type of elbow Forgione, his mechanics and his engineers tested. Iron elbows lasted nearly a year and longer 10-foot radius long-sweep el - bows lasted only 18 months. Each line failure required a shutdown. Inspecting elbows became a frequent task while maintenance personnel became expert at replac - ing elbows to keep the silos in service. Each time an elbow required replacement, it consumed many hours and incurred unexpected costs. "It's very difficult for us to replace an elbow," said Forgione. "The elbows at ground level are not easily accessed and the ones on top of the silos are four stories up. It's a safety concern as well as a cost concern." Meanwhile, operations personnel were being diverted from their formal responsibilities to help with the cleanups. "We hit a brick wall,” said Forgione. “We needed to make the elbows last longer and we needed it done fast." Forgione became aware of a deflection elbow from HammerTek Corp. that had been installed at a nearby wastewater treatment plant in Al- exandria, VA to solve an identical lime handling problem. Under For - gione's direction, a UOSA process control engineer and the mechanical manager toured the Alexandria facility. "They were very happy and hadn't had a single blowout since installing the manufacturer’s Smart Elbow® design," the process control engineer said, also noting the cleanliness of their facility. "You could see they weren't having any of the problems with leaks that we were having." The elbow is characterized by a spherical chamber that protrudes slightly beyond the desired 90 or 45 degree flow path, causing a loose ball of ma - terial to rotate slowly in the same direction as the air stream that powers it, gently deflecting incoming material around the bend. Self-renewing, the ball gradually releases material in a first-in, first-out progression, promoting directional change without affecting system pressure. Forgione tested the Smart Elbow design for more than a year and, after finding no signs of wear, replaced all pebble lime elbows at the facil - ity. Five 45-degree, four-inch diameter elbows were installed where the trucks off-load their lime and twelve 90-degree, four-inch diam - The Upper Occoquan Water Reclamation plant has gone 16 years without an elbow failure after installing short radius Smart Elbow® deflection elbows.
The Smart Elbow® deflection elbow features a spherical chamber in which incoming particles swirl in a slowly rotating ball, gently deflecting incoming material around the bend without impacting or abrading the elbow wall.
eter elbows were installed at the tops of the silos. A custom alloy was specified based on characteristics of the pebble lime and the length and velocity of the pneumatic conveying system. More than 16 years have elapsed since the installation of the deflec - tion elbows at UOSA’s facilities without a blowout. "With the Smart Elbow deflection elbow, we've eliminated the primary source of lime dust along with the hazardous conditions it creates," Forgione said. Maintenance and labor costs have been reduced, safety and air quality have been upgraded, and the buildings are visibly cleaner. He added, "The delivery was fast and our mechanics were able to install them quickly without complaints. If we ever get wear in an elbow anywhere in the plant, we'll replace it with one of these elbows." The Upper Occoquan Water Reclamation Plant supplies over 30 million gallons per day of potable water to a population of more than 300,000.
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