Henri Coanda and his Effect on Compressed Air

Henri defined the Coanda Effect – 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.

Compressed air flows through the inlet (1) to the Full Flow (left) or Standard (right) 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.

Henri-Marie Coanda (1885-1972) discovered the Coanda Effect in1930. He observed that a stream of air (fluid) emerging from a nozzle tends to follow a nearby curved surface, if the curvature of the surface or angle the surface makes with the stream is not too sharp. For example, if a stream of fluid is flowing along a solid surface which is curved slightly from the stream, the fluid will tend to follow the surface.

A number EXAIR products are designed to utilize the Coanda Effect and aid their performance. In some products, the Coanda Effect aids to create an amplification area where additional ambient air is drawn into the total airflow to increase total volume of air upon a target. This creates a more efficient and effective product. Also, since not as much compressed air is required, the noise levels decrease for products like EXAIR’s air knives, air nozzles, air jets and air amplifiers. EXAIR has been successful with positive impact for compressed air energy savings and noise reductions helping us meet or exceed OSHA Standard 29 CFR-1910.95 9(a) Maximum Allowable Noise Exposure.

Please contact EXAIR with regards to our Intelligent Compressed Air Products. We can help you with your next cooling, blow-off, drying or any compressed air needs.

Eric Kuhnash
Application Engineer
Email: erickuhnash@exair.com
Twitter: @EXAIR_EK

1- Spoon Coanda image- https://creativecommons.org/licenses/by-sa/2.5/deed.en

EXAIR Efficiency Lab at Your Service

I couldn’t count the number of times we have written a blog about the EXAIR Efficiency Lab because its that cool, unlike the number of wins the Cincinnati Reds have right now. I can count that on two hand 10………10-26 as of writing this blog and I could go on and on about the pain but I will spare you the tears and write about how amazing the Efficiency lab is for any company that utilizes compressed air!

Is the Mascot signing something? Or hanging his head? We will never Know!

First – what is the EXAIR Efficiency Lab? Well several years ago EXAIR created a free program called the Efficiency Lab.  This program is to compare your current pneumatic blow-off device with an EXAIR engineered product.  The values we compare are air consumption, noise level and force. We generate a detailed report to send to you for review.  It is a free service that EXAIR provides for U.S. and Canadian companies to know more details about solutions you are currently using in your processes.

The EXAIR Efficiency Lab

Why do we offer this?  Air Compressors demand significant electrical power and compressed air is considered to be a fourth utility within plants and industries.  Many people do not realize the cost and safety concerns when using improper blow-off devices.  As an example, if you look at a single 1/8” open pipe for blowing compressed air, it can cost you over $2,000 a year to operate.  This will add to your overhead and cut profits.  Another reason to consider your blow-off device is that compressed air can be dangerous.  With that same 1/8” open pipe, it can violate OSHA standards for noise exposure and dead-end pressure.  In deciding your “vehicle” for blowing compressed air, cheap is not typically best option.  To put it in other terms, a cheap nozzle is like a cheap old car, it’s cheap because it gets 3 MPG with faulty brakes.

With our Efficiency Lab, a comparison it is quite simple to do.  An easy way is to call us and explain the details. These details can be data such as the inside diameter and length of a an open tube you are using, or the actual performance data of a cheap air nozzle you have chosen to use. Perhaps the easiest way to make the comparison is to let EXAIR do it – send in your blowoff product or a sample of the tube, nozzle, modified fitting, etc. We will then put them through our testing process. You can also fill out our Product Efficiency Survey on our website to give the conditions for testing. 

We will run the tests at the specified conditions or in a range of settings.  We will then return your pneumatic device back to you at our cost with a detailed report of the comparison.  Your information will be confidential, and we will not share it without your permission.  We will also provide a simple ROI – many customers like to use this report to show managers, executives, HSE, etc. on the improvements that EXAIR can provide including cost savings and safety.

How do we do the Efficiency Lab?  We use calibrated equipment and standardized procedures to test for noise levels, flow usage, and force measurements.  We will recommend an EXAIR engineered solution as a replacement to your current device to do the comparison.  With the analytical information, we can also figure the total amount of air savings, return on investment, payback period and safety improvements.

Don’t Swing and miss…. (Like the Reds)  You do not want to sacrifice safety, time, and money with a sub-standard product.  Let EXAIR solve this dilemma with our free service; the Efficiency Lab.  Take advantage of our expertise by using the Efficiency Lab service, we will provide you a detailed report with a comparison analysis to make a great choice. 

Jordan Shouse
Application Engineer

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Twitter: @EXAIR_JS

Reds Image Provided by IndyDina with Mr. Wonderful via Creative Commons Attribution 2.0 Generic (CC BY 2.0)

EXAIR High Temperature Cabinet Cooler System

Inside, outdoors, high temperature, dirt/dust/humidity, corrosive and classified environments are no problem for EXAIR Cabinet Cooler Systems

EXAIR Cabinet Cooler® Systems will help eliminate downtime due to heat, dirt and moisture. Our Cabinet Cooler® Systems are UL listed to maintain NEMA 4, 4X and NEMA 12 integrity. All high temperature cabinet coolers are UL listed and CE compliant. Our Cabinet Coolers are a reliable way to cool and purge electrical control panels from the use of vortex tube technology, which creates cold air from normal compressed air.

One of our specialized applications are for Cabinet Cooler® Systems in areas with hotter than normal ambient temperatures. Sometimes electrical cabinets are located in environments near high heat sources such as boiler rooms, furnaces, ovens or other heat sources. If the ambient temperature is above 125° F (52° C) we offer a High Temperature Cabinet Cooler systems.

EXAIR High Temperature coolers offer relief for ambient temperatures ranging from 125° – 200° F (52°C – 93°C). Our Cabinet Cooler calculator found at www.EXAIR.com will automatically determine if the High Temperature cooler is required for your specific application.

The High Temperature Cabinet Cooler systems are stock items, ready to ship and easily installed. If you have questions or need more information please contact any of our Application Engineers.

Eric Kuhnash
Application Engineer
Email: erickuhnash@exair.com
Twitter: @EXAIR_EK

Compressed air Storage: Do you need a Receiver Tank?

Maintaining a “supply and demand” balance in the design & operation of compressed air systems often includes receiver tanks.

Just like in economics, we have to consider both sides – supply AND demand – to best maintain this balance.  Also like in economics, there are numerous factors…on both sides…but the two most critical factors are:

  • Compressor capacity control (supply side)
  • System storage (demand side)

I wrote a blog on “Air Compressor Motors and Controls, Working Together”, outlining the ‘supply side’ variables, today lets look at the system storage. Distribution piping makes up a certain amount of this, and another great blog from my colleague, Tyler Daniel – “Intelligent Compressed Air: Distribution Piping and Pressure Drop” – gets me off the hook for THAT part of the discussion today.

We can consider the air capacity of system piping to be fixed for the purposes of this discussion, so our “variable” will be the capacity of storage tanks. Let’s start with the reasons for the need for system storage: Strategically placed point-of-use air receivers provide stored energy for intermittent demands.  This enables the compressed air system to handle fluctuating loads, efficiently & reliably.  It also minimizes impact (e.g., sudden and often detrimental drops) on the system pressure.

Next, we’ll look at location. There are a couple of common options to consider:

  • The intermittent demand. Installing a receiver here will provide enough air for short duration, high consumption events, protecting the rest of the system from pressure excursions. Dedicating the receiver to this application will mean isolating it from the rest of the system with a check valve (so it only supplies the load in question) and a needle valve (so recharging the receiver itself, between the intermittent uses, doesn’t adversely affect total system pressure).
  • The critical load(s). Instead of using stored air for the intermittent load, you can also use it for the important loads you’re trying to protect. All sorts of machinery with pneumatic components can “crash” if a nearby intermittent demand starts up & “steals” their air. You’ll use a check valve (same as above), but using a needle valve to throttle the air flow that recharges the receiver risks “starving” the critical load. Don’t do that unless there’s a really good (and likely really specific) reason for it.

Finally, we’re going to do some math, so we know how big this receiver has to be. Here’s the equation we use to do that:

Let’s calculate the receiver size needed to supply an intermittent load of 400 SCFM (C) @80psig (P2), that’ll run for one minute (T). You can use data specific to your system to come up with a value for (Cap) but here I’m going to assume we want the receiver to be able to handle the whole thing, so Cap = 0. I’m also going to assume we’re at sea level, so Pa = 14.7psia and that our compressor’s discharge pressure (the pressure at which the receiver can be charged to) is 120psig (P1):

That’s an awfully big tank. Now, let’s calculate the receiver size needed to protect a critical load that uses 55 SCFM @60psig, and that due to the system design, we can count on 25 SCFM @120psig from the compressor:

This is a much more manageable size, in fact, our 60 Gallon Receiver Tank (Model 9500-60) would be ideal. It’s 20″ in diameter and just over 50″ tall, so it doesn’t take up a lot of floor space. It comes with a drain valve and connections for compressed air flow in & out, pressure gauge, relief valve, etc.

Step Five of our Six Steps To Optimizing Your Compressed Air System: Use intermediate storage near the point of use.

Now, the above example is a completely hypothetical situation, and I purposely chose exaggerated values to show that there can indeed be a clear “winner” in the choice between the two installation points. If you have a situation like this, and would like help in finding the solution that makes the most sense, give us a call.

Jordan Shouse
Application Engineer

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Find us on the Web 
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Twitter: @EXAIR_JS