length metric or imperial between the ranges above.

    PVC Super Air Knife
  • Other materials: There isn’t a single material that is inert to all chemicals. In some rare cases, the environment can chemically attack our Stainless Steel or PVDF Super Air Knives.  So, a different material may have to be used.  For the customer above, they required a PVC material for a phosphorous environment.

    Curved and Thin Super Air Knives
  • Critical Dimensions: When the Super Air Knives have to adapt inside machines or in tight areas, we can modify the profile.  We have two special applications (reference above) that needed a design change for fit and function.  A curved Super Air Knife was used to hold tubes on a rotary table; and a thin Super Air Knife that was only 11/16” (17.5mm) thick cleaned a mold for circuit chips.

    Super Air Knife special mounting
  • Add-ons: EXAIR understands the importance of connecting to our Super Air Knives to get the greatest performance.  Our stock product has ¼” NPT inlet air ports along the bottom and one at each end.  We have ¼” – 20 threaded holes for mounting along the bottom as well.  But if you want threaded holes in a specific location for mounting or need the inlet air ports to be metric threads, EXAIR can accommodate these features.

    Double-sided Super Air Knife
  • Situational Applications:  Super Air Knives can have complex or simple changes depending on the application.  As an example, EXAIR created a design for a double-sided Super Air Knife to blow a laminar stream of air 180 degrees apart (reference photo above).   A simpler proposal was to replace the cap screws in a 316SS Super Air Knife with hygienic screws for food applications to remove crevices for bacterial growth.
  • OE Protection: In today’s market, it is important to protect your business.  At EXAIR, we can make a special Super Air Knife to blow, dry, or cool in your custom machines.  With a unique model number, EXAIR can help support and protect your business for future and replacement business.

Remember, your imagination is the beginning of creation.  If you cannot find a specific design to be used in your compressed air application, don’t give up.  Contact an Application Engineer at EXAIR to see if we can help you.  We have a team of engineers that can evaluate the fit and function to create a “Super” blow-off solution.  For the customers above, we were able to propose a unique Super Air Knife to work in their application; not the other way around.

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