Category: Compressor

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

Intelligent Compressed Air: Rotary Scroll Compressors

Published on by Russ BowmanLeave a comment

If you need compressed air, there are a number of ways to get it (see chart above) and they all have their pros & cons. In order to choose the right compressor (or compressors), there are also a number of factors which will influence that decision:

  • Specific requirements of the facility with regard to how much airflow, and at what supply pressure(s) is needed for the compressed air-operated equipment.
  • Location of the facility…and the air compressor. Environmental considerations will absolutely influence the selection of filtration, drying, and even the type of compressor.
  • Power cost – energy consumption is, by far, the largest portion of the total lifetime cost of any compressed air system.

With that in mind, the purpose of today’s blog is to lay out the case for rotary scroll compressors. These are positive displacement machines, meaning that they draw in a fixed volume of air and push it into a smaller volume, increasing the pressure. The earliest air compressors were positive displacement reciprocating piston types, where a piston moves back & forth in a cylinder, drawing in atmospheric pressure air on the ‘up’ stroke, and discharging it into the compressed air system on the ‘down’ stroke. These are simple machines – by adding cylinders, you can add air capacity, and by adding stages, you can generate high pressures.

The rotary scroll air compressor is a fairly recent development. While the first patent for one was issued in 1905, the machining technology required to make it work wasn’t available until the 1950’s, and it was the 1970’s before they started to enter mainstream use. Here’s how it works:

Two spirals, or scrolls, are intermeshed. The rotating (black) one orbits eccentrically with the fixed one, continually decreasing the volume for the gas to flow through (from the outer left & right sides) as it is pushed to the center, where it is fully compressed according to the compressor’s rating.

The main benefits of choosing a rotary scroll compressor are:

  • Quiet operation. They can be thought of as the polar opposite of reciprocating piston models in this regard. Instead of slamming solid pieces of metal back & forth in a confined space, the continuous motion of the rotating scroll never brings it into contact with the stationary scroll, so mechanical sound generation and vibration are all but eliminated.
  • Energy efficiency. Two main factors come in to play here:
    • Continuous compression – if the rotary scroll is in motion, it’s compressing air constantly, in proportion to its speed of rotation.
    • Low friction – because the scrolls don’t contact each other, they don’t lose energy due to friction between moving parts.
  • Pulsation free operation. This is another benefit of continuous compression, as opposed to the pulsating airflow from a reciprocating piston design. This means less wear & tear on pretty much everything immediately downstream of the compressor.
  • Fewer moving parts. The only moving part, really, is the rotating element. Compared to the pistons, rings, connecting rods, cylinders and valves of a reciprocating compressor, the reliability & durability of the rotary scroll compressors can’t be beat.
  • Oil free air. No metal to metal contact in the air end means no lubrication is required.

That said, they’re not without limitations and potential drawbacks:

  • Higher purchase price. The precision machinery needed to manufacture their high tolerance components aren’t cheap, and neither is their operation.
  • Limited capacity. Because of the centrifugal force the rotary element generates, it’s necessarily limited in mass and therefore, size. Rotary scroll compressors typically top out at about 100 SCFM worth of capacity.
  • Higher repair costs. Because of the tight tolerances and the fact that the air end has to be hermetically sealed, repairs of these compressors are high-tech operations…and the highly trained technicians with the specialized tools & equipment to perform such repairs don’t come cheap.

At EXAIR, we want to help you get the most out of your compressed air system. If you’d like to talk about that, give me a call.

Russ Bowman, CCASS

Application Engineer
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Compressed Air Wet Receivers and Condensate Drains: Keeping your Systems Running Clean and Efficient

Published on by Jordan T ShouseLeave a comment

Compressed air systems are the backbone of countless industries and operations, from powering tools to cleaning, cooling and drying products in process. But behind the scenes, components like the wet receiver and condensate drain play pivotal roles in ensuring these systems deliver clean, reliable air. If you’re involved in facility management, maintenance, or just curious about how compressed air systems tick, understanding these elements can make all the difference. Let’s break it down!

What is a Wet Receiver in Compressed Air Systems?

In a compressed air setup, a receiver is a storage tank that holds pressurized air after it’s been compressed but before it’s distributed to the point of use. A wet receiver, specifically, is positioned downstream of the compressor but before the air dryer or major filtration stages. This means it stores “wet” compressed air—air that still contains moisture, oil, and other contaminants picked up during compression.

The “wet” designation comes from the fact that the air hasn’t been treated yet. As air is compressed, it heats up, and when it cools in the receiver, moisture condenses into liquid water. The wet receiver acts as a buffer, smoothing out pressure fluctuations and giving that moisture a place to settle before the compressed air moves further down the line. Think of it as a staging area that helps protect downstream equipment from surges and contaminants.

Condensate Drain

As air cools in the wet receiver, water vapor turns into liquid condensate—often mixed with traces of oil and dirt. If this condensate isn’t removed, it can corrode the receiver, clog pipes, or damage tools and equipment downstream. The condensate drain is the unsung hero that gets rid of this unwanted liquid.

Typically mounted at the bottom of the wet receiver , the drain can be manual, automatic, or timer-based:

  • Manual drains require someone to open a valve periodically.
  • Automatic float drains open when enough liquid accumulates.
  • Electronic timer drains release condensate at set intervals.

No matter the type, the goal is the same: keep the system dry and free of buildup.

A well-maintained wet receiver and condensate drain mean cleaner air, longer equipment life, and lower operating costs. Wet air can cut tool efficiency by 20% or more, while corrosion from neglected condensate can force early replacements for all downstream equipment. On the flip side, a little attention to these components keeps your compressed air system humming—and your bottom line happy.

Next time you hear the hiss of a pneumatic tool or the hum of a compressor, think about the wet receiver and condensate drain. They’re not flashy, but they’re indispensable.

Jordan Shouse
Application Engineer

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Photo: Blue Air Receiver Attribution – CC BY-ND 2.0

Types of Compressors: Sliding Vane

Published on by Al WooffittLeave a comment

We frequently receive inquiries regarding the type of air compressor that customers should purchase. While we strongly advise consulting a local, reputable air compressor dealer to discuss your specific requirements, we do know a thing or two about various compressor types and their advantages. In this blog, I will focus on a specific category of air compressor: Sliding Vane Compressors.

Sliding Vane Compressors (also referred to as Rotary Vane Compressors) fall under the category of positive displacement compressors (as opposed to dynamic). More specifically, they are a form of rotary compressor in the positive displacement family. You can see this from the following diagram:

1. Diagram of Compressor Technologies.

In positive displacement compressors, a specific volume of air is confined within a compression chamber. This volume is then mechanically compressed, resulting in an increase in pressure. Sliding Vane Compressors are composed of an external housing, known as the stator, and an internal circular rotor that is positioned eccentrically. The rotor features radially arranged (and sometimes offset) slots that accommodate vanes. As the rotor spins, centrifugal forces act on the vanes, causing them to extend outward and press against the inner surface of the stator bore. This interaction generates compression zones formed by the vanes, the rotor surface, and the stator bore.

Due to the eccentric positioning of the rotor, the volume of these compression zones decreases as the gap between the rotor surface and the stator narrows. As the rotor rotates counterclockwise, the vanes are pushed back into the rotor slots while maintaining contact with the stator surface. This reduction in the compression zone results in an increase in air pressure.

The advantages of the Sliding Vane Compressor are as follows:

  • Compact size
  • Relatively low initial cost
  • Vibration-free operation – no special foundation needed
  • Routine maintenance includes basic lubricant and filter changes.

A few of the disadvantages are:

  • Lubricant gets into the compressed air stream, requires an air/lubricant separation system.
  • Requires periodic lubricant change and disposal
  • Less efficient than rotary screw type
  • Not as flexible as rotary screw in terms of capacity control in meeting changing demands

If you would like to discuss your compressed air application, then give us a call!

Al Wooffitt
Application Engineer

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Al Wooffitt
Application Engineer

Send me an Email
Find us on the Web
Like us on Facebook
Twitter: @EXAIR_AW

  1. Compressed Air & Gas Handbook. Diagram of Compressor Technologies.