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R-Mer Shield standing-seam roof system has a 2-in.-high vertical seam with an extruded aluminum clip and top rail system said to provide unrivaled wind-uplift performance, ensuring watertight protection in harsh environments.  e roof system can span open purlins on slopes to 1/4:12 and has a 1/2-in. clearance between the panel and substrate to increase ventilation beneath the panel.  e one-piece clip and top rail provide thermal movement. A double bead of factory-applied seam sealant is isolated from the clip.

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Outdoor-living brick BrickScapes outdoor-living products include mailboxes, fi re pits, grills, trashcans, fi replaces, and fence posts. Items are available in six stock brick colors with custom colors also available. Finished products are delivered onsite with minimal foundation requirements.

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Air-barrier system Along with Tremco Commercial Sealants & Waterproofi ng, the company has available Securock ExoAir 430 air-barrier system. Combining Securock glass-mat sheathing panels and ExoAir membrane, the gypsum panel features a pre-applied air/water barrier. The process is said to produce a uniform membrane with superior bond to the substrate.

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EPS insulation Foam-Control Plus+ expanded polystyrene insulation supports a wide range of applications, including perimeter and underslab insulation, cavity-wall insulation and sheathing, pre-cast concrete cores, green roofs and plaza decks, and waterproofi ng. The product is available in a range of high compressive strengths with high R-value.

ACH Foam Technologies, Denver Circle 59 achfoam.com

Unitized curtain wall 2500 UT Unitwall curtain-wall system is a high-performance unitized system that provides a range of design options for seamless aesthetics. The ultra-thermal system offers reduced fabrication and assembly times due to the one-piece polyamide thermal break, eliminating the need for pressure plates and fasteners. Stacked joints within the system account for building movement, and two-piece verticals allow a continuous snap engagement to maximize strength.

Kawneer Co. Inc., Norcross, GA Circle 58 kawneer.com

Molded pipe fl ashing Wrapid Flash pipe fl ashing is said to make wrapping any cylindrical penetration simple and consistent. The molded boot uses a single injected-molded piece to reportedly eliminate faulty fi eld-fabricated seams. Installation takes approximately 4 to 5 min. The fl ashing has integrated measurements and cut guidelines for accurate trimming.

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At Symphony Hall in Atlanta, a rushing sound generated by the concert hall’s old cooling towers at times penetrated the ceiling above the orchestra, distracting and annoying the audience.

HDPE Cooling Towers Get The Noise Out

Improved cooling-tower technology eliminates sound and vibration from HVAC systems at Atlanta Symphony Hall.

Imagine attending a symphonic concert, and right in the middle of a violin solo you hear a rushing sound coming from the ceiling above the orchestra and overwhelming the concert hall’s painstaking acoustic design.

Or perhaps you are performing surgery in a medical-center suite or giving a business presentation in the penthouse conference room of an office building and that same rushing noise, generated by the facility’s

HVAC cooling tower, infiltrates the environment, leaving individuals distracted and annoyed.

That rushing or ringing sound is generated by air turbulence at cooling-tower fans and water flowing through the cooling tower into the collection basin. It is the bane of residents and operators of office, residential, and institutional buildings. Finding a solution can be difficult and expensive unless a more advanced cooling-tower technology is applied.

In the case of the Symphony Hall at the Woodruff Arts Center, home to the Atlanta Symphony Orchestra, Alliance Theatre, and High Museum of Art, the noise was coming from conventional cooling towers located on the roof directly above the concert hall.

Steve Trott, director of engineering at the full-spectrum arts-center campus, says the sound was similar to that of a jet aircraft passing over the Memorial Arts Building where the Atlanta Symphony performs on the top floor.

Fortunately, the noise problem was eliminated and several other problems solved when new cooling towers were installed.

“Our old, metal cooling towers were ‘end of life,’ and we knew that we had to replace them soon,” explained Trott. “We considered typical metal towers, stainless steel, and partial stainless steel. We looked at cross-flow and counter-flow designs. Then we looked at the HDPEbased cooling towers, which were recommended by the

Atlanta office of DLB Associates Consulting Engineers. We found those cooling towers were very quiet and would provide the sound attenuation needed without having to go to a special quiet-tower package, which would really increase the cost.”

The HDPE (high-density polyethylene) design that Trott’s team discovered was pioneered by Delta Cooling Towers, Roxbury Township, NJ, primarily to solve corrosion problems that have plagued metal towers due to problems such as soft water and ambient factors such as salt air or caustic industrial gases.

While the dramatically improved lifespan of these HDPE towers has been a major factor in purchasing decisions for years, more recently the quieter operation has taken on significant importance for many applications.

GETTING RID OF THE DECIBELS Noise pollution generated by commercial HVAC equipment has become an increasingly unwanted problem for communities across the nation in recent years.

Martin M. Previtera, regional manager for Delta Cooling Towers, said that the continued development of inner cities and the closer proximity of commercial and industrial buildings to residential neighborhoods have caused heightened concerns among building owners and municipal governments.

For example, the Franklin Institute building in Philadelphia recently replaced its cooling towers and, by city ordinance, was mandated to restrict the sound output to less than 50 dBA, which is less than the normal noise output of a traditional cooling tower.

“They decided on HDPE cooling towers for a combination of factors,” Previtera explained. “They were able to achieve better pricing while also meeting the dBA rating of less than 50. This is a four-cell cooling tower, the same type installed at Woodruff Arts Center in Atlanta.”

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High-density polyethylene (HDPE) units from Delta Cooling Towers offer not only corrosion resistance but also quieter operation.

To appreciate the surprising difference between decibel levels, Temple Univ. Department of Civil/Environmental Engineering, Philadelphia, describes the difference of just 10 dBA as very substantial, with 70 dBA being the equivalent to a vacuum cleaner, and 50 dBA being the equivalent of a quiet, suburban home.

“In many cities, businesses are encroaching on residential areas, and some cities require that new office buildings incorporate residential spaces in the top portions of the buildings,” said Trott. “Certainly the occupants of those expensive spaces don’t want to hear the noise of cooling towers.”

OTHER BENEFITS The cooling towers that Woodruff Arts Center selected for the symphony hall building were two sets of twin-cell Delta Series 500-ton models, each featuring a 20-year warranty on corrosion or other physical damage.

Trott said these HDPE towers are providing other important benefits as well. “One of the other reasons we chose these cooling towers was that they are available with direct-drive motors,” he explained. “That means no gearbox and no belt, which greatly improves operating reliability and reduces maintenance requirements. At the same time it provides significant energy savings.”

Trott added that his new cooling towers feature variable-speed fan drives, which provide very smooth operation and very consistent water temperature. During the first summer of operation, most of the time the fans were running at 50% speed or less, which was, obviously, more economical than conventional fan drives.

Trott noted that the Delta cooling towers are unusual looking compared with traditional ones. “Ours are a nice tan color that blends in with the roof; so that is not something that attracts the eye in a way that would call attention to the machinery on the roof. We feel that the aesthetic features of the cooling-tower design are beneficial in a high-visibility location; since all of our neighbors are in taller buildings that look down on our roofs, it is nice that they are less conspicuous than traditional towers.”

The end result is that the new cooling towers downplay appearance and unwanted sound, allowing concertgoers to experience a quiet and comfortable night listening to music at the symphony. CBP

Want more information? The resources below are linked on our website at cbpmagazine.com and in our digital magazine at cbpmagazine.com/digital/sep2015.

Circle 12 on the Reader Service Card.

Learn the principles of cooling towers. Read about cooling tower materials.

Access a cooling tower sizing program.