[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-110-1-fire-science-012":3},{"subject":4,"subjectSlug":5,"subjectKicker":6,"subjectShort":7,"question":8,"related":27,"sameNumber":52,"hasEssay":26},"火災學概要","fire-science","火災學 · Fire Science","火災學",{"id":9,"webId":10,"year":11,"session":12,"subject":4,"number":13,"stem":14,"options":15,"answer":20,"answerNote":21,"images":22,"imagesPending":23,"lawTimestamp":11,"explanation":24,"explanationDeep":25,"freq":12,"indexable":26},"fire-110-1-火災學概要-012","fire-110-1-fire-science-012",110,1,12,"根據 NFPA265 對閃燃現象（flashover）之定義，下列敘述何者錯誤？",{"A":16,"B":17,"C":18,"D":19},"上層煙氣之溫度達 500 ~ 600 ℃","到達地面之輻射熱通量達 20 kW\u002Fm2","火焰總熱釋放率最少達到 2 MW","火焰到達開口","C",null,[],false,"本題考點：NFPA 265 房間角落試驗對閃燃（flashover）所採的判定指標數值，本題問敘述錯誤者。\n【正解理由】NFPA 265 以可觀測的門檻條件界定閃燃發生：熱煙層上層溫度達約 500 至 600 ℃、地板面接收的輻射熱通量達 20 kW\u002Fm²、火焰自試驗室開口竄出，以及總熱釋放率達到約 1 MW。選項 C 寫成「最少達到 2 MW」，與該定義所採的 1 MW 門檻不符，敘述錯誤，故選 C。\n【逐項排除】\n(A) 上層熱煙層溫度 500 至 600 ℃ 是閃燃最通用的溫度判準，敘述正確，非本題所選。\n(B) 地板面輻射熱通量 20 kW\u002Fm²，是室內可燃物幾乎同時受熱引燃的能量水準，敘述正確。\n(C) 熱釋放率門檻寫成最少 2 MW，數值高於該試驗定義所採用者，即為本題應選的錯誤敘述。\n(D) 火焰自開口竄出是閃燃最直觀的外部徵候，代表室內產生的可燃氣體量已超過室內氧氣所能消耗，敘述正確。\n【記憶點】閃燃四指標：五六百度、二十千瓦每平方公尺、一百萬瓦、火出開口。","閃燃是室內火災由成長期跨入最盛期的瞬間現象：室內可燃物表面因熱煙層回饋而同時達到熱裂解溫度，可燃氣體在極短時間內全面著火，室溫與熱釋放率同時跳升。由於它是連續過程中的一個轉折，各標準都必須用可量測的門檻把它「操作型定義」出來，NFPA 265 與 ISO 9705 這類房間角落試驗即屬此。\n四項門檻彼此其實是同一件事的不同量測面：上層煙氣達 500 至 600 ℃ 時，其向下的輻射恰好使地板附近熱通量接近 20 kW\u002Fm²，而這個能量水準足以在數秒內引燃報紙、木片等薄質可燃物；此時燃燒所需空氣已超過開口所能供應，未燃氣體便自開口竄出形成外部火焰；換算成能量，標準試驗室的規模對應的總熱釋放率約在 1 MW 量級。記憶時把「溫度、熱通量、熱釋放率、外部火焰」四個面向串起來，比死背單一數字可靠。\n閃燃發生所需熱釋放率也有理論估算式，常引用 Thomas 的關係 Q_fo = 7.8A_T + 378A_o√H_o（單位 kW），其中 A_T 為扣除開口後的室內總表面積、A_o 與 H_o 為開口面積與高度。式中兩項分別代表「加熱室內壁面所需」與「加熱流入空氣所需」的功率，說明房間愈大、開口愈大，閃燃門檻愈高。\n易混淆概念必須分清：閃燃（flashover）發生於通風尚足、火勢成長階段末期；爆燃或稱回燃（backdraft）則發生於通風不足、悶燒累積大量未燃氣體後突然供氧的瞬間，徵候為門縫吸吐氣流與黃灰色濃煙；閃火（flash fire）指可燃蒸氣雲被引燃後迅速掠燃而過，三者機制不同。延伸考法包括問閃燃的溫度區間、問哪一項不是閃燃指標、問回燃與閃燃的先後與供氧條件差異。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-110-1-fire-science-011","輻射熱是造成木造建築物延燒原因之一，下列何者正確？",11,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-110-1-fire-science-013","有一開口面積為 10.0 m2，開口高度為 1.44 m 之居室，當其發生火災而形成通風控制燃燒時，根據 P. H. Thomas 之研究結果，則燃燒速度為多少 kg\u002Fmin？",13,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-110-1-fire-science-010","甲基乙基酮過氧化物（MEKPO）常用於聚合物的生產，加熱至 100 ℃時會發生爆炸，此化合物屬於那一類公共危險物品？",10,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-110-1-fire-science-014","自然發火性物質中的原棉，主要是因為下列何種熱之蓄積而發火？",14,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-110-1-fire-science-009","碳化鈣（CaC2，俗稱電石）常用於水果的催熟，屬於公共危險物品，遇水會起激烈反應產生下列何種可燃性氣體？",9,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-110-1-fire-science-015","下列有關液化天然氣（LNG）與液化石油氣（LPG）之比較，何者正確？",15,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-113-1-fire-science-012",113,"直徑一公尺的柴油儲罐因火災受熱溫度達到 727 度，其柴油輻射率為 0.99，波茲曼常數為 5.67×10 -11 (kW\u002Fm 2 K4 )，請問會產生多少的輻射熱（kW\u002Fm 2 ）？",{"webId":58,"year":59,"stem":60,"number":13},"fire-112-1-fire-science-012",112,"下列何種化合物不是可燃性物質？",{"webId":62,"year":63,"stem":64,"number":13},"fire-111-1-fire-science-012",111,"密閉空間燃燒中天花板會向地面放射大量輻射熱促進地面可燃物燃燒速度，此現象為何？",{"webId":66,"year":67,"stem":68,"number":13},"fire-109-1-fire-science-012",109,"下列常見之乾粉滅火藥劑敘述何者正確？",{"webId":70,"year":71,"stem":72,"number":13},"fire-108-1-fire-science-012",108,"建築物之中性帶高度受室內溫度、室外溫度及上下開口的影響，下列敘述何者錯誤？",1785129967005]