Staff at the Department of Public Works for the Borough of Fort Lee, N.J., were faced with replacing three aging dry-pit vertical coupled sewage pumps at the Westview Pump Station. When one of the station's main sewage pumps finally failed, the borough authorized Rapid Pump and Meter Service Co., of Paterson, N.J., to temporarily install two EMU dry-pit submersible pumps from USFilter Davis Products.
Many dry-pit pumping stations share the problems and shortcomings that the Westview station encountered with its existing pumps. Two central difficulties common to all dry-pit pumping applications are susceptibility of pump seals to leakage, with the result of motor failure due to moisture intrusion, and the inability of conventional pumping technology to adequately cool pump motors, with the result of overheating and eventual failure of the entire system.
For these reasons, Borough of Fort Lee personnel decided to retrofit their station with an advanced dry-pit submersible pump technology that already had been successfully installed in another station within the borough. Two years previously, the Rapid Pump and Meter Service Co. had retrofitted the borough's Bluff Road Pump Station with two EMU 80.5 HP Dry-Pit submersible pumps.
Both of those pumps had been in continuous service since installation without problems of seal integrity failure or overheating.
The borough decided to installed three EMU Dry-Pit submersible pumps at the Westview station: two 18 HP pumps (each with 600 GPM capacity) and one 56 HP pump (with 1425 GPM capacity). The scope of the project included removal of the existing pumps, bases and motors; installation of the three EMU pumps and base elbows; and minor piping modifications to accommodate the pump discharge.
Upon startup, the pump operators were surprised by the low noise level of the EMU pumps. In addition, they commented on the noticeable reduction in heat levels within the facility as a result of the pumps running cooler. From the standpoint of safety, the operators were pleased that they were no longer exposed to shafts and couplings running at high speeds.
EMU Dry-Pit submersible pump technology is engineered specifically to address problems of seal failure and heat buildup.
Conventional submersible pump seals have been constructed of thin sections of tungsten carbide soldered to a stainless mounting plate. This solder is soft and can be worn away. The EMU pump technology virtually eliminates this difficulty. Seal integrity is maximized by the use of silicon carbide seal material in both the upper and lower mechanical seal positions. Seals made of silicon carbide consist of thick sections that are sintered, so that the entire seal face and mounting surfaces are one-piece construction. They have no soft parts to wear or leak.
Also, EMU pumps are engineered to run cooler. The company's proprietary submersible pump technology is based on a self-contained internal heat exchange system which enables the motor's heat-exchanger to transfer the oil's heat load to the liquid being pumped. The temperature increase of pumped fluids is negligible because the flow of liquid through the pump normally exceeds 100 times the flow of liquid through the heat exchanger itself.
