SuperSeal® Edge Treatment is designed to protect the cut edges of the fiberglass duct liner with the same acrylic polymer used to factory coat the product, maintaining the integrity of the coating and providing compliance with local building codes and engineering specifications. (Photos courtesy of Johns Manville.)
DENVER - Architects and owners have depended on M.E. Engineers Inc., a mechanical engineering and consulting firm, for the company's expertise in projects from Wimbledon Stadium in England to Minute Maid Ballpark, home of major league baseball's Houston Astros. The firm was called upon again for the development of the Colorado Convention Center expansion in Denver.

This $268 million expansion is scheduled to double the size of the Colorado Convention Center. The project includes 292,000 square feet of new exhibit space, a 50,000-square-foot ballroom, and a 5,000-fixed seat auditorium. M.E. Engineers was called in to develop and install an efficient and quiet air distribution system.

As the engineering and consulting firm is quick to point out, ducts carrying large volumes of cooled air at high speeds can be at risk for condensation collecting on the outside of the cool duct. Another potential problem involves noise from the airflow and the ventilation equipment.

The key to preventing both problems, in M.E. Engineers' estimation, is insulating the ductwork. Having used it successfully before, M.E. Engineers specified Johns Manville's Spiracoustic Plusâ„¢ system of fiberglass duct lining products because the firm believed it would prevent both problems.

"We used our standard specification for this project," said Steve Ferguson, project manager for M.E. Engineers. "We have never had a problem with this product. It does a good job and there wasn't any reason to change."

Large spiral ducts for the Colorado Convention Center were lined at Hercules Industries, Denver, with Spiracoustic Plus™ duct liner from Johns Manville. After being cut to the proper circumference, the liner is formed into a round configuration and taped along the seam. Then it is collapsed into a heart shape, inserted into the duct, and snapped into place.

Cost-Effective Solution

Spiracoustic Plus was designed to be a cost-effective, reliable alternative to perforated metal double-wall insulation for lining round air ducts. Rising steel prices figure into the equation, as Spiracoustic Plus cuts in half the amount of sheet metal required, said Greg Turner, project manager for Skidmore (Aurora, Colo.), the HVAC contractor on the project.

"Our steel prices went up 20 percent in March," said Turner. "And it is reported that they are going to go up again."

Hercules Industries of Denver was responsible for both making the ductwork and lining it. Pieces of duct were fabricated at the shop, and the duct liner was delivered in flat sheets. The fiberglass liner is designed to bend and conform naturally to a round shape, said the manufacturer.

After being cut to the proper circumference, it is formed into a round configuration and taped along the seam. Afterward, it is collapsed into a heart shape, inserted into the duct and snapped back into a round shape.

The liner is self-supporting in most round applications. However, it may require minimal pinning or the use of adhesive for fittings. In this project, Hercules found that installing Spiracoustic Plus was much easier than other insulating solutions.

"It is better than double-wall because it isn't as labor intensive," said Rod Valdez, general manager at Hercules' Denver location.

As ductwork was fabricated and insulated, it was sent to the site to be hung. The ease of installing the insulated ductwork was appreciated by the installers.

"I would say double-wall insulated ductwork takes at least twice as long to install, and that is if the connectors are in good shape," said Turner. "The ends on double-wall are really hard to meet up because there are twice as many connectors. With lined duct, you only need to meet up the connectors on the outside."

Spiracoustic Plus is designed to be both functional and sturdy, said the manufacturer. According to Johns Manville, the Permacote® acrylic polymer coating on the air-stream surface "withstands high air velocity and prevents infiltration of dust and dirt." A biocide, approved by the Environmental Protection Agency (EPA) for use in HVAC applications, is incorporated into the coating.

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Publication date: 10/25/2004