1. Technical Field
This invention generally relates to a fire door control system and more specifically to a method of controlling a fire door and a fire door control system that remains active before, during, and after an alarm condition. The fire door control system of the present invention maintains control of the fire door in some situations by a clutch.
2. State of the Art
The fire door control systems of the past have largely incorporated fusible links that are activated by the heat of a fire when it reaches the fire door. Thus, the fire doors of the past are generally placed in an irreversible alarm mode that is passive since it does not require or respond to input from a person trying to actively stop or otherwise control the fire door. These fire doors require a specialist to come to the site of the door to reset the door and to set the limits for the system. Other fire doors of the past have incorporated other release means that utilize smoke or heat sensors, and drive motors for moving the fire doors. These doors implement a variety of backup arrangements including secondary power sources for running drive motors, for example. The systems of the past have also implemented a variety of complex mechanisms including brakes and governors for slowing fire doors that are made to fall by their own weight under the influence of gravity.