[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-108-1-fire-science-010":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-108-1-火災學概要-010","fire-108-1-fire-science-010",108,1,10,"安裝爆炸氣道（或洩爆孔、氣孔）可適度降低侷限空間中粉塵爆炸的危害，則下列敘述何者錯誤？",{"A":16,"B":17,"C":18,"D":19},"氣孔截面積越大效果越好","氣孔若連接導管，則導管越短越好","粉塵最大爆壓較大者，氣孔比亦宜相對加大","室內空間較小者，氣孔比亦宜相對縮小","D",null,[],false,"本題考點：侷限空間粉塵爆炸的洩爆設計原理——洩爆面積、導管長度、爆壓大小與氣孔比之間的關係。\n【正解理由】洩爆的目的是在爆炸壓力尚未升到破壞值之前提供釋放路徑，使容器或室內的最大壓力低於結構耐壓強度。所需洩爆面積隨容積、粉塵爆炸猛烈度（最大爆壓與壓力上升率）而增加，但氣孔比（洩爆面積與容積之比）並非隨容積等比例調整：小容積空間的壓力上升更快、可供洩放的時間更短，單位容積所需的洩爆面積反而要更大，也就是氣孔比應相對加大。選項所述「室內空間較小者，氣孔比亦宜相對縮小」與此相反，題目問敘述何者錯誤，故選 D。\n【逐項排除】\n(A) 敘述正確。洩爆口截面積越大，單位時間可排出的燃燒氣體越多，容器內壓力峰值越低，洩爆效果越好。\n(B) 敘述正確。導管會產生流動阻力並使管內發生二次燃燒而回壓，導管越長洩爆壓力越高，故以短直為佳。\n(C) 敘述正確。最大爆壓與壓力上升率較大的粉塵，需要更大的洩放能力才能壓住峰值，氣孔比自應相對加大。\n(D) 敘述錯誤，為本題應選者。小空間壓力上升更快，氣孔比應相對加大而非縮小，否則洩放速度追不上壓力上升。\n【記憶點】洩爆口要大、導管要短；爆壓越猛、空間越小，氣孔比越要往上加。","洩爆（explosion venting）是損害限制手段，前提是承認爆炸會發生，改以「導引」取代「阻擋」。設計核心量是壓力上升率與洩放速率的競賽：粉塵爆炸的壓力上升率遵循立方根律 K_st =（dP\u002Fdt）_max × V^(1\u002F3)，同一種粉塵在小容積內的（dP\u002Fdt）_max 明顯較大，代表壓力衝到峰值的時間更短。洩放面積提供的流量卻只與開口面積成正比，因此小空間必須以更高的面積／容積比（氣孔比）才追得上，這正是本題的關鍵反直覺處。\n設計上另有幾個常被命題的參數。其一是洩爆裝置的動作壓力 P_stat：破裂片或洩爆門必須在低壓即開啟，動作壓力越高，開啟時容器內已累積的壓力越大，洩爆後的實際峰值 P_red 也越高。其二是洩爆導管：若洩爆口不在外牆而須以導管引至戶外，導管的慣性與摩擦阻力會抬高 P_red，且未燃粉塵在管內續燒會產生額外壓力，故規範要求導管盡量短、直、少彎頭，並確認結構足以承受。其三是洩放方向：洩爆口應朝向無人通行且無鄰近建物的安全側，並考慮排出的火焰與壓力波範圍。\n與洩爆並列的對策還有抑爆（在壓力上升初期由感測器觸發，瞬間噴入抑制劑撲滅火焰）、惰性化（把氧濃度壓到極限氧濃度以下）、以及耐壓設計（把容器做成足以承受最大爆壓的全耐壓或耐壓緩和構造），並輔以隔爆閥防止火焰經由管路傳播到相鄰設備而引發連鎖爆炸。相關考點包括洩爆與抑爆的適用差異、K_st 分級與洩爆面積的定性關係，以及二次爆炸的防止思維。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-108-1-fire-science-009","就同一種可燃性粉塵而言，下列何種措施有助於降低發生粉塵爆炸的危險性？",9,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-108-1-fire-science-011","室內火災所產生的熱煙層由天花板向下沉降的時間直接影響逃生；以此觀點而論，下列何者較不利於逃生？",11,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-108-1-fire-science-008","若乙烷的燃燒熱為 350 kcal\u002Fmole，依據 Burgess-Wheeler 法則，下列何者最為接近乙烷的燃燒下限？",8,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-108-1-fire-science-012","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？",12,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-108-1-fire-science-007","下列有關蒸氣爆炸的敘述何者錯誤？",7,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-108-1-fire-science-013","比較室內火災閃燃（Flashover）與複燃（Backdraft），下列敘述何者正確？",13,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-113-1-fire-science-010",113,"火場中煙的能見度取決於其濃度，因此裝設避難指示燈的距離攸關逃生可及之視線距離。若某煙層的單位長度光學密度為 0.05（m-1），則裝置其中的避難指示燈能見度應為多少公尺？",{"webId":58,"year":59,"stem":60,"number":13},"fire-112-1-fire-science-010",112,"依據 NFPA（美國防火協會）危險性物品標示，有關「反應性」的敘述，下列何者正確？",{"webId":62,"year":63,"stem":64,"number":13},"fire-111-1-fire-science-010",111,"火場當中煙毒危害，下列敘述何者錯誤？",{"webId":66,"year":67,"stem":68,"number":13},"fire-110-1-fire-science-010",110,"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？",{"webId":70,"year":71,"stem":72,"number":13},"fire-109-1-fire-science-010",109,"有水之場所的插頭應加裝何種裝置以防止感電發生？",1785129967504]