smoke from the building. Studies such as these c<strong>on</strong>tributeto a quantitative understanding <str<strong>on</strong>g>of</str<strong>on</strong>g> the interacti<strong>on</strong> betweensprinklers and the buoyant layer. They are theoretical,however, and most have not yet been validated by full-scaletesting.In the absence <str<strong>on</strong>g>of</str<strong>on</strong>g> full-scale test data <strong>on</strong> the maximumfire size to be expected in a sprinklered <str<strong>on</strong>g>of</str<strong>on</strong>g>fice building,Morgan and Hansell (1985) c<strong>on</strong>ducted a review <str<strong>on</strong>g>of</str<strong>on</strong>g> Britishfire loss statisticsc Their objective was to identify' a "designfire" size for use in designing smoke ventilati<strong>on</strong> systems foratria in sprinklered and unsprinklered buildings. Theirreview indicated that the maximum heat release rates andareas <str<strong>on</strong>g>of</str<strong>on</strong>g> fire involvement in sprinklered buildings weremuch lower than in unsprinklered buildings. Fires insprinklered buildings were estimated to have attained heatrelease rates between 285 and 2,850 Btu/s (300 and 3,000kW) before being extinguished by the sprinklers, with theprobability <str<strong>on</strong>g>of</str<strong>on</strong>g> occurrence <str<strong>on</strong>g>of</str<strong>on</strong>g> smaller fires much higher thanfor larger fires. This study supported the British designpractice for smoke c<strong>on</strong>trpl systems <str<strong>on</strong>g>of</str<strong>on</strong>g> assuming a 5-MWdesign fire under sprinklered c<strong>on</strong>diti<strong>on</strong>s, with an area <str<strong>on</strong>g>of</str<strong>on</strong>g> 10n:Jl. Morgan and Hansell's informati<strong>on</strong> is a useful startingpoint for examining the questi<strong>on</strong> regarding the likelihood <str<strong>on</strong>g>of</str<strong>on</strong>g>occurrence and size <str<strong>on</strong>g>of</str<strong>on</strong>g> shielded fires in sprinklered buildings.Gustafss<strong>on</strong> (1989), Heskestad (1974), Hinkley (1989),and Battrick (1986) report <strong>on</strong> the l<strong>on</strong>g-standing c<strong>on</strong>troversybetween sprinkler and ventilati<strong>on</strong> experts about whether ornot ventilati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> hot gases from a sprinklered buildingthrough ro<str<strong>on</strong>g>of</str<strong>on</strong>g> Vel)tS during a fire is beneficial to the c<strong>on</strong>trol<str<strong>on</strong>g>of</str<strong>on</strong>g> the fire. <str<strong>on</strong>g>Sprinkler</str<strong>on</strong>g> experts argue that automatic smokevents detract from proper performance <str<strong>on</strong>g>of</str<strong>on</strong>g> the sprinklersystem. <strong>Smoke</strong> ventilati<strong>on</strong> specialists, in tum, argue thatreduced smoke logging <str<strong>on</strong>g>of</str<strong>on</strong>g> the building improves interiorfirefighting and reduces smoke damage. Although somefull-scale studies have been d<strong>on</strong>e (Gustafss<strong>on</strong> 1989), theyare usually based <strong>on</strong> either a <strong>on</strong>e-story warehouse buildn1gor a shopping mall, with ro<str<strong>on</strong>g>of</str<strong>on</strong>g> vents, and are therefore notimmediately useful for analyzing the impact <str<strong>on</strong>g>of</str<strong>on</strong>g> sprinklers <strong>on</strong>an operating z<strong>on</strong>ed smoke c<strong>on</strong>trol system in a high-risebuilding.Two notable excepti<strong>on</strong>s to the shortage <str<strong>on</strong>g>of</str<strong>on</strong>g> full-scaleexperimental work involving sprinklers and smoke c<strong>on</strong>trolmeasures are studies c<strong>on</strong>ducted by the Seattle Fire Depart- .ment in an <str<strong>on</strong>g>of</str<strong>on</strong>g>fice building (Seattle FD 1984) and by Kloteat a hotel in Washingt<strong>on</strong>, DC (Klote 1990). The Seattlework looked at fire pressures generated by sprinklered andunsprinklered fires; carb<strong>on</strong> m<strong>on</strong>oxide generated by sprinklered,shielded fires; and the performance <str<strong>on</strong>g>of</str<strong>on</strong>g> three smokec<strong>on</strong>trol approaches: stairwell· pressurizati<strong>on</strong>, elevator shaftpressurizati<strong>on</strong>, and z<strong>on</strong>ed smoke c<strong>on</strong>trol. The Seattle studyc<strong>on</strong>cluded that sprinklers were indeed effective in reducingfire pressures and thereby improved the likelihood thatsmoke c<strong>on</strong>trol systems designed to current standards (forassumed n<strong>on</strong>sprinklered c<strong>on</strong>diti<strong>on</strong>s) would prevent smokespread. There was no suggesti<strong>on</strong> that design standards couldbe reduced for sprinklered fire c<strong>on</strong>diti<strong>on</strong>s. Problems <str<strong>on</strong>g>of</str<strong>on</strong>g> lossASH RAE Transacti<strong>on</strong>s: Research<str<strong>on</strong>g>of</str<strong>on</strong>g> stair pressurizati<strong>on</strong> <strong>on</strong> opening <str<strong>on</strong>g>of</str<strong>on</strong>g> doors, with subsequentc<strong>on</strong>taminati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> the stairshafts, were noted. The resultsprovide a useful starting point for further validating studies.Klote (1990) studied n<strong>on</strong>sprinklered fires with smokec<strong>on</strong>trol and sprinklered · filllS without smoke c<strong>on</strong>trol in aseries <str<strong>on</strong>g>of</str<strong>on</strong>g> full-scale tests in a h9tel in Washingt<strong>on</strong>, DC,which was destined to be demolished. He noted that firepressures were very low in the sprinklered fires and wouldnot likely pose a challenge for a smoke c<strong>on</strong>trol systemdesigned to meet current standards (Klote and Milke 1992;NFPA 1988). Klote (1990) noted that more tests would berequired, however, to determine how operati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> thesmoke c<strong>on</strong>trol system in the sprinklered fires would havechanged smoke spread bey<strong>on</strong>d the fire floor. He also notedthat, for sprinklered fires that are not rapidly extinguished,smoke producti<strong>on</strong> could be significant and smoke c<strong>on</strong>trolcould be useful.The ability <str<strong>on</strong>g>of</str<strong>on</strong>g> sprinkler systems to c<strong>on</strong>trol and extitiguishunshielded fires is well established (Richards<strong>on</strong> 1983;Walt<strong>on</strong> 1988; Madrzykowski and Vettori 1992). In resp<strong>on</strong>seto Klote's c<strong>on</strong>cerns about shielded fires, however, it wasdecided to pay particular attenti<strong>on</strong> to fires that could not beextinguished immediately by· the sprinklers and that wouldresult in sustained smoke producti<strong>on</strong> under cool c<strong>on</strong>diti<strong>on</strong>s.On the basis <str<strong>on</strong>g>of</str<strong>on</strong>g> Klote' s suggesti<strong>on</strong>s for further research, theTechnical Committee (TC 5.6) <strong>on</strong> Fire and <strong>Smoke</strong> C<strong>on</strong>trol<str<strong>on</strong>g>of</str<strong>on</strong>g> the American Society <str<strong>on</strong>g>of</str<strong>on</strong>g> Heating; Refrigerating and AirC<strong>on</strong>diti<strong>on</strong>ing Engineers, Inc. (ASHRAE), agreed to providefunds for research to investigate the effects <str<strong>on</strong>g>of</str<strong>on</strong>g> sprinklers <strong>on</strong>the performance <str<strong>on</strong>g>of</str<strong>on</strong>g> a z<strong>on</strong>ed smoke c<strong>on</strong>trol system. TheNati<strong>on</strong>al Fire Laboratory <str<strong>on</strong>g>of</str<strong>on</strong>g> the Institute for Research inC<strong>on</strong>structi<strong>on</strong> at the Nati<strong>on</strong>al ReSearch Council <str<strong>on</strong>g>of</str<strong>on</strong>g> Canadaalso fu~ded the project.EXPERIMENT DESCRIPTIONA series <str<strong>on</strong>g>of</str<strong>on</strong>g> experiments involving shielded, sprinkleredfires was c<strong>on</strong>ducted at. the Nati<strong>on</strong>al Fire Laboratory's fullscalefire test facility located near Ottawa, Canada. Thefacility c<strong>on</strong>sists <str<strong>on</strong>g>of</str<strong>on</strong>g> a very large Bum Hall, in which a <strong>on</strong>estoryfire test room· was c<strong>on</strong>structed, and a 10-storyexperimental tower (referred to as the Tower). Both theTower and the <strong>on</strong>e-story test room were used to carry outthe testing for this project.One-Story Test RoomA <strong>on</strong>e-story fire test room (Figure 1) was c<strong>on</strong>structedinside the Bum Hall, equipped with sprinklers and instrumentedwit!t pressure, temperature, and gas analysis equipment.A products-<str<strong>on</strong>g>of</str<strong>on</strong>g>-combusti<strong>on</strong> collector attached to thetest room allowed oxygen calorimetry to be used to measurethe heat release rates <str<strong>on</strong>g>of</str<strong>on</strong>g> sprinklered fires. The roommeasured 20ft by 20 ft by 12ft (6.1 m by 6.1 m by 3.6 m)with an a!tached corridor that was 20 ft l<strong>on</strong>g by 8 ft wideby 12ft high (6.1 m by 2.4 m by 3.6 m) <strong>on</strong> <strong>on</strong>e side. Thecorridor could be pressurized independently <str<strong>on</strong>g>of</str<strong>on</strong>g> the test room495
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