Patent attributes
A self priming regenerative pump comprising an impeller with a plurality of vanes formed on its periphery, casings 1a and 1b which house said impeller in a rotatable manner and a pressurizing passage consisting of a gap between said casing and the outer periphery of said impeller, further comprising: a small diameter part formed at a position communicating with pressurizing passage of a discharge flow passage, in particular, formed smaller than the diameter of a discharge port; and; a passage for communicating between discharge port side of smaller diameter part of discharge flow passage and pressurizing passage in order to allow the fluid in discharge flow passage to return to pressurizing passage, wherein said position communicating with pressurizing passage is outwardly offset from the center of the width of impeller.