Two Important Safety Factors When Choosing Air Nozzles

At EXAIR, we have a statement, “Safety is everyone’s responsibility”.  And we also manufacture safe compressed air products.  In the United States, we have an organization called Occupational Safety and Health Administration, OSHA, that enforces directives for safe and healthy working environments.  They do training, outreach programs, and educational assistance for manufacturing plants.  They will also enforce these directives with heavy fines for violations.  The two most common violations with compressed air are air guns and blow-off devices are described in 29CFR 1910.242(b) for dead-end pressure/chip shielding and 29CFR 1910.65(a) for maximum allowable noise exposure.

Here is an example of a nozzle that is dangerous.  As you can see, there is only one opening where the air can come out from the nozzle.  Other types of nozzles that would fall into this same group would include copper tube, extensions, and open pipes.

Unsafe Nozzle

They are dangerous as the compressed air cannot escape if it is blocked with your body or skin.  If operated above 30 PSIG (2 bar), these nozzles could create an air embolism within the body which can cause bodily harm or death.  This is a hazard which can be avoided by using EXAIR Super Air Nozzles and Safety Air Guns.  The nozzles are designed with fins which allows the air to escape and not be blocked by your skin.  So, you can use the EXAIR Super Air Nozzles safely even above 30 PSIG (2 bar).

Unsafe Air Gun

To counteract the dead-end pressure violation, some nozzle manufacturers create a hole through the side of the nozzle (Reference photo above).  This will allow for the compressed air to escape, but, now the issue is noise level.  With an “open” hole in the nozzle, the compressed air is very turbulent and very loud.  The National Institute for Occupational Safety and Health, NIOSH, states that 70% to 80% of all hearing loss within a manufacturing plant is caused by compressed air.  OSHA created a chart to show the maximum allowable noise exposure.  This chart shows the time and noise limits before requiring hearing protection.  The EXAIR Super Air Nozzles, Super Air Knives, Super Air Amplifiers are designed to have laminar flow which is very quiet.  As an example, the model 1210 Safety Air Gun has a sound level of only 74 dBA; well under the noise exposure limit for 8 hours.

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.

NIOSH created an overview of how to handle hazards in the workplace.  They call it the Hierarchy of Controls to best protect workers from dangers.  The most effective way is by eliminating the hazard or substituting the hazard.  The least effective way is with Personal Protective Equipment, or PPE.  For unsafe compressed air nozzles and guns, the proper way to reduce this hazard is to substitute it with an engineered solution.

One of the last things that companies think about when purchasing compressed air products is safety.  Loud noises and dead-end pressure can be missed or forgotten.  To stop any future fines or additional personal protective equipment (PPE), it will be much cheaper to purchase an EXAIR product.  And with the Hazard Hierarchy of Controls, the first method is to remove any hazards.  The last method for control is to use PPE.  In the middle of the hierarchy is for an engineered solution.  EXAIR products are that engineered solution.  If you would like to improve the safety in your facility with your current blow-off devices, an Application Engineer can help you.

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

Picture:  Safety First by SuccoPixabay License

What is a Decibel Level?

Decibel level also known as dBA, is how the industry measures sound intensity’s effect on the human ear and is an important value when discussing noise exposure for employees and operators within manufacturing. Manufacturing personnel can be at risk for hearing damage when exposed to high decibel levels if the proper precautions are not taken. For reference, 0 dBA is the softest level that a person can hear. Normal speaking voices are around 65 dBA. A rock concert can be about 120 dBA.

Sounds that are 85 dBA or above can permanently damage your ears. The more sound pressure a sound has, the less time it takes to cause damage. This damage occurs within a sensitive part of our ear called the cochlea, which contain thousands of hair cells used to allow our brains to detect sounds. For example, a sound at 85 dBA may take as long at 8 hours to cause permanent damage, while a sound at 100 dBA can start damaging hair cells after only 30 minutes of listening.

OSHA Max Noise Exposure Chart

The Center for Disease Control (CDC) estimates that 22 million workers are exposed to potentially damaging noise at work each year. Whether you work near machinery, at a sports venue, on a tarmac, or operate a jackhammer—hearing loss is preventable.

Noise may be a problem in your workplace if you:

  • Hear ringing or humming in your ears when you leave work.
  • Have to shout to be heard by a coworker an arm’s length away.
  • Experience temporary hearing loss when leaving work.

If you need to raise your voice to speak to someone 3 feet away, noise levels might be over 85 decibels. Sound-measuring instruments are available to measure the noise levels in a workspace.

The first step to lowering your sound level is to take a baseline reading of your various processes and devices that are causing the noise. EXAIR’s Sound Level Meter, Model 9104, is an easy to use instrument that provides a digital readout of the sound level. They come with an NIST traceable calibration certificate and will allow you to determine what processes and areas are causing the most trouble.

From there, EXAIR has a wide range of Intelligent Compressed Air Products® that are designed to reduce compressed air consumption as well as sound levels. For noisy blowoffs where you’re currently using an open-ended pipe or a loud commercial air nozzle, EXAIR’s Super Air Nozzles are the ideal solution. Not only can they pay for themselves over a short period of time time due to compressed air savings, but your operators will thank you when they’re able to hear later on in life!

 EXAIR has the tools you need to reduce sound level in your processes. If you’d like to talk to an Application Engineer about any applications that you feel could benefit from a sound reduction, give us a call.

Jordan Shouse
Application Engineer

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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 and the Hierarchy of Controls

The CDC (Center for Disease Control) published a useful guide called “Hierarchy of Controls” that details (5) different types of control methods for exposure to occupational hazards while showing the relative effectiveness of each method.

NIOSH_Hierarchy_of_Controls
Hierarchy of Controls

 

The least effective methods are Administrative Controls and Personal Protective Equipment (PPE). Administrative Controls involve making changes to the way people perform the work and promoting safe practices through training. The training could be related to correct operating procedures, keeping the workplace clean, emergency response to incidents, and personal hygiene practices, such as proper hand washing after handling hazardous materials. PPE is the least effective method because the equipment (ear plugs, gloves, respirators, etc.) can become damaged, may be uncomfortable and not used, or used incorrectly.

In the middle range of effectiveness is Engineering Controls. These controls are implemented by design changes to the equipment or process to reduce or eliminate the hazard. Good engineering controls can be very effective in protecting people regardless of the the actions and behaviors of the workers. While higher in initial cost than Administrative controls or PPE, typically operating costs are lower, and a cost saving may be realized in the long run.

The final two, Elimination and Substitution are the most effective but can be the most difficult to integrate into an existing process. If the process is still in the design phase, it may be easier and less expensive to eliminate or substitute the hazard. Elimination of the hazard would be the ultimate and most effective method, either by removing the hazard altogether, or changing the work process so the hazard is no longer part of the process.

EXAIR can help your company follow the Hierarchy of Controls, and eliminate, or substitute the hazards of compressed air use with relative ease. 

Home of Intelligent Compressed Air Products

Engineers can eliminate loud and unsafe pressure nozzles with designs that utilize quiet and intelligent compressed air products such as Air NozzlesAir Knives and Air Amplifiers. Also, unsafe existing products such as air guns, can be substituted with EXAIR engineered solutions that meet the OSHA standards 29 CFR 1910.242(b) and 29 CFR 1910.95(a).

In summary, Elimination and Substitution are the most effective methods and should be used whenever possible to reduce or eliminate the hazard and keep people safe in the workplace. EXAIR products can be easily substituted for existing, unsafe compressed air products in many cases. And to avoid the hazard altogether, remember EXAIR when designing products  or processes which require compressed air use for cooling, cleaning, ejection, and more. 

If you have questions about the Hierarchy of Controls and safe compressed air usage from any of the 15 different EXAIR 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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Hierarchy of Controls Image:  used from  Public Domain