The pump manufacturer installed the pumps more than two years ago; however, since the pumps did not meet the noise specifications, final payment for the pumps was withheld. Over a two-year period, three acoustical consultants were brought in to take measurements using standard sound level meters, however none of them could identify the root cause of the problem, or develop a solution that satisfied the noise requirements.
Lahnie Johnson, president and founder of Acoustiblok Inc. says, “As a supplier and innovator of noise attenuation solutions for over 20 years we weren’t surprised when Acoustiblok was contacted to assist in resolving the pump noise. Acoustiblok is unique in that not only does it provide acoustical/vibration consulting and engineering using the ARTVIS System, but it also manufacturers in-house an array of sound abatement products to resolve the problems that have been determined. As such, custom fabrication requirements for those unique situations are readily accommodated by the company.”
Because of high ambient noise levels in a facility, it is usually impossible to determine specific noise sources with the use of a sound meter. In light of this, Acoustiblok performed the troubleshooting using the ARTVIS System which allows one to see sound in real-time (as you would see thermal contours with a Flir infrared camera). Not only can one measure the intensity and overall frequency content of the noise, but also visually identify the direction, source and reflections of the noise.
It also helps in revealing modal transitions of resonance in buildings and structures that a standard spectrum analyzer does not reveal. Acoustical data collection and assessment which in the past may have taken hundreds of hours to compile, and even then much being conjecture, can now be visually observed and measured with a higher degree of confidence within hours resulting in time and cost savings.
Within two hours of testing despite the high ambient noise in the facility, the ARTVIS revealed the root cause of the problem was sound escaping through the bottom of the cabinet on which the motor was mounted. Two areas of high sound intensity were found, one centered on the motor and the other centered near the bottom of the cabinet. In effect, the cabinet was acting like the body of an acoustic guitar, amplifying the noise from the motor, which then leaked out of the numerous openings in the cabinet.
Further examination of the acoustic levels with the sound level meter found that the average overall sound levels within the cabinet reach 106.3 dBA compared to the average overall sound levels around the motor of 97.4 dBA, an increase of 9 dB, which would appear to be almost twice the loudness. A comparison of the sound levels at the peaks in the chart indicates that the sound levels within the cabinet are 7 dB higher at 1250 Hz and 10 dB higher at 2500 Hz.
Based on these results, Acoustiblok recommended a multi-faceted solution involving their noise attenuation materials. These recommendations included: installation of QuietFiber sound absorption material within the cabinet to eliminate sound reverberation; implementation of Acoustiblok heavy mineral-filled viscoelastic polymer sheet material, adhering it to all cabinet surfaces to increase mass and deaden resonance and to block the sound escaping out of the cabinet openings; and installation of Acoustiblok All Weather Sound Panels around the motor to directly attenuate the motor noise.
Johnson says, “We are pleased with the success of the Acoustical Real-Time Video Imaging System in the finding the noise source; it was able to solve a seemingly unsolvable noise problem that had been going on over two years. We anticipate using ARTVIS as our diagnostic tool on industrial noise problems such as this one in the future because an ARTVIS is able to identify all of the noise sources and the frequency ranges.
“This information enables us to determine the noise control solutions because we can identify the specific sources, frequency ranges and intensity of the noise problems. Noise issues often have multiple noise sources with a wide frequency range that make pinpointing the noise sources difficult even for experienced engineers.”
More about Acoustiblok’s Acoustical Real Time Video Imaging System
The Real-Time Video Imaging System (ARTVIS) not only allows one to catch sight of sound it also helps in revealing modal transitions of resonance in buildings and structures that a standard spectrum analyzer does not reveal. Acoustical data collection and assessment which in the past may have taken hundreds of hours to compile, and even then much being conjecture, can now be visually observed and measured with a higher degree of confidence within hours. Acoustiblok is now pioneering the use of the ARTVIS systems in the United States and internationally. While Acoustiblok’s investment in the systems is over $200,000 each, the savings to the client in terms of money and time are incalculable as one can now quiet the precise noise source rather than the whole building. Acoustiblok has successfully used the ARTVIS system on many projects involving industrial and power plant noise.
Solutions to Chiller Noise Issues
QuietFiber Sound Absorbing Material
Hydrophobic, QuietFiber noise absorbing material is recommended to absorb sound within an enclosure or large areas on walls and ceilings as well as use in walls to increase STC. QuietFiber is a versatile solution to many industrial, commercial and residential noise issues.
QuietFiber is available in numerous densities and thicknesses. Areas of high noise levels including sound reverberation can be resolved by introducing QuietFiber into as much of the area as is possible. The amount of noise reduction in highly reflective rooms will be directly relative to how much of the QuietFiber material can be installed into the room.
Unlike other fibrous materials or fiberglass which does not have the high NRC ratings that QuietFiber has, QuietFiber is hydrophobic. QuietFiber (NRC 1.00), Class A Fire Rated (1100 degrees), white or black faced is easy to install and reduce sound levels in virtually any environment.
Acoustiblok Sound Isolation Material
The thin 1/8-inch thick Acoustiblok material is an advanced sound barrier material that is placed between a noise source and the noise receiver. The acoustical property of Acoustiblok is an STC 26. Due to the lack of stiffness and extreme mass per square foot, Acoustiblok has a linear T.L. Acoustiblok material is not to be confused with NRC type of materials and is used for sound/noise isolation not absorbency. A layer of 16 ounce Acoustiblok can reduce sound transmission by as much as 30 decibels depending on the frequencies. It has more sound deadening effectiveness than some treatments with lead.
Independent lab tests show that one 1/8 inch layer of Acoustiblok added to a stud wall can reduce more sound than 8 inches of poured concrete. Rather than attempting to block or absorb sound as other materials do, the Acoustiblok material transforms sound energy into inaudible internal friction energy as the soft heavy material flexes from sound waves (the same as lead without the environmental problems or costs).
Acoustiblok material does not require any special care. Environmentally friendly, Acoustiblok contains no barium, lead or asbestos, is UV resistant and impervious to water and mold and 100 percent recyclable; it is UL rated and classified for virtually all wall, floor and ceiling assembly installations.
Industrial All Weather Sound Panels (patent pending)
Acoustiblok’s 2 inch thick Industrial All Weather Sound Panels (IAWSP’s) are comprised of several layers of different types of materials to maximize noise control. They have filtering materials, absorption materials, and blocking materials for attenuating noise. This allows them to not only absorb sound, but also stop the sound from penetrating through the panels. They have an extraordinarily high STC of 29 (Sound Transmission Class), and NRC 1.00 (Noise Reduction Coefficient) and are UL Std 723 fire tested: Flame spread zero, smoke developed zero.
Acoustiblok’s IAWSP’s are constructed of quality material and craftsmanship. Strain hardened 0.040 inches (1.016millimeters) corrosion resistant perforated aluminum front is resistant to abuse and sharp objects.