Tag: air compressor

What’s So Awful About A Drilled Pipe For A Conveyor Blowoff?

Published on by Russ BowmanLeave a comment

A technician from a company that performs comprehensive audits of compressed air systems called me with a sad, sad story. A client had just installed a brand-new state-of-the-art rotary scroll compressor with a variable speed drive…they were going all-out on efficiency, which is great. During the technician’s walk-through, however, he noticed a blowoff on a conveyor belt — they actually heard it before they could see it — a black iron pipe with a series of holes drilled along the length, plumbed with compressed air being supplied, unregulated, from a 100psig header.

The pipe was 18″ long and had 30 holes, 1/8″ diameter each, drilled along the length. From the table below, we can presume that this drilled pipe was consuming as much as 475.8 SCFM:

I say “as much as 475.8 SCFM” because the technician noted the holes were simply drilled through, they weren’t rounded, so I calculated the flow from a 1/8″ orifice at 100psig (26.0 CFM) with a 0.61 multiplier for sharp edges orifices. Also, the inlet pressure of the drilled pipe is not known. With a 1″ pipe supplying it, the flow could be limited to around 350 SCFM, due to line loss in the pipe.

The technician first asked about installing Air Nozzles in the drilled pipe. That’d mean drilling those holes out and tapping them individually. This COULD be done, and the drilled pipe could be fitted with 30 Model 1110-PEEK Nano Super Air Nozzles, with an air consumption of 8.3 SCFM @80psig each, for a total of 249 SCFM. That’s a significant reduction, but also a lot of work on the drilled pipe. I recommended replacing it entirely with a Super Air Knife.

A Model 110018 18″ Aluminum Super Air Knife consumes only 52.2 SCFM @80psig — almost an order of magnitude reduction! Let’s do the math on the costs:

First, the drilled pipe: Let’s give all the benefit of the doubt here and assume that the line loss had indeed limited the air consumption to 350 SCFM. Operating 8 hours a day, 5 days a week, 52 weeks a year, and using the US Department of Energy’s estimate that compressed air costs $0.25 per 1,000 Standard Cubic Feet used, the annual operating cost of the drilled pipe was $10,920.00:

350 SCFM X 60 min/hr X 8 hrs/day X 5 days/week X 52 weeks/year X $0.25/1,000 SCF = $10,920.00

Drilling & tapping those holes for EXAIR Nano Super Air Nozzles (8.3 SCFM ea X 30 = 249 SCFM total) would result in an annual operating cost of $7,768.80:

249 SCFM X 60 min/hr X 8 hrs/day X 5 days/week X 52 weeks/year X $0.25/1,000 SCF = $7,768.80

Replacing the drilled pipe with an EXAIR 18″ Super Air Knife (52.2 SCFM) drops the annual operating cost even further, to $1,628.64:

52.2 SCFM X 60 min/hr X 8 hrs/day X 5 days/week X 52 weeks/year X $0.25/1,000 SCF = $1,628.64

To put that further into perspective, the 2025 List Price for an 18″ Aluminum Super Air Knife is $533.00. It costs almost $9,300.00 per year LESS to operate than the drilled pipe. That means the Air Knife will have paid for itself in operating costs in just under 21 days.

To put that even FURTHER into perspective, the ~300 SCFM reduction in compressed air consumption is approximately 75HP worth of a typical industrial air compressor load. It’s not uncommon for a mid-to-large sized company to have more than one air compressor, and 50HP is a common size for a backup compressor. If that was the case in the facility that my technician caller was auditing, he’d be letting them know that this $533.00 investment that’s going to save them over $9,000.00 a year is ALSO going to allow them to shut down one of their air compressors. Completely.

So, THAT’S what’s so awful about a drilled pipe. If you have any in your facility, we should talk.

Russ Bowman, CCASS

Application Engineer
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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

Dryers On A New Level – Deliquescent Level Even.

Published on by Brian FarnoLeave a comment

Today I want to discuss dryers and not the type that I have repaired many times due to having three kids in my house. Speaking of which, the amount of hair that gets trapped within a dryer is one of the things my nightmares are made from. You’d think we have a Yeti living in our home. While the picture below is of our first dryer and washer, that platform has been repurposed into a workbench and the metals have all been recycled back into something else now. That’s not what we are here to talk about. Instead, we are going to discuss deliquescent dryers.

Deliquescent dryers can sometimes be confusing. Some compressed air dryer vendors use the terms deliquescent and desiccant synonymously, as if they were interchangeable in describing their equipment. Deliquescent dryers are not complex drying systems and are most commonly found in the petrochemical industry.

Deliquescent Dryer

Unlike any other dryer, a deliquescent dryer is also used to reduce or remove moisture before it turns to liquid water. These dryers can be installed indoors, outdoors, offshore, or in any remote location. They do not require electricity for operational purposes or have any moving parts, making them easy to maintain and economically more efficient. In a deliquescent dryer, moist air (gas) passes over a layer of deliquescent tablets that absorb moisture. The pressure dew point lowers as the tablets slowly dissolve, the condensation falls into the drain area, and the drier air flows through the outlet into the piping system.

The best deliquescent materials are salts due to their strong attraction to moisture. Deliquescent desiccants (drying tablets) are formulated from calcium chloride, magnesium chloride, potassium chloride, and lithium chloride. Not all deliquescent desiccants are equal. The final formulation and properties of the desiccant can significantly impact the design of a dryer tank. That is, the surface of the desiccant chemical, often beads or pellets, will liquefy, and the resulting liquid will flow to the bottom of the vessel. There is either a drain (manual or auto) at the base of the deliquescent dryer which is used to expel the collected fluid.

Some factors that will affect the consumption of the desiccant are the type of adsorbent, type of adsorbate, the size of the adsorbent bead or pellet, the concentration of the adsorbate in the compressed air stream, and the temperature of that air stream.

You will want to have a water trap, also known as a general-purpose compressed air filter, plumbed in line just upstream from the deliquescent dryer. Otherwise, any liquid water flowing with the compressed air into the air dryer will make short work of the desiccant chemical, requiring a more frequent—and expensive—recharge.

Compressing air generates heat. That hot, moist compressed air will consume the desiccant chemical in the deliquescent dryer much more quickly. The best practice is to ensure the airflow to the dryer is as cool as possible, with a long airline and a dwell tank before the deliquescent dryer, to allow the air to cool and have water saturate out naturally.

A deliquescent dryer can be expected to reduce the compressed air dew point by 20 – 30 deg. F, or so. The degree of drying depends how saturated the airflow is going in and on the type of deliquescent chemical used.

Unlike other forms of compressed air dryers, a deliquescent unit doesn’t guarantee the air will reach a certain dew point. The amount of water vapor in the air that exits the dryer is completely predicated on how much water vapor is in the air going into the dryer.

Brian Farno, MBA – CCASS Application Engineer

BrianFarno@EXAIR.com
@EXAIR_BF