Six Steps to Compressed Air Optimization: Step 3 – Use Efficient and Quiet Engineered Products

Compressed air is expensive, and you should treat it that way.  Frequent readers of the EXAIR Blog are familiar with our Six Steps to Compressed Air Optimization, and you may have seen these recent installments on Steps 1 and 2:

Six Steps to Optimization: Step 1 – Measure the Air Consumption

Six Steps to Compressed Air Optimization: Step 2 – Find and Fix Leaks

Now, there isn’t a strict order in which you MUST perform these steps, and they’re not all applicable in every air system (looking at you, Step 5: Use Intermediate Storage,) but these are likely the steps that a certified auditor will take, and the order in which they’ll take them.  If you’re looking for immediate, quantifiable results, though, Step 3 is a great place to start.  Consider:

  • A 1/4″ copper tube blow off can consume as much as 33 SCFM when supplied with compressed air at 80psig.  It’ll give you a good, strong blow off, for sure.  You can crimp the end and get that down to, say, 20 SCFM or so.  Or, you can install a Model 1100 Super Air Nozzle with a compression fitting, and drop that to just 14 SCFM.
    • If you’re tracking your compressed air usage, you’ll see that replacing just one of them saves you 45,600 Standard Cubic Feet worth of compressed in one 5 day (8 hour a day) work week.  That’s $11.40 in air generation cost savings, for a $42 (2020 List Price) investment.
    • If you spend time in the space where it’s installed, you’ll notice a dramatic improvement in the noise situation.  That sound level from the copper tube is likely over 100 dBA; the Super Air Nozzle’s is only 74 dBA.
This user was only a handful of compression fittings & nozzles away from over $800 in annual compressed air savings.
  • Drilled pipes are another common method to create a blow off.  They’re easy & cheap, but loud & expensive to operate.
    • A pipe drilled with 1/8″ holes and supplied @80psig will consume 13 SCFM per hole, and the holes are typically drilled on 1/2″ centers.
    • An EXAIR Super Air Knife consumes only 2.9 SCFM per inch of length, and because it’s an engineered product, it’s a LOT quieter as well.  Drilled pipes are, essentially, open ended blow offs just like the copper tube mentioned above.  When you let compressed air out of a hole like that, all the potential energy of the pressure is converted to force…and noise.
    • Drilled pipes are among the worst offenders; almost always well in excess of 100 dBA.  Super Air Knives generate a sound level of only 69 dBA with 80psig compressed air supply.  They are, in fact, the quietest compressed air blowing product on the market today.
This Model 110048 48″ Aluminum Super Air Knife replaced a drilled pipe for over $5,000 annual compressed air savings.

These aren’t just theoretical “for instances” either – the data, and the photos above, come from actual Case Studies we’ve performed with real live users of our products.  You can find them here, and here (registration required.)

These are two examples of EXAIR product users who only used Step 3 of our Six Steps, although BOTH of them were already practicing Step 4 (Turn off the compressed air when it isn’t in use)…they had their blow offs supplied through solenoid valves that were wired into the respective machine controls, and the Air Knife user HAD to do Step 6 (Control the air pressure at the point of use) to keep their product from being blown clear off the conveyor..

But we’ll be happy to help you with optimizing your compressed air system using any or all of the Six Steps. Give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Measuring And Adding Sound Levels Together

What sound level do you get when you feed an EXAIR Super Air Nozzle at 80psig? What if there are two of them?  Or three?  Grab your scientific calculators, folks…we’re gonna ‘math’ today!

But first, a little explanation of sound power & sound pressure:

Strictly speaking, power is defined as energy per unit time, and is used to measure energy generation or consumption.  In acoustics, though, sound power is applicable to the generation of the sound…how much sound is being MADE by a noisy operation.

Sound pressure is the way acoustics professionals quantify the intensity of the sound power at the target.  For the purposes of most noise reduction discussions, the target is “your ears.”

The sound levels that we publish are measured at a distance of 3 feet from the product, to the side.  The units we use are decibels, corrected for “A” weighting (which accounts for how the human ear perceives the intensity of the sound, which varies for different frequencies,) or dBA.  Also, decibels follow a logarithmic scale, which means two important things:

  • A few decibels’ worth of change result in a “twice as loud” perception to your ears.
  • Adding sources of sound doesn’t double the decibel level.

If you want to know how the sound level from a single source is calculated, those calculations are found here.  For the purposes of this blog, though, we’re going to assume a user wants to know what the resultant sound level is going to be if they add a sound generating device to their current (known) situation.

Combined Sound Level (dBA) = 10 x log10[10SL1/10 + 10SL2/10 + 10SL3/10 …]

Let’s use an EXAIR Model 1100 Super Air Nozzle (rated at 74dBA) as an example, and let’s say we have one in operation, and want to add another.  What will be the increase in dBA?

10 x log10[1074/10 + 1074/10] = 77.65 dBA

Now, there are two reasons I picked the Model 1100 as an example:

  • It’s one of our most versatile products, with a wide range of applications, and a proven track record of efficiency, safety, and sound level reduction.
  • We proved out the math in a real live experiment:

Why do I care about all of this?  My Dad experienced dramatic hearing loss from industrial exposure at a relatively young age…he got his first hearing aids in his early 40’s…so I saw, literally up close and very personal, what a quality of life issue that can be.  The fact that I get to use my technical aptitude to help others lower industrial noise exposure is more than just making a living.  It’s something I’m passionate about.  If you want to talk about sound level reduction in regard to your use of compressed air, talk to me.  Please.

Russ Bowman
Application Engineer
EXAIR Corporation
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EXAIR NEW Product Offering – Pressure Sensing Digital Flowmeters

Six Steps to Optimizing Your Compressed Air System

The first step to optimizing compressed air systems within an industrial facility is to get a known baseline. To do so, utilizing a digital flowmeter is an ideal solution that will easily install onto a hard pipe that will give live readouts of the compressed air usage for the line it is installed on.  There is also an additional feature that we offer on the Digital Flowmeters that can help further the understanding of the compressed air demands within a facility.

The Pressure Sensing Digital Flowmeters are available from 2″ Sched. 40 Iron Pipe up to 8″ Sched. 40 Iron Pipe.  As well as 2″ to 4″ Copper pipe.  These will read out and with the additional Data Logger or Wireless Capability options record the information. When coupled with the wireless capability an alarm can be set for pressure drops that give live updates on the system as well as permits data review to see trends throughout the day of the system.

EXAIR Digital Flowmeters w/ Wireless Capabilities

Generating a pressure and consumption profile of a system can help to pinpoint energy wasters such as timer-based drains that are dumping every hour versus level based drains that only open when needed. A scenario similar to this was the cause of an entire production line shut down nearly every day of the week for a local facility until they installed flowmeters and were able to narrow the demand location down to a filter baghouse with a faulty control for the cleaning cycle.

If you would like to discuss the best digital flowmeter for your system and to better understand the benefits of pressure sensing, please contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

The Importance Of Properly Sized Compressed Air Supply Lines

EXAIR Corporation manufactures a variety of engineered compressed air products that have been solving myriad applications in industry for almost 37 years now.  In order for them to function properly, though, they have to be supplied with enough compressed air flow, which means the compressed air supply lines have to be adequately sized.

A 20 foot length of 1/4″ pipe can handle a maximum flow capacity of 18 SCFM, so it’s good for a Model 1100 Super Air Nozzle (uses 14 SCFM @80psig) or a Model 110006 6″ Super Air Knife (uses 17.4 SCFM @80psig,) but it’s going to starve anything requiring much more air than those products.  Since compressed air consumption of devices like EXAIR Intelligent Compressed Air Products is directly proportional to inlet pressure, we can use the flow capacity of the pipe, the upstream air pressure, and the known consumption of the EXAIR product to calculate the inlet pressure of a starved product.  This will give us an idea of its performance as well.

Let’s use a 12″ Super Air Knife, with the 20 foot length of 1/4″ pipe as an example.  The ratio formula is:

(P2 ÷ P1) C1 = C2, where:

P2 – absolute pressure we’re solving for*

P1 – absolute pressure for our published compressed air consumption, or C1*

C1 – known value of compressed air consumption at supply pressure P1

C2 – compressed air consumption at supply pressure P2

*gauge pressure plus 14.7psi atmospheric pressure

This is the typical formula we use, since we’re normally solving for compressed air consumption at a certain supply pressure, but, rearranged to solve for inlet pressure assuming the consumption will be the capacity of the supply line in question:

(C2 P1) ÷ C1 = P2

[18 SCFM X (80psig + 14.7psia)] ÷ 34.8 SCFM = 49psia – 14.7psia = 34.3psig inlet pressure to the 12″ Super Air Knife.

From the Super Air Knife performance chart…

This table is found on page 22 of EXAIR Catalog #32.

…we can extrapolate that the performance of a 12″ Super Air Knife, supplied with a 20 foot length of 1/4″ pipe, will perform just under the parameters of one supplied at 40psig:

  • Air velocity less than 7,000 fpm, as compared to 11,800 fpm*
  • Force @6″ from target of 13.2oz total, instead of 30oz*
  • *Performance values for a 12″ length supplied with an adequately sized supply line, allowing for 80psig at the inlet to the Air Knife.

Qualitatively speaking, if you hold your hand in front of an adequately supplied Super Air Knife, it’ll feel an awful lot like sticking your hand out the window of a moving car at 50 miles an hour.  If it’s being supplied with the 20 foot length of 1/4″ pipe, though, it’s going to feel more like a desk fan on high speed.

The type of supply line is important too.  A 1/4″ pipe has an ID of about 3/8″ (0.363″, to be exact) but a 1/4″ hose has an ID of only…you guessed it…1/4″.  Let’s say you have 20 feet of 1/4″ hose instead, which will handle only 7 SCFM of compressed air flow capacity:

[7 SCFM X (80psig + 14.7psia)] ÷ 34.8 SCFM = 19psia – 14.7psia = 4.3psig inlet pressure to the 12″ Super Air Knife.

Our Super Air Knife performance chart doesn’t go that low, but, qualitatively, that’s going to generate a light breeze coming out of the Super Air Knife.  This is why, for good performance, it’s important to follow the recommendations in the Installation Guide:

This table comes directly from the Installation & Operation Instructions for the Super Air Knife.
All Installation Guides for EXAIR Intelligent Compressed Air Products contain recommended air supply line sizes for this very reason.  If you have any questions, though, about proper compressed air supply, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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