Page 198 - Know and Understand Centrifugal Pumps
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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
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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.
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