▁the ▁dispers ed ▁phase ▁to ▁move ▁away ▁from ▁or ▁towards ▁the ▁central ▁core ▁of ▁the ▁vor tex . ▁ ▁A ▁hydro cy clone ▁will ▁normally ▁have ▁a ▁cyl ind rical ▁section ▁at ▁the ▁top ▁where ▁liquid ▁is ▁being ▁fed ▁tang entially , ▁and ▁a ▁con ical ▁base . ▁The ▁angle , ▁and ▁hence ▁length ▁of ▁the ▁con ical ▁section , ▁plays ▁a ▁role ▁in ▁determ ining ▁operating ▁characteristics . ▁ ▁Design ▁ ▁A ▁hydro cy clone ▁is ▁a ▁class ifier ▁that ▁has ▁two ▁ex its ▁on ▁the ▁axis : ▁one ▁on ▁the ▁bottom ▁( under flow ▁or ▁reject ) ▁and ▁one ▁at ▁the ▁top ▁( overflow ▁or ▁accept ). ▁The ▁under flow ▁is ▁generally ▁the ▁dens er ▁or ▁co ar ser ▁fraction , ▁while ▁the ▁overflow ▁is ▁the ▁l ighter ▁or ▁fin er ▁fraction . ▁It ▁has ▁no ▁moving ▁parts ▁and ▁its ▁operation ▁depends ▁on ▁two ▁major ▁parameters : ▁ ▁The ▁characteristics ▁of ▁the ▁feed ▁stream . ▁ ▁The ▁geometry ▁of ▁the ▁cy clone . ▁ ▁The ▁characteristics ▁of ▁the ▁feed ▁stream ▁include ▁size ▁distribution ▁of ▁sol ids ▁in ▁the ▁feed ▁stream , ▁pul p ▁density ▁( percent ▁sol ids ▁in ▁the ▁sl ur ry ), ▁pul p ▁vis cos ity ▁and ▁the ▁in let ▁pressure ▁for ▁solid / liqu id ▁separation . ▁In ▁liquid / liqu id ▁feed ▁streams , ▁for ▁example ▁in ▁o ily ▁water , ▁the ▁main ▁feed ▁characteristics ▁are ▁based ▁on ▁oil ▁dro ple t ▁size ▁and ▁distribution , ▁oil ▁density , ▁water ▁density , ▁oil ▁concentration , ▁vis