As one of only two regional surface treatment facilities, the city of Monroe Water Treatment Plant in Louisiana faced a challenge. Several hydraulically actuated, diaphragm metering pumps in caustic soda, liquid aluminum sulfate and potassium permanganate service, were in constant disrepair. Replacement parts were difficult to find and expensive, and demands on the six-man maintenance/electrical crew were extreme. The various pump models and unique plumbing requirements added to the problem. It often took two workers eight hours to tear down and service one pump. Poor linear flow and accuracy required constant calibration, which wasn't achievable within the parameters. The team concluded the pumps were too costly to repair, and replacements were necessary.
Leading the efforts to resolve the challenge were Electrical/Instrumentation Supervisor Gerald Battaglia and Maintenance Supervisor Daren Johnson. "We looked at numerous pumps and had a clear direction," Battaglia said. The specification dictated uniformity, broad flow ranges and easy maintenance. The plan was for six operational pumps with two available backups when any one went offline. "We wanted one common pump for all three applications without
changing wet ends," Johnson said.
Nikkiso Pumps America was the low bidder. "We never heard of Nikkiso and were concerned," Battaglia said. Bound by the formal bid process, the men contacted Nikkiso and were surprised to find themselves speaking directly to the president of the company. "It impressed us to talk with the top guy and get answers quickly," Johnson said. The new pumps were eight simplex hydraulically actuated diaphragm API-675 pumps, designed for flows from 0 to 116 gph, pressures to 225 psig, 316SS wet ends and PTFE diaphragms. Efficient 1⁄2 hp, 3-phase, 208-volt, TEFC motors were supplied for energy savings.
Installation and start-up
When the pumps were delivered, Battaglia was struck by the American Petroleum Institute (API) design. "The other pumps we considered were much lighter," he said. According to Mark Murphy, general manager at Nikkiso, "The API design provides a proven durable pump that many in the water and wastewater industry would like to have but are not yet aware."
Johnson was in charge of the header stand design and installation while Battaglia handled the electrical requirements and SCS connections. "We wanted to replace our steel header system with PVC to avoid crystallization problems," Johnson said. The standardized API pump design provided uniform dimensions, making header fabrication simple and allowing pump interchangeability. Nikkiso representatives were available to start up and calibrate the first pump. "Start-up was straightforward, and we activated the remaining pumps ourselves," Battaglia said.
The pumps have been operating continuously since 2002. Battaglia and Johnson estimate a $10,000/year overtime reduction. "Considering the linearity of these units with reduced spare parts requirement, the savings have multiplied," Battaglia said. Also, the standardized header maximizes flexibility and provides real-time SCS feedback with zero production downtime. In 2003, two additional pumps were ordered for capacity improvements.