An improved impeller for a pump of the type wherein the impeller is sealed within a pump housing and driven by a rotating external drive magnet magnetically coupled to an impeller magnet forming a portion of the impeller.Chemical pumps An improved impeller for a magnetically coupled pump of the type wherein the impeller is rotatably supported on a shaft disposed within a pump housing and wherein rotation is imparted to the impeller by a rotating drive magnet disposed externally to the pump housing and magnetically coupled to the impeller,Magnetic pumps the improved impeller comprising: a hub mounted on the shaft for rotation thereabout; a vane assembly mounted on a forward portion of the hub, the vane assembly having a plurality of vanes extending radially with respect to the shaft for pumping fluid through the pump housing in response to the rotation of the hub; an impeller magnet slidably mounted on a rear portion of the hub for coupling with the drive magnet; forward stop means supported by the hub for limiting the forward disposition of the impeller magnet on the hub; rear stop means supported by the hub for limiting the rear disposition of the impeller magnet on the hub; and angular positioning means supported by the hub for circularly positioning the impeller magnet on the hub whereby rotation of the impeller magnet via the magnetic coupling between the impeller magnet and the rotating drive magnet rotates the impeller. Magnetically coupled pumps; that is, pumps having an impeller rotatably mounted within a sealed pump housing and coupled magnetically to an external drive magnetic which is rotated to rotate the impeller, are advantageously used in many pumping applications. For example, the pump may be used to circulate a fluid which is corrosive so that stringent chemical requirements are placed on the materials of which the pump is constructed. If the impeller of the pump is driven by a shaft which passes through a seal in the pump housing, the seal must, in general, meet the same chemical requirements. Since the seal must also have physical properties dictated by its primary function of permitting the shaft to rotate while preventing the escape of fluid from the pump, it can be difficult to find suitable materials for constructing seals. This problem is avoided in magnetically coupled pumps by eliminating the need for such seals. Problems can also be encountered in magnetically coupled pumps. In many applications, the impellers of such pumps are often subjected to temperature variations in the fluid being pumped. Since the impeller must contain a magnet for coupling to the external drive magnet, differences between the thermal expansion properties of the impeller magnet and other portions of the impeller can result in repeated stressing of the impeller and such repeated stressing can shorten the lifetime of the pump. Moreover, materials which have suitable magnetic properties for construction of the impeller magnet may not have desirable chemical properties with regard to the fluid passing through the pump in a particular application.

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2012-01-10

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