(57) The hydraulic sealing ring (1) on the inlet (5) of the impeller (6), particularly
for single-stage and multistage pumps is made in a rubber-like material the inner
face (3) whereof couples to the outer surface (4) of the inlet (5) of an impeller
(6). The ring (1) has substantially radial openings which connect a shimming face
to the outer one to allow a slight injection of liquid bled from the higher-pressure
chamber in output from the impeller blades in the shimming region and to allow the
creation and the maintainance of an extremely thin layer of liquid adapted to ensure
a lubrication of the scraping surfaces with a reduced leakage towards the lower-pressure
region at the input of the impeller (6) and to counterbalance the radial force which
tends to press the ring around the inlet (5) of the impeller (6), said force being
generated by the pressure of the liquid acting on the outer face (4) of said ring.
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