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

Sound: What Is It … More Importantly, Weighted Scales of Frequencies

We’ve blogged about sound and what exactly it is before, see the link. Understanding that sound is vibration traveling through the air which it is utilizing as an elastic medium.  Well, rather than me continue to write this out, I found a great video to share that is written in song to better recap how sound is created.

Now that we have that recap and understand better what sound is let’s dig a little deeper to better understand why some sounds may appear louder to a person when they may not appear different on a sound scale that is shown by something like a Digital Sound Level Meter.

Loudness is how a person perceives sound and this is correlated to the sound pressure of the frequency of the sound in question.  The loudness is broken into three different weighing scales that are internationally standardized. Each of these scales, A, C, and Z apply a weight to different frequency levels.

  1. The most commonly observed scale here in the USA is the A scale. A is the OSHA selected scale for industrial environments and discriminates against low frequencies greatly.
  2. Z is the zero weighting scale to keep all frequencies equal, this scale was introduced in 2003 as the international standard.
  3. C scale does not attenuate these lower frequencies as they are carrying the ability to cause vibrations within structures or buildings and carry their own set of risks.

To further the explanation on the A-weighted scale, the range of frequencies correlates to the common human hearing spectrum which is 20 Hz to 20kHz. This is the range of frequencies that are most harmful to a person’s hearing and thus were adopted by OSHA. The OSHA standard, 29 CFR 191.95(a), that corresponds to noise level exposure permissible can be read about here on our blog as well.

When using a handy tool such as the Digital Sound Level Meter to measure sound levels you will select whether to use the dBA or dBC scale.  This is the decibel reading according to the scale selected. Again, for here in the USA you would want to focus your measurements on the dBA scale. It is suggested to use this tool at a 3′ distance or at the known distance an operator’s ears would be from the noise generation point.

Many of EXAIR’s engineered compressed air products have the ability to decrease sound levels in your plant. If you would like to discuss how to best reduce sound levels being produced within your facility, please contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

1 – Fun Science: Sound – @charlieissocoollike – https://youtu.be/xH8mT2IQz7Y

 

Video Demonstration of Compounding Sound Levels

In industrial settings, having a single air nozzle or other blowoff product is often not the scenario that is seen.  Many applications require multiple points of blowoff, even if not in the same direction or for the same position within the machine.  In the scenario where multiple nozzles are used, sound levels can get tricky to calculate and is often thought of as a mystery.  If you follow our blog then you may have seen this excellent blog that shows all the math behind calculating the total decibels when multiple sources of noise will be present. The video below gives a demonstration of utilizing two of the EXAIR model 1100 – 1/4″ FNPT Super Air Nozzle.

In the video you see a model 1100 being operated and producing a sound level of 74 dBA from 3′ away from the nozzle point.  When the second nozzle is turned on (also producing 74 dBA individually), the pressure is adjusted back up to the same input pressure and the sound level meter registers 78 dBA from 3′ away.  Following the math laid out in the “excellent blog” link above, the sound level calculated comes out to be the same 78 dBA that is shown in the video using EXAIR’s Digital Sound Level Meter.

If you would like help determining the sound levels within your facility, check out the EXAIR Digital Sound Level Meter as well as reach out to an Application Engineer.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

Image of Ear auricle Listen by geraitCC0 Create Commons.

Sound: Explaining Power and Pressure

Sound Power…  When I hear that term all I can think of is the classic commercial Maxell®Sound made in 1983.  I was only a year old when that commercial graced the presence of everyone’s TV.  I did see it throughout the years and recall recording Casey Kasem’s Top 40 on Maxell cassettes.  Then, in college it was a classic poster you would see around the dorms.

1(Maxell / Retrontario, 2009)

Needless to say, this does show sound power and sound pressure which is the point of this blog. This video however is not an industrial environment that most of us are accustomed to when worrying about the sound power / sound pressure within an environment.

If you observe the video above the speakers and the driver of the speakers is the generator of sound power.  That is the energy rate emitted by a source.  This power then begins to fill a space which is equivalent to the sound intensity.  This is because the sound energy has a direction that is given to it, think of the speaker.  The speaker gives the sound energy a vector to travel.  Then when the vector hits surfaces that is the sound intensity.

This sound intensity can then be interpreted as the sound power transfer per unit of surrounding surface at a distance.  This will then give the information needed to convert the information to the Sound Pressure level.  This is the force of a sound on a surface area perpendicular to the direction of the sound.

With this information we can then observe the logarithmic unit (or value) used to describe the ratio of sound power, pressure, and intensity, the decibel.  The decibel is what all industrial hygienists and safety personnel are concerned with.   In the end, all of this is started at the point of power generation, when observing compressed air blowoffs, this is the exit point of air from the device.  If you optimize the point of use device to use the least amount of compressed air and be the most efficient then the amount of sound power being generated and eventually being measured as decibels at an operator’s work station, then the result will be lower ambient noise levels.

If you would like to see any of the math behind these conversions (an amazing blog by our own Russ Bowman), click the link. If you want to discuss optimizing your compressed air operations and lower the noise level of the compressed air products in your plant, please contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

 

 

Video Source: Classic Maxell Cassette commercial – Retrontario – https://www.youtube.com/watch?v=Zk71h2CQ_xM