(19)

(11)

EP 0 528 805 A1

(12)

(43) Date of publication: 03.03.1993 Bulletin 1993/09 (21) Application number: 91906521.0 (22) Date of filing: 14.03.1991

(51) International Patent Classification (IPC):  B03C 3/ 68( . ) (86) International application number: PCT/US1991/001745 (87) International publication number: WO 1992/016302 (01.10.1992 Gazette 1992/25)

(84) Designated Contracting States: CH DE DK FR GB LI SE (71) Applicants: HITRAN CORPORATION Flemington, NJ 08822 (US) BHA GROUP, INC. Kansas City, MO 64133-4883 (US)	(72) Inventors: JOHNSTON, David Yorktown, VA 23693 (US) BIRSCAK, Peter Rampton, NJ 08827 (US) (74) Representative: Graalfs, Edo, Dipl.-Ing. Patentanwälte Hauck, Graalfs, Wehnert, Döring, Siemons, et al  Postfach 30 24 30 D-20308 Hamburg D-20308 Hamburg (DE)