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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Protecting Employees With PPE vs. Engineered Controls and Substitution

PPE has been a hot topic and new buzzword for a lot of people and throughout many industries over the past 6 months, and rightfully so. When you look at manufacturing though, PPE has been a buzzword for decades. We continue to evolve processes, equipment, and wearables to ensure the safety of operators.  It all boils down to the fact that PPE and the equipment have to be used, and used appropriately in order to be effective.

When reviewing the CDC’s guides for Hierarchy of Controls the least effective method to protect workers is PPE that they must implement and wear/use properly. The fact is, PPE is one of the cheaper entry levels to get to safe working conditions upfront. However, the cost of ownership can quickly surpass more effective methods of providing safe conditions for operators, such as installation of engineered controls or even substituting the hazard w/ engineered solutions.

CDC’s Hierarchy of Controls

 

So what exactly does that mean to the people on the shop floor? Rather than having to grab a set of pinch and roll earplugs every day on the way through the breezeway to get to the production line, permanently installing quiet products like Super Air Nozzles or Super Air Knives in place of open-ended pipes and drilled pipe blowoffs could eliminate the need for these uncomfortable nuisances. And reliance on personnel to use them correctly, or use them at all is a gamble.

How else can EXAIR help in this pursuit of operator safety and happiness? We offer a free service, the EXAIR Efficiency Lab, which will test your current blow-off products for force, flow, air consumption and noise level. We then recommend an engineered solution if we can improve upon those parameters (spoiler alert, we can) that will meet or exceed OSHA standards for dead-end pressure and allowable noise level exposure.

EXAIR’s Free Efficiency Lab

For this example, installing a quiet product to aid in lowering noise levels can create an environment that no longer needs PPE for protecting personnel. The fix is permanent and eliminates forgotten, lost or broken PPE and the expensive associated with them.

If you would like to discuss any of these options further, please let me know.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

Reduce Sound Levels In Less Than A Minute

Okay, I will admit, the title may be a tad bit leading.  The fact is, it can be done.  I speak to customers almost daily who are struggling with the noise levels produced from open pipe blowoffs.  With Noise Induced Hearing Loss (NIHL) a significant problem among manufacturing workers, reducing the noise form compressed air can be a simple solution and contribute toward reducing overall noise exposure levels. Many of these calls and emails revolve around reducing these exact noise levels, sometimes the open pipes have existing threads on them to install the solution immediately.

To reduce these noise levels, we need to simply reduce the amount of energy that is being expelled through the pipe. How do we do this you might ask?  The use of an air nozzle will reduce the energy being dispersed from an open pipe.  This will result in lower air consumption as well as lower sound levels while actually increasing velocity as the pipe will maintain higher operating pressures. Be cautious about the air nozzle you choose, however, they are not all created equal. EXAIR’s engineered air nozzles are among the quietest and most efficient air nozzles available.

Family of Nozzles

What size pipes can we fit nozzles to?  That’s a great question.  We have nozzles that range from a 4mm straight thread all the way up to 1-1/4″ NPT thread.  This also includes nearly any size in between especially the standard compressed air piping sizes.  For instance, a 1/4″ Sched. 40 pipe that has 1/4″ MNPT threads on it can easily produce over a 100 dBA noise level from 3 feet away.  This can easily be reduced to below 80 dBA from 3′ away by utilizing one of our model 1100 Super Air Nozzles.  All it takes is a deep well socket and ratchet with some thread sealant.

This doesn’t just lower the sound level though, it reduces the amount of compressed air expelled through that open pipe by creating a restriction on the exit point.  This permits the compressed air to reach a higher line pressure causing a higher exit velocity and due to the engineering within the nozzle, this will also eliminate dangerous dead-end pressure and complies with OSHA standard 29 CFR 1910.242(b).

Easy Install

All in all, a 30-second install can make an operator’s work station considerably quieter and potentially remove the need for hearing protection.  If you would like to discuss how to lower noise levels in your facility, contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

EXAIR Flat Air Nozzles: Powerful, Quiet, Safe and Adjustable

Are you tired of your current compressed air being so loud? Well then, we have a solution for you; EXAIR’s Flat Super Air Nozzles. The patented design of the 1” and 2” Flat Super Air Nozzles makes it great for applications that require a powerful but precise flat stream of air. The Flat Super Air Nozzles work much like our Super Air Knives, the main difference being that the Flat Super Air Nozzles provides a more forceful stream of air. The design of the Flat Super Air Nozzles also provides a greatly reduced sound level.

2″ Flat Super Air Nozzle

EXAIR’s Flat Super Air Nozzles are safe, reliable, and efficient. The nozzles are specifically designed in a way to prevent dead head pressure as stated in OSHA Standard 1910.242(b). The directive stats that compressed air used for cleaning purposes can not exceed a dead-end pressure of 30 psig. If a dead-end pressure were to exceed that pressure then there is potential for an air embolism to form. EXAIR has designed our Flat Super Air Nozzles so that they cannot be dead-ended; this allows you to run at a typical 80-100 psig from your compressed air system.

Various Applications of Flat Super Air Nozzles

EXAIR Flat Super Air Nozzles are designed to also be quiet while operating at those higher pressures. When operating at 80 psig the 2” Flat Super Air Nozzle is going to have a sound level of 77 dBA were as the 1” Flat Super Air Nozzle when operated at 80 psig is going to have a sound level of 75 dBA. The higher the pressure the more air is going to flow through the nozzle; the more air flowing though the nozzle the louder it is going to be.

2″ Flat Super Air Nozzle

EXAIR’s High Power Flat Super Air Nozzles are designed for those tougher applications where you need more force, and will operate at slightly louder levels. The HP series Flat Super Air Nozzles have a thicker shim in them that allows for more air to escape out the end delivering a high force. The High powered 2” Flat Super Air Nozzle when operated at 80 psig has a sound level of 83 dBA where the 1” is only 82 dBA.

All of EXAIR’s flat Super Air Nozzles are designed with an internal patented shim which allows for adjusting the total volume of airflow and force that the nozzle produces. These shims are available in different thicknesses and aid in keeping noise levels down, provide gross adjustment of airflow and the flexibility for achieving a successful application. 

If you have any questions or want more information on EXAIR’s Flat Super Air Nozzles or any of our products, give us a call, we have a team of application engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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