Permanent electrical charging of fibrous filter materials by corona is one of the ways to increase filtration efficiency without increase in the pressure drop. The authors present teoretical
and experimental knowledge of charging process. Charging of various fibrous materials and their
surface finish are the topics described in a part "Experimental". Various fibrous materials are
corona charged by TANRET METHOD. The results of the experiments and new arising questions
Írom the experiments are discussed in cons|usion.