(19)

(11)

EP 0 491 742 A1

(12)

(43) Date of publication: 01.07.1992 Bulletin 1992/27 (21) Application number: 90912989.0 (22) Date of filing: 13.08.1990

(51) International Patent Classification (IPC):  B01D 53/ 50( . ) B01D 53/ 81( . ) B01D 53/ 68( . ) (86) International application number: PCT/SE1990/000524 (87) International publication number: WO 1991/002583 (07.03.1991 Gazette 1991/06)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB IT LI LU NL SE (30) Priority: 22.08.1989 SE 19890002797 (71) Applicant: ABB FLÄKT AKTIEBOLAG S-104 81 Stockholm (SE)	(72) Inventor: LINDAU, Leif S-352 51 Växjö (SE) (74) Representative: Dahlstrand, Björn  ABB FLÄKT AB S-120 86 Stockholm S-120 86 Stockholm (SE)