(19)

(11)

EP 0 434 790 A1

(12)

(43) Date of publication: 03.07.1991 Bulletin 1991/27 (21) Application number: 90909057.0 (22) Date of filing: 14.06.1990

(51) International Patent Classification (IPC):  G08B 17/ 107( . ) (86) International application number: PCT/GB1990/000920 (87) International publication number: WO 1990/016053 (27.12.1990 Gazette 1990/29)

(84) Designated Contracting States: AT BE CH DE DK ES FR IT LI LU NL SE (30) Priority: 15.06.1989 GB 19890013773 (71) Applicant: FIRST TECHNOLOGY FIRE & SAFETY LIMITED Stevenage, Hertfordshire SG1 4QS (GB)	(72) Inventor: EDWARDS. John, Charles Chilworth Surrey GU4 8NQ (GB) (74) Representative: W.P. THOMPSON & CO.  Eastcheap House Central Approach Letchworth, Hertfordshire SG6 3DS Letchworth, Hertfordshire SG6 3DS (GB)