Pump having seal means and protective means

Claim 1

An impeller type pump including: a front casing comprising a first ceramic main portion defining therein an inlet, one part of a pump chamber and one half of a discharge port, and a first protection member covering the first ceramic main portion; a back casing confronting the front casing and comprising a second ceramic main portion defining therein the other part of the pump chamber and the other half of the discharge port, and a second protection member covering the second ceramic main portion; a plurality of projections each having a flattened end surface, extending toward the second protection member and formed in spaced relation with each other on that marginal surface of the first protection member which confronts the second protection member; a plurality of projections each having a flattened end surface, extending toward the first protection member and formed in spaced relation with each other on that marginal surface of the second protection member which confronts the first protection member, said projections of the second protection member being so arranged that the flattened end surfaces of the projections of the second protection member abut against the respective flattened end surfaces of the projections of the first protection member; a continuous packing disposed between the marginal areas of the first and second ceramic main portions; and a plurality of overlapping, concentrical rims radially spaced from one another and integrally formed on those areas of the mutually confronting marginal surfaces of the first and second ceramic main portions which are adjacent to the pump chamber, said rims being so arranged that the rims of the first main portion form, with the rims of the second main portion, a narrow passage for decreasing the circumferential speed of waste water in said narrow passage from the circumferential speed of waste water in the pump body.