Centrifugal pump with sealing means

A centrifugal pump for pumping a gas-containing medium comprising:

• a centrifugal pumping housing (50) having an inlet (52) and an outlet for said medium;
• a centrifugal impeller (60) within said centrifugal pumping housing (50);
• a liquid ring vacuum pump (70) adjacent said centrifugal pumping housing (50), said vacuum pump including a vacuum pump chamber (76) defined by first and second opposed side walls (112, 110) spaced apart by a circumferential annular wall (100);
• a vacuum pump rotor eccentrically positioned within said vacuum pump chamber (76), said rotor having a central portion (102) carrying a plurality of blades with outwardly extending opposed side edges facing said vacuum pump side walls (112, 110) and forming a clearance therebetween;
• a rotary shaft (58) extending through said vacuum pump chamber and into said centrifugal pump housing (50);
• said central portion (102) having an outer surface defined radially outwardly from said rotary shaft (58);
• said centrifugal pump impeller and said vacuum pump rotor being mounted on said shaft in spaced relation to each other;
• and
• means within at least one of said vacuum pump side walls (112, 110) for supplying a sealing liquid to said clearance (122) between said rotor central portion (102) and at least one of said side walls (112, 110) of said vacuum pump chamber (76) at a location between said central portion outer surface and said rotary shaft (58).