| 摘要 |
<p>A multi-stage metallic pump or chemical pump with plural impellers arranged in series. The impeller of the first-stage is integrally provided with radial flow ribs on the under surface of the impeller and with backside radial ribs on the upper surface of the impeller, which are larger than the front radial flow ribs as regards the diameter of the circle formed by the respective tips of the ribs. A flange is formed as an extension beyond the circumference of the first-stage impeller and is integrally provided with a protruding ring on the upper surface of the flange. The protruding ring rotates in a fixed recess formed in a casing, with a certain gap kept. Because of the rotation, the liquid which flows into the clearance between the fixed wall of the casing and the rotating ring creates a turbulent flow there, preventing movement of air therethrough. As for liquid leaks, since the backside radial ribs are larger in outer diameter, they are higher in peripheral speed and pressure and thus force back the liquid migrating from the radial flow ribs. Thus the liquid is stopped. Therefore, no seal member is required.</p> |
