PURPOSE: To prevent generation of cavitation by a method wherein a communicating hole is provided in the shroud of the impeller and a part of flowing water increased in the pressure thereof by the impeller is introduced into the inlet of the impeller through said communicating hole to increase the static pressure of the inlet port of the impeller.
CONSTITUTION: A communicating hole 13 is provided in a front shroud 1a and a gap 8 between a fixed wall 6 and the front shroud 1a is communicated directly with the inlet port of the impeller. Therefore, the static pressure of the inlet port of the impeller may be increased by introducing a part of the flowing water, increased in its pressure by the impeller, from the gap 8 into the inlet port of the impeller even when the suction pressure of the pump is reduced. According to this method, the cavitation will never be generated, and therefore, corrosion due to the cavitation may be prevented.
MASE MASAHIRO
IINO TOSHIYOSHI
