Ventilating duct damper

Claim 1

A DAMPER ASSEMBLY IN COMBINATION WITH A VENTILATING DUCT FOR CONTROLLING THE AIR FLOW IN SAID DUCT AND FOR AUTOMATICALLY CLOSING SAID DUCT IN THE EVENT OF A FIRE COMPRISING A DAMPER BLADE MOUNTED IN SAID DUCT FOR MOVEMENT BETWEEN AN OPENED POSITION AND A CLOSED POSITION, MEANS BIASING SAID DAMPER BLADE TOWARD SAID CLOSED POSITION, A CONTROL AND ACTUATING ELEMENT, OPERATING MEANS FOR SELECTIVELY MOVING SAID DAMPER BLADE, SAID CONTROL AND ACTUATING ELEMENT OPERATIVELY INTECONNECTED BETWEEN SAID DAMPER BLADE AND SAID OPERATING MEANS FOR TRANSMITTING MOVEMENT FROM SAID OPERATING MEANS TO SAID DAMPER BLADE, SAID CONTROL AND ACTUATING ELEMENT INCLUDING ING AT LEAST TWO SEPARATE MUTUALLY MOVABLE MEMBERS AND A LOW MELTING POINT MATERIAL NORMALLY RIGIDLY INTERCONNECTING SAID MEMBERS, ONE OF SAID MEMBERS BEING CONNECTED TO SAID DAMPER BLADE AND THE OTHER OF SAID MEMBERS BEING CONNECTED TO SAID OPERATING MEANS, SAID CONTROL AND ACTUATING ELEMENT BEING INEFFECTIVE TO TRANSMIT MOVEMENT FROM SAID OPERATING MEANS TO SAID DAMPER BLADE AT AN ELEVATED AMBIENT TEMPERATURE IN EXCESS OF THE MELTING POINT OF SAID LOW MELTING POINT MATERIAL, AND RATCHET MEANS INTERCONNECTING SAID TWO MEMBERS PERMITTING MOVEMENT THEREBETWEEN IN THE DIRECTION OF CLOSING SAID DAMPER BLADE AND PREVENTING MOVEMENT THEREBETWEEN IN THE DIRECTION OF OPENING SAID DAMPER BLADE.