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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Cooling Electronics Down With Cabinet Coolers

As the summer days have reached maximum temperatures, I find myself busting out my kayak and heading down to the wild whitewater rivers for a weekend full of adventure in the cool water. I personally am not a fan of the heat and as most people enjoy the water and swimming, I partake in the high adventure sport of whitewater kayaking. I’ve been around the sport of whitewater most of my life and have kayaked some of the hardest rivers east of the Mississippi including the well-known rivers of the Upper Gauley, the New River, and the Tallulah.

When the temperature rises and I start to overheat and kayaking is the best way that I enjoy to cool off and enjoy the weekend; splashing around in the wild waves. With plenty of summer heat ahead of us it’s a perfect chance for all to get outside and jump in a lake, swimming pool, or even a river to cool down and take a chance to enjoy a little fun.

Baby Falls on the Tellico River

But what about your electrical cabinets; they deserve to stay nice and cool on the inside as well. All electrical components are not 100% efficient meaning that when an electrical current is flowing through them a certain amount of heat is generated. This phenomenon is commonly referred to as heat loss and VFD’s and other drives are typical offenders. Heat loss is not the only thing that can attribute to electrical cabinets overheating, sun light is another big factor for outside electrical cabinets. Based on the color of a cabinet sitting out in the sun a specific percentage of heat is absorbed into the cabinet; black absorbs the most heat and white absorbs the least. In most cases solar heat can be negated by installing a cover over top of the cabinet to provide shade.

From right to left: Small NEMA 12, Large NEMA 12, Large NEMA 4X

At EXAIR we have designed a cost-effective way to cool down these overheated cabinets during these summer months. EXAIR’s Cabinet Coolers are designed to provide cooling using just a source of compressed air; they utilize our vortex tube to provide a constant source of cold air as long as they are connected to a source of compressed air. Our Cabinet Coolers have also been designed to be used in a large variety of environments ranging from standard production to Classified environments.

NEMA 4 Dual Cabinet Cooler System with ETC

EXAIR also can provide our Electronic Thermostat Control system or ETC for short which can give a user much better control over the temperature inside the cabinet as well as visual feedback of the internal temperature. The ETC allows for easy and constant changing of what internal temperature is desired. The ETC will also provide live temperature readings on the internal temperature of the cabinet.

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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Reliable Heat Protection Right Now: The EXAIR Cabinet Cooler System

Electrical and electronic devices can be finicky creatures.  Shutting them away inside a sealed enclosure keeps dust, fumes, and humidity away, but it’s about the worst thing you can do to them, heat-wise.  If you don’t provide some means of cooling, they’re going to simply burn up, and you’ll have to replace them.  If they’re critical for your operation, you better keep a spare, because they’re not always on the shelf, and they’re not even always in the country.

Conventional wisdom, then, says you should provide some method of cooling.  You can use a vented enclosure, with a fan & louvers, assuming it’s not in a spray down/wash down area.  But if it’s in a dusty and/or humid and/or fume-ridden area, well, you’ve just compromised the reason you put them in an enclosure in the first place.

Refrigerant based panel coolers are prolific…they come in all shapes & sizes, and they’re probably sold by the folks you got the electrical panel from.  Thing is, they can be susceptible to the same dust, fumes, and humidity that you’re trying to keep from wrecking what’s inside the enclosure.  If the filters get clogged, the tubes get fouled, a refrigerant leak develops, the motor burns out, the compressor fails (just to name a few potential problems,) we’re back to recommending keeping spare parts around, or, even worse, opening up the panel for emergency cooling…

Don’t let this happen to you, or your control panels!

We talk to folks all the time who are looking for a better method of heat protection for the finicky gear inside their control panels, and the one common factor is reliability.  They all simply want something that works.  All day and every day.

So we introduce them to EXAIR Cabinet Cooler Systems.  They’re compressed air operated and have no electric motor to burn out.  They have no moving parts to break down, no filters or tubes to clean, no refrigerant to leak.  They install in minutes, and if you supply them with clean, moisture free air, they’ll run darn near indefinitely maintenance free.  And the only thing the inside of your panel will ever see is cold, clean, moisture free air.

Oh, and there’s no need for spare parts…other than filter elements for the compressed air supply.  Barring catastrophic physical damage, again, there’s really nothing to go wrong with them.

One last thing, which prompted me to write this blog today:  They’re on the shelf and ready for immediate shipment, unlike the refrigerant based panel cooler that a caller earlier today was looking to replace…their vendor was 2-3 weeks away from getting them one, which was 2-3 weeks longer than they could afford to wait.

This NEMA 4 Dual Cabinet Cooler System protects a critical equipment panel on a hot roll steel line.

It’s getting warmer by the day here in the Northern Hemisphere, so I expect calls about panel cooling will be increasing.  Not to worry; we’re ready for it.  If you want to find out more about reliable heat protection for your electronics, drives, and other critical components, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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