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Separable blade agitator assembly and disassembly method

  • US 4,314,396 A
  • Filed: 10/19/1979
  • Issued: 02/09/1982
  • Est. Priority Date: 03/05/1979
  • Status: Expired due to Term
First Claim
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1. A method of replacing, in situ within a vessel, the separable impeller of a separable blade agitator comprising the steps of:

  • a. providing a vessel with a separable blade agitator suspended therein, the agitator having a separable impeller portion fixed to the lower end of a vertically oriented hollow drive shaft, said drive shaft having its lower end closed and its outer surface exposed to the contents of the vessel including said lower end provided with a glass coating, said separable impeller having a hub with a bore therethrough, the hub surface defining the I.D. of said bore also being provided with a glass coating wherein the glass coated lower end of said drive shaft extends through said glass coated bore to join said separable impeller and shaft in an interference fitted, gasketless, glass surface-to-glass surface connection;

    b. introducing a cooling fluid into said drive shaft adjacent said lower end to cool shrink the O.D. thereof to loosen the interference fit between said glass coated lower end and said glass coated bore;

    c. lowering said impeller to remove the same from said shaft;

    d. wrapping the glass coated lower end of said shaft with a removable, protective wrap immediately after the removal of said impeller;

    e. locating a replacement impeller below said shaft, said replacement impeller having a bore therethrough axially aligned with said shaft, the surface of said impeller defining the I.D. of said bore being glass coated and sized to provide an interference fit about 0.0025 to 0.0075 inches per inch of diameter with said shaft O.D. when said shaft and impeller have equalized in temperature;

    f. removing the wrap from the lower end of said shaft;

    g. raising said replacement impeller until the lower end of said shaft passes through said bore; and

    h. terminating the introduction of cooling fluid and supporting said replacement impeller in said raised position until said lower end and said impeller bore have equalized in temperature to provide a gasketless, glass surface-to-glass surface interference fitted connection.

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