Basics of the Compressor Room

EXAIR Corporation has staked our reputation on a keen ability to help you get the most out of your compressed air system since 1983.  Now, the bulk of our expertise lies in the implementation and proper use of engineered products on the demand side, but we fully recognize that there are critical elements for optimization on the supply side too.  And that, quite literally, starts in the compressor room.  This is not an exhaustive, specifically detailed list, but here are some you might consider to get the most from the (again, quite literally) beginning:

  • Location.  If you’re building a new facility, or doing a major rehab of your existing one, having the compressor room as close as practical to the point(s) of use is best, IF all other things are equal.  You’ll use less pipe if you don’t have to run it so far.  You’ll also be able to use smaller diameter lines because you won’t have to worry about line loss (pressure drop due to friction as the air flows through the total length) as much.
  • Location part 2.  If all other things are NOT equal, having the compressor room close to the point of use may not be best for you.
    • Your air compressor pulls in air from the immediate environment.  It’s better to go with longer and bigger pipe in your distribution system than it is to put your compressor in a location where it’ll pull in dust & particulate from grinding operations, humidity from a boiler plant, fumes from chemical production, etc.
    • There are some pretty darn quiet air compressors out there, but there are some pretty loud ones too.  Especially in small to mid size facilities, putting the compressor in an area that upsizes the required piping is still likely a better idea, due to the downsizing of the noise levels that personnel will be exposed to.
  • Environment.  No matter where your compressor is located, the machine itself should be protected from heat and other harsh environmental elements.  That means if it’s inside the plant, the compressor room should be adequately ventilated.  In some situations, the compressor may be best installed outside the plant, in its own building or protective structure.  This should be designed to protect against solar load…in addition to the high temperature associated with a hot summer day, the sun’s rays beating down on your air compressor will radiate a tremendous amount of heat into it.
  • Filtration.  Whatever is in the air in your compressor room is going to get into your compressed air.  This is doubly problematic: particulate debris can damage the air compressor’s moving parts, and it can likewise damage your pneumatic cylinders, actuators, tools, motors, etc. as well.  Make sure the intake of your compressor is adequately filtered.
  • Maintenance.  Air compressors, like any machinery with moving parts, require periodic preventive maintenance, and corrective maintenance when something inevitably breaks down.  There should be adequate space factored in to your compressor room’s layout for this.  The only thing worse than having to fix something is not having the room to fix it without taking other stuff apart.
Patrick Duff, a production equipment mechanic with the 76th Maintenance Group, takes meter readings of the oil pressure and temperature, cooling water temperature and the output temperature on one of two 1,750 horsepower compressors. Each compressor is capable of producing 4,500 cubic feet of air at 300 psi. The shop also has a 3,000 horsepower compressor that produces 9,000 cubic feet of air at 300 psi. By matching output to the load required, the shop is able to shut down compressors as needed, resulting in energy savings to the base. (Air Force photo by Ron Mullan)

These are a few things to consider on the supply end.  If you’d like to talk about how to get the most out of your compressed air system, EXAIR is keen on that.  Give us a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Super Air Knives Are Ideal For Super Aggressive Environments

Hydrochloric Acid. Sodium Hydroxide. Nitric Acid. Hydrogen Peroxide. Whether you know it or not, these are all commonly used around the house as tile/grout cleaners, drain openers, lawn fertilizers, and disinfectant for cut & scrapes, respectively.

They’re also used in a variety of industrial applications, such as the making of plastics, glass, pharmaceuticals, and wastewater treatment, respectively…all of which also have applications for which EXAIR Corporation’s Intelligent Compressed Air Products provide safe, efficient, and quiet solutions for.

Stainless Steel Super Air Knife Kits include the Air Knife itself, a Shim Set, an Automatic Drain Filter Separator, and a Pressure Regulator. The Air Knife & Shim Set are all Stainless Steel (grade 303 or 316, depending on which is specified) construction.

Consider the Super Air Knife: If you need one that’ll stand up to contact with hydrochloric acid, you’re looking for PVDF construction. Nitric acid is a different story – our 303SS, 316SS construction Super Air Knives are well suited for those applications.

On the other end of the (pH) spectrum, any of those materials are suitable for exposure to Sodium Hydroxide. PVDF is still the best choice, as the Stainless Steels will be subject to discoloration or slight corrosion, depending on the concentration.

PVDF Super Air Knife Kits include the Air Knife itself (PVDF body, Hastelloy C-276 hardware, and PTFE Shims,) a PTFE Shim Set, an Automatic Drain Filter Separator, and Pressure Regulator.

Acids and bases aside, oxidizers are also very corrosive, especially in higher concentrations.  Hydrogen peroxide is a commonly used oxidizer in industries as diverse as pulp & paper, soap & detergent, and water sterilization.  Like other chemicals, compatibility depends on the concentration, but like nitric acid & sodium hydroxide, our PVDF Super Air Knives are still the best, but the Stainless Steel models are still acceptable.

These are just a few, very basic, examples of chemical compatibility.  If you have an application that calls for installing one of our compressed air products in an area where you’re concerned about corrosion, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Siphon Fed No-Drip Atomizing Spray Nozzles

With 142 distinct models in stock, the Atomizing Spray Nozzles are easily EXAIR Corporation’s most diverse product line. If you need a reliable method of creating a fine mist of liquid flow with a flow rate as high as 303 gallons per hour (or as low as 0.1 gallons per hour,) with a spray pattern as large as 13 feet (or as small as 2-1/2 inches) in diameter, look no further – we have a spray nozzle for you, on the shelf and ready to go.

Siphon Fed models are the subject of today’s blog – they don’t require that the liquid be under pressure; you can feed them from the vessel the liquid comes in from a siphon height of up to 36 inches, or, for higher flows, from a gravity height of as low as 6 inches.

EXAIR Siphon Fed Nozzles work with non-pressurized liquids, either siphoned (left) or gravity fed (right.)

All Atomizing Spray Nozzles are available with EXAIR’s patented No-Drip option, which positively shuts off liquid flow when the compressed air supply is shut off.  One benefit of this is realized in coating applications, where an errant droplet of liquid would mar an otherwise smooth, even coating.  Operationally, though, it also means you can precisely turn the liquid flow on & off, in short, quick bursts, up to 180 times a second.

By far, the simplest way to do this is with a valve installed in the air supply line to the Atomizing Spray Nozzle.  A manual 1/4 turn ball valve works fine if you want the operator to control it.  Solenoid valves are often used to automate the process, and if you’ve got something to open & close the valve, you’re all set.  For example, if you want to spray coolant onto a cutting tool, just wire the solenoid valve into the on-off switch of the machine, like in the example shown to the right.

Alternately, our EFC Electronic Flow Control System provides a ready-to-go solution.  It comes pre-wired; all you have to do is plumb the valve into the air supply line and plug it in to a 120VAC grounded wall outlet.  When the photoelectric sensor “sees” the part you want to spray, it opens the valve.  When the part passes, it shuts the valve.  Easy as that.

I like this whole video, but if you just want to see the EFC Electronic Flow Control & Atomizing Spray Nozzle in action, skip to the 4:05 mark.

If you have a need to spray a fine, controllable liquid mist, EXAIR has a wide range of solutions.  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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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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