Tag: Hearing Protection

Noise In The Workplace

Published on by Russ BowmanLeave a comment

The Center for Disease Control (CDC) estimates that 22 million workers are exposed to potentially dangerous levels of noise at work every year. That’s “only” about 15% of the total number of people who are employed in the United States, but if you’re one of them, you should absolutely know the risks, and how to protect yourself. Obviously, high noise levels can cause hearing loss, but do you know what else it causes?

  • Cardiovascular disease. Constant noise exposure causes stress, and stress triggers the release of hormones that increase your blood pressure, which can lead to ischemic heart disease, strokes, and arrhythmia.
  • Sleep disruption. Studies show chronic noise exposure during the day can cause difficulty falling asleep, shortened sleep cycles, and frequent wake-ups during the night. All this leads to chronic fatigue and a host of long-term health issues.
  • Immune system suppression. While the exact nature of the relationship is unclear, recent studies have indicated that noise can cause changes in our immune systems.
  • Cognitive impairment: Continued noise exposure causes memory impairment, attention deficits, and reduced concentration.
  • Mental health issues. Not only does continued noise exposure release hormones like cortisol & adrenaline (causing the chronic stress that’ll literally break your heart; see above), it directly influences anxiety, depression, and irritability.
Don’t let this happen to you.

So, how do we protect ourselves? If you said “ear plugs,” you’re not wrong…but did you know that hearing protection in the form of personnel protective equipment (PPE) is considered the LEAST effective method of mitigating noise exposure? The National Institute for Occupational Safety and Health (NIOSH, a sister agency of the Occupational Safety and Health Administration, or OSHA) developed a hierarchy of controls…a “good, better, best” framework, if you will, of methods to address workplace hazards:

Even though hearing protection (the PPE in this case) is least effective, the intent of the hierarchy graphic is not to dismiss it, but to categorize it as a last resort. If all else fails (or, more often, comes up short,) ear plugs are your – and your hearing’s – best friend.

If the source of the noise cannot be eliminated (and let’s face it, an awful lot of industrial processes are necessarily loud), the next best thing to do is to substitute a quieter method or device. That’s where EXAIR comes in: the design of our engineered Air Knives, Air Nozzles, and Air Amplifiers exploits certain principles of fluidics to mitigate the noise levels associated with the rapid depressurization of compressed air when it’s blown for cleaning, drying, cooling, etc. The key to this is entrainment:

EXAIR Intelligent Compressed Air Products such as (left to right) the Air Wipe, Super Air Knife, Super Air Nozzle, and Air Amplifier are engineered to entrain enormous amounts of air from the surrounding environment.

While this entrainment makes EXAIR products EXTREMELY efficient (the compressed air consumption ends up being a fraction of the total developed flow), it also creates a low velocity boundary layer around the primary high velocity & forceful airflow. This layer attenuates the sound level of that high velocity flow.

Compressed air use can be loud, wasteful, and dangerous, but it doesn’t have to be. If you’re looking for a quiet, safe, and efficient solution for your use of compressed air, give me a call.

Russ Bowman, CCASS

Application Engineer
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Compressed Air Safety Dos and Don’ts

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In the Navy, it was a universally accepted fact that NOTHING onboard the ship was “sailorproof.” Regardless of how it was designed, what it was made of, how many interlocks, mechanical stops, automatic shutoffs, etc., something had, any & all of those features could be overridden (by accident or on purpose) and cause a wide range of chaos, and/or damage, and/or injury. That’s why training and procedures are so important.

It’s the same in any civilian/corporate industry too – any device, tool, instrument, machinery, etc., can be inherently dangerous if it’s not used properly. And “used properly” for a LOT of those includes personal protective equipment, commonly known as PPE.

In the United States, the Occupational Safety & Health Administration (OSHA) publishes a couple of standards relevant to the safe use of compressed air:

Standard 1910.242(b) applies to the use of compressed air for cleaning. It states “Compressed air shall not be used for cleaning purposes except where reduced to less than 30 p.s.i. and then only with effective chip guarding and personal protective equipment.”

  • Do wear eye protection, at a bare minimum, in regard to the personal protective equipment, no matter what. If the debris you’re blowing off is sharp or jagged, a full face shield & long sleeves are likely called for as well.
  • Don’t operate a blowoff device in a manner where the static pressure at the outlet of the nozzle will reach or exceed 30 p.s.i. If you’re using an engineered product like an EXAIR Super Air Nozzle, it’s perfectly fine to use a higher air supply pressure than that. They’re designed so that the outlet pressure won’t exceed 30 p.s.i. no matter what the supply pressure is.
EXAIR engineered Air Nozzles, like the Model 1100 Zinc Aluminum Super Air Nozzle shown here, discharge the compressed air flow through a series of holes, recessed between an array of fins. This means that there’s always a relief path for the airflow, so the outlet pressure cannot reach a dangerous level.

Standard 1910.95(a) isn’t exclusive to the use of compressed air, but since the discharge of a high pressure gas to atmospheric pressure can create quite a racket, noise levels associated with the use of compressed air often exceed exposure limits published in this standard.

  • Do protect your ears, same as you do your eyes. This one is near & dear to me, because my Dad lost a significant amount of his hearing in his early 40’s as a result of occupational noise exposure, and I saw first-hand what an impact that has on quality of life…for him, and frankly, for us too. There are a number of ways to do this, and the National Institute of Safety & Health (NIOSH) ranks them in order of effectiveness in their Hierarchy of Controls.
  • Don’t make earplugs, earmuffs, headphones, etc., the first and only line of defense. Don’t get me wrong; they work GREAT when the right ones are used properly…”right” and “properly” being the key words there.
  • So, DO make selection, training, and enforcement of their usage a high priority if the source of the noise cannot be:
    • Eliminated – this can be a toughie, because whatever’s making the noise is very likely there for a reason.
    • Substituted – this is a much more common, and still highly effective method, as engineered products like EXAIR manufactures can dramatically lower noise levels while maintaining the effectiveness of compressed air usage.
Examples of some sound levels we’re all familiar with, and how some EXAIR products compare favorably.

In closing, my last dos & don’ts are: Do heed OSHA’s safety standards, so you don’t get a hefty fine for endangering yourself or the folks you work with. Frankly, if they catch you before anyone gets hurt, you got off light. If you’d like to find out more about how EXAIR Intelligent Compressed Air Products can improve safety with your compressed air usage, give me a call.

Russ Bowman, CCASS

Application Engineer
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The Story Behind Decibels

Published on by Russ BowmanLeave a comment

While ‘sound’ has been around (almost quite literally) forever, our units of quantifying it are relatively new. Most of us are familiar with the word ‘decibel’ and know that it has something to do with how ‘loud’ a sound is. The word ‘decibel’ originated, however, as a unit to quantify the loss of the strength of a signal as it traveled through telephone and telegraph wires. From the invention of the telegraph in the 1840’s, miles and miles (and miles) of cable started crisscrossing the country, and eventually the world. The unit they used to quantify signal loss back then was known as a “mile of standard cable” or “MSC”. And it was just that: the loss of signal energy as it traveled through one mile of standard (approximately 19 gauge wire back then) cable.

In 1924, Bell Telephone Laboratories introduced a new unit: the Transmission Unit (TU) which changed the math from linear to logarithmic. One TU was defined such that the number of TUs was ten times the base-10 logarithm of the ratio of measured power to a reference power. In 1928, the Bell folks proposed using a new word they’d coined: ‘decibels’, instead of TU’s, in honor of the founder of their technology and namesake of their company, Alexander Graham Bell.

While the decibel is still the commonly accepted unit of measure for signal loss in cable, it also became popularized as a unit to quantify sound pressure level, since that’s a logarithmic measurement as well, of the ratio of actual sound pressure being applied (determined by the frequency & amplitude of the sound waves hitting your eardrum) to a base level of sound pressure (the low threshold of hearing for a typical person…what we might informally call “complete silence”.)

There are two ways to determine sound pressure level: you can do the math, or you can use a device that measures it, like the EXAIR Model 9104 Digital Sound Level Meter. These will tell us how ‘loud’ a sound (or the overall sound in a given space) is.

In contrast to the 98dBA sound level from this array of nozzles, the sound pressure level from an EXAIR Super Air Knife is only 69dBA.

This is important because too much of ANYTHING is likely to be detrimental, and sound pressure level is absolutely in that category. Exposure to extraordinarily loud sounds, even momentarily, can irreversibly damage your hearing. And constant exposure to moderately loud sound levels can do it too.

In the United States, the Occupational Safety and Health Administration (OSHA) published Standard 1910.95(a) to identify the maximum allowable noise exposure by hours, and sound level. The proper use of hearing protection is mandated if personnel are exposed to levels in excess of these limits for a given period of time:

Working in areas that exceed these levels will require hearing protection.

When I was little, my Dad had to get hearing aids as a result of occupational noise exposure, so I know first-hand what an impact has on one’s quality of life – and that of the people they spend a lot of time around. It’s one of the big reasons that I always talk about how quiet EXAIR engineered compressed air products are, compared with air blowoffs that aren’t designed to attenuate sound pressure levels.

The ability to hear well is a wonderful gift, and one worth preserving. If you have to work in a loud environment, get some good ear plugs or ear muffs. They make them now with noise-canceling features, so you can still hear people talk while wearing them. If you have questions about whether the environment is “too loud”, it very well might be. Take measurements. If they’re higher than the OSHA limits above, consider the source and whether it can be mitigated, or even eliminated. And if the source is from compressed air blow offs, EXAIR can definitely help – give me a call.

Russ Bowman, CCASS

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

Published on by Brian FarnoLeave a comment

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