Muaj ob lub ntsiab ntawm cov khoom siv rov qab rau cov khoom siv hmoov txheej: lim cov hom lossis ob chav cyclone. Cov khoom lim dej rov ua dua tshiab tso siab rau lub siab - kev ua haujlwm lim khoom (filter element), raws li qhia hauv daim duab hauv qab no, uas tuaj yeem rov ua dua tshiab.