Compressed Air Supply Side: What Is A Deliquescent Dryer, And When Would You Use One?

As we head in to the colder months here in Ohio, I will soon be getting my humidifier out of the basement and set up in my bedroom. The dry air that accompanies the onset of winter chaps my lips, cracks the skin on my knuckles, affects my nasal passages, and oftentimes makes me wake up with a sore throat…something I definitely don’t want to happen in the middle of a pandemic! So I put some water vapor in my home’s air, on purpose, to take care of all of that.

Moisture in an industrial compressed air system, however, isn’t good for anything.  It’ll corrode your pipes, get rust in your pneumatic tools, motors, and cylinders, and spit out of your blow off devices, all over whatever you’re using your air to blow off.  Depending on the type of compressor, where, and how, it’s used, there are different types of dryers.  Today, dear reader, we’re taking a look at one of the most basic moisture removal systems: the deliquescent dryer.  The principle of operation is as follows:

  • Deliquescent dryer: how it works (1)
    Incoming compressed air enters near the base, where a form of mechanical separation occurs…the air flows back & forth, around trays of desiccant.  The simple act of changing direction causes a certain amount of free liquid to just fall out and collect in the bottom.
  • The air then flows upwards through the desiccant bed. The desiccant in a deliquescent dryer absorbs moisture (as opposed to the adsorption that occurs in a regenerative desiccant dryer) until they get so wet, they dissolve.
  • The desiccant level has to be monitored (commonly via a sight glass) so it can be replaced as it’s consumed.
  • After the desiccant does its job, moisture free air flows out the top, and gets on with it’s work.

Deliquescent dryers, owing to their simplicity, are the least expensive air dryers.  They have no moving parts and no electricity, so the only maintenance involved is replacing the desiccant media as it’s consumed.  This makes them especially popular in mobile/on-site applications involving portable or tow-behind, engine driven compressors, since they don’t need power to run.

There are several disadvantages, also owing to their simplicity:

  • The deliquescent media has to be periodically replenished.  If you don’t stay on top of it, you can find yourself shut down while you go back to the shop to get a big bag of salt.  That’s time your boss can’t charge your customer for.  Also, the cost of the new media is a continual operating cost of the dryer…something you don’t have to account for with the regenerative desiccant models.
  • Disposal of the waste media can be a concern…you definitely want to check your local environmental regulations before dumping it in the garbage.  Your boss won’t like talking to the EPA about THAT either.
  • They have to be equipped with a particulate filter on the discharge to keep the deliquescent media (which, being a salt, is corrosive in nature) from entering your system.  That would be even worse than water moisture…which this is there to prevent in the first place.
  • They don’t get near as low of a dewpoint as other dryers – the best you can hope for is 20°F to 30°F.  Which is fine, given the above mentioned nature of applications where these are commonly used.  You just wouldn’t want to use them to supply a product like an EXAIR Vortex Tube…which can turn that in to -40°F cold air, causing the water vapor to turn to liquid, and then to ice.  In a hurry.

EXAIR Corporation is in the business of helping you get the most out of your compressed air.  If you want to learn more, please follow our blog.  If you have specific questions, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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(1) – Deliquescent Dryer Image: VMAC Air Innovated: The Deliquescent Dryer – https://www.vmacair.com/blog/the-deliquescent-dryer/

Six Steps to Compressed Air Optimization: Step 3 – Use Efficient and Quiet Engineered Products

Compressed air is expensive, and you should treat it that way.  Frequent readers of the EXAIR Blog are familiar with our Six Steps to Compressed Air Optimization, and you may have seen these recent installments on Steps 1 and 2:

Six Steps to Optimization: Step 1 – Measure the Air Consumption

Six Steps to Compressed Air Optimization: Step 2 – Find and Fix Leaks

Now, there isn’t a strict order in which you MUST perform these steps, and they’re not all applicable in every air system (looking at you, Step 5: Use Intermediate Storage,) but these are likely the steps that a certified auditor will take, and the order in which they’ll take them.  If you’re looking for immediate, quantifiable results, though, Step 3 is a great place to start.  Consider:

  • A 1/4″ copper tube blow off can consume as much as 33 SCFM when supplied with compressed air at 80psig.  It’ll give you a good, strong blow off, for sure.  You can crimp the end and get that down to, say, 20 SCFM or so.  Or, you can install a Model 1100 Super Air Nozzle with a compression fitting, and drop that to just 14 SCFM.
    • If you’re tracking your compressed air usage, you’ll see that replacing just one of them saves you 45,600 Standard Cubic Feet worth of compressed in one 5 day (8 hour a day) work week.  That’s $11.40 in air generation cost savings, for a $42 (2020 List Price) investment.
    • If you spend time in the space where it’s installed, you’ll notice a dramatic improvement in the noise situation.  That sound level from the copper tube is likely over 100 dBA; the Super Air Nozzle’s is only 74 dBA.

This user was only a handful of compression fittings & nozzles away from over $800 in annual compressed air savings.

  • Drilled pipes are another common method to create a blow off.  They’re easy & cheap, but loud & expensive to operate.
    • A pipe drilled with 1/8″ holes and supplied @80psig will consume 13 SCFM per hole, and the holes are typically drilled on 1/2″ centers.
    • An EXAIR Super Air Knife consumes only 2.9 SCFM per inch of length, and because it’s an engineered product, it’s a LOT quieter as well.  Drilled pipes are, essentially, open ended blow offs just like the copper tube mentioned above.  When you let compressed air out of a hole like that, all the potential energy of the pressure is converted to force…and noise.
    • Drilled pipes are among the worst offenders; almost always well in excess of 100 dBA.  Super Air Knives generate a sound level of only 69 dBA with 80psig compressed air supply.  They are, in fact, the quietest compressed air blowing product on the market today.

This Model 110048 48″ Aluminum Super Air Knife replaced a drilled pipe for over $5,000 annual compressed air savings.

These aren’t just theoretical “for instances” either – the data, and the photos above, come from actual Case Studies we’ve performed with real live users of our products.  You can find them here, and here (registration required.)

These are two examples of EXAIR product users who only used Step 3 of our Six Steps, although BOTH of them were already practicing Step 4 (Turn off the compressed air when it isn’t in use)…they had their blow offs supplied through solenoid valves that were wired into the respective machine controls, and the Air Knife user HAD to do Step 6 (Control the air pressure at the point of use) to keep their product from being blown clear off the conveyor..

But we’ll be happy to help you with optimizing your compressed air system using any or all of the Six Steps. Give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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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