Warren Rupp® SANDPIPER® Pumps Cut Plant’s Costly Repairs
A Pennsylvania wastewater treatment plant processes 12 million to 27 million gallons of wastewater a day. For years, lobe pumps transferred the sludge from thickening tanks to the belt press for dewatering. But the two lobe pumps were a constant source of downtime, labor and parts costs. The city replaced about six sets of lobes in a two-year period at a cost of about $1285 per set (1994). A new housing and sheared shaft cost the city more than $5000 in parts alone. Even when operating properly, the lobe pumps leaked oil and sludge.
When one of the pumps failed, a complete pump rebuild was quoted at $7400. Total replacement of the pump would cost the city $15,000.
The city’s Redevelopment Authority contract officer, decided to look for another solution. “I have to look at money,” he said, “and the pumps we were using were a financial nightmare.” They met with equipment vendors and decided on an air-operated diaphragm pump fitted with flap-style valves.
“People…were telling us it was a good pump, but they thought the noise and vibration would be incredible. It was their collective opinion that surging and uneven loading of the belt presses would occur. They also advised that we would be constantly replacing diaphragms. We really needed a 30 day trial to convince everyone.”
The SANDPIPER distributor for Warren Rupp of Mansfield, Ohio, agreed to provide us a wastewater model W15-4 flap valve diaphragm pump on a 30-day trial.
“That pump ran 24 hours a day, six days a week, we were able to feed as much volume as the incinerator could handle–about 50 gpm. We pump against a 30 ft. head, at a distance of approximately 150 ft. The flow is pumped into a 114 gallon flocculation tank to provide even loading to the belt presses. This system eliminates the need for surge suppressors in line. The pump is rated at 260 gpm. Because we’re running at the low end of the curve, noise and vibration were never a problem.”
The diaphragm pump also emptied holding tanks completely to the bottom, something lobe pumps could not do because of low head and settling out of fibers and rags.
The city bought the pump. The plant purchased and installed a second W15 as a back-up two months after the trial run, and now the pumps work on alternate weeks, running six days a week, 24 hours a day. After nearly a year of operation, the pumps have required no maintenance, no repairs, and no replacement parts. The diaphragm pumps were installed on the existing concrete pads. They occupy less than half the space of the lobe pumps. Purchase price of the two pumps, plus a 20 horsepower rotary screw compressor, totaled about $14,000 less than the price of one lobe pump.