Liquid Handling With Compressed Air: An Overview

There are some very good reasons to consider an EXAIR compressed air operated Industrial Housekeeping Product for liquid applications:

*Durability. No moving parts means nothing to wear or get damaged.
*Safety. No electricity means no dragging an energized cord through a wet area.
*Convenience. All you need is a supply of compressed air.
*Reliability. If you supply it with clean, dry air, it’ll run darn near indefinitely, maintenance free.

Depending on the needs of the application, we have different models to choose from:

Reversible Drum Vacs

If you’ve got a closed top steel drum that’s in good condition, look no further than the Reversible Drum Vac System.  It comes with everything you need to turn that drum into a powerful, 2-way liquid pumping system.  This is great if you just need to park the drum in one spot and suction out a sump or tank on a regular basis, using its 10 foot Vacuum Hose & Suction Wand.  They’re in stock for your existing 30, 55, and 110 gallon drums.  A 5 Gallon Mini Reversible Drum Vac System is also available; it includes the drum as well.

Reversible Drum Vac Systems come in sizes from 5 to 110 gallons.

If you’d like a little mobility, and a way to clean up floor spills, then the Deluxe Reversible Drum Vac System might be what you’re looking for.  It adds a Drum Dolly and our Spill Recovery Kit…it consists of a floor-length wand and a dual squeegee tool.  It also comes with a set of plastic tools (crevice tool, small skimmer, and two 20″ extensions) and a Tool Holder with clips for the tools, and magnets to attach to the drum.  We keep them in stock for your existing 30 and 55 gallon drums.  It also comes in the 5 Gallon Deluxe Mini Reversible Drum Vac System (drum included.)


Deluxe Systems add a Spill Recovery Kit, and a Dolly for your drum.

For a complete system, the Premium Reversible Drum Vac Systems have everything you need for most any liquid drum transfer job: they add a drum, lid & latch ring, as well as a compressed air supply hose & shutoff valve, and an upgrade to Heavy Duty Aluminum Tools.  They’re available with 30, 55, or 110 gallon drums; in stock.

Premium Reversible Drum Vac Systems come with everything you need, right out of the box.

Any of the 30, 55, or 110 Gallon systems are also available with our High Lift Reversible Drum Vac.  These provide for increased performance with more viscous liquids, and/or when the liquid needs to pumped from a depth of up to 15 feet.  They are outfitted identically to the standard Reversible Drum Vac Systems, except they come with a 20 foot Vacuum Hose.

The High Lift Reversible Drum Vac System converts a drum and dolly into a mobile pumping system.

As versatile as the Reversible Drum Vacs are, we also incorporate them into another 2-way pumping system, designed to help you get maximum life and performance from machine tool coolant and cutting oils:  The award-winning Chip Trapper Systems.

The vacuum hose (1) is attached to the barbed connection of the Chip Trapper (2). The directional flow control valve on the top of the drum (3) and knob on the pump (4) are set to the “fill” position. The air supply valve is opened to permit compressed air at 80-100 psig (5.5-6.9 BAR) to flow through the pump which pulls the liquid through the hose, then into the reusable filter bag (5). When all liquid is in the drum, the air supply is turned off. The filtered liquid can then be pumped out by setting the directional flow control valve on top of the drum and the knob on the pump to the “empty” position. Once the air supply valve is opened, the air pushes the liquid back through the hose while all solids remain in the reusable filter bag.

Powered by the Reversible Drum Vac, the Chip Trapper System draws the incoming liquid into the drum through a Filter Bag, which retains (or “traps”) any particulate as the drum fills with liquid.  Then, the freshly filtered liquid can be immediately pumped back out, while the particulate remains in the bag.  Once the bag is full, simply remove the drum lid, unhook the bag, empty it out, and return it to service.  The Chip Trapper System comes with two Filter Bags, in fact, so you can clean one while you use the other.  They are available, from stock, in 30, 55, and 110 gallon sizes.  They are all three available in High Lift configuration as well, with a 20 foot Vacuum Hose.

If you’d like to find out more about safe, reliable and effective liquid handling with EXAIR’s compressed air operated Industrial Housekeeping Productsgive me a call.

Russ Bowman
Application Engineer
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How To Make Compressed Air Get Cold…A Couple Of Different Ways

The Vortex Tube makes cold air for the same reason that a can of compressed air gets cold when I clean my computer keyboard, right?

That’s a common question, and since they both start with compress air and end up with cold(er) air, it’s not an unreasonable assumption.  But the answer is no; they’re not the same.   Both are curious physical phenomena, though:

Cans of compressed air get cold while they’re discharging because of a thermodynamic principle known as the adiabatic effect.  When you pressurize a gas by compressing it into a container, you’re putting all those molecules into a smaller volume of space…and you’re adding potential energy by the compression.  Then, when you release that gas back to atmospheric pressure, that energy has to go somewhere…so it’s given off in the form of heat – from the air inside the can, as the pressure inside the can decreases.  Now, the air that’s not under as much pressure as it was when you pushed the button on top of the can is going to start coming out of the can pretty soon.  I mean, there’s only so much air in there, right?  So, since it’s given off that energy immediately upon the drop in pressure, when it comes out of the can, it’s at a lower temperature than it was before you started spraying it out.

Vortex Tubes, on the other hand, generate a flow of cold air by a completely different phenomenon of physics called, maybe not so curiously, the Vortex Tube principle:

You can get a lot more cold air – and a much lower temperature – from a Vortex Tube than you can from a can of compressed air.

If you need a reliable and dependable flow of cold air, look no further than EXAIR’s comprehensive line of Vortex Tubes and Spot Cooling Equipment.  We’ve got 24 models of Vortex Tubes to choose from, as well as “out of the box” solutions for cooling applications like the Adjustable Spot Cooler, Mini CoolerCold Gun Aircoolant Systems. and, to protect your sensitive electrical and electronic enclosures from heat, Cabinet Cooler Systems.  If you’d like to find out more, give me a call.

Russ Bowman

Application Engineer
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Sound Power Level and Sound Pressure

Energy…all day (and night) long, we humans are surrounded by – and bombarded by – all kinds of energy. Sometimes, the effects are pleasant; even beneficial: the warmth of the sun’s rays (solar energy) on a nice spring day is the sure-fire cure for Seasonal Affective Disorder, and is also the catalyst your body needs to produce vitamin D. Good things, both. And great reasons to get outside a little more often.

Sometimes, the effects aren’t so pleasant, and they can even be harmful. Lengthy, unprotected exposure to that same wonderful sun’s rays will give you a nasty sunburn. Which can lead to skin cancer. Not good things, either. And great reasons to regularly apply sunblock, and/or limit exposure if you can.

Sound is another constant source of energy that we’re exposed to, and one we can’t simply escape by going inside. Especially if “inside” is a factory, machine shop, or a concert arena. This brings me to the first point of today’s blog: sound power.

Strictly speaking, power is energy per unit time, and can be applied to energy generation (like how much HP an engine generates as it runs) or energy consumption (like how much HP a motor uses as it turns its shaft) For discussions of sound, though, sound power level is applied to the generation end. This is what we mean when we talk about how much sound is made by a punch press, a machine tool, or a rock band’s sound system.

Sound pressure, in contrast, is a measure of the sound power’s intensity at the target’s (e.g., your ear’s) distance from the source. The farther away you get from the sound’s generation, the lower the sound pressure will be. But the sound power didn’t change.

Just like the power made by an engine and used by a motor are both defined in the same units – usually horsepower or watts – sound power level (e.g. generation) and sound pressure (e.g. “use” by your ears) use the same unit of measure: the decibel.  The big difference, though, is that while power levels of machinery in motion are linear in scale, sound power level and pressure scales are logarithmic.  And that’s where the math can get kind of challenging.  But if you’re up for it, let’s look at how you calculate sound power level:

Sound Power Level Equation


Wis reference power (in Watts,) normally considered to be 10-12 W, which is the lowest sound perceptible to the human ear under ideal conditions, and

W is the published sound power of the device (in Watts.)

That’s going to give you the sound power level, in decibels, being generated by the sound source.  To calculate the sound pressure level:

Sound Power Level to Sound Pressure Equation


Lis the sound power level…see above, and

A is the surface area at a given distance.  If the sound is emitted equally in all directions, we can use the formula for hemispheric area, 2πrwhere r=distance from source to calculate the area.

These formulas ignore any effects from the acoustic qualities of the space in which the sound is occurring.  Many factors will affect this, such as how much sound energy the walls and ceiling will absorb or reflect.  This is determined by the material(s) of construction, the height of the ceiling, etc.

These formulas may help you get a “big picture” idea of the sound levels you might expect in applications where the input data is available.  Aside from that, they certainly put into perspective the importance of hearing protection when an analysis reveals higher levels.  OSHA puts the following limits on personnel exposure to certain noise levels:

Working in areas that exceed these levels will require hearing protection.

EXAIR’s line of Intelligent Compressed Air Products are engineered, designed, and manufactured with efficiency, safety, and noise reduction in mind.  If you’d like to talk about how we can help protect you and your folks’ hearing, call us.


Six Steps To Optimizing Your Compressed Air System – Step 1: Measure

“To measure is to know – if you cannot measure it, you cannot improve it.”
-Lord Kelvin, mathematical physicist, engineer,and pioneer in the field of thermodynamics.

This is true of most anything. If you want to lose weight, you’re going to need a good scale. If you want to improve your time in the 100 yard dash, you’re going to need a good stopwatch. And if you want to decrease compressed air consumption, you’ll need a good flowmeter. In fact, this is the first of six steps that we can use to help you optimize your compressed air system.

Six Steps To Optimizing Your Compressed Air System

There are various methods of measuring fluid flow, but the most popular for compressed air is thermal mass air flow.  This has the distinct advantage of accurate and instantaneous measurement of MASS flow rate…which is important, because measuring VOLUMETRIC flow rate would need to be corrected for pressure in order to determine the true compressed air consumption.  My colleague John Ball explains this in detail in a most excellent blog on Actual (volume) Vs. Standard (mass) Flows.

So, now we know how to measure the mass flow rate.  Now, what do we do with it?  Well, as in the weight loss and sprint time improvements mentioned earlier, you have to know what kind of shape you’re in right now to know how far you are from where you want to be.  Stepping on a scale, timing your run, or measuring your plant’s air flow right now is your “before” data, which represents Step One.  The next Five Steps are how you get to where you want to be (for compressed air optimization, that is – there may be a different amount of steps towards your fitness/athletic goals.)  So, compressed air-wise, EXAIR offers the following solutions for Step One:

Digital Flowmeter with wireless capability.  This is our latest offering, and it doesn’t get any simpler than this.  Imagine having a flowmeter installed in your compressed air system, and having its readings continually supplied to your computer.  You can record, analyze, manipulate, and share the data with ease.

Monitor your compressed air flow wirelessly over a ZigBee mesh network.

Digital Flowmeter with USB Data Logger.  We’ve been offering these, with great success, for almost seven years now.  The Data Logger plugs into the Digital Flowmeter and, depending on how you set it up, records the flow rate from once a second (for about nine hours of data) up to once every 12 hours (for over two years worth.)  Pull it from your Digital Flowmeter whenever you want to download the data to your computer, where you can view & save it in the software we supply, or export it directly into Microsoft Excel.

From the Digital Flowmeter, to your computer, to your screen, the USB Data Logger shows how much air you’re using…and when you’re using it!

Summing Remote Display.  This connects directly to the Digital Flowmeter and can be installed up to 50 feet away.  At the push of a button, you can change the reading from actual current air consumption to usage for the last 24 hours, or total cumulative usage.  It’s powered directly from the Digital Flowmeter, so you don’t even need an electrical outlet nearby.

Monitor compressed air consumption from a convenient location, as well as last 24 hours usage and cumulative usage.

Digital Flowmeter.  As a stand-alone product, it’ll show you actual current air consumption, and the display can also be manipulated to show daily or cumulative usage. It has milliamp & pulse outputs, as well as a Serial Communication option, if you can work with any of those to get your data where you want it.

With any of the above options, or stand-alone, EXAIR’s Digital Flowmeter is your best option for Step One to optimize your compressed air system.

Stay tuned for more information on the other five steps.  If you just can’t wait, though, you can always give me a call.  I can talk about compressed air efficiency all day long, and sometimes, I do!


The Case For The EXAIR Super Air Wipe

If you’ve ever used an air gun to blow something off, you’re familiar with the cleaning ability of compressed air.  If you can get the whole object blown off from where you’re standing, there really is no substitute…but what if you need to get to the other side…or sides?

Even if your product is not on fire, you probably wouldn’t want to “limbo” under it with an air gun…

This is where the EXAIR Super Air Wipe comes in…they allow you to blow a continuous, uniform 360° air stream, all around your product.  Consider their benefits:

*Sizes: the Super Air Wipe’s compact ring design means it won’t take up a lot of room; you just need a few inches, in any direction, to install one.  We stock them in eleven sizes, from 11″, all the way down to our brand-new 3/8″ diameter.

*Durability:  All EXAIR Super Air Wipes are assembled with stainless steel shims and hardware.  Models up to 4″ come with a rugged, stainless steel wire braided hose, connecting the two halves for compressed air supply.

The aluminum Super Air Wipe is available in 11 sizes; the stainless steel Super Air Wipe comes in 5 sizes…all from stock.

*Ease of installation:  Smaller sizes can be supported by the compressed air supply line, if a pipe is used and threaded into the connector hose’s 1/4 NPT port.  Larger sizes can likewise be adequately supported with pipe to both halves. All models have a bolt circle of 1/4″-20 tapped holes for more permanent and rigid mounting.  The split ring design is another key feature:

Simply open the two halves, and clamp them around your product…no threading!

*Corrosion resistance: Depending on the environment in which the Super Air Wipe will be installed, we offer them with aluminum (3/8″ – 11″ sizes) or stainless steel (3/8″ – 4″ sizes) bodies.

*Temperature rating: Aluminum Super Air Wipes are good to 400°F (204°C) and stainless steel models are good to 800°F (427°C.)

*Range of operation: We install a 0.002″ thick shim in all stock Super Air Wipes; this is suitable for a wide range of typical industrial/commercial blow off applications…a Pressure Regulator can then be used to “dial in” the air flow precisely to meet specific needs.  If a job calls for higher force & flow, additional 0.002″ shims can be installed.  Shim Sets come with the Super Air Wipe Kits, or individual shims can be ordered separately.

*Performance: Before the Super Air Wipe, a ring of nozzles was commonly used.  In fact, they still are, but we’re trying to fix that, at every opportunity we come across.  Problem with those is, it’s hard to get an even air flow all around, which leads to inconsistent blow off.  They can also be loud & inefficient, as we’ve found in numerous Efficiency Lab tests and Case Studies, like this one…

These wasteful and loud modular plastic tube blow offs…
…were replaced with EXAIR Super Air Wipes. 24 such replacements netted the customer an annual compressed air cost savings of over $13,000.00.

…and this one…

Implementing a Super Air Wipe salvaged a $30,000 job for this customer. Click on the picture to read all about it in our Case Study Library (registration required.)

Do you have a challenging blow off application that you need help with?  Call us to find out how an EXAIR Super Air Wipe (or another one of our Intelligent Compressed Air Products) can be a simple, quick & easy solution.

Custom Shims – Literally A Breeze For EXAIR

As proud as we are of being able to ship most any catalog product, same day, from stock (99.9831% of the time for on-time shipping in 2017…22 years straight for 99.9% or better,) we take a certain amount of pride in our ability to offer custom solutions for challenging applications as well. Our Engineering and Production teams have a deep well of resources (knowledge, experience, and capability) to draw from, which allows us to meet those challenging applications head-on, in short order.

The one I’m writing about today isn’t exactly one of those challenging ones…

A machine fabricator had a special need for an Air Knife. It had to be Stainless Steel, and it had to be 30″ long. No problem so far…that’s a Model 110030SS 30″ Stainless Steel Air Knife, and it’s on the shelf. Thing is, they only needed 26″ worth of air flow; a full 30″ width was going to disturb, and maybe damage, the edges of the sheet of material that the air was being blown onto.

So we made a custom shim for the Air Knife.  Now, we make these all the time, in all kinds of configurations…hence the term “custom.”  Since this one was blowing onto a web where they didn’t want to disturb the material on the far edges, we made this shim to provide 26″ of flow, on center.  We could just as easily made it to provide 26″ of flow starting at one end or the other, or a specified distance from one end or the other.  Or 13″ of flow on both ends, with 4″ of no flow in the middle, for a total of 26″.

If your application is more challenging than a custom shim, we’ve also made Air Knives with (left to right) curved radius, special material (glass filled PEEK shown here,) flat, double-sided, and even one with end-mount threaded holes.

Regardless of how challenging (or not) your compressed air product application is, we’re here to discuss, any time you’re ready.  Call us.


Line Loss: What It Means To Your Compressed Air Supply Pipe, Tubing, And Hose

“Leave the gun. Take the canolli.”

“What we’ve got here is failure to communicate.”

“I’ll get you my pretty, and your little dog too!”

“This EXAIR 42 inch Super Air Knife has ¼ NPT ports, but the Installation and Operation Instructions recommend feeding it with, at a minimum, a ¾ inch pipe…”

If you’re a movie buff like me, you probably recognize 75% of those quotes from famous movies. The OTHER one, dear reader, is from a production that strikes at the heart of this blog, and we’ll watch it soon enough. But first…

It is indeed a common question, especially with our Air Knives: if they have 1/4 NPT ports, why is such a large infeed supply pipe needed?  It all comes down to friction, which slows the velocity of the fluid all by itself, and also causes turbulence, which further hampers the flow.  This means you won’t have as much pressure at the end of the line as you do at the start, and the longer the line, the greater this drop will be.

This is from the Installation & Operation Guide that ships with your Super Air Knife. It’s also available from our PDF Library (registration required.)

If you want to do the math, here’s the empirical formula.  Like all good scientific work, it’s in metric units, so you may have to use some unit conversions, which I’ve put below, in blue (you’re welcome):

dp = 7.57 q1.85 L 104 / (d5 p)


dp = pressure drop (kg/cm2) 1 kg/cm2=14.22psi

q = air volume flow at atmospheric conditions (FAD, or ‘free air delivery’) (m3/min) 1 m3/min = 35.31 CFM

L = length of pipe (m) 1m = 3.28ft

d = inside diameter of pipe (mm) 1mm = 0.039”

p = initial pressure – abs (kg/cm2) 1 kg/cm2=14.22psi

Let’s solve a problem:  What’s the pressure drop going to be from a header @80psig, through 10ft of 1″ pipe, feeding a Model 110084 84″ Aluminum Super Air Knife (243.6 SCFM compressed air consumption @80psig)…so…

q = 243.6 SCFM, or 6.9 m3/min

L = 10ft, or 3.0 m

d = 1″, or 25.6 mm

p = 80psig, or 94.7psia, or 6.7 kg/cm2

1.5 psi is a perfectly acceptable drop…but what if the pipe was actually 50 feet long?

Again, 1.5 psi isn’t bad at all.  8.2 psi, however, is going to be noticeable.  That’s why we’re going to recommend a 1-1/4″ pipe for this length (d=1.25″, or 32.1 mm):

I’m feeling much better now!  Oh, I said we were going to watch a movie earlier…here it is:

If you have questions about compressed air, we’re eager to hear them.   Call us.

Russ Bowman
Application Engineer
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