EXAIR Air Nozzles And Jets: Quiet, Efficient, and Safe Solutions For Blow Off

Compressed air, as a utility, dates back to ancient Egypt, where metal alloy production was enhanced by using bellows devices to force air into furnaces in order to generate the extremely high temperatures needed to meld iron ores.  Major industrial use began in the mid-19th century, as pneumatic drills became popular for tunneling and mining operations.  With the development and large scale production of the modern air compressor in the 20th century, many other uses for compressed air were discovered.

Among the most prevalent of these additional applications is cleaning & blow off.  Mechanical or chemical methods such as washing, scrubbing, brushing, wiping, etc. often take time and considerable effort, when a quick blast of high velocity air from a pressurized source can make quick work of debris and/or moisture removal.  Thing is, unfettered discharge of high pressure air without concern for safety or efficiency has consequences:

  • Open end blow offs without a relief path for the air in case the device is dead ended, can have enough energy to break the skin, causing a dangerous and potentially fatal condition known as an air embolism.  The Occupational Safety and Health Administration (OSHA) specifically addresses this danger in 29 CFR 1910.242(b).
  • They’re also incredibly loud, usually higher than 100 decibels, which exceeds OSHA’s noise exposure limits per 29 CFR 1910.95(a).
  • As if that wasn’t enough, they can waste an awful lot of compressed air too.  The U.S. Department of Energy even goes so far as to classify it as an Inappropriate Use of Compressed Air.

Given these drawbacks, you might wonder why ANYONE would do such a thing!  Well, that’s the nature of our business at EXAIR Corporation: manufacturing quiet, safe, and efficient compressed air products for industry.  Among these are the first engineered products developed by EXAIR:  Air Nozzles and Jets.  No matter what your blow off needs are, we’ve got a solution.  Consider:

  • Performance.  With 73 distinct models to choose from, EXAIR can provide blow off solutions from the pin-pointed precision of our Atto Super Air Nozzle (uses 2.5 SCFM, generates 2 oz of force) to our High Force 1-1/4 NPT Super Air Nozzle (uses 460 SCFM, generates 23 lbs of force.)

    From the Atto Super Air Nozzle’s 2.5 oz pinpoint focus of air flow to the Model 1121’s 23 pounds of force blast, EXAIR has 73 distinct models to choose from.
  • Durability.  Some environments where blow off is required are downright aggressive: high heat, exposure to corrosive chemicals, etc.  With these situations in mind, we offer Air Nozzles & Jets in a variety of materials of construction, as shown to the right:
    • Zinc Aluminum alloy
    • Types 303 and 316 Stainless Steel
    • PEEK (polyether ether ketone) thermoplastic
    • Aluminum
    • Brass
  • Range of operation.  Any blow off device’s performance can be varied by regulating the compressed air supply pressure.  EXAIR offers several products with even greater ability for change:
    • The Model 1009 (Aluminum) and 1009SS (303SS) Adjustable Air Nozzles have a micrometer-like dial that allows you to very precisely set the flow & force to exact requirements.
    • Adjustable Air Jet Models 6019 (brass) and 6019SS (303SS) feature similar operation with a micrometer-like gap adjuster/indicator.
    • Our 1″ and 2″ Flat Super Air Nozzles (available in Zinc Aluminum or 316SS) have a replaceable shim.  The standard models have a 0.015″ thick shim installed, and the High Power models have 0.025″ thick shims.  We also offer individual shims, and sets, ranging from 0.005″ to 0.030″ thicknesses.
    • High Velocity Air Jets come in brass or 303SS, and also have replaceable shims.  The one that comes installed is 0.015″ thick.  The Shim Set gives you a 0.006″ and 0.009″ shim.

      Adjustable Air Nozzles & Jets (left) feature micrometer-type adjustment; Flat Super Air Nozzles and the High Velocity Air Jet (right) have replaceable shims to vary performance.
  • Function. Most of our Air Nozzles generate a high velocity air stream coming straight from its end.  We’ve also engineered some nozzles for specific applications:
    • Model 1144 2″ Super Air Scraper is our popular 2″ Flat Super Air Nozzle with a corrosion resistant scraper blade, making quick work of removing stubborn materials like tape, gaskets, labels, grease, paint, or sealant.  It’s particularly handy when installed on a Soft Grip Safety Air Gun with an appropriate length of pipe extension.
    • Back Blow Air Nozzles are made to clean out inside diameters or blind holes.  Three sizes are available for ID’s of 1/4″ to 16″.

If you’d like to find out more about how EXAIR Intelligent Compressed Air Products can help you get the most out of your compressed air system, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Importance Of Proper Pneumatic Tube, Pipe, And Fittings

When it comes to engineered compressed products, the number one cause of less-than-optimal performance is improper supply line sizing.  This can mean one of two things:

  • The hose, pipe, or tubing running to the device is too small in diameter.
  • The hose, pipe or tubing is big enough in diameter, but too long.

The problem with either of these is line loss (follow that link if you want to do the math.)  Put simply, the air wants to move faster than it’s physically permitted to.  Any time fluid flows through a conduit of any sort, friction acts on it via contact with the inside surface of said conduit.

With smaller diameters, a larger percentage of the air flow is affected…no matter what diameter the line is, the air closest to the inner wall is affected by the friction generated.  When diameter increases, the thickness of this affected zone doesn’t increase proportionally, so larger diameters mean less of the air is affected by friction.  It also means there’s a lot more room (by a factor of the square of the radius, times pi…thanks, Archimedes!) for the air to flow through.

Likewise, with longer lengths, there’s more contact, which equals more friction.  Length, however, is often a non-negotiable.  You can’t just up and move a 100HP air compressor from one part of the plant to another.  So, when we’re talking about selecting proper supply lines, we’re going to start with the distance from the compressed air header to our device, and pick the diameter that will give us the flow we need through that length.  In fact, that’s exactly how to use the Recommended Infeed Pipe Size table in EXAIR’s Super Air Knife Installation & Maintenance Guide:

This table comes directly from the Installation & Operation Instructions for the Super Air Knife.

Once we have the correct line size (diameter,) let’s consider the fittings:

  • Tapered pipe threads (NPT or BSPT) are the best.  They offer no restriction in flow, and are readily commercially available.  If you’re using pipe, these are the standard threads for fittings.  If you want to use hose, a local hydraulic/pneumatic shop can usually make hoses with the fittings you need, at the service counter, while you wait.
  • If you need to frequently break and make the connection (e.g., a Chip Vac System that’s used throughout your facility,) quick connects are convenient and inexpensive.  Push-to-connect types are by far the most common, but a word of warning: they’re notoriously restrictive, as the inside diameter of the male end is markedly smaller than the line size.  If you use them, go up a size or two…a quick connect made for 1/2 NPT connections will work just fine for a 1/4″ line:
  • The nice thing about these quick connects is that you don’t have to depressurize the line to make or break the connection.  If you have the ability to depressurize the line, though, claw-type fittings (like the one shown on the right) provide the convenience of a quick connect, without the restriction in flow.

Proper air supply is key to performance of any compressed air product.  If you want to know, at a glance, if you’re supplying it properly, install a pressure gauge right at (or as close as practical) to the inlet.  Any difference in its reading and your header pressure indicates a restriction.  Here’s a video that clearly shows how this all works:

I want to make sure you get the most out of your compressed air system.  If you want that to, give me a call with any questions you might have.

Russ Bowman
Application Engineer
EXAIR Corporation
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Steps to Find Compressed Air Leaks in your Facility

The Second Step to optimize your compressed air system is to Find and fix leaks in your compressed air system. The reason leaks are important to find and fix is because they can account for 20-30% of a compressors total output. A compressed air leak fixing process can save 10-20% of that lost volume.

6-steps-from-catalog

Unintentional leaks will result in increased maintenance issues and can be found in any part of a compressed air system. Leaks can be found at a poorly sealed fitting, quick disconnects and even right through old or poorly maintained supply piping. Good practice will be to develop an ongoing leak detection program.

The critical steps needed for an effective leak detection program are as follows:

  1. Get a foundation (baseline) for your compressed air use so you have something to compare once you begin eliminating leaks. This will allow you to quantify the savings.
  2. Estimate how much air you are currently losing to air leaks. This can be done by using one of two methods.
    • Load/Unload systems, where T= Time fully loaded and t=Time fully unloaded:
        • Leakage percent = T x 100
          ——
          (T + t)
    • Systems with other controls where V=cubic feet, P1 and P2=PSIG, and T=minutes
        • Leakage = V x (P1-P2) x 1.25
          ————–
          T x 14.7
  3. Know your cost of compressed air so you can provide effectiveness of the leak fixing process.
  4. Find, Document and Fix the leaks. Start by fixing the worst offenders, fix the largest leaks. Document both the leaks found and the leaks fixed which can help illustrate problem areas or repeat offenders, which could indicate other problems within the system.
  5. Compare the baseline to your final results.
  6. Repeat. We know you didn’t want to hear this but it will be necessary to continue an efficient compressed air system in your plant.

EXAIR has a tool to assist you in finding these leaks throughout your facility, the Ultrasonic Leak Detector. Check one of our other Blogs here, to see how it works!

Leak Detector

 

If you’d like to discuss how to get the most out of your compressed air system – or our products – give me a call.

Jordan Shouse
Application Engineer
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What’s So Great About Air Entrainment?

Air entrainment is the phenomenon that occurs when air (or any gas) under pressure is released from a device in such a way that a low pressure is generated in the immediate area of the air (or gas) discharge.  Air (or gas) from the surrounding environment is then pulled (or entrained) into the discharged air stream, increasing its volumetric flow rate.  EXAIR Corporation has been engineering & manufacturing compressed air products to take maximum advantage of this phenomena since 1983…and we’ve gotten better & better at it over the past 36 years.

Obviously, the first thing that’s so great about air entrainment is…free air flow.  Every cubic foot that’s entrained means that’s a cubic foot that your compressor didn’t have to spend energy compressing.  Considering the EXAIR Super Air Knife’s entrainment ratio of 40:1, that makes for a VERY efficient use of your compressed air.

Another thing that’s so great about air entrainment is…it’s quiet.  As you can see from the graphic at the top of this blog, the Super Air Knife entrains air (the lighter, curved blue arrows) into the primary compressed air stream (the darker, straight blue arrows) from above and below.  The outer layers of the total developed flow are lower in velocity, and serve as a sound-attenuating boundary layer.  The sound level of a Super Air Knife (any length…here’s why) is only 69dBA.  That means if you’re talking with someone and a Super Air Knife is running right next to you, you can still use your “inside voice” and continue your conversation, unaffected by the sound of the air flow.

I always thought it would be helpful to have more than just a graphic with blue arrows to show the effect & magnitude of air entrainment.  A while back, I accidentally stumbled across a stunning visual depiction of just that, using a Super Air Knife.  I had the pleasure of talking with a caller about how effective a Super Air Knife might be in blowing light gauge paperboard pieces.  So I set one up in the EXAIR Demo Room, blowing straight upwards, and tossed paper plates into the air flow.  It worked just as expected, until one of the paper plates got a little closer to the Super Air Knife than I had planned:

As you can see, the tremendous amount of air flow being entrained…from both sides…was sufficient to pull in lightweight objects and ‘stick’ them to the surface that the entrained air was being drawn past.  While it doesn’t empirically prove the 40:1 ratio, it indisputably demonstrates that an awful lot of air is moving there.

If you’re looking for a quiet, efficient, and OSHA compliant solution for cleaning, blow off, drying, cooling…anything you need an even, consistent curtain of air flow for – look no further than the EXAIR Super Air Knife.  If you’d like to discuss a particular application and/or product selection, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Chip Shields, OSHA, And You

Safety is a key part of our culture at EXAIR Corporation.  We have regularly scheduled, all-hands required, safety training on a number of topics.  Our Order Entry team can likely tell you as much about our lockout/tagout procedures as our Machinists can.  Nobody even thinks about entering The Shop without safety glasses, and it’s not just because of the signs.

We pay attention to these…
…so we don’t ever have to use this.

OSHA 1910.242(b) states that “Compressed air shall not be used for cleaning purposes except where reduced to less than 30 p.s.i. and then only with effective chip guarding and personal protective equipment. (emphasis mine)  All EXAIR Intelligent Compressed Air Products are engineered to meet the requirements of the first part (30psi outlet pressure to prevent dead ending…we’ve written about that numerous times, including here, here, and here) and we can also provide pre-installed devices to satisfy the second part:  the EXAIR Chip Shield.

Any EXAIR VariBlast or Heavy Duty Safety Air Gun can come fitted with a Chip Shield, and any Soft Grip Safety Air Gun, except for those with Stay Set Hoses, can as well.  Safety Air Guns with Back Blow Nozzles automatically come with a Chip Shield. The principle is simple: a clear polycarbonate (so you can still see what you’re doing) round disc slips over a short (or long if you want) pipe extension between the gun & the nozzle.  It’s fitted with a rubber grommet so you can position it to where it’s most effective – sometimes that might be closer to the part being blown off; sometimes it may be back a little closer to the operator.

EXAIR Safety Air Guns are available, from stock, with Chip Shields.

If you already have an air gun that’s doing the job, you can easily add an EXAIR Chip Shield to it.  They’re made to fit a wide range of extension diameters, and can even come with the extension if you need it.  We also stock a number of adapter fittings; if you know what threads your air gun has (or if you can send us some photos) we can quickly & easily spec those out for you.

Convenient and inexpensive “thumb guns” with cross drilled nozzles (left) are compliant with the first part of OSHA 1910.242(b). Fitting one with an EXAIR Chip Shield (center) makes it compliant with the second part. A Model 1102 Mini Super Air Nozzle (right) makes it quiet & efficient.
We can provide a Chip Shield for most any device with a threaded fitting. I couldn’t find a way to re-use the non-OSHA-compliant nozzle that came with this gun (thank goodness.)
Another example of a larger air gun fitted with a more powerful cross drill nozzle (left) that can be made totally OSHA compliant with an EXAIR Chip Shield (center.) An EXAIR High Force Super Air Nozzle (right) keeps the power, while reducing noise level and compressed air consumption (right.)

Since 1983, EXAIR Corporation has been manufacturing quiet, safe, and efficient compressed air products for industry (emphasis mine.)  If you have concerns or questions about safety in regard to your compressed air use, call me.

Russ Bowman
Application Engineer
EXAIR Corporation
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EXAIR Standard Air Knife: Engineered For Performance

In 1983, EXAIR Corporation was founded with the goal of engineering & manufacturing quiet, safe, and efficient compressed air products for industry.  By 1988, the EXAIR-Knife (now known as the Standard Air Knife) was quickly becoming the preferred choice for replacing loud and inefficient drilled pipes, long nozzle manifolds…anywhere an even, high velocity curtain of air was required.

The EXAIR Standard Air Knife’s design takes advantage of a fascinating principle of fluidics to achieve quiet and efficient operation: the Coanda Effect, which is the tendency of a fluid jet to stay attached to a convex surface.  If you want to see it for yourself, hold the back of a spoon, handle up, under the kitchen faucet.  Those who haven’t seen it before may assume that gravity will take over and the water will fall from the bottom of the spoon’s ‘bowl’ – but it doesn’t:

Likewise, the air flow (which is just another example of a fluid jet) exiting the Standard Air Knife’s shim gap follows a convex surface (which we call the “Coanda profile”) causing it to entrain large amounts of air from the surrounding environment:

Compressed air flows through the inlet (1) to the Standard 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.

This entrainment does two things for us:

  • First, because we’ve engineered the design for maximum entrainment, it’s very efficient – creating a high flow rate, while minimizing air consumption.  In the case of the Standard Air Knife, the entrainment ratio is 30:1.
  • Secondly, this entrainment forms an attenuating boundary layer for the air flow, resulting in a high velocity, high volume airflow that is also incredibly quiet.

The EXAIR Standard Air Knife comes in lengths from 3″ to 48″, and in aluminum or 303SS construction.  All sizes, in both materials, are on the shelf and available for immediate shipment.  For most applications, we recommend the Kit, which includes a Shim Set (to make gross changes to flow & force,) an Automatic Drain Filter Separator (keeps the air clean & moisture free,) and a Pressure Regulator (to dial in the performance.)  Deluxe Kits add our Universal Air Knife Mounting System and EFC Electronic Flow Control.

(From left to right) Aluminum Standard Air Knife Kit, SS Standard Air Knife Kit, Deluxe Aluminum Standard Air Knife Kit, Deluxe SS Standard Air Knife Kit.

If you need a hard hitting curtain of air for blow off, drying, cleaning, cooling, environmental separation, etc., the EXAIR Standard Air Knife is an easy and economical solution.  If you’d like to discuss your application and/or product selection, give me a call.

Russ Bowman

Application Engineer
EXAIR Corporation
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Vortex Tube Cold Fractions Explained

Simply put, a Vortex Tube’s Cold Fraction is the percentage of its supply air that gets directed to the cold end. The rest of the supply air goes out the hot end. Here’s how it works:

The Control Valve is operated by a flat head screwdriver.

No matter what the Cold Fraction is set to, the air coming out the cold end will be lower in temperature, and the air exiting the hot end will be higher in temperature, than the compressed air supply.  The Cold Fraction is set by the position of the Control Valve.    Opening the Control Valve (turning counterclockwise, see blue arrow on photo to right) lowers the Cold Fraction, resulting in lower flow – and a large temperature drop – in the cold air discharge.  Closing the Control Valve (turning clockwise, see red arrow) increases the cold air flow, but results in a smaller temperature drop.  This adjustability is key to the Vortex Tube’s versatility.  Some applications call for higher flows; others call for very low temperatures…more on that in a minute, though.

The Cold Fraction can be set as low as 20% – meaning a small amount (20% to be exact) of the supply air is directed to the cold end, with a large temperature drop.  Conversely, you can set it as high as 80% – meaning most of the supply air goes to the cold end, but the temperature drop isn’t as high.  Our 3400 Series Vortex Tubes are for 20-50% Cold Fractions, and the 3200 Series are for 50-80% Cold Fractions.  Both extremes, and all points in between, are used, depending on the nature of the applications.  Here are some examples:

EXAIR 3400 Series Vortex Tubes, for air as low as -50°F.

A candy maker needed to cool chocolate that had been poured into small molds to make bite-sized, fun-shaped, confections.  Keeping the air flow low was critical…they wanted a nice, smooth surface, not rippled by a blast of air.  A pair of Model 3408 Small Vortex Tubes set to a 40% Cold Fraction produce a 3.2 SCFM cold flow (feels a lot like when you blow on a spoonful of hot soup to cool it down) that’s 110°F colder than the compressed air supply…or about -30°F.  It doesn’t disturb the surface, but cools & sets it in a hurry.  They could turn the Cold Fraction down all the way to 20%, for a cold flow of only 1.6 SCFM (just a whisper, really,) but with a 123°F temperature drop.

Welding and brazing are examples of applications where higher flows are advantageous.  The lower temperature drop doesn’t make all that much difference…turns out, when you’re blowing air onto metal that’s been recently melted, it doesn’t seem to matter much if the air is 20°F or -20°F, as long as there’s a LOT of it.  Our Medium Vortex Tubes are especially popular for this.  An ultrasonic weld that seals the end of a toothpaste tube, for example, is done with a Model 3215 set to an 80% Cold Fraction (12 SCFM of cold flow with a 54°F drop,) while brazing copper pipe fittings needs the higher flow of a Model 3230: the same 80% cold fraction makes 24 SCFM cold flow, with the same 54°F temperature drop.

Regardless of which model you choose, the temperature drop of the cold air flow is determined by only two factors: Cold Fraction setting, and compressed air supply pressure.  If you were wondering where I got all the figures above, they’re all from the Specification & Performance charts published in our catalog:

3200 Series are for max cooling (50-80% Cold Fractions;) 3400’s are for max cold temperature (20-50% Cold Fractions.)
Chocolate cooling in brown; welding/brazing in blue.

EXAIR Vortex Tubes & Spot Cooling Products are a quick & easy way to supply a reliable, controllable flow of cold air, on demand.  If you’d like to find out more, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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