Patent ID: 7059824

Claim:
A centrifugal pump comprising a pump body housing an impeller keyed onto a motor shaft, and provided with a suction mouth and a discharge mouth for communicating with, respectively, a suction pipe and a discharge pipe, wherein a chamber is provided between the suction mouth and the suction pipe, the chamber communicating with a tank situated at a generally higher level than the pump, the tank being interposed between the discharge mouth and the discharge pipe, being in communication with both the discharge mouth and the discharge pipe, and in also communication with the chamber through a recirculation duct having a section generally smaller than that of the suction pipe, between the tank and the chamber, a valve further being provided for cutting off a flow of fluid controlled by pressure existing in the tank and for automatically causing the fluid to be recirculated through the chamber and into the pump when the pressure in the tank drops below a predetermined value wherein a body is interposed between the suction mouth and the suction pipe, the body delimiting the chamber and being provided with an inlet port and an outlet port in coaxial positions, the diameter of the inlet port being generally equal to the diameter of the suction pipe, the body being further provided with a recirculation port connected to the recirculation duct that communicates with the tank, and wherein a pipe stub having an internal diameter generally equal to the diameter of the suction pine extends coaxially from the inlet port into the chamber and toward the outlet port, the chamber having a portion that converges toward the outlet port, such that the free end of the pipe stub defines an annular passage with the converging portion of the chamber.