Sound Levels in Your Facility

One of the most common and dangerous hazards that occur within a manufacturing and production facility is the noise level within the plant. Noise is measured in units known as decibels. Decibels are a ratio of the power level of the sound compared to a logarithmic scale. If an employee is an exposed for too long to high levels of noise, they can begin to lose their hearing. That is where the OSHA 29 CFR 1910.95 regulation comes into play.

Hearing loss is the best known, but not the only, ill effect of harmful noise exposure. It can also cause physical and psychological stress, impair concentration, and contribute to workplace accidents or injuries.

This OSHA standard doesn’t just provide the protection against noise in the work place but monitoring as well. Companies shall provide at no cost audiometric tests for all employees to ensure that no damage is being to the hearing of all personnel. This program is to be repeated every six months and the results are to be made accessible to all personnel.                

Hearing is very important to our everyday lives and must be protected due to the fact that once it is damaged hearing loss cannot be lost be repaired. The OHSA 29 CFR 1910.95 is there to protect and monitor this dangerous hazard in the workplace so that all employees can go home safe and sound.

Here at EXAIR we design all of our products to safe and quite. Weather it is using one of our mufflers for vortex tubes or E-vac’s or one of our Super air nozzles we strive to meet and exceed the OSHA standard. One could also purchase EXAIR’s Digital Sound Level Meter which can give a accurate and responsive reading of how loud your compressed air sources are.

For more information on EXAIR’s Digital Sound Level Meter and any of EXAIR‘s Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Jordan Shouse
Application Engineer

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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

 

Safety Air Guns – Using Engineered Air Nozzles For High Performance

Inexpensive air guns can be picked up just about anywhere, and you generally get what you pay for. Most will be very noisy and waste lots of compressed air.  And many will be unsafe, violating two of OSHA’s standards put in place to protect worker safety. The first is Standard 29 CFR 1910.95(a) which sets limits to the maximum noise exposure, and the second is Standard 29 CFR 1910.242(b) which says that the nozzle cannot be dead-ended, or exceed a 30 PSIG pressure limit.

These guns may seem like a perfect fit for a handheld blowoff application. The truth is, the cost saved up front will easily be paid throughout the cost of ownership.  This is due to the lack of an engineered nozzle which meets and exceeds the OSHA standards mentioned above.   The “cheap” guns often have a cross drilled hole to meet or exceed the OSHA standard for dead-end pressure. While this may be true, it causes a large wind sheer which escalates noise levels to well over the allowable noise level exposure set by OSHA.  These tips sometimes offer large force outputs because they are equivalent to an open pipe.  We have publicized numerous times about how an open pipe blow off does not permit pressure to be utilized all the way to the point of blowoff, and is also a waste of energy.

In order to determine how much compressed air your current blow guns utilize, the level of noise they product, and the sound level they produce, consider taking advantage of the EXAIR Efficiency Lab.  The Efficiency Lab is a free service that you can read more about here.

An EXAIR Safety Air Gun is engineered and designed to comply both of the OSHA standards mentioned above, ensuring safe operation for company personnel.  On top of the safety designed into the guns, we also ensure all of our guns are efficient by offering only engineered nozzles on them.

EXAIR offers (4) types of Safety Air Guns – the VariBlast, the Soft Grip, the Heavy Duty, and the Super Blast.  Each type of Safety Air Gun is offered with a plethora of nozzles, as well as varying length extensions, with or without the Chip Shield.

Safety Air Guns
The VariBlast, Soft Grip and Heavy Duty Style of Pistol Grip Safety Air Guns

Super Blast
The Super Blast Style of Safety Air Gun

 

We invite you to try out an EXAIR Safety Air Gun, and get the free 1″ Wide Flat Super Air Nozzle as a bonus. Click here for more details about this special promotional offer.

To discuss your application and how an EXAIR Intelligent Compressed Air Product can improve your process, feel free to contact EXAIR, myself, or one of our other Application Engineers. We can help you determine the best solution!

Brian Bergmann
Application Engineer

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Sound – It Adds Up! How to Calculate Decibel Levels

Keeping noise levels in check and at safe levels is very important to ensure employee safety and well being.  OSHA (the Occupational Safety and Health Administration) through standard 29 CFR-1910.95(a) has studied the situation and set Maximum Allowable Noise Exposure limits in Hours per Day based on the Sound Level, in dBA, of exposure.

For existing processes, a Digital Sound Meter is a valuable tool to measure the sound level to ensure that the source of loud noises can be quickly identified and isolated for immediate corrective action.

For new processes, or changes to an existing process, it is important to estimate the sound level prior to installation and start-up, so that precautions can be taken as needed.

For example, let’s say we are going to add a blow off station to clean off a part on a conveyor to improve the process and increase the throughput.  A typical set-up might be a 12″ Super Air Knife (model 110012) blowing off the top and a pair of Super Air Nozzles (model 1100) to blow off the sides.

SAK and ASAN
12″ Super Air Knife and Super Air Nozzle

If we look at the performance data for the (2) different blow off devices, we find that the Super Air Knife is rated at 69 dBA and the nozzles at 74 dBA, when operated at 80 PSIG of compressed air supply.

SAK and ASAN

When asked, “what is the sound level for (1) of the knives, and (2) of the nozzles” a little Acoustic Engineering is in order. The decibel scale is logarithmic, and determining the total sound level when all (3) devices are in operation is not as easy as adding up the three sound level values (which would equal 218 dBA, way off the charts!).  Thankfully, both the actual sound level and the numerical value are determined another way.  I’ll spare you a lot of the math but the equation is as below.

Capture

… where SL1, SL2, SL3, … are the sound levels in dBA of the each sound makers, for as many that are being combined (in our example SL1 = 69, SL2 = 74 and SL3 = 74)

Plugging in the numbers into the equation, the combined sound level works out to be a quiet 77.65 dBA — well within the OSHA limit for exposure for a full 8 hour period.

To discuss your application and how an EXAIR Intelligent Compressed Air Product can make your process better and quieter, feel free to contact EXAIR and myself or one of our other Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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