Page 201 - Know and Understand Centrifugal Pumps
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Know and Understand Centrifugal Pumps






                                                        - SEALGLAND
                                                              SECONDARY STATIC









                                "0" RING
                                                    STATIONARY
                                                       RING
        Fiaure 13-3


        The mechanical seal


         The mechanical seal is a device that forms a barrier between rotary and
         stationary  parts  in  the  pump.  The  seal  must  block  leakage  at  three
         points (Figure 134):

             Between the faces (rotary and stationary) of the seal.
             Between  the  stationary  element  and  the  seal  chamber housing  of
             the pump.

             Between the rotary element and the shaft or sleeve of the pump.
         These  basic  components  and functions  are common  to all  seals. The
         form,  style,  and  design  vary  depending  on  the  service  and  the
         manufacturer.  The  basic  theory  of  its  function  and  purpose
         nevertheless, remains the same.

         The set screw that transmits the torque from the shaft is connected to
         the rotary face through the spring. It also provides for the positive and
         correct positioning of all rotary parts.


                          SEALING POINTS         I




                                                                 BETWEEN SEAL
                                                                 AND HOUSING
        BETWEEN SHAFT                                            BETWEEN ROTARY
             AND SEAL                                            AND STATIONARY
                                                                -
                                                                 FACES
        Fiaure 13-4

            184 I
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