Managing Pneumatic Sound

I recently took my daughter to a basketball game to watch Xavier University’s Lady Musketeers play. Due to Covid the arena felt empty and we could hear the players on the court and also the the coaches from the opposite side. If this was a regular season game we could barely hear ourselves let alone the teams and coaches. The obvious reason why there was not much noise is that there wasn’t much of a crowd and the crowd makes a lot of sound. So, what is sound?

Sound can be defined as “vibrations that travel through the air or another medium and can be heard when they reach a person’s or animal’s ear”. Sounds hit our ears at different pressure levels depending on its strength (“loudness” or volume) and is measured in decibels (dB).

When sound travels and comes into contact with a surface, a portion will be absorbed and another portion will be reflected. Manufacturing environments obviously can be the source of a lot of sound and personnel near the sources should be protected as much as possible. One extremely effective way to do this is to substitute a loud noise source with a quieter one or remove the source all together. PPE can be effective but is much less reliable due to people forgetting to use PPE, using PPE improperly or even deciding for themselves they do not need it.

To substitute or eliminate means something like the strategic placement of air compressor which is not near personnel or recognizing the type of product you choose to use is vital to sound management and the health and safety of people working near the point of use. Many EXAIR products can help you reduce the sound level of your current point-of-use compressed air by replacing commercial air nozzles, open pipes and homemade blowoff solutions with our Engineered Air Nozzles, Safety Air Guns, Air Amplifiers, or Super Air Knives. These products are all designed to minimize compressed air noise and can contribute to lowering the overall noise exposure of your personnel. The additional benefit is that you customers will also typically see a reduction in air consumption which saves money on generating compressed air.

EXAIR’s Digital Sound Level Meter is a tool used to identify and quantify the particular noise levels within an area. The source of loud noises can be quickly identified and isolated so corrective measures can be implemented.

Compressed air noise levels often exceed OSHA (Occupational Safety and Health Administration) noise level exposure requirements. EXAIR pneumatic products meet or exceed the OSHA Standard 29 CFR-1910.95(a) and can be used to reduce sound levels in your compressed air environment.

EXAIR has has many engineered compressed air products that can help reduce your sound levels. Our Application Engineers are ready and eager to help assist your sound level decrease projects. Please contact us at www.EXAIR.com so we can be a vital part of your successful sound reduction program.

Eric Kuhnash
Application Engineer
E-mail: EricKuhnash@exair.com
Twitter: Twitter: @EXAIR_EK

Video Blog: Laminar and Turbulent Flows

I have written blogs about laminar and turbulent flows as related to the Reynold’s number.  Now, let’s demonstrate the difference between the two flows and the advantages of laminar flow from EXAIR’s engineered air nozzles; as demonstrated by our VariBlast Safety Air Gun.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

EXAIR Celebrates Manufacturing Day With A Win For A Manufacturer

In 2012, the National Association of Manufacturers organized an effort to proclaim the first Friday in October (hey, that’s today!) as Manufacturing Day.  According to the Advanced Manufacturing National Program Office (a division of NIST, the National Institute of Standards & Testing,) the purpose of MFG Day is “to raise awareness among students, parents, educators and the general public about modern manufacturing and the rewarding careers available.”

Today is kind of a big deal around here.  Not only is EXAIR Corporation a manufacturer, but many of the companies that use our products are as well.  A lot of us have a rich story, woven into the cloth of the history of American manufacturing (which, in turn, is woven into the larger cloth of American history.)  Have you heard the one about the motivated inventor with an idea to make innovative products who started an operation out of his home that, with inspired direction & vision, became a worldwide leader in their industry?

Yeah; that’s us.  Today, we’re honoring Roy Sweeney’s legacy (he founded the company in October 1983,) and celebrating MFG Day, by publishing a new Case Study, proving out the benefits of the use of EXAIR Intelligent Compressed Air Products in regard to the monetary savings associated with the reduction in compressed air use, and the noise level reduction from the implementation of our engineered products.

You can download the complete Case Study here, but while we’re on the subject, here’s a basic rundown:

  • A roll forming operation used to blow off their product with a combination of loud and inefficient devices: copper tubing and modular flexible hose which is designed primarily for machine tool coolant, but often misapplied for use with compressed air.
  • It worked just fine, but an engineering study noted it as a potential wasteful use of compressed air.  That’s when they called us.
  • By replacing those blow offs with Model 1100 Super Air Nozzles and Model 1122 2″ Flat Super Air Nozzles, their noise levels dropped from 107 dBA to 83.8 dBA.  To put that in perspective, it went from the approximate sound level of a rock concert to that of a leaf blower. (ref: Centers for Disease Control & Prevention: What Causes Hearing Loss?)
  • Compressed air consumption dropped by more than half, from 190 SCFM to 86.8 SCFM…an annual savings of over $3,200.00.  All for an investment of $654.00 (2020 pricing) for those engineered Air Nozzles, Stay Set Hoses, and Magnetic Bases.  That means they’ll have paid for themselves in just under two months.
  • In addition to that, for participation in this Case Study, we’re giving them a generous credit on their order.  Happy Manufacturing Day!

And frankly, I think the engineered products just look better too.

Last but certainly not least, this reduction in compressed air usage decreases the load on their air compressors, reducing the electrical power consumed.  Product impact, along with our own consumption of resources and waste recycling, is a key component of EXAIR Corporation’s Sustainability Plan.  We’re making the world a better place, by making products that make the world a better place, using methods that make the world a better place.  I can’t think of a better way to celebrate Manufacturing Day.  If you want to get in on it, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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MFG Day logo courtesy of nist.gov

OSHA 29 CFR 1910.95 (a) – It’s a Noise Exposure Standard, Not Just a Confusing Number

Strings of numbers and characters can often appear daunting.  For instance, if I wrote in binary code it would be a string of ones and zeros.  (01000101 01101110 01100111 01101001 01101110 01100101 01100101 01110010 01101001 01101110 01100111 00100000 01101001 01110011 00100000 01000001 01010111 01000101 01010011 01001111 01001101 01000101.) That can look like gibberish and cause concern if unknown or it can make sense to programmers and people familiar with binary code.

Other alphanumeric strings may cause some concern for industry professionals.  Take, for instance, OSHA standards. The OSHA standard 29 CFR 1910.95 (a) may be unfamiliar to some, and thus concerning. Many Environmental Health and Safety Engineers will recognize this code.  It is an OSHA standard that revolves around the amount of time an employee is permitted to be exposed to specific sound levels. These sound levels are all based on the weighted sound level of the noise the operators are exposed to. To better understand how the octave and frequency of the sound play into this, there is a chart provided below.

Equivalent A-Weighted Sound Level Chart – (1)

The weighted sound level is the level at which a Digital Sound Level Meter will read the current level of noise within an environment. This scale is then used to move further into the OSHA directive that we focus on helping companies meet to best provide safe environments for their employees to work in.

If you notice, the lowest weighted sound level is 90 dBA, this is also the lowest-rated noise level that OSHA speaks of in 1910.95(b)(2). It has been shown that noise levels over this level for extended periods will result in permanent hearing loss. The standard then goes on to discuss the duration an employee can be exposed to noise levels even with the use of personal protective equipment as well as even impulsive or impact noise.  The table of permissible time limits is shown below.

Permissible Noise Exposures (2)

As you can see from the table above provided by OSHA, any noise level that an operator is exposed to for eight hours cannot exceed 90 dBA. Noises within an industrial environment can also be variable throughout the day. For instance, the operator stands outside of a sheet metal press and the concussive strike on the press gives off a 90 dBA strike for every stroke of the press. This would not be a continuous noise level. Maybe the operator is operating a CNC machine that is cutting a nest of parts and uses a handheld blowgun to remove debris and coolant from the parts before taking them from their fixture. This blowgun is not used continuously and therefore would not be rated as such for the exposure time. A time study would be conducted on the average length of time the operator is utilizing this gun along with the level of noise it produces during use. OSHA then gives a calculation to use to appropriately combine the sound level while the gun is being used and when it is not in use. That equation is written out below.

Mixed Environment Exposure Fraction
C1/T1+C2/T2+… = ____
Total Exposure Fraction
Cn/Tn = ____

Where:
C1 = Duration of time for a specified noise level
T1 = Total time of exposure permitted at that level
Cn = Total time of exposure at a specified noise level
Tn = Total exposure time permitted at that level

Should the summation of the fractions for different exposures be greater than the Total Exposure fraction, the summation value should be used. As mentioned above, a time study on exposure to noise levels will be needed to obtain the information needed for this type of study. Once the study is done the process can proceed to the next level within the OSHA standard which is a hearing conservation program.

I would like to interject a small side-step at this point. Rather than rolling straight into the implementation of PPE which is proven to be the lowest reliable factor of protection by the CDC and NIOSH. If any of these noise levels being generated are due to the use of compressed air points of use, EXAIR can potentially lower the noise of these point of use applications. In the events, open blowoffs or “band-aid” fixes are in place to keep processes running, and Engineered Solutions can easily be implemented that will reduce the noise level produced by this operation. Whether it is on the handheld Safety Air Gun in the hands of a CNC operator, or if it is a part/scrap ejector that is blowing the sheet metal press out after every strike, we have products that have proven time over time using an Engineered Solution will save air, reduce noise levels, and still get the job done.

If you would like to discuss OSHA directives revolving around compressed air, share with us a recent citation you received from an inspector for this standard, or just discuss compressed air usage in general, contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

1 – Equivalent A-Weighted Sound Level Chart – Retrieved from OSHA.Gov – https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=9735&p_table=standards

2 – Permissible Noise Exposures – Retrieved from OSHA.Gov – https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=9735&p_table=standards