FIRE CONTAINMENT BY VENT OPENING PROTECTIVES IN THE OPEN STATE

摘要

Air transfer openings in fire resistance rated construction are traditionally protected by fireresistance rated close circuit air ducts as well as by assemblies of ducts and fire rated mechanicaldampers or combination thereof and sometimes with non-combustible rated grilles that become sealedupon heat exposure . The time duration before the dampers close or seal - The open state period,varies from seconds up to five minuets under flaming exposure. Furnace test methods recognize thedeficiency of opening protectives to allow for movement time for mechanical dampers, hence timesup to 60 or 120 sec before performance measurements are taken and some record test criteria failuresfrom 5 minutes onwards only from the start of the fire exposure. The paper reports on laboratory testscarried out by SINTEF NBL in Norway, to determine the performance of fire resistance rated ventedconstruction during the open state period. The construction included a non-mechanical damper andwas subjected to sudden flame impingement from a wood crib. The damper was designed to blockfire spread through openings during the open state period. Test criteria and instrumentation setupwere adopted from EN 1363-1 and EN 1366-4 as the vented construction is regards as a linear jointand was previously tested in a furnace test according to these standards. The furnace test determinesthe long term fire resistance performance of maintaining integrity and insulation after several minutesof exposure to fire. The new test was developed to give the vented construction a suddenexposure of flaming fire and monitor the response on the unexposed side with great detail during thefirst minutes and seconds of the open state period. The paper discusses this new technology fireperformance and the implications on current specifications and practices as it introduces an advancedand non-compromising solution to protect openings for applications that hitherto have beenimpractical to achieve. The new patented technology draws on established fire and explosionsuppression techniques combined in an innovative way so as to extend the quenching gap effectperiod of small gaps and openings. In terms of fire resistance, such passive devices effectively act assolid air tight construction even during their open state before being sealed by intumescing or ablativematerials. This technology permits various applications such as duct-free air transfer grilles, cavityand void seals, perimeter barriers, draft and fire stops to be available in vented designs - referred to asfire rated vented construction. The paper presents how the added benefits of the new technologyallows these systems to respond just as air tight wall and block direct flame impingement. An ad-hoctest method is considered with a view for development of a standard method for determining openstate fire resistance performance of air transfer openings. The paper describes the ad-hoc testsconducted at SINTEF where a test module was designed and was used to determine the response ofvarious non-mechanical vented construction dampers to direct flame exposure. The paper discussesbackground for developing the ad-hoc test, outlines the test method and discusses its usefulness andpotential resulting amendments to current testing methods and performance specifications for ventedfire stops in cavities and voids.