ZERO INTERNATIONAL is recognized for its leadership in intumescent technology for the door and hardware industry. Our commitment to this technology is both pragmatic and philosophical. Our initial decision to build intumescent protection into ZERO gaskets, which led ultimately to the development of new technology, was a response to several concerns:

• International Sales

   Most international fire-door tests are governed by the ISO 3008 standard, which requires positive-pressure furnace conditions. Widely used for wood door assemblies in Europe for more than 25 years, intumescent seals are used extensively with both wood and metal doors wherever this standard prevails. For ZERO and other U.S. door and hardware manufacturers, intumescent capabilities are therefore necessary for effectively marketing fire-rated systems overseas.

• Rising Smoke Standards

   NFPA 105 "Recommended Practice for the installation of Smoke Control Door Assemblies" introduced demanding new test procedures and standards. Conventional smoke control seals made from materials such as vinyl, EPDM, Santoprene and neoprene can block "cold" or ambient smoke effectively but begin to burn and degrade at around 180-200^oF (82-93^oC). Very high grade, specialized silicone materials designed to retain integrity at these temperatures are extremely costly, and ZERO recognized that intumescent action was the most efficient and cost-effective way to seal gaps at the 400^oF (204^oC) "warm" smoke levels of test standard UL 1784.

• New Role for Gasketing in the U.S.

   As a specialist in door sealing systems, ZERO anticipated that the role of gasketing in fire door assemblies was destined to change fundamentally as U.S. building code adoption enforces a more demanding standard. Previously, gasketing designed for these assemblies was rated if it did not promote additional flaming or cause failure of the door. However, this passive role has been transformed by the positive-pressure requirements for testing fire doors and smoke control assemblies, which have been adopted by the International Conference of Building Officials (ICBO) in the 1997 Uniform Building Code governing 21 primarily western states.

   The UBC 7-2 1997 Fire Door Standard requires assemblies to withstand positive-pressure conditions, similar to the international model, and also references air leakage test procedures adapted from NFPA 105 for controlling smoke leakage at door perimeters. The smoke control measures from NFPA 105 are now being drafted into a revision to enforceable language by an NFPA task force. Positive-pressure and air-leakage testing requirements that are virtually identical to UBC 7-2, 1997 remain in the new International Building Code scheduled for publication in 2000.

   The practical impact of these code changes is that gasketing now has a fire and air-leakage function in protecting door openings under furnace conditions. And the performance of the gaskets has become critical to the listing of the assembly--as well as its ultimate purpose of protecting lives. Integral intumescence ensures the gasketing's ability to fulfill its expanded mission.