Tag: air flow

Webinar Replay: SCFM, ACFM, ICFM, CFM – Why So Many Terms For Air Flows?

Published on by Tyler DanielLeave a comment

EXAIR’s latest addition to the Fall Webinar series was a discussion on the topic of volumetric air flow terms: SCFM, ACFM, ICFM, and CFM. In the compressed air world, these terms are used often to quantify the performance of a compressor or the point-of-use equipment on the supply side of your system. Since conditions will vary from one site location to another, it’s important that we understand how certain variables can change the performance of your system. The webinar is available to view on demand on the EXAIR.com.

The term SCFM (Standard Cubic Feet Per Minute) is used to allow us to make an apples to apples comparison across different equipment. The performance is rate at a set of “standard” conditions to remove any potential variables from the equation. CAGI, or the Compressed Air and Gas Institute, uses the standard conditions of: 14.5 psia, 0% relative humidity (RH), and 68°F. This allows us to compare different devices without needing to make any sort of adjustments.

Variables such as elevation (barometric pressure), relative humidity, and temperature all change the performance and must be considered.

With elevation, we’re looking at the atmospheric or barometric pressure at the location of operation. One way to illustrate this to consider a balloon. If you inflated a balloon at sea-level, or 14.5 psia, then carry that same balloon up to the top of Mt. Everest what would happen? Using Boyle’s Law (P1 x V1 = P2 x V2), we’re able to calculate the exact volume of the balloon. At the peak of Mt. Everest, pressure is significantly lower at roughly 4.5 psi. The balloon when taken to the peak at 4.5 psi would become 3.2x it’s original size as the pressure acting on the outside of the balloon decreases.

Relative humidity tells us how much moisture content is contained within a specific volume of air. Water molecules cannot be compressed, so when the air is compressed this water takes up the same volume. The water condenses in the inter-coolers and after-coolers or is removed via drains and dryers downstream. So, 1 cubic foot of air coming into the compressor weigh more than 1 cubic foot of air out due to this water vapor loss.

As temperature increases, so does air pressure as the molecules in the air speed up and come into contact with one another and the walls of its container at a more rapid pace. Air can also hold a greater volume of moisture at higher temperatures. So, the balance between RH and temperature is an important consideration when determining actual performance, or ACFM.

In the webinar, we walked through two different examples to highlight the changes in these variables and how it impacts the performance of a compressed air system. If you were unable to attend live, the webinar is available to view on demand on the EXAIR website. We have this latest webinar posted there on the website along with all prior webinars as well! There, we talk about topics ranging from compressed air system optimization, static electricity, OSHA Compliance, and more! Check out the available webinars on the Resources tab of the EXAIR.com page today for all the knowledge you’ll need about your compressed air system and processes.

Tyler Daniel, CCASS

Application Engineer

E-mail: TylerDaniel@EXAIR.com

Twitter: @EXAIR_TD

Full Flow Air Knife Creates “Smoke Screen” In Haunted House Attraction

Published on by Russ BowmanLeave a comment

EXAIR Corporation’s engineered Air Knife products have a number of uses in industry. The laminar, even flow is conducive to generating a stripping/sweeping action that is particularly effective for blowing off, cooling, cleaning, drying, etc. The way that they entrain enormous amounts of air from the surrounding environment makes them incredibly efficient. This entrainment also makes them very quiet, as it forms a boundary layer that attenuates the sound level of the high velocity flow of the compressed air exiting the Air Knife. These two features have a distinct benefit in a rather unique application in a decidedly non-industrial setting, though.

A company that services amusement parks & carnivals was making a “haunted house” type attraction. At one point, the victims visitors are to be surprised by animated figures “floating” in the air. Their idea was to project the animation on a wall/screen of smoke…spooky, right? They tried discharging the smoke through a series of holes, and even a thin slot, but could not get the effect they wanted, so they called EXAIR to talk about Air Knives.

Smoke escaping small holes or a thin slot doesn’t have much velocity, so it didn’t make a great ‘curtain’ for projection. It’s also turbulent in nature, so it tends to billow & plume (like the top graphic). Engineered compressed air products like EXAIR’s Air Knives generate a laminar flow (like the bottom graphic) whose velocity can be precisely controlled by regulating the air supply pressure.

They found their solution for this application in a Model 2836SS 36″ Stainless Steel Full Flow Air Knife Kit. The Full Flow Air Knife is the most compact design for any given length, and with rear ports for the compressed air supply, it was easy to conceal from the visitors’ sight. When smoke is introduced from behind, it gets pulled in (entrained), and discharges in a laminar, even curtain that the animated figures magically appear on. The extraordinarily low sound level contributes to the magic, as it can’t be heard over the din of eerie sound effects & music that are synonymous with the haunted house experience.

Compressed air flows through the inlet (1) to the Full Flow (left) or Standard (right) Air Knife, into the internal plenum. It then discharges through a thin gap (2), adhering to the Coanda profile (3) which directs it down the face of the Air Knife. The precision engineered & finished surfaces optimize entrainment of air (4) from the surrounding environment.

EXAIR Corporation has been in the business of providing quiet, safe, and efficient compressed air products for all kinds of applications for almost 39 years now. If you want to find out more about introducing more quietness, safety, efficiency…or magic…into your operation, give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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Turn the Pressure Down, Save Operation Costs

Published on by Jordan T ShouseLeave a comment

I recently recommended to a customer to turn their air pressure down on their system as low as their process would allow. Meaning regulate the pressure so you have enough to complete the operations needed but find that happy medium where your compressor isn’t working as hard to build those high pressures for no reason!

Compressed air is an amazing tool to have, and when used properly it can be more efficient that other non compressed air tools that run off electricity. How ever its pretty common to see compressed air systems running at their max just because.

Lowering the air system pressure reduces the compressor power consumption by about 1% for every two psi of lower pressure. Lowering the pressure also makes any unregulated operations reduce consumption by almost 1% for every one psi of pressure reduction. Not to mention the extra savings if your compressor system can turn down the compressor power because of the reduced flow and possibly shut off compressors that are no longer needed!

The best pressure at which to set your system is the level where your production can operate efficiently and effectively without waste: There is no right pressure—it depends on your operations and tools. You may have 90 to 100 psig at the compressor, but at the production machine, where the actual work is being done, you could have only 65 to 70 psig. In some cases, it may be even lower due to pressure drops in undersized piping, filters, regulators. The goal is to lower compressor discharge pressure without affecting the the operations at the end of the line.

Having artificially high plant-pressure can help you deal with surges in compressed air demand that might occasionally cause low-pressure and affect production. The higher pressure acts to store reserve air in the various volumes made up of receivers, pipes and such in your system. However, the higher pressure costs more to produce and makes unregulated end uses consume more air, which is an expensive trade-off. Another option is to make sure you have line pressure regulators at each point of use. This will allow you to regulate the operation to the pressure needed being sure to save compressed air and keep the over all system running more efficient.

You can regulate those point of use lines with a number of EXAIRs Pressure Regulators!

EXAIR offers a range of Pressure Regulators capable of handling air flow of up to 700 SCFM.

If we can help size a regulator, or have any other questions on how EXAIR can help you save compressed air in your system please reach out to me or one of our other Application Engineers!

Jordan Shouse
Application Engineer

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6 Important Factors when Choosing a Safety Air Gun

Published on by Russ BowmanLeave a comment

If you look at operating costs alone, compressed air can be just about the most inefficient method there is for cleaning parts. If you just look at the risks, it’s potentially very dangerous too. Don’t even get me started on the insufferable noise it can make.

For cleaning parts, most folks are familiar with the use of an air gun. You can find the simplest of these in many industrial settings: a valve (often in the form of a handheld trigger device) fitted with a nozzle of some sort (often in the form of an open ended tube, pipe, or fitting to focus or direct the air flow). These have all three of the “downsides” I opened this blog with. Of course, these concerns can be mitigated to a high degree by using the right tool for the job. That’s where engineered products like EXAIR Safety Air Guns come in. Let’s look at how we can address these three “downsides”:

Efficiency: This is all about compressed air consumption. In the simplest of air guns mentioned above, consumption is only limited by the passages in the valve (or trigger) and the discharge fitting…and those limits are usually negligible. Modifying the ends (see examples below) to focus the air flow usually has minimal effect, because you’re not appreciably changing the total cross sectional area of the discharge opening:

Here are a few modified thumb trigger air guns that were sent in for Efficiency Lab testing. Left to right, compressed air consumption at 80psig supply pressure was 34.2 SCFM, 30.9 SCFM, and 28.2 SCFM. For comparison (more on this later,) EXAIR Model 1210 Soft Grip Safety Air Gun uses only 14 SCFM and generates a very similar flow pattern.

Safety: Remember learning about kinetic and potential energy in grade school? Well, when you compress air to 100psig, fitting all that air into a much smaller space creates a TREMENDOUS amount of potential energy:

The block on the left represents a cubic foot of air at atmospheric pressure. The one on the right represents how much space the first one takes up when compressed to 100psig. The energy imparted by this process HAS to be handled with care.

One problem with the thumb guns above is, if you were to jam into the palm of your hand and pull the trigger, a large component of that potential energy (pressure) turns into kinetic energy (force)…more than enough to break the skin and cause a potentially fatal condition known as an air embolism. In the United States, OSHA (Occupational Safety and Health Administration) regulates compressed air devices used for cleaning purposes. All EXAIR Safety Air Guns comply with Standard 1910.242(b) by providing a relief path to ensure that it cannot be dead ended, and thus never create over 30psi measurable at the outlet)

EXAIR Super Air Nozzles cannot be dead ended, ensuring the outlet pressure won’t reach OSHA limits, regardless of supply pressure.

Noise: Another problem is, another component is turned into sound pressure…discharging air from a direct opening is quite loud. OSHA standards address these with limitations on outlet pressure and sound level. All EXAIR Safety Air Guns comply with Standard 1910.242(b), which limits the outlet pressure (by providing a relief path to ensure that it cannot be dead ended, and thus never create over 30psi measurable at the outlet) and all but our largest Super Blast Safety Air Guns comply with Standard 1910.95(a) limits for continuous 8 hour sound level exposure.

Which brings us to the topic of this blog: How exactly did THEY (our customer who used to use the thumb guns above) select the right Safety Air Gun, and how can we apply that to getting the right Safety Air Gun for YOU?

These steps aren’t all-inclusive, and they don’t necessarily need to be followed in order, but if you call an EXAIR Application Engineer about selecting a Safety Air Gun, here’s what we’re gonna talk about:

Ergonomics: We offer five distinctive styles of Safety Air Guns:

From small part cleaning by hand, to wide area blowoff, and all points in between, EXAIR has a Safety Air Gun for most any application.

Our thumb gun user (as I alluded to above) chose the Model 1210 Soft Grip Safety Air Guns (top right). They had a number of typical industrial applications where the operators had the parts or surfaces to be blown off right in front of them. They liked the integral storage hook and rubberized hand grip, but the VariBlast Compact (top middle) or Heavy Duty Safety Air Guns (bottom left) were also considered. The VariBlast Precision (top left) and Super Blast Safety Air Guns (bottom right) were too focused or more powerful, respectively, than needed.

Airflow pattern: Honestly, I could make a good case for this being the first consideration. Selection of any blowoff product – be it an Air Nozzle, Air Amplifier, Air Knife, Air Wipe, etc., will largely depend on the size and shape of the airflow.

variety of airflow patterns…and effective distances…are available from EXAIR’s comprehensive line of Super Air Nozzle products.

Application specific concerns: Everything we’ve discussed so far has involved aiming the blow off stream away from the operator, in the direction the device is aimed. In addition to wide variety of engineered Air Nozzles, EXAIR offers a number of options for these products:

Atto Back Blow Nozzles can blow out recesses or holes as small as 1/4″ in diameter.
Scrape off, and blow away, stubborn debris with the Model 1244-48 Soft Grip Super Air Scraper.

If you’re looking for a portable, hand-held compressed air blow off product that’s quiet, safe, and efficient, look no further than EXAIR Corporation’s extensive line of Safety Air Guns. If you’d like to find out more, give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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