[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-113-1-fire-science-039":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-113-1-火災學概要-039","fire-113-1-fire-science-039",113,1,39,"有關於液化石油氣之性質與事故發生之處置原則，下列敘述何者錯誤？",{"A":16,"B":17,"C":18,"D":19},"洩漏時應立即關閉容器開關","氣體因較空氣重，容易沉降於地板附近","滅火後以溼毛巾纏繞洩漏口，並將鋼瓶移至空曠處","可開啟抽風機將瓦斯排出室外，降低氣體濃度","D",null,[],false,"本題考點：液化石油氣之蒸氣比重與爆炸界限特性，以及洩漏現場避免製造點火源的處置原則。\n【正解理由】液化石油氣主成分為丙烷與丁烷，蒸氣比重約為空氣的 1.5 至 2 倍，洩漏後沉積於地板附近形成可燃混合氣。抽風機屬電氣機具，其開關接點與馬達啟動瞬間會產生電弧火花，當室內濃度已落在爆炸界限之內，開機動作本身即成為點火源，足以引發室內氣體爆炸；正確處置是切斷氣源後以開啟門窗的自然通風方式驅散氣體，並避免任何電器開關動作，故選 D。\n【逐項排除】\n(A) 洩漏第一時間關閉容器開關可阻斷持續外洩，是氣體事故處置的首要動作，敘述正確。\n(B) 丙烷、丁烷之蒸氣比重均大於空氣，洩漏後確實沉降並積聚於地板附近及低窪處，敘述正確。\n(C) 火焰熄滅後以溼毛巾纏繞洩漏口可降低外洩速率，再將鋼瓶移至空曠通風處，屬正確處置。\n(D) 啟動抽風機會製造電氣火花，在可燃範圍內構成點火源，屬錯誤處置。\n【記憶點】瓦斯外洩只做兩件事：關氣源、開門窗自然通風；任何電器開關，包含抽風機與電燈，都是火種。","液化石油氣的主成分是丙烷與丁烷。丙烷蒸氣比重約 1.5、丁烷約 2.0，都重於空氣，因此洩漏後會沿地面流動並積聚於低窪處、地板附近或地下室。這是它與天然氣最重要的差異——天然氣主成分甲烷比重約 0.55，輕於空氣而積聚於天花板附近，兩者的積聚位置相反，偵測位置與通風著眼點也就不同。\n爆炸界限方面，丙烷約為 2.1％ 至 9.5％、丁烷約為 1.8％ 至 8.4％，下限都很低，換言之只要少量外洩即足以形成可燃混合氣。液化石油氣屬混合氣體，其爆炸下限可用勒沙特列公式，由各成分的體積分率除以各自的爆炸界限求和後取倒數推估。液態氣化後體積約膨脹二百五十倍，一只鋼瓶的洩漏量便足以充滿整個廚房，這也是它危害程度高的根本原因。\n液化石油氣本身無色無臭，為便於察覺而添加乙硫醇等加臭劑，這就是聞得到瓦斯味的由來。氣體火災在學理上有一句核心原則：先止漏、後滅火。若在未切斷氣源的情況下先撲滅火焰，氣體會持續外洩並蓄積，反而可能形成範圍更大的氣體爆炸；同理，容器受火焰加熱而內壓上升時，可能發生沸騰液體膨脹蒸氣爆炸，即 BLEVE，是火場的重大危害之一。\n另有兩個常被忽略的性質：爆炸界限並非固定值，溫度或壓力升高時，下限會下降、上限會上升，可燃範圍隨之變寬，因此夏季高溫或密閉受熱環境的危險性更高；而丙烷、丁烷的最小引火能量僅約零點二五毫焦耳，人體活動所產生的靜電火花即足以引燃，這正是抽風機以外的電器開關同樣不可觸碰的原因。\n延伸考點：本科常把比重、爆炸界限、氣化膨脹倍數與處置原則合併命題，記法可寫成「重於空氣往下沉、關源通風不碰電」；與甲烷的比重對照則是每年幾乎必考的辨識點。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-113-1-fire-science-038","惰性氣體滅火藥劑 IG541 的組成分不包括下列何者？",38,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-113-1-fire-science-040","有關複燃之敘述，下列何者錯誤？",40,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-113-1-fire-science-037","主成分為碳酸氫鉀的乾粉滅火藥劑不適用下列何種火災？",37,{"webId":41,"stem":42,"number":12,"year":43,"session":12},"fire-114-1-fire-science-001","火場中輻射為熱傳遞主要的方式之一，輻射熱之性質及其計算的方式下列何者錯誤？",114,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-113-1-fire-science-036","依美國防火協會（NFPA）危險物品標示規定，黃色代表何種危險性？",36,{"webId":49,"stem":50,"number":51,"year":43,"session":12},"fire-114-1-fire-science-002","建築物火災成長過程中有關衰退期的敘述何者錯誤？",2,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-112-1-fire-science-039",112,"假設定量乙醇(C2H5OH)與理論空氣量混合後產生完全燃燒，其後將燃燒廢氣冷卻至常溫，則其中二氧化碳的濃度約為多少%？",{"webId":58,"year":59,"stem":60,"number":13},"fire-111-1-fire-science-039",111,"撕下新購的電視機螢幕保護封膜時遭受靜電，其原因為下列何者？",{"webId":62,"year":63,"stem":64,"number":13},"fire-110-1-fire-science-039",110,"某建築物內部的空氣溫度為 27 ℃，發生火災的房間溫度為 627 ℃，流入該起火房間的空氣體積流量為 4 m3\u002Fs，若忽略燃燒熱分解過程而產生的質量流率，請計算流出起火房間的煙霧體積流量約為多少？",{"webId":66,"year":67,"stem":68,"number":13},"fire-109-1-fire-science-039",109,"帶電物體或其附近之接地體，有突出部分或刃狀部分時，在該等前端近旁，所出現之微弱發光放電，此現象稱為？",{"webId":70,"year":71,"stem":72,"number":13},"fire-108-1-fire-science-039",108,"高壓氣體的爆炸界限，通常較常壓下為廣，爆炸上限也明顯提高，但下列何種氣體之爆炸範圍及爆炸上限在高壓下卻降低？",1785129966405]