When Air Flow, Not Force, Makes The Difference

I recently had the pleasure of talking with a CAGI Certified Compressed Air Systems Specialist, who was working with a client to improve energy efficiency in the use of their compressed air. One particular application that was particularly taxing on their system is the use of hose barb fittings (basically, an open blow device) to fold over a cardboard box flap on a packaging line.

We discussed the possibility of trying something out, but the client wanted to look at some data, showing what their expected savings could be. Hose barb fittings are quite common, and they DO focus the flow of a compressed air discharge into a forceful little blast, which is quite effective at folding a box flap.

The client’s main concern was the force applied. In truth, there’s no better way to maximize force than by discharging a compressed gas directly through an open ended device. Excessive force, however, isn’t the only way to solve an application like this, as I proved in a test in our Efficiency Lab.  Here’s what happened:

EXAIR 1″ and 2″ Flat Super Air Nozzles can be fitted with a variety of shims for variable performance.
  • All of them folded the box flap easily.  The Model HP1125 folded it just as far as the hose did in the test I rigged, and with a 37% reduction in compressed air consumption.  The others folded it very nearly as far, with 62% (Model 1122) and 70% (Model HP1126) reductions.
  • Not to mention the drastic reduction in noise levels.

Lastly, I documented it all in a short video:

We field calls all the time from callers wanting to know how much force our Intelligent Compressed Air Products can generate.  Applications like part ejection do indeed require a certain amount of force to, say, move an object in motion from a conveyor belt…that’s just physics.  Most blow off applications (and folding over a flat box flap, for instance,) just need air flow…which engineered products from EXAIR Corporation can handle just fine, and at a fraction of the compressed air use & sound levels associated with open end blowing devices.

If you’d like to find out how EXAIR Corporation can help save you money on compressed air consumption, and ear plugs, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Air! image courtesy of Barney Moss  Creative Commons License

The Makeup of Earth’s Air

Most people know that oxygen, makes up about 20% of the earth’s atmosphere at sea level, and that almost all the rest is nitrogen. But did you know there’s an impressive list of other gases in the air we breathe

whats in air
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. But because water vapor is 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 third place!

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.

But here at EXAIR we care about how compressed air can be used efficiently to better your process! 

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 to ionize than nitrogen.  You can certainly supply a Gen4 Static Eliminator with pure nitrogen if you wish, but the static dissipation rate may be lesser.

If you want to learn more about the compressed air or any of our point of use compressed air products, you can contact an Application Engineer.  We will be happy to help you.

Jordan Shouse
Application Engineer

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Air photo courtesy of Barney Moss Creative Commons License

Cooling With Compressed Air: Air Knife vs. Vortex Tube Products

One of the popular applications for the EXAIR Super Air Knife is cooling. When mounted so that the air flow sweeps across the surface of a product, the laminar nature of the air flow works to maximize the contact time with the surface, which also maximizes the heat transfer…which means better product cooling than, say the turbulent air flow from a fan or blower.

Still, it’s common for us to get questions about how to provide even faster cooling.  Well, the two main variables in heat transfer are the time the air is in contact with the product, and the difference in temperature between the product surface and the air.

We’ve already touched on “time in contact”…sweeping the laminar flow across the surface at as low of an angle as you can, against the direction of travel, is ideal.  Combine that with the extraordinarily high air flow due to the entrainment level of the Super Air Knife, and you get an awful lot of air in contact with the surface, for a (relatively) long time.

Super Air Knives cool steel casting from 1,725°F (940°C) to 200°F (93°C) in under 20 minutes.

The difference in temperature, though, is a little trickier to deal with.  Because the developed flow from the Super Air Knife is mostly entrained ambient temperature air from the surrounding environment, you’re at the mercy of that ambient temperature.  One of the most common question – of the common questions about faster cooling – is, can you feed a Super Air Knife with cold air from a Vortex Tube?  The answer is no, for two big reasons:

  • The Vortex Tube’s cold flow can’t be back pressured, which would happen if you fed it through the plenum of a Super Air Knife and tried to make it come out the 0.002″ gap.
  • Even if it did work, the entrained air which, remember, makes up most of the flow, is still room temperature…meaning the total developed flow is a lot closer to room temperature than however cold the air you fed the Super Air Knife would be.

If the surface area to be blown on, to effect the desired cooling, is suitably sized, a Vortex Tube can be installed at a low angle to sweep its flow across.  The cold air flow from a Vortex Tube can also be distributed to more than one point, to cover more surface area.  That’s exactly what we do with our Dual Point Hose Kits for our Adjustable Spot Coolers, Mini Coolers, and Cold Gun Aircoolant Systems:

Dual Point Hose Kits can distribute air to both sides of a part, or onto a wider surface, than a single point discharge.

In fact, both the Single and Dual Point Hose Kits have a variety of tips they can be fitted with for tighter, or broader, flow patterns:

In some cases, multiple Vortex Tube products can be used, and, in other situations, the cold air can be directed through a manifold of some sort:

There are numerous methods to distribute the cold air flow from a lone, or a series of, Vortex Tubes.

Applications like the two on the right above (setting molten chocolate in molds, and keeping those white plastic parts during ultrasonic welding, respectively,) commonly start out as Air Knife inquiries, but the need for refrigerated air leads to creative Vortex Tube solutions.

If you’d like to discuss whether your application is best served by a Super Air Knife or a Vortex Tube Spot Cooling Product, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Process Improvement, ROI and Safety from One Air Nozzle

Process improvement projects can be detailed, complex, expensive, and take a long time to prove their worth.  Today, I want to tell you about one that WAS NOT ANYTHING like that.

A metal stamping company used compressed air to blow their products from their dies.  They did what many do – they ran some copper tubing, and aimed it at the platen so it would properly eject the parts as they were stamped.  They KNEW it was loud, and they suspected it was inefficient as well.

After discussing the setup and seeing a picture of it (the one on the left, below,) I recommended installing a few engineered Super Air Nozzles to lower the noise levels considerably.  Boy, was I wrong.  About “a few” nozzles, that is…turns out, they only needed one Model 1122-9212 2″ Flat Super Air Nozzle with 12″ Stay Set Hose.  The copper tubes come from a manifold that already had 1/4 NPT ports – installation took a matter of minutes.  Nothing detailed, complex, or expensive about it:

This loud & inefficient copper tubing blowoff was just a compression fitting (and a Model 1122 2″ Flat Super Air Nozzle) away from being quiet and efficient.

It didn’t take much longer than that to prove its worth either: as soon as they noticed how much the noise level went down on THIS press, they ordered them for the other eighteen presses in their facility as well.

The 1/4″ copper tubes blew continuously from a pressure regulator set @60psig…the three of them theoretically consumed a total of ~80 SCFM.  The Model 1122, at 60psig supply, consumes only 17.2 SCFM.  Simple return on investment was as follows:

  • 80 SCFM was costing them $48.00 a week
    • 80 SCFM X 60 min/hr X 8 hr/day X 5 days/week X $0.25/1,000 CFM = $48.00
  • 17.2 SCFM, using the same formula, only costs $10.32 a week (I’ll let you do the math; it’s good practice.)
  • They saved $37.68 a week.  The Model 1122-9212 costs $116.00 (2020 pricing) – that means that each of them paid for themselves in just a hair over three weeks.
  • $37.68 x 50 work weeks per year = $1884.00 saved annually per nozzle
  • $1884 x 18 (the number of presses) = $33,912 saved annually 

Considering they also didn’t have to listen to those very loud open ended copper tube blowoffs, I think you’ll have to agree it made for a very good investment.  They did. The new nozzle runs at 77 decibels, a comfortable level and well below the OSHA standard [29 CFR – 1910.95(a)] for allowable noise exposure.

If you’d like to find out how EXAIR Intelligent Compressed Air Products can save you money on compressed air – and save everyone’s hearing – give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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