NATIONAL PROTECT YOUR HEARING MONTH

The following article was written by Richard Anthony, Director, dB Noise Reduction

One of my sisters is a health and wellness expert. She has stated for years that, “Sitting is the new smoking”.  Our Mother had died of lung cancer, so she was not trivializing smoking but instead pointing out that sitting TOO MUCH  has a profoundly negative effect on human health.

Since learning about the adverse effects of noise on human health, I have modified this phrase to make the point: “NOISE is the new smoking”

If you haven’t yet heard about them, please let me introduce a great organization to you: the good people at the Hearing Health Foundation.   (www.hearinghealthfoundation.org).  They want to remind us that October is also “NATIONAL PROTECT YOUR HEARING MONTH”.

These people perform a great service in publishing facts about noise and awareness about Tinnitus and the most damaging type of hearing loss:  Noise Induced Hearing Loss (NIHL).  They also inform us about new technologies and advancements in physics and medical research that point the way to one day being able to repair hearing damage – until then, NIHL remains irreversible BUT PREVENTABLE. 

For a perspective on the scale of today’s noise problem,  Hearing Loss (NIHL and Tinnitus) affects up 50 million people; 20% of teenagers (think: earbuds/headphones) and 60% of active military and veterans.  These statistics are for the USA only!   Adverse health effects from Hearing Loss are not limited to deafness – it can also contribute to cardiovascular and other physical and/or mental health conditions.

The prerequisite of prevention is AWARENESS.  When exposed to loud noise, The Hearing Health Foundation advises to Walk (literally, walk away – noise dissipates with distance), Block (use ear plugs and/or ear muffs; use noise barriers, or even put your hands over your ears in an urgent situation), Turn (turn down the volume; throttle-back machinery; adjust the direction of the noise source).  

 Please protect your hearing – for life.

 About dBNR:  dB Noise Reduction provides custom noise control, acoustic and vibration isolation solutions for any application.  Contact sales@dbnoisereduction.com for assistance.

Extreme Silencer Applications

Silencers, Mufflers, Attenuators, Splitters, Baffles, Sound Traps – they are all similar but slightly different.

In general, these noise reduction devices are designed to reduce noise (unwanted sound) from within an air intake system or exhaust system (which could be exhausting air or a gas other than air).   Any such device that invades the airstream will invoke a pressure drop on the system, as it obstructs flow.

It is for this reason that these noise control devices require proper engineering to balance the required noise reduction against the allowable pressure drop within the system.  More extreme and critical applications, such as gas turbines, high temperatures/velocities/mass flow; airstream particulate and such require commensurately appropriate extreme engineering and manufacturing capabilities.

Such is also the case with vent and blowdown silencers*.  These particular noise reduction devices are inherently pressure vessels, and must be precisely designed and manufactured to withstand extreme conditions.  The attention to detail and quality for critical internal components cannot be overlooked, since safety must always be the primary consideration when designing for these extreme conditions.

While specializing in extreme noise control engineering and systems, dB Noise Reduction is your source for all environmental, industrial, architectural and vibration isolation noise control systems.  dB Noise Reduction even has acoustic barrier and noise control enclosure panels up to 24’ long in a single span – the longest in the industry; offering superior labor savings and a monolithic appearance.

Please visit our website, or contact sales@dbnoisereduction.com for assistance with selecting the appropriate silencer or noise control system for your application.

Richard Anthony
Director

*Source:  “A Practical Guide to the Specification and Selection of Vent and Blowdown Silencers” John E. Praskey, dB Noise Reduction, presented at INCE Inter.Noise 2015

“Silencer Selection Web App”, a new addition to the dB Noise Reduction website

We have added a new tool to our website that provides our customers with the ability to easily select the correct silencer for their noise control requirements. The silencer selection tool was designed to provide customers with a quick and easy process that will facilitate their silencer selection.

This new selection program allows customers to obtain a quote on the most cost effective and efficient silencer that will meet their requirements with a simple input screen. The App requires some basic information about the intended silencer, such as orientation, connection, target noise level, etc…This will provide the customer with a listing of silencer options and detailed information, including pricing, regarding each alternative. Once the ideal silencer has been selected, customers can contact the dB Noise Reduction sales team directly from the silencer selection tool page.

The silencer selection tool is currently available for circular and rectangular silencers and is the first of many software sets. “This project is an ongoing development process that will eventually include all of our products.” said President of dB Noise Reduction, John Praskey. The goal is to provide the best service to customers by providing a fast and simple tool to order quality products. The next undertaking will be the addition of vent silencers to the new tool.

To access the dB Noise Reductions Web Apps, please visit www.dbnoisereduction.com and click on the “Web App” button on the navigation bar or follow the link: www.dbnoisereduction.com/web-app.php.

How does a fan silencer work?

Sound can be thought of like the ripples in a lake when you throw a stone into it creating ripples and the ripples travel outward in every direction. If you then took that lake and squeeze it into a canal those ripples would now be channeled to flow through the length of the canal. This is what’s happening when you connect your ductwork to a fan. All the sound waves from the fan are now being channeled through the ductwork.

The ductwork acts as a barrier preventing the sound waves from escaping, but there could be some breakout noise. Going back to our analogy, as the ripples travel through the canal still trying to protrude outward in every direction, some will fall on the shore or walls of the canal creating some noise. In the same way, breakout noise is the sound waves (caused by the airflow and/or fan) trying to escape through the duct.

This is where a fan silencer comes in. Placing a fan silencer in the airstream will help to absorb some of these sound waves. The amount of sound waves the silencer absorbs varies on acoustic media used in the silencer, the open area of the silencer (ratio of open space verses absorptive material), length of the silencer and materials used.

When the sound waves enter the silencer, the perforations in the baffle allow the sound wave to expand into the acoustic media of the baffle. The acoustic media is made up of millions of air pockets. When the sound waves impinge on the air pockets it causes the molecules to move and collide with each other dissipating energy in the form of heat. This is what gives you your noise reduction.

The more baffles you can put in a silencer the more noise reduction you can achieve, however you also increase the pressure drop. All fans create pressure to push air forward. If there is an obstruction creating resistance in the air stream, it produces pressure against the fan dropping the pressure the fan can create to push the air. There is a fine balance between the pressure drop allowed by the fan and the resistance of airflow created by the silencer.

At dB Noise Reduction our engineers have a wealth of knowledge and years of real world experience. We take the guess work out of the equation ensuring our customers get the highest performance from their industrial silencers. The quality of our products and the attention to customer service makes dB Noise Reduction the best in the business. Our business is to reduce noise caused by industry and create a peaceful environment.

Turnkey solution for a mine ventilation system

A nickel and copper mine ventilation system, which needed to be in operation twenty-four hours a day, seven days a week, was creating excessive noise problems for employees and nearby residents. Not only were noise violations an issue, the condition of the existing ventilation enclosure was a concern. Extensive clean up was needed, including the removal of hazardous material.

Working alongside the mining company’s acoustical consultant, dB Noise Reduction developed a customized industrial silencer solution to manage the noise problems created by the 104 dBA axial fan used for ventilation. In order to address all concerns, the project included the disassembly of the existing steel structure to remove corrugated asbestos paneling. The dB Noise Reduction team was uniquely qualified for this project given their experience as noise reduction specialists with an engineering focus. We were able to coordinate all phases of the mine ventilation system upgrade for a complete turnkey solution.

The initial phase of the project included cleaning up the existing structural steel using a high pressure water blasting process. Environmentally harmful chemicals were not needed and the potential for dust and debris was eliminated. This was especially important because the ventilation fan needed to remain in operation. Following the clean up process, the steel structure was given a protective paint finish.

The removal of the corrugated asbestos was the only phase of the project during which the operation of the ventilation fan had to be stopped, due to the potential for asbestos exposure. Special precautions were required, and the area had to be evacuated. The dB Noise Reduction team contracted with a certified removal team, who completed the work within a day for minimal downtime. The newly cleaned and treated steel structure was improved with the installation of four modular fan intake silencers, two absorptive acoustic walls, and an absorptive acoustic roof.

As a result of the new fan silencer system engineered and installed by the dB Noise Reduction team, the noise level dropped from 104 dBA to 72 dBA. This was a 32 dBA reduction from the original noise level, and comfortably in compliance with all applicable government noise regulations.