Page 198 - Know and Understand Centrifugal Pumps
P. 198

Mechanical Seals

        one on the pump that fills and drains the washer, and another seal on
        the agitator shaft. How many drips are on the laundry room floor?




            Does your house have air conditioning,  or a hea  it pump? Do you have solar heating, a
            Jacuzzi bath, SI Jvimming pool, aquarium, solar  ’ heating, a roof mounted water storage
            tank, a well, a  power assisted commode,  a ml  otorboat, a jet ski, An/  or camper? Then
            you have even more mechanical sealed pump  s.  We have mechanical se,  aled pumps in
                                                     ___I_ ,__A <--
                                   J-..  I:<-
                                         --A
            practically all facci:, UI  uur evcryuay  iiic, anu  ir  irsr pump >rail iax iur years without
                       ^^_*_ ^C
                                            LL___
            problems.
        The environmental laws favor mechanical seals over packings. The need
        to conserve energy favors mechanical seals. The needs to reduce labor
        costs and  consumption  of natural  resources  favor  the  mechanical seal
        over packings.
        The majority of pump manufacturers offer their products with standard
        or optional mechanical seals. The mechanical seal manufacturers make
        seal models designed to substitute packings. The majority of pumps can
        be converted to mechanical seals without machining or design change.
        And still other pumps can be converted to mechanical seals with a slight
        design adjustment that doesn’t affect flow or head. The conversion to a
        mechanical seal improves the pump’s efficiency. The cost of the seal and
        the labor to convert the pump will  be  returned  in reduced  operating
        costs in just a few months.

        The mechanical seal runs in the same space previously occupied by the
        packing rings (Figure 13-1  and Figure 13-2,  next page).
        The mechanical seal on the radiator water pump of your car has to work
        under  severe  conditions.  This  seal  must  resist  the  pressures  and
        temperatures,  corresponding  to  the  velocities  of  the  motor,  and  the
        variable operating times. This seal is not a precision seal (it has stamped
        parts  rather  than  machined  components) and the pump  is  a portable
        pump. The pump doesn’t use a direct coupling but a v-belt pulley with
        radial loading. The seal must  resist  many vibrations  commencing with
        the v-belt slapping and whipping.
        The seal must also resist the vibrations from the explosions of internal
        combustion  in  the  engine,  chassis  and  wheel  vibrations,  and  even
        potholes in the road. This seal must resist strong chemicals (anti-freeze,
        anti-rust agents, radiator stop-leak and sealant chemicals, gasoline and
        lubricant residuals),  and  also  solid particles  (rust, iron  slag, minerals,
        asbestos fibers, and silica from the engine casting mold). In spite of all
        this, the mechanical seal on the water pump of your car can run 7, 10,
        even 15 years without problems.


                                                                   181
   193   194   195   196   197   198   199   200   201   202   203