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DURA SEAL M ANUAL / SECT IO N V I/PAG E 2
until the second filter requires attention. Atypical dual
filtering system is illustrated inFigure VI-A.
The liquid entering the filter shell mustpass through the filter
element before reachingthe outlet connection. The filter elements
them-selvesare made from various materials the mostcommon being
cotton paper and fiberglasscapable of filtering particles down to 2
micronsin size. Since these materials vary widely in
theirresistance to chemical attack care must beexercised in
selecting an element compatiblewith the liquid to be filtered.
Some industrial filters are equipped with abypass valve which
opens and allows the liquidto circumvent the filter when the
element be-comes clogged thus insuring a continuous flow.Other
filters not equipped with a bypass shouldhave a flowmeter installed
on the discharge sideof the filter manifold. Monitoring this
flowmeterat predetermi ned intervals wi II tell the userwhen a
filter change is necessary.
V l.l.2 CYCLONE SEPARATORSD URA D IRT D IV ERTE RS
A cyclone separator is another device thatcan be used to remove
abrasive particles from abypass flush system. It is particularly
suited forprocesseswhere foreign particles are conti nuallybeing
introduced into the system making itimpractical to completely
remove them fromthe processliquid. In an application of this
typewhere the dirty product is circulated only oncethrough the pump
before moving on to otherprocessesfilters would rapidly become
clogged.Abrasive particles also may be a very necessarypart of a
liquids composition. A cyclone separa-tor therefore does not
collect and retain thesolids it removes but simply separates
andreturns them to the process system while dis-
charging clean liquid to the flush connectionover the seal
faces.
A cyclone separator is nothing more than acontinuous flow
centrifuge. Particle separationis accomplished as illustrated in
Figure VI-B.Liquid is piped from the discharge of the pumpto the
feed of the cyclone separator which isdri lied on a tangent to the
cone shaped boreinside the cyclone body. This causes the liquidto
spin around the walls of the bore upon entry.The resulting
centrifugal force displaces thesolids from the center to the
outside of thewhirling liquid. The liquid containing the
solidsfollows the vortex flow to the underflow whilethe lighter
clean liquid flows up to the over-flow and can be piped to the
seal. The liquidcontaining concentrated solids is returned tothe
process by a line connecting to the pumpsuction from the bottom of
the separator. A
C len Liqu idO erflow
Abrasi e __Feed
S lu rr y R ot ati on O ev elo peH i gh C e n tr if u g F o r
ceT hr ou gh ou t C yc lo ne
L iq uid M on I nw ard n dU pw ard A I Spira llin g V ortn S
uspended S olid Or ienTow ard C yc lone W II endO o w n w rd in A
ccelerating S piral
F I G V I BP R I N C I P L E S O F AC Y C L O N E S E P A R A T
O R Abrasi eUnderflow
