Abstract: A centrifugal pump including a casing containing an impeller mounted on a shaft with a circular shroud fixed on a hub, a plurality of relatively long radial vanes fixed on the shroud and spaced around the hub at equally spaced intervals, a series of shorter vanes extending radially and spaced around the hub with at least two shorter vanes located between each pair of longer vanes, the inner end of each shorter vane being located radially outward from the inner ends of the adjacent longer vanes, each pair of adjacent longer vanes forming between them a single passage extending radially outward from the hub and flowing into at least three smaller passages formed between said pair of adjacent longer vanes and the shorter vanes located between said pair of adjacent longer vanes, and a series of oblong shaped pressure balancing holes located in said shroud and opening into said passages.