Tag: Air Knives

Air Entrainment & EXAIR’s Intelligent Compressed Air Products

Published on by Tyler DanielLeave a comment

Air entrainment is a term that we bring up quite often here at EXAIR. It’s this concept that allows many of our products to dramatically reduce compressed air consumption. The energy costs associated with producing compressed air make it an expensive utility for manufacturers. Utilizing engineered compressed air products that will entrain ambient air from the environment allow you to reduce the compressed air consumption without sacrificing force or flow.

Entrainment
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.

Products such as the Super Air Knife, Super Air Nozzle, Air Amplifier, and Super Air Wipe all take advantage of “free” air that is entrained into the primary supplied airstream. This air entrainment occurs due to what is known as the Coanda effect. Named after renowned Romanian physicist, Henri Coanda, the Coanda effect is used in the design of airplane wings to produce lift. As air comes across the convex surface on the top, it slows down creating a higher pressure on the underside of the wing. This creates lift and is what allows an airplane to fly.

nozzle_anim_twit800x320
EXAIR Super Air Nozzle entrainment

This is also the same principle which is allowing us to entrain ambient air. As the compressed air is ejected through a small orifice, a low-pressure area is created that draws in additional air. Our products are engineered to maximize this entrained air, creating greater force and flow without additional compressed air. Super Air Amplifiers and Super Air Nozzles are capable of up to a 25:1 air entrainment ratio, with just 1 part being the supplied air and up to 25 times entrained air for free!! The greatest air entrainment is achieved with the Super Air Knife at an incredible ratio of 40:1!

This air entrainment principle allows you to utilize any of these products efficiently for a wide variety of cooling, drying, cleaning, or general blowoff applications. In addition to reducing your compressed air consumption, replacing inefficient devices with engineered products will also dramatically lower your sound level in the plant. Sound level in some applications can even be reduced down to a point that would eliminate the need for hearing protection with the OSHA maximum allowable exposure limits set at 90 dBA for an 8-hour shift.

If you have inefficient blowoff devices in your facility, give us a call. An Application Engineer will be happy to help you select a product that will “quietly” reduce your compressed air consumption!

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

How It’s Made: Static Charge

Published on by Russ BowmanLeave a comment

For me, one of the first signs that winter is here takes place at the grocery store. I’ll stop on the way home to pick up a thing or two, and proceed to the automated self-scan…not because I don’t like people, but because they’re the closest to the exit and, while I DO actually like a LOT of people, I REALLY like dinner. Anyway, the drop in humidity that comes with colder temperatures outside leads to what the buried-wire pet containment folks call a “mild correction” when I touch the self-scan terminal.

I won’t rehash my disdain of cold weather (like I did here, here, here, or here) and while those nuisance static shocks aren’t at the top of the list of reasons why, they actually can be quite severe in other cases.  For example, the minor jolt you get from touching a grounded terminal after pushing a rubber-wheeled shopping cart over the vinyl-tiled floor of the produce aisle isn’t near as bad as the shock that a plastic extrusion machine operator gets when he touches a conveyor duct carrying hundreds of pounds of plastic pellets per hour.

Why one is so much worse than the other?  To fully understand the answer to that question, we’ll need to better understand how static charge is generated.  Scientists have been studying the phenomenon since at least the 17th Century, and studies continue to this day of its creation (mainly at universities) and control (right here at EXAIR Corporation.)  Simply put, when two solid surfaces touch each other, the contact can result in electrons in the outer valences of atoms on one surface to “jump ship” and end up in the outer valences of atoms on the other surface.

It’s called the triboelectric effect.  The prefix “tribo” comes from the Greek word “to rub,” and while many common demonstrations of static charge involve rubbing…for example, rubbing a balloon on a wool sweater sleeve and ‘sticking’ it to the wall…mere contact is all it takes – and that’s where we’ll start:

Static charge from simple contact between this injection molded plastic part & the mold caused defects in a subsequent metallic coating process (left,) which were eliminated after an EXAIR Super Ion Air Knife was installed (right.)

Separation of material – lifting the top sheet from a stack, peeling off a protective layer,  or unrolling plastic film, for example – can also cause those weaker-held electrons to leave one surface for another.

Separation of contacting surfaces can generate a considerable static charge. The 16.9kV charge on this roll of film (left) shortened the life of print heads in a downstream process until EXAIR Ionizing Bars (center) dissipated the charge to an inconsequential 0.4kV (right.)

Some processes involve surface contact, and separation.  And more contact, and separation.  And oftentimes, one surface is in relative motion with the other…and that’s what REALLY puts the “tribo” (“to rub,” remember?) in “triboelectric effect.

The constant motion of these plastic jugs on the conveyor (left,) generated (and multiplied) a static charge so great, it resulted in adhesive labels folding or wrinkling while being applied. A pair of EXAIR Super Ion Air Knives (right) solved the problem.

These are just a few examples of the mechanisms behind, and the solutions for, static charge.  For more details, I encourage you to read EXAIR’s Basics Of Static whitepaper (registration required) or watch our recorded Webinar: Understanding Static Electricity.  If you have a static problem you’d like help with, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
Visit us on the Web
Follow me on Twitter
Like us on Facebook

Super Air Knife Plumbing Kits Ensure Proper and Optimum Operation

Published on by Leave a comment

The EXAIR Super Air Knife is a Highly Engineered and intelligently designed point of use compressed air powered device that delivers a 40:1 air amplification ratio!  This simply means that for every one part compressed air supplied to an EXAIR Super Air Knife it will entrain 40 parts ambient air into the exiting compressed air stream.  Almost as good as “money for nothing”!  Also the EXAIR Super Air Knife is designed to provide an even or “laminar” flow of air.  This is due to it being an intelligent, highly engineered compressed air product.

However if an EXAIR Super Air Knife is not connected to the compressed air supply with the appropriate number of inlet ports being fed, poor and/or erratic performance is likely.  This would manifest itself as uneven air flow and lower performance from the air knife.  In order to make this plumbing easier we offer optional plumbing kits for all Super Air Knives starting with the 24″ length all the way up to the 108″!  The 24″ and longer Super Air Knive’s require that compressed air must be supplied to multiple air inlets along its length for optimal performance.  This will ensure that the air flow is laminar and the force is even across the entire length of the Super Air Knife.  All our products are shipped with an installation guide referencing the proper recommended pipe sizes for various lengths of supply pipe.

The Plumbing Kits for Aluminum Super Air Knives provide properly sized Nitrile/PVC Hoses, Brass Fittings and a Pressure Gauge which monitors the inlet pressure to the air knife.  If the gauge shows a pressure drop when the Super Air Knife is turned on this indicates that there is an air starvation issue.  For the 303SS, 316SS and PVDF Air Knives the Plumbing Kits contain 5/8 OD SS tubing X .034 wall thickness tubing and SS fittings.

AirKnifePlumbing

So when ordering your next Super Air Knife be sure to designate the Plumbing Kit to ease your installation and to ensure top performance.

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
Send me an email
Find us on the Web 
Follow me on Twitter
Like us on Facebook

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

Published on by Leave a comment

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
Send me an email
Find us on the Web 
Follow me on Twitter
Like us on Facebook