Abstract: An impeller type pump has a pump body consisting of a front casing and a back casing. Each of the casings comprises a ceramic main portion and a protection member covering the main portion. The protection members of both the main portions are interconnected with each other at their confronting marginal portions through a continuous packing. Those confronting marginal portions of both the main portions which are adjacent to a pump chamber defined by inner surfaces of both the main portions are provided each with a plurality of concentrical rims loosely interdigitated to form a labyrinthine narrow passage restricting the flow of waste water therebetween, resulting in reduction of wear of the packing.

Abstract: An impeller type pump has a pump body defining a pump chamber therein, and an impeller disposed in the pump chamber having a center shaft. A hollow cylindrical connector is mounted in the center shaft having internal screw threads engageable with external screw threads on the end of a drive shaft for rotating the impeller. The connector is provided with thermal expansion-absorbing slits arranged in equally spaced relation along the circumference of the connector which extend lengthwise of the connector with an unslit portion left on that end of the connector which is close to the other end of the drive shaft.

Abstract: An impeller type pump has a pump body consisting of a front casing and a back casing. Each of the casings comprises a ceramic main portion and a protection member covering the main portion. The protection members of both the main portions are interconnected with each other at their confronting marginal portions through a continuous packing. Those confronting marginal portions of both the main portions which are adjacent to a pump chamber defined by inner surfaces of both the main portions are provided each with an annular rib such that the annular ribs of both the main portions define a narrowed clearance restricting the flow of waste water therebetween, resulting in reduction of wear of the packing.

Abstract: A method comprising the steps of casting molten nonferrous metal ingots, skimming scum foaming on the surface of the molten metal in each mold, cooling the molds to release ingots therefrom, stacking the ingots released from the molds to form ingot stacks each comprising a plurality of layers of ingots arranged in vertically stacked relation alternately in two different patterns, weighing the ingot stacks, and tightly binding the weighed ingot stacks with steel bands.