Air & Water DO Mix – Why That’s A Problem for Compressed Air Systems

Wherever you go, humidity – and its effects – are an inescapable fact of life. Low humidity areas (I’m looking at you, American Southwest) make for a “dry heat” in the summer that many prefer to the wet & muggy conditions that areas with higher humidity (like much of the rest of the United States) encounter during the “dog days” of summer.

Regardless of human comfort level issues, all atmospheric air contains water vapor in some finite proportion…in fact, next to nitrogen and oxygen, it makes up a bigger percentage of our air’s makeup than the next eleven trace gases combined:

Reference: CRC Handbook of Chemistry and Physics, edited by David R. Lide, 1997.

And, because warmer air is capable of holding higher moisture concentrations (a 20°F rise in temperature doubles the potential for holding moisture), chances are good that it’ll become a bigger problem for your compressed air system in the summertime. So…how BAD of a problem is it? Let’s do some math. Consider a nice, typical summer day in the midwest, when it’s 80°F outside, with a relative humidity of 75% and we’ll use the data from the tables below to calculate how much water collects in the compressed air system:

Source: Compressed Air & Gas Institute Handbook, Chapter 3
Source: Compressed Air & Gas Institute Handbook, Chapter 3

Let’s assume:

  • An industrial air compressor is making compressed air at 100psig, and at a discharge temperature of 100°F.
  • The demand on the compressed air system (all the pneumatic loads it services) is 500 SCFM.

Table 3.3 tells us that, at 80°F and 75% RH, the air the compressor is pulling in has 0.1521 gallons per 1,000 cubic feet.

Table 3.4, tells us that, at 100°F and 100psig, the compressor is discharging air with a moisture content of 0.0478 gallons per 1,000 Standard Cubic Feet.

The difference in these two values is the amount of water that will condense in the receiver for every 1,000 SCF that passes through, or 0.1521-0.0478=0.1043 gallons. Since the demand (e.g., the air flow rate out of the receiver) is 500 SCFM, that’s:

500 SCFM X 60 min/hr X 8 hr/shift X 0.1043 gallons/1,000 SCF = 25 gallons of condensate

That’s 25 gallons that has to be drained from the receiver tank over the course of every eight hours, so a properly operating condensate drain is crucial. There are a few types to choose from, and the appropriate one is oftentimes included by the air compressor supplier.

So, you’ve got a condensate drain on your compressor’s receiver, and it’s working properly. Crisis averted, right? Well, not so fast…that 100°F compressed air is very likely going to cool down as it flows through the distribution header. Remember all that moisture that the hot air holds? Assuming the compressed air cools to 70°F in the header (a reasonable assumption in most industrial settings), a bunch of it is going to condense, and make its way to your air tools, cylinders, blow off devices, etc., which can cause a host of problems.

Reversible Drum Vacs have tight passages where contaminants (like pipe rust) can accumulate and hamper performance. Fortunately, they are designed to be easy to clean and returned to peak performance.

And…I trust you saw this coming…we’re going to calculate just how much condensation we have to worry about. Using table 3.4 again, we see that the header’s air (at 100psig & 70°F) can only hold 0.0182 gallons per 1,000 SCF. So, after cooling down from 100°F (where the air holds 0.0478 gallons per 1,000 SCF) to 70°F, that means 0.0296 gallons per 1,000 SCF will condense. So:

500 SCFM X 60 min/hr X 8 hr/shift X 0.0296 gal/1,000 SCF = 7.1 gallons of condensate

Qualified installers will have sloped the piping away from the compressor, with drip legs strategically placed at low points, so that condensate can drain, collect, and be disposed of…oftentimes via similar devices to the condensate drains you’ll find on the compressor’s main receiver. Good engineering practice, of course, dictates point-of-use filtration – EXAIR Automatic Drain Filter Separators, with 5-micron particulate elements, and centrifugal elements for moisture removal, are also essential to prevent water problems for your compressed air operated products.

Good engineering practice calls for point of use filtration and moisture removal, such as that provided by EXAIR Filter Separators.

EXAIR Corporation remains dedicated to helping you get the most out of your compressed air system. If you have questions, give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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Video Blog: How To Remove, or Move, A Digital Flowmeter By Using Block-off Rings

If you need to remove (or move) a Digital Flowmeter, EXAIR has Block-off Rings that are used to safely cover & seal the holes that were drilled in the pipe for installation. Here’s how they work:

If you’ve got any questions about Block-off Rings, Digital Flowmeters, or would like to find out more about EXAIR Corporation can help you get the most out of your compressed air system, give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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More And More Award Winning Products From EXAIR

As you might expect, a LOT of things have changed at EXAIR Corporation since 1983. Most of our current senior management had yet to graduate high school, and a fair number of current employees had yet to BE BORN. According to our computer system (another BIG change since 1983), our first ten customers were here in southwest Ohio (#11 was in Michigan), and now, we sell direct across the US & Canada, and our worldwide distributor network offers representation on six continents. One thing that hasn’t changed, though, is our founder’s vision of manufacturing quiet, safe, & efficient compressed air products for process improvement in just about any industry that uses compressed air. And THAT, dear reader, continues to gain high profile attention. The photo above shows the seven awards that our products have recently won, which were announced in 2021 or early 2022. Here’s a rundown:

Plant Engineering 2020 Product of the Year (Fluid Handling) GOLD AWARD:
1/2 NPT No Drip External Mix Air Atomizing Spray Nozzles

No Drip External Mix Atomizing Spray Nozzles

The 1/2 NPT models are the latest addition to our newest product line. The External Mix version offers the highest liquid flow rate, and largest pattern coverage. Among the applications where they’ve excelled so far are:

  • Snack food provider – applying flavoring to bulk snack materials.
  • Commercial bakery – spraying cooking oil onto pans used in a conveyor oven.
  • Sporting goods manufacturer – applying adhesive to the tops of skateboard decks to glue the grip tape on.

Plant Engineering 2020 Product of the Year (Material Handling Systems) GOLD AWARD:
2-1/2 NPT 303SS Threaded Line Vac

EXAIR's Threaded Line Vac Family
EXAIR Threaded Line Vac + Your Pipe + Compressed Air = Instant Conveyor System

For bulk material conveyance, it really doesn’t get any simpler than EXAIR Air Operated Conveyors. Stainless Steel models are especially popular when the environment – or the product – is corrosive, or hot…they’re good to 400F (204C), and can even be modified with High Temperature components for exposure up to 900F (482C). The Threaded versions have been successfully used to:

  • Recycle sprinkles applied to wafers into a return hopper in a candy production facility.
  • Replacing an auger conveyor to allow for homogenous mixing of grains & supplements in feed stock at an agricultural mill.
  • Providing a low cost solution to convey product into a hopper at a grain processing plant.

Plant Engineering 2020 Product of the Year (Maintenance Tools & Equipment) SILVER AWARD
Occupational Health & Safety 2021 New Product of the Year (Industrial Hygiene-Dust Control) WINNER
Occupational Health & Safety 2021 New Product of the Year (Health & Safety/Cleanup) PLATINUM

EasySwitch® Wet-Dry Vac

Like our Spray Nozzles product line, our Industrial Housekeeping Products line has also grown considerably over the years. The Deep Hole Vac-u-Gun and Heavy Duty HEPA Vac were real game changers when they came along, and the EasySwitch® Wet-Dry Vac Systems are likewise making an impact. Switching from wet to dry operation is, as advertised in the name itself, INCREDIBLY easy. Among our satisfied customers are:

Occupational Health & Safety 2021 New Product of the Year (Lab Safety) WINNER
Intellistat® Ion Air Gun™

The newest innovation in a long line of EXAIR static elimination solutions, the Model 8500 Intellistat® Ion Air Gun is made for laboratories, clean rooms, medical & electronic applications, and carries an ISO 14644-1 Class 5 rating for clean room use. Because of their rapid decay rates and lightweight construction, they’re used in a diverse range of applications and areas, including:

  • A supplier of fiberoptic parts uses an Intellistat® to remove dust and static charge from product prior to packaging.
  • A medical device manufacturer has one in a Class 7 clean room for silicone parts cleanliness.
  • A nutritional supplements maker uses their Intellistat® to remove static charge & powder residue from the tops of plastic bags before sealing them. The excess/residual powder causes them not to seal correctly.

Machine Design 2021 Big Idea! (Electrical Components) BRONZE AWARD
Gen4® Static Eliminator Power Supply

All EXAIR Gen4 Static Eliminators use one of two Power Supplies – your choice of the 2-port Model 7960, or the 4-port Model 7961.

EXAIR Static Eliminators produce ionized air via a Corona discharge, which requires high voltage, low current electricity. The Gen4® Static Eliminator Products feature armored & shielded cables with an internal ground, for safety and reliability. The ground path is completed through the cable and the Power Supply port, eliminating the need for an external ground connection. Faults in external ground connections result in the majority of the problems with those devices, so the internal ground is a “Big Idea!” indeed. The Gen4® Static Eliminator Power Supplies are switchable for 115VAC or 230VAC voltages, and are offered in 2, or 4 outlet designs, which can power any 2, or 4 EXAIR Static Eliminator Products. Like most EXAIR Intelligent Compressed Air Products, they’re used for a wide range of applications, in a wide range of industries:

If you’d like to find out more about these, or any of our other engineered compressed air products (we’re pretty proud of them all), give me a call. I can talk about them all day long…and sometimes I do!

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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Compressed Air System Equipment – What You Need To Know

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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