Abstract: A pump for liquids made up of a tube having an inlet and an oulet with a shaft extending through it. The lower end of the shaft has an impeller and a motor drives the upper end of the shaft. A seal is supported on the shaft between the outlet and the motor preventing liquid from moving up past the seal. The seal fits tightly in the tube and has an inwardly-extending flange with an axially-extending flange with a central bore which receives the shaft. The bore in the axially-extending flange is smaller than the shaft so that the shaft expands the axially-extending flange thereby providing a liquid-tight seal around the shaft.