11 May 2009
11 May 2009
When foul smells appeared at a park in Austin, Texas, engineers found a solution in a biological system from odour control specialist Bay Products.
The system’s technology is based on proprietary aggregate media that are housed in a fibre-reinforced polymer (FRP) composite structure made with corrosion-resistant Vipel vinyl ester resin from AOC.
The green space and playgrounds of the 7.6-acre Montopolis Park and Recreation Area are popular draws for local residents and students of the nearly Austin Community College-Riverside. The park is in a low-lying, riverside area that by chance includes an underground wastewater conveyance tunnel. Sewer gases inside the tunnel emitted noxious odors that were a major nuisance for park-goers, college students and local residents alike.
“Bay Products was contracted to develop a cost-effective odour-control solution that would stay within the city’s constrained budget,” said Jeff Jones, Engineering Manager, Bay Products. “By offering several different odour-control technologies, we can tailor a solution based on the cause and magnitude of the problem.”
Bay Products was responsible for supplying a complete system which included various components manufactured using AOC resins. These components included the vessel, ductwork and isolation dampers tested to protocols established by the American Composites Manufacturers Association.
The anti-odour process creates a highly acidic internal operating environment where pH levels can get as low as 2. As a result, Bay Products manufactured the system’s composite components using a Vipel K022C bisphenol A epoxy vinyl ester resin from AOC. In addition to its corrosion resistance, the Vipel resin with minimal synergist addition meets the site’s critical requirement for an ASTM E84 Class 1 fire rating.
“It was imperative that the large panels in the system stay flat and uniform through our manufacturing process,” Jones said. “If the exotherm heat in a vinyl ester cure cycle is too high or spikes too quickly, a large panel may exhibit unwanted warpage,” he said. “For this application, Eric Stuck of AOC helped us develop a resin formulation that ensured the panels would be extremely flat and uniform.”
The flat composite panels were assembled into a shell that was 10 feet (3 meters) wide by 36 feet (11 meters) long by 9 feet (2.7 meters) high. The panels and composite damper components were made by hand lay-up of alternating layers of resin-impregnated fibreglass chopped strand mat and fibreglass woven roving.
The 16-inch (40.6-centimeter) diameter cylindrical ductwork components for moving air were filament wound from continuous fibreglass roving wet-out with the Vipel vinyl ester. “The resin processed perfectly for both our open moulding and filament winding operations,” Jones stated.
Surfaces that are directly exposed to the odour-scrubbing process were manufactured with a layer of synthetic surfacing veil. This technique resulted in a resin-intensive layer that provides maximum corrosion protection of the reinforcing fibres encapsulated within the composite.