Tag: air drier

Compressed Air Pipe

The Power of Deliquescent Driers in Compressed Air Systems

Published on by Jordan T ShouseLeave a comment

In industrial manufacturing, compressed air is the unsung hero powering tools, machinery, and processes across manufacturing, painting, blasting, and beyond. But here’s the catch: moisture. That sneaky water vapor lurking in your compressed air lines can wreak havoc, causing corrosion, freezing, and contaminating sensitive equipment. Deliquescent driers are low-maintenance systems designed to tackle humidity head-on. In this blog, we’ll dive into what makes these driers tick, their pros and cons.

What Are Deliquescent Driers, Anyway?

Picture this: a simple tank packed with hygroscopic (water-loving) salt tablets that dissolve into a brine as they absorb moisture from compressed air. That’s the 1000-foot view of a deliquescent drier. Unlike refrigerated or desiccant dryers that rely on complex refrigeration cycles or regeneration, deliquescent driers use chemistry to do the heavy lifting. The process is elegantly straightforward:

  • Incoming air enters the bottom of the vessel, preheated from compression and loaded with water vapor.
  • It flows upward through a bed of deliquescent desiccant—typically formulated from salts like calcium chloride, lithium chloride, or potassium chloride.
  • The salts “deliquesce” (hence the name), attracting and dissolving water vapor into a liquid brine that collects at the base.
  • Dry air exits the top, with a pressure dew point suppressed by about 15-20°F below the inlet temperature, depending on conditions.

No electricity, no moving parts—just pure, passive drying. These driers have been a staple since the 1940s, especially in rugged settings like petrochemical plants, outdoor blasting ops, or mobile equipment where reliability is the largest concern.

Why Choose Deliquescent Driers? The Pros (and a Few Cons)

Deliquescent driers aren’t for every scenario, but when they fit, they’re a game-changer. Let’s break it down:

The Advantages:

  • Zero Energy Consumption: No power required means lower operating costs and no electrical hazards in wet or explosive environments. Ideal for remote sites or intermittent use.
  • Rugged and Portable: Mount them indoors or outdoors—they thrive in extreme temps, even subzero conditions, with the right setup. Perfect for mobile contractors in painting or abrasive blasting.
  • Low Maintenance: Just drain the brine every 8-hour shift and top up the desiccant a few times a year. A sight glass lets you monitor levels at a glance.
  • Cost-Effective Upfront: Cheaper to buy and install than high-tech alternatives, with no filters or separators to fuss over.

The Drawbacks:

  • Limited Dew Point Control: They suppress dew point by a fixed amount (e.g., 20°F), so hot inlet air means warmer outlet air—fine for many apps but not ultra-dry needs.
  • Corrosion Potential: The brine is salty and corrosive, so vessels need robust coatings, and downstream lines require after filters to catch salt carryover.
  • Pre-filtration Required: Oil from compressors can foul the desiccant, so a coalescing pre-filter is a must.

In short, if you’re blasting in humid conditions, painting in the field, or running air tools in cold weather, deliquescent driers deliver freeze-proof, reliable performance without the fuss.

At EXAIR Corporation, we’re keen on compressed air efficiency. The attention to detail we pay to our products – from design, to manufacturing & assembly, to availability, and right on through to technical support – bears out our commitment to helping you get the most out of your compressed air system. If you’ve got questions, Give me a call.

Jordan Shouse, CCASS

Application Engineer

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Image courtesy of Brian S. Elliott, Wikimedia Commons Creative Commons Attribution-Share Alike 4.0 International License

Compressed Air System Equipment – What You Need To Know

Published on by Russ BowmanLeave a comment

The use of compressed air in industry is so widespread that it’s long been called “the fourth utility” (along with electricity, water, and natural gas). As a function of energy consumption (running an air compressor) to energy generated (operation of pneumatic equipment), only 10-15% of the energy consumed is converted to usable energy stored as compressed air. Its “bang for the buck”, however, comes when you consider the total cost of ownership – yes, it costs a lot to generate, but:

  • It’s relatively safe, when compared to the risks of electrocution, combustion, and explosion associated with electricity & natural gas.
  • Air operated tools, equipment, and products are generally much cheaper than their electric, gas, or hydraulic powered counterparts.
  • Air operated products, like anything, require periodic maintenance, but oftentimes, that maintenance simply comes down to keeping the air supply clean and moisture free, unlike the extensive (and expensive) maintenance requirements of other industrial machinery.

Even with these advantages, though, it’s still critical to get all you can out of that 10-15% of the energy you’re consuming to make that compressed air, and that starts with having the right stuff in the right place. Now, all of the following “stuff” might not apply to every compressed air system. I once worked in a repair shop, for example, with a small compressor that was used for a couple of blow off guns, impact drivers, and a sidearm grinder. I’ve also done field service in facilities with hundreds of pneumatic cylinders & air motors that operated their machinery. Those places had even more “stuff” than I’m devoting space to in this blog, but here’s a list of the “usual suspects” that you’ll encounter in a properly designed compressed air system:

  • Air compressor. I mean, of course you need a compressor, but the size and type will be determined by how you’re going to use your air. The small repair shop I worked in had a 5HP reciprocating positive displacement compressor with a 50 gallon tank, and that was fine. The larger facilities I visited often had several 100 + HP dynamic centrifugal or axial compressors, which get more efficient with size.
  • Air preparation. This includes a number of components that can be used to cool, clean, and dry the air your compressor is generating:
    • Pressurizing a gas raises its temperature as well. Hot compressed air could cause unsafe surface temperatures and can damage gaskets, seals, and other components in the system. Smaller compressors might not have this problem, as the heat of compression is often dissipated through the wall of the receiver tank and the piping at a rate sufficient to keep the relatively low (and often intermittent) flow at a reasonable temperature. Larger compressors usually come with an aftercooler.
    • The air you compress likely has a certain amount of moisture in it…after nitrogen and oxygen, water vapor usually makes up more of the content of atmospheric air than all other trace gases combined. There are a number of air dryer types; selection will be dictated by the specifics of your facility.
    • Your air is going to have other contaminants in it too. We did welding & grinding in the repair shop where our compressor sat in the corner. We kept a few spare intake filters handy, and replaced them regularly. In conjunction with the aftercooler & dryer, larger industrial compressors will also have particulate filters for these solids. For extra protection, coalescing filters for oil vapor, and adsorption filters for other gases & liquid vapors, are specified.
  • Distribution. In the repair shop, we had a 3/4″ black iron pipe that ran across the ceiling, with a few tees & piping that brought the air down to the individual stations where we used it. The larger facilities I visited had larger variations of this “trunk and branch” type network, and some were even big enough to make use of a loop layout…these were especially popular when multiple air compressors were located throughout the facility. In addition to black iron, copper & aluminum pipe (but NEVER PVC) are commonly used too.
  • Condensate removal. The small repair shop compressor had a valve on the bottom of the tank with a small hose that we’d blow down into a plastic jug periodically. Larger systems will have more complex, and oftentimes automated condensate management systems.

So, that’s the system-wide “stuff” you’ll usually encounter in a properly designed compressed air system. After that, we’ll find a number of point-of-use components:

  • Air preparation, part 2. The compressor intake & discharge filtration mentioned above make sure that you’re putting clean air in the distribution piping. That’s fine if your distribution piping is corrosion resistant, like aluminum or copper, but black iron WILL corrode, and that’s why you need point-of-use filters. EXAIR Automatic Drain Filter Separators have 5 micron particulate elements, and centrifugal elements that ‘spin’ any moisture out. If oil is an issue, our Oil Removal Filters have coalescing elements for oil/oil vapor removal, and they provide additional particulate protection to 0.03 microns.
  • Pressure control. Your compressor’s discharge pressure needs to be high enough to operate your pneumatic device(s) with the highest pressure demand. Odds are, though, that not everything in your plant needs to be operated at that pressure. EXAIR Pressure Regulators are a quick & easy way to ‘dial in’ the precise supply pressure needed for specific products so they can get the job done, without wasting compressed air.
  • Storage. This could also be considered system “stuff”, but I’m including it under point-of-use because that’s oftentimes the reason for intermediate storage. Having a ready supply of compressed air near an intermittent and/or large consumption device can ensure proper operation of that device, as well as others in the system that might be “robbed” when that device is actuated. They’re good for the system, too, as they can eliminate the need for higher header pressures, which cause higher operating costs, and increased potential for leaks. EXAIR Model 9500-60 60 Gallon Receiver Tanks are an ideal solution for these situations.

For more information on proper installation and use of compressed air system “stuff” like this, the Compressed Air & Gas Institute’s Compressed Air and Gas Handbook has a good deal of detailed information. The Air Data section of EXAIR’s own Knowledge Base is a great resource as well.

Of course, all the attention you can pay to efficiency on the supply side doesn’t matter near as much if you’re not paying attention to HOW you’re using your compressed air. EXAIR Intelligent Compressed Air Products are designed with efficiency, safety, and noise reduction in mind. Among the other ways my fellow Application Engineers and I can help you get the most out of your compressed air system, we’re also here to make sure you get the right products for your job. To find out more, give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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Intelligent Compressed Air: What You Need To Know About Deliquescent Dryers

Published on by Russ BowmanLeave a comment

Moisture free air is a “must” for industrial use, for a number of reasons:

  • An awful lot of distribution systems incorporate iron pipe. It’s inexpensive, readily available, easy to work with, rated for pressure, and has a long history of successful installations. Iron pipe will also oxidize (make rust) in the presence of water:
Here’s what we find a lot of the time inside a Reversible Drum Vac that’s been sent in for refurbishment because it’s not drawing effective vacuum anymore.
  • Regardless of what your distribution lines and components are made of, water droplets can erode them. Compressed air itself is a gas; it follows the curves in elbows, and flows around valve discs & regulator diaphragms. Water droplets, on the other hand, run full speed INTO those things, often at high velocity. This eventually causes pitting, which is bad enough…those pits, though, are little pockets for salts, acids, or alkalines to effect their destructive little chemical reactions.
  • When used for blow off applications, anything in your compressed air will get on anything you’re blowing off. If the intent is to remove moisture from a surface, moisture in your compressed air supply decidedly works against your goal.
  • Water can freeze as it is carried along with air flow through orifices. This can quickly block the flow of air. The US Navy lost a submarine, USS Thresher (SSN-593) and all hands in 1963. A number of factors contributed to the sinking, but a significant one was that compressed air being blown into the ballast tanks (to create negative buoyancy) had higher than permissible moisture content, and froze in orifice plates in the lines. The ballast tanks stayed full of water, and 129 sailors & shipyard personnel died as the boat passed crush depth.

There are a number of types of air dryers that are commonly fitted to industrial air compressors to take care of moisture problems. The least expensive one of these is the Single Tower Deliquescent Dryer. Here’s how they work:

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 some of the water 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.
  • After the desiccant does its job, moisture free air flows out the top, and gets on with it’s work.

In addition to the low price tag, other things to like about them are:

  • Low pressure drop.
  • No moving parts or electrical components.
  • Can be used outdoors, and in hazardous, mobile, dirty, or corrosive environments.

Of course, there are things to NOT like about them as well:

  • Limited suppression of dew point – because they are drying the air to a specific relative humidity, as opposed to a specific dew point, the attainable dew point is dependent on the incoming air temperature, the chemical composition of the desiccant salt, and the ambient temperature where it’s installed. Unless you use some sort of specialty salt desiccant, the typical dew point is only 20-25ºF lower than the air inlet temperature.
  • Desiccant carryover – speaking of those specialty salts, they’re even more corrosive than the basic sodium chloride that’s often used. Any carryover will wreak havoc on your distribution system and air operated devices.

Deliquescent dryers’ particular set of “pros and cons” presents challenges for their use in industrial settings, for sure. But if the primary concern is preventing pipes from freezing up, then their low cost, low maintenance, and simplicity make them a great choice.

At EXAIR Corporation, we’re keen on compressed air efficiency. The attention to detail we pay to our products – from design, to manufacturing & assembly, to availability, and right on through to technical support – bears out our commitment to helping you get the most out of your compressed air system. If you’ve got questions, we can talk about this all day long…and most of the time, we do. Give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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Image courtesy of Brian S. Elliott, Wikimedia Commons Creative Commons Attribution-Share Alike 4.0 International License

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

Published on by Russ BowmanLeave a comment

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/