Abstract: A fire or smoke barrier (1) having a head box (2) for housing a curtain (4) which is open at its underside to allow the curtain to be deployed and withdrawn. The head box (2) houses a roller (3) for the curtain (4) to be rolled from for deployment and rolled back onto for withdrawal and attached at the bottom of the curtain (4) is a bottom bar (7) for weighing down the curtain (4) when deployed. The head box (2) has one or more apertures (14, 15) for cleaning air circulation and being provided at the, or each, aperture (14,15) with a spring (22) loaded trap (16,17) normally held open by a fusible link (31), the link fusing (31) in event of fire.

Abstract: An alarm system for a smoke or fire barrier, including alarm circuits have a normally closed switch position. A control circuit connected to the alarm circuits applies a voltage to create a non-activation situation or remove a voltage to create an activation situation when the switch is open. The alarm circuit further including either a series connected resistance or a normally open switch position in parallel to the normally closed switch position, to create a “fault” condition in the absence of detection of the resistance, or an open switch position and a closed switch position.