| 摘要 |
An improved immersible magnetically-coupled mixer has rollable bearings readily cleanable by flushing in place and easily removable and replaceable without damage to either the mixer impeller or the bearings. The rollable bearings are resistant to corrosion, capable of running without lubrication, and have low propensity for batch contamination through wear. The rolling and fixed elements of the bearings are impervious to attack by the process materials being mixed, the rollable elements, preferably balls, being formed of a hybrid ceramic such as silicon nitride, and the races being formed of either a nickel-beryllium or cobalt-chromium-tungsten alloy. A mixer impeller having a central bore is rotatably mounted on the rollable bearings on a fixed impeller shaft attached to the inner wall of a vessel at the bottom of the mixing space, which shaft extends through the impeller bore. The impeller contains magnets and is couplable in driving relationship to an external magnetic mixer drive. The impeller bore is larger in diameter than the fixed shaft, and two sets of rollable bearings are disposed between the impeller and the shaft. The bearings are exposed to the liquid in the vessel during agitation, and the impeller provides a continual flow of liquid across the bearing balls and races, preventing formation of stagnant areas of process materials within the mixer assembly and permitting cleaning of all mixer surfaces by flushing.
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