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-, <br /> I � <br /> ,. <br /> � � ., �. . � <br /> s Conwed <br /> � <br /> Bulletin t79-41 <br /> March 1F, 1979 <br /> TO: Ceiling Products Customers <br /> Ce�ling Products Sales Representetives <br /> Ceiling Products Regional M.lnagers <br /> Internal Distribution <br /> eUBJECT: Use Of Hold-doMn Clips In Firc Rccictive �seembliee <br /> The 1979 UL Fire Resistance Directury states that hold-down <br /> clips are not required for assemblies incorporating ceiling <br /> panela weighing not less than one pound per squace foot. <br /> Several conditions have made this possible. <br /> First, it has been shown that room pressures during a fire2 <br /> may reach a maximum of +0. 15 iRches oE watec or .78 lbs/ft . <br /> Thus, panels weighing 1 lb/ft. should not raise during <br /> actual fire conditions. <br /> Second, panels weighing approximal•ely 1 lb/ft.2 and located <br /> immediately next to door openings into confined areas may <br /> be raised slightly, but will not become, permanently dis- <br /> lodged when the door is opened rapidly. <br /> Third, comments Erom the technical staffs of thr�e Model <br /> Building Code groups indicated there were no records of <br /> panels upliftin� under nnrmal use or fire exposure whgre <br /> the uncllpped lay-in panels weighed at least 1 lb/ft. . <br /> Con�•�ed fire rated lay-in ceiling panels weigh 1 lb/ft.2 and <br /> thus comply with the conditiona set forth in the 1979 UL <br /> Fire Resistance Directory. <br /> �.� 1 <br /> �� L-t Ltl . <br /> t�� ,/y <br /> Stanley 'A. Skoglu d � <br /> Product Manager , Manufactured Producta � <br /> SAS:pg <br /> CEILING PNODUCiS OIVISION 7���g�p�y�_�555•CAOIf�.tCNWFA <br /> ' Y32 MINNESOTA STREET,PD.BOIl/32J7.ST P4Ul.M�NNESOTA 55161•PHONE'18t21?2�•1��• <br />