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Ebara Engineering Review No.214

Water-level Fluctuation in a Pump Sump with Coupled Pit and Countermeasures against Unfavorable Vortices

by Masashi OHBUCHI, & Masashi TAGOMORI

A finding was made that the water-levels of each of two mirror-symmetrical, coupled pits of a pump sump fluctuated alternatively. This phenomenon, attributed to a fluctuation in flow pattern at the expanding duct situated upstream the sump pits, was able to be predicted by CFD (Computational Fluid Dynamics) analysis. The following discusses this and includes an outline on the mechanism of submerged and air-entrained vortices in the pits, as well as on a practical countermeasure against these unfavorable vortices.

Pump sump, Flow analysis, Vortex, Water-level fluctuation, Sump diagnosis, Countermeasures against vortices

The DML Model Submersible Pump for Manhole Pump Units in Japan


The DML model submersible pump, whose performance has been proven overseas and which features highly efficient passage of foreign substances, is being installed in manhole pump units in Japan. This pump enables a saving in running costs of manhole pump units, namely in terms of power consumption and maintenance. The following introduces experimental and on-site tests conducted prior to commissioning.

Manhole pump unit, Pump efficiency, Foreign substance passage test, Impeller passage, Electricity fee, Vortex type, Non-clog type

Reconstruction of the Pump Facility at Inba Drainage Pump Station

by Hiroshi YAMAGUCHI

EBARA has completed the reconstruction of the large-scale pump facility at Inba Drainage Pump Station (capacity: 92 m3/s) in Northern Chiba Prefecture. The reconstruction, featuring multiple unprecedented totalized engineering techniques, was conducted between March 2003 to July 2006. A total of 6 new pumps, two each year, were installed. Unlike the construction of a new such pump facility, the work was done in a totalized manner, involving civil, structural, mechanical and electrical engineering techniques. This approach enabled a considerable saving in construction time and costs. Notable is that several actual drainage operations were able to be conducted during the course of the construction, thus contributing to the regional community.

Drainage pump station, Restore functions, Renovation, Vertical axial flow pump, High efficiency, Short construction schedule, Concrete cutter with low vibration, Wire saw, Short length multiple guide vanes, Lightweight

Cryogenic Pump Test Center

by Yoshio MOGI, Toshiyuki OGAWA, & Takafumi KOGUCHI

EBARA's Cryogenic Pump Test Center, located in the Sodegaura Plant, is a facility for testing the performance of EBARA's cryogenic submerged motor pump. The facility is capable of tests using LNG (Liquefied Natural Gas) and LPG (Liquefied Petroleum Gas). This facility's capacity includes a maximum flow rate of 3000 m3/h, a maximum pressure of 10 MPa, and a maximum motor power of 2000 kW. Its data acquisition specifications comply with ISO 9906 (Rotodynamic pumps - Hydraulic performance acceptance tests-Grades 1 and 2) and other than performance tests, functional tests such as NPSH tests and vibration measurement tests and can be carried out simultaneously. Labor-saving facility management, such as by remote monitoring and automatic control, and reduction in testing time, by automatic measurement, are featured as well.

Cryogenic pump, Test center, Liquified Natural Gas (LNG), Liquified Petroleum Gas (LPG), Performance test, NPSH test, Automatic measurement, Central control, Automatic control, Sodegaura plant