Because of the large amount of energy required to run an air compressor, the pneumatic system is considered the fourth utility in a manufacturing plant. And saving this commodity and using it as efficiently as you can, should be a priority. EXAIR has many products that can save this energy safely and effectively. And the story behind the efficiency of EXAIR products is Bernoulli’s equation.
Bernoulli’s principle explains how a high velocity fluid can generate a low pressure. (You can read more about Bernoulli’s principle HERE.) Let’s start by looking at Equation 1.
Equation 1:
P + p * V2/2 = C
P – pressure
p – density of the fluid
V – velocity
C – a constant
As you can see from Equation 1, when the velocity goes up, the pressure must go down. When we have a lower pressure, then the surrounding fluid will have to fill that void. Since air is a fluid, this is how we can entrain the free ambient air while only using a small amount of compressed air. Bernoulli’s Principle can be applied in two ways; as a Coanda and as a Venturi. EXAIR uses both methods in our products for creating low-pressure effects.
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.
The first way is from a Coanda profile. Coanda, named after Henri Coanda, noticed that a fluid would “hug” a curved surface. (You can read more about Henri Coanda HERE.) The high velocity air going around the curved surface will generate a low pressure above it. We use this with our Full Flow and Standard Air Knives, our Air Wipes, and our Air Amplifiers. With a Coanda profile, the low pressure will entrain the surrounding air to add mass to the air stream. We can get an amplification ratio up to 30:1, which means that for every 1 part of compressed, 30 parts of ambient air are entrained. We are able to create an efficient air moving (blow-off) device by using the Coanda profile.
Generating even lower pressures can be accomplished with a Venturi. This phenomenon is named after Giovanni Venturi, who discovered that by increasing the velocity through an orifice, the surrounding fluid will move with it, generating a lower pressure. (You can read more about Giovanni Venturi HERE.) Remember the higher the velocity, the lower the pressure. We use the Venturi effect on our Super Air Knives, E-Vacs, Line Vacs, and Super Air Nozzles. When compared to our Full Flow and Standard Air Knives, the Super Air Knives can generate an amplification ratio of 40:1. We were able to engineer the product to increase the air entrainment efficiency even further.
EXAIR has been manufacturing Intelligent Compressed Air® products since 1983. We provide solutions that are efficient, effective, and safe for air moving and blow-off systems. Consider the following analogy; homemade air movers and blow-off devices are the equivalent to incandescent light bulbs. EXAIR products are the equivalent to LED light bulbs. More efficient design leads to lower operating cost, higher efficiency and a higher level of effectiveness. Entrainment of free ambient air can save you a lot of money and increase your mass flow with your compressed air use to generate higher forces on your targets. If you would like to discuss solutions to use less compressed air, an Application Engineer is available to help.
John Ball Application Engineer Email: johnball@exair.com Twitter: @EXAIR_jb
We have mentioned here on the EXAIR Blog numerous times just how bad static can get in cooler, dryer regions with low humidity. The amount of moisture in the air is expressed as relative humidity. This value is given as a percentage of water vapor in the air, compared to how much it could hold at that temperature. In conditions of lower relative humidity, static charges build up much easier. When the relative humidity is high, there’s a higher concentration of water molecules present in the air. These water molecules “coat” the surface of the material, allowing electrons to move more freely and form a layer over the material. This layer of water molecules acts like a lubricant, reducing the forces that cause static to generate. There are many applications that static may only pose an issue once the climate changes.
This could lead one to deduce that tropical climates don’t experience static, given the high humidity present in these areas. While it may be LESS common to experience static troubles in humid conditions, it’s far from impossible.
Such was the case during my recent visit with our partners in Costa Rica. A client of theirs that handles a variety of extruded PVC pipes and shapes was having some problems with a printing process. In their line, after the pipes are extruded, they must mark a batch code and company name on the outside of the pipe. On some days the residual static charge is so high that the ink won’t properly adhere to the outside of the pipes.
A process that should be automatic was requiring them to station an operator nearby to keep an eye on the printer. When issues arise, they must stop production, clean the marking off, and run it back through again. They don’t have the man-power to allocate a person to stand there and monitor things continuously, so this has led to some batches going out marked wrong and leading to rejection and subsequent return.
Fortunately, EXAIR has a wide variety of products designed specifically for use in treating industrial static problems. After checking out the application, it was clear that one of our Ion Air Jets was going to provide a great solution for the customer. Since the specific location of the marking varies depending on the diameter of pipe, they needed something that could also be adjusted. I recommended our Stay Set Ion Air Jet to be installed just prior to the printing head and directed onto the pipe where we’re to apply the marking.
After installation, they continued to monitor closely for a few shifts and managed to make it through a complete day without any rejected material. They no longer have a need to monitor this step in the process and can free up personnel for more important tasks in the facility.
As winter draws to a close, don’t assume static will just automatically go away when the warmer temperatures of spring and summer arrive. In some cases, as was in this application, static can be present despite humid conditions.
As we all start off the new year, I have been reflecting and bouncing around between what has happened in the past, as well as what kind of outlook I have/want for the future. I think it is human nature for us all to do this and dare I say the holidays and reconnecting with some people we don’t see often increases the focus on the past.
While I love watching the videos of projects that I have completed personally over the years. In some images below, I try to focus more on how I can continue to pull the positives out and prevent the pitfalls. Things like demolishing the “finished” part of our basement and building it into a brighter and more functional space for our family of 5. Some of the highlights included my daughters at every step of the process, even down to leaving “notes” on the walls for the next person who works in the room. I still do my best to make sure they get involved with any project, and it has to be far more than just watching or holding this while I do work. I take the time to educate them and ensure they get to add experiences to their memory and I hope it all takes root throughout the years, and they can call back on these experiences as they move forward.
That’s one saying that has stuck with me since the Marvel series Luke Cage. When it seemed as though he was getting pulled backward or potentially taking the wrong direction, he would say, “Always forward, never back.” This was the motto of his mentor, Pops, who encouraged Luke to move in the right direction and not step backward in his progress. It’s my experience though that, like Luke, this will get tested many times throughout the year and experience is the only true way to learn something. That is why I try to encourage experiences in all aspects of my life. I let my daughters do things and try solutions they come up with as long as they are safe. If they ask for input, I will offer it. Sometimes I try to steer them clear of big mistakes and try to get them some direction as to why.
This year I have already started a project that involves rebuilding a basketball hoop and installing it for my family and friends to use. Now, I could have gone out and bought replacement parts and even a new goal. While my budget wouldn’t really allow new and replacement parts seem to be a bit high, I am taking the time to further my skills, and my daughter’s experiences, and spend some intentional time with my family in the process.
This came with some work to do from finding the original specs on the arms that hold the backboard on and also refreshing my CAD skills while learning new software that I could use for free at home to help me verify the angles the pieces need to be cut at. From here I will start making cuts and then weld up new arms. You had better believe that I will have each one of my daughters out in the garage with me learning how to at least try and weld, so they can understand the level of effort that goes into making something out of what someone else may consider trash.
So what does all of this have to do with EXAIR and how we conduct our business? Well, as a member of the team here, I devote myself to continuously improving and learning. This could be things like testing myself like others have on the CCASS certification and deeper dives into our product offerings like the flow curves on a pressure regulator. I’m not the only one here that has that drive either. The entire team here is constantly pushing and driving forward to ensure we bring our customers and contacts the highest-level products, knowledge, and experience, and can confidently share our experiences with you to increase your potential success when implementing an engineered solution.
If you want to advance your process and knowledge, or just see if EXAIR has any experience with what you are having trouble with, contact an Application Engineer today.
I actually came up with a few more reasons, but I’d already told the boss I was writing a “Top 10” blog, so here we go:
1. Cost of ownership. Several factors have to be considered here:
Purchase price. If you have compressed air available, the Super Air Knife is going to win this one all day, every day. The cost of the rotary element alone of a blower system will eclipse the cost of any Super Air Knife.
Maintenance. A Super Air Knife has no moving parts. If you supply it with clean air, it’ll run darn near indefinitely, maintenance free. This means the only preventive maintenance required is to periodically replace the element in the filter. Blowers, on the other hand, have a number of moving parts; non-sealed bearings require periodic lubrication. Sealed bearings require periodic replacement. Couplings, drive belts & pulleys need to be kept in proper alignment, or you’ll be replacing those bearings at even more frequent intervals. Even if you do keep up with stringent planned maintenance, the fact that they’re moving parts means that bearings will seize, seals will fail, belts will break, motor windings will burn out…and then you’re going to lose production in whatever process the blower is supporting.
Operating cost. The electric cost associated with operating a blower motor can indeed be lower than the operating cost of an air compressor. When you consider factors like being able to start & stop compressed air flow to Super Air Knives instantly and on demand (as opposed to a continuously running blower motor) and the ability to regulate supply pressure (instead of needing a variable frequency drive on the blower motor to vary the flow & force of the air), it’s entirely likely that engineered compressed air products can be less expensive to operate.
2. Ease of installation. Rotating equipment, like centrifugal & regenerative blowers, have to be mounted on a suitable surface in such a way as to prevent vibration (or you’ll be doing a LOT of the aforementioned repairs). This usually involves specialized contractors, and a fair amount of time, especially if reinforcing and/or grouting the floor space is required. Installation of most Super Air Knives involves a handful of very common 1/4″-20 hardware and a compressed air hose. If you know how to use an open end wrench, you can likely install a Super Air Knife in just a few minutes. For added ease of installation, we’ve got Plumbing Kits and Mounting Systems too.
A 72″ Super Air Knife w/ Plumbing Kit Installed, supported by Model 9060 Universal Air Knife Mounting Systems, blowing debris off a part being laser cut.
3. Small, compact footprint. If you don’t have the floor space for the blower near the point of use, you might have to install it where you DO have space and run air ducts to where you want the air to blow. The installation space required for a Super Air Knife is no more than its length, and a profile envelope of 1.75″ (45mm) X 1.44″ (37mm). Stainless Steel models are even a little smaller in profile – 1.44″ (37mm) X 1.03″ (26mm) – and if the mounting space is tighter than that, Standard & Full Flow Air Knives have a smaller profile.
If space is tight, Standard & Full Flow Air Knives are certainly worth a look.
4. Sound levels. Blower motors make noise. If the blower is belt driven, THAT makes noise. The air flow discharging from the blower’s air knife makes noise, and when that turbulent flow hits the surface of what you’re blowing on, that can make quite a racket too. The only sound associated with a Super Air Knife is the sound of the air flow, which is mitigated by a low velocity boundary layer, developed by the entrained air. Ignoring any impingement sound, the sound level of any Super Air Knife supplied @80psig is only 69dBA. That’s well under typical ambient noise level in many industrial settings.
EXAIR Super Air Knives are incredibly quiet, by design.
5. Operational control. As I mentioned above under “Operating Cost”, engineered compressed air products like a Super Air Knife can be turned on and off as frequently – or as seldom – as the application requires. In fact, that’s one of our Six Steps To Optimize Your Compressed Air System. Blower-type products can certainly be turned off when you shut down for the evening or the weekend, but (and not to sound like a broken record here), if you cycle a blower’s motor on & off frequently, you’ll be doing a LOT more repair work than if you just let it run & accept the operating cost as an unavoidable expense.
EXAIR’s EFC Electronic Flow Control dramatically reduces compressed air costs by Turing off the air when no part is present.
6. Operational control part 2. I touched on this one under “Operating Cost” too, but in addition to limiting what you spend on running it, you can also precisely ‘dial in’ the performance you need with a Pressure Regulator. That keeps you from blowing small or lightweight objects all over the place if it only takes a moderate breeze, or even just a whisper, of air flow to do the job.
Super Air Knife Kits include a Shim Set, Filter Separator, and Pressure Regulator.
7. Even, laminar flow. When a blade rotates, it “slaps” the air to impart motion. This causes turbulence, which means that the air flow from most blower systems really just beats on the surface of what you’re blowing off. The flow from an engineered product like a Super Air Knife is laminar by design, which makes for a stripping or sweeping action across the surface, which is more efficient for blowing. The air curtain from a Super Air Knife is also pretty even in velocity & force from end to end, so there’s no extra length jutting out on either end.
8. Reliability. I mentioned this under “Maintenance” above, but the fact that the Super Air Knife has no moving parts makes it an incredibly reliable product. The primary causes of failure are really limited to a casualty with the air compressor, or catastrophic damage to the Air Knife itself.
9. Higher force. Because a blower is imparting discharge head to the air supply going to the air knife, it can generate a lot of volume (depending on the diameter of the rotating element) and velocity (depending on the speed of rotation), but they’re limited in the amount of force that the discharged air can apply to a surface. Because they’re fed with PRESSURIZED air, Super Air Knives are capable of generating a tremendous amount of force by discharging that air out of the 0.002″ thick gap between the cap & body, you can put a thicker shim (they come in 0.001″, 0.002″, 0.003″, and 0.004″ thicknesses) in and get a proportional increase in the force applied.
Super Air Knife with Shim Set
10. Free stuff. If all of that isn’t enough, we’ve got a seasonal promotion running RIGHT NOW, through December 31, 2023. With any qualifying Super Air Knife purchase, you’ll get a free Soft Grip Safety Air Gun with a Super Air Nozzle. It’s our way of thanking you for trying a Super Air Knife, and a chance to show off our most popular handheld blow off product. If you use air guns, we’re pretty sure you’re going to like this one, a lot.
The EXAIR Super Air Knife is, for any given size, the most efficient and quietest compressed air blowing product on the market. If you’d like to find out which one is right for your application, give me a call.
Russ Bowman, CCASS
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