An ejective system of dust extraction from a cyclonic deduster has been discussed. The influence of rate of extraction m0 on the characteristics of purification efficiency and flow drag of cyclonic dedusters and individual cyclones has been presented. The values of optimum extraction rate have been given. The authors have analyzed the reasons for lower efficiency of multicyclone extraction versus the extraction of an individual cyclone, from which mutlicyclones are composed. A methodology of experimental research of extraction uniformity from individual cyclones of a multicyclone has been presented. Streams QSC have been measured from individual cyclones of a multicyclone in the air cleaner. The authors have analyzed the performed investigations.