可燃物
作者 楊永斌
What is Fuel?
什么是可燃物
Fuel is the material that is burning. It can be any kind of combustible material, especially petroleum-based products, and wildland fuels.可燃物是指能夠燃燒的材料,可以是任何一種可燃材料,特別是石油類產品和山林中的可燃物。 For wildland fire, it is usually live, or dead plant material, but can also include artificial materials.對于山林火災,通常是指活著的、或枯死的植物材料,同時也可能包括人造材料。 Artificial materials are items such as houses, sheds, fences, pipelines, and trash piles. 人造材料是指房屋、棚屋、柵欄、管道和垃圾堆等。 Fuel Distribution 可燃物分布 Firefighters can be called to respond to incidents in different parts of the country, climate zones, and fuel types. 撲火隊員可能要面對不同地區、不同氣候帶和不同可燃物類型的火災。 There are geographic and regional distinctions across the country in regards to the predominate fuel types in the area. 就某地區可燃物的主要類型來講,會由于地理和地區的不同而存在差別。 The amount of water in the soil and elevation change are some of the reasons behind different fuel types.土壤中含水量和海拔高度的變化也是造成可燃物類型差異的原因。 Fuel Type 可燃物類型 Wildland fuels are grouped into six fuel types, based on the primary fuel that carries the fire.根據參與山林火災的主要材料,可燃物可以分為6種類型。 An identifiable association of fuel elements of distinctive species, form, size, arrangement, or other characteristics that will cause a predictable rate of spread or resistance to control under specified weather conditions.在特定的氣候條件下,如果能夠確定可燃物種類、形狀、大小、分布或其他特征因素之間的組合,能夠在一定程度上預測火勢蔓延速度及控制火勢的阻力。 Grass(草) Responds quickly to wind and changes in relative humidity, and burns the fastest of the fuel types. It is common to hear the term wind-driven when referring to grass fires, due to the impact wind can have on this fuel. 燃燒速度最快的燃料,對風力和濕度的反應靈敏,因此“風力驅動”一詞通常用于草地火災。 Fire can spread very quickly, but can also burn out very quickly, leaving areas safe to move through just seconds after the flaming front passes. 草火燃燒速度非常快,但同時燒燼的速度也會很快,因此火焰前沿經過數秒鐘后,會留下一片安全區域。 Potential to become the prevalent fuel in an area after a fire has occurred. For example, after a fire in timber, grass will regenerate first, introducing a new predominate fuel to that area. 草可能會成為火災后火場區域最普遍出現的可燃物。例如,林場發生火災后,草最先再生,成為該地區新的主要可燃物。 Shrub(灌木) Shrubs are found in most regions and include some low-growing trees, such as scrub oaks. 灌木的分布廣泛,其中也包含長勢低矮的樹木,比如矮櫟。 May burn very actively, or may slow the spread of fire depending on type of shrub and time of year. 這類可燃物是形成活躍的燃燒,還是會減緩火勢蔓延,主要取決于灌木的類型和在一年中所處的時間段。 The shrub type is highly influenced by drought conditions. 灌木類型受干旱條件的影響很大。 When the shrub type is receptive, it has the potential to spread fire quickly. 如果植物是親水的,有可能形成快速的火勢蔓延。 Grass-Shrub(灌草) Commonly found in the plains regions and high deserts, grass-shrub is a mixture of fine grass and shrubs.常見于平原和沙漠高原,是細草和灌木的混合體。 Fire behavior in this type combines the features of the grass fuel type and the shrub fuel type.灌草火災行為兼具草原火災和灌木火災的特點。 Fires may spread rapidly with wind, but more slowly than a grass fuel type.在風的作用下火勢蔓延快,但比單純的草原火慢很多。 Shrubs add intensity to the fire and may produce spotting, but fires are less intense than in the Shrub type.灌木的加入會增強火勢,但比單純灌木火勢要弱,同時可能會產生飛火點。 Where it may be safe to move in the grass type immediately after fire passes, it may not be safe in this type because of longer-burning shrubs .由于灌木燃燒時間較長,所以不會形成像草原上火焰過后立刻形成的安全區。 Timber litter refers to dead leaves, needles, and twigs on the forest floor.枯枝落葉層是指落在地面上枯葉、針葉和細枝條。 Fires generally move more slowly in timber types than in grass or shrubs, but burn for longer, and are harder to control. 火勢蔓延速度慢于草原和灌木火,但燃燒時間更長,火勢控制更難。 When fires burn through the upper canopy of trees they can move very quickly and with extreme intensity.當燃燒蔓延到樹冠,會轉變為火勢很強的非常快速的燃燒。 Timber-understory refers to a canopy of trees with other plants (such as shrubs and small trees) growing below them. 林下植物是指樹木樹冠下生長的植物(比如灌木和小樹)。 Fires in this type combine the features of the timber litter type and the shrub type, moving faster than fires in timber litter, but burning longer than fires in shrubs. 此類型可燃物的火災兼具枯枝落葉層和灌木火的特點。比枯枝落葉層的火勢蔓延速度快,燃燒時間長于灌木火。 Fires in this fuel type can move very quickly and with intensity, especially when understory trees/shrubs act as a ladder for fire to climb into the upper canopy.當火勢借助林下樹木和灌木的“階梯作用”爬上上面的樹冠,燃燒會轉變為非常快速的猛烈燃燒。 Slash-blowdown is debris resulting from such natural events as wind, fire, or snow breakage, or human activities such as road construction, logging, pruning, thinning, or brush cutting. 砍伐或刮倒樹木是由風、火、雪等自然事件或人類活動(如道路施工、伐木、修剪等)造成的樹木殘骸。 Fire in this fuel type does not commonly spread quickly. However, due to the sheer amount of fuel that is available, a fire that is established in this fuel type can be very intense and difficult to extinguish. 這類可燃物火災通常不會迅速蔓延。但是,由于可用的可燃物量很大,火勢可能非常猛烈,且難以撲滅。 Slash typically includes: 包括: Logs.原木 Chunks of wood.木塊 Bark.樹皮 Branches.樹枝 Stumps.樹樁 Broken understory trees or brush.砍伐掉的林下樹木和灌木叢 Artificial 人造材料 Although not necessarily considered a fuel type, artificial, or constructed fuels are often present in the wildland environment. 雖然不一定被認為是可燃物類型,但在野外環境中經常存在人工或人造可燃物。 In many cases, the location of artificial fuels, such as trash piles, or drug production facilities, is unknown until discovered by firefighters.在許多情況下,諸如垃圾堆、生產設施等人工燃料的位置,在消防隊員發現之前是未知的。 Examples of artificial or constructed fuels include: 人工制造或建造的可燃物包括: Houses.房屋 Vehicles.車輛 Tires.橡膠輪胎 Trash.垃圾 Log decks.原木加工設施 Above ground oil and natural gas pipelines.地上的石油和天然氣輸送管道 Artificial or constructed fuels can present special hazards, such as toxic chemicals, and explosion potential, to wildland firefighters.人為制造和建造的可燃物可能存在特殊的危險,比如毒性化學物質、爆炸物等,會對撲火隊員形成潛在威脅。 Available Fuel 可用可燃物 The portion of the total fuel that would burn under various environmental conditions.所有可燃物中能夠在各種環境條件下燃燒的部分。 Fuels availability for combustion is dependent on its characteristics. However, species of the plant, its age, and the time of year are other important factors.可燃物的燃燒特性主要取決于自身性質,但同時,樹齡、一年中所處的時間段等其他重要的影響因素。 For dead fuels, fuel moisture content depends on how much moisture is in the environment and how quickly the fuel absorbs or loses moisture. 對于枯死的可燃物,其含水量取決于環境濕度以及其吸收或散失水分的速度。 Fuel Characteristics 可燃物特征 Fuel characteristics influence how fires typically behave.可燃物的性質會影響火災發展的典型行為特征。 The different fuel types can vary in behavior due to their specific characteristics.可燃物的火災行為會由于其自身特征不同而不同。 Example: A timber fuel type in the Pacific Northwest region may have different characteristics than the same timber fuel type in the Eastern region.比如:太平洋西北海岸地區的木材可能與東部地區相同的木材具有不同的特征。 Identifying fuel characteristics can give an estimated prediction of fire behavior.識別可燃物類型可以對火災行為進行估測。 The amount of fuel present expressed quantitatively in terms of weight of fuel per unit area.火災荷載:給定面積內燃料的數量 This may be available fuel (consumable fuel) or total fuel and is usually dry weight. 質量采用燃料的干重(燃料干燥之后的重量) The loading of fuels in any given area does not necessarily mean that fire will burn with great intensity. 火災荷載的大小并不能完全代表火勢的強弱。 Chemical content refers to the presence of substances in the fuel such as: 燃料中的化學成分指的是: Oils油脂 Resins樹脂 Wax植物蠟 Pitch瀝青 Fuels with high amounts of these substances can contribute to rapid rates of spread and high fire intensities. 如果可燃物中此類化學成分含量高,將有助于形成快速蔓延并猛烈燃燒的火勢。 Fuel arrangement is divided into two primary categories: 可燃物的分布分為兩個方面: Horizontal Continuity水平方向上的連續性 Vertical Arrangement豎直方向上的分布 Fuel Continuity is the degree or extent of continuous or uninterrupted distribution of fuel particles in a fuel bed thus affecting a fire‘s ability to sustain combustion and spread. This applies to aerial fuels as well as surface fuels. 燃料連續性描述的是可燃物分布連續性或不間斷性的程度,這會影響可燃物持續燃燒的能力和火勢蔓延的速度與范圍。 Horizontal, continuous fuels are closely packed and in direct contact with one another. 水平方向上連續的可燃物緊密地堆積在一起,彼此直接接觸。 Two main categories: 根據水平連續性可以分為兩類: Uniform Fuels.均勻分布 Patchy Fuels.分散分布 Uniform, continuous fuels describe areas containing a network of connected fuels, allowing a continuous path for fire to spread. 均勻連續性分布會在一定區域內形成可燃物彼此相連的網絡,能夠為火勢蔓延提供連續性路徑。 The fuels affect the rate of ignition and spread potential by allowing fire to move steadily from one piece of fuel to the next.這種分布能夠使火災在不同可燃物間穩定的傳播,從而影響引火和蔓延速度。 Objects blocking the continuous distribution of fuels include:阻隔可燃物連續分布的物體包括: Rocks.巖石 Bare dirt.裸露的土地 An intermixing with a fuel type that ismuch less flammable, such as green grass, or aspen trees。可燃物中夾雜的可燃性很低的物質,比如青草、白楊樹 Vertical arrangement of fuels is broken into four categories: 從豎向分布角度可以將可燃物分為四類: Ground fuels.底層可燃物 Surface fuels.表面可燃物 Ladder fuels.爬梯可燃物 Aerial fuels.空中可燃物 All combustible materials below the surface litter, including duff, tree, or shrub roots, punky wood, peat, and sawdust, which normally support a glowing combustion without flame. 地面枯枝落葉層下的可燃物,包括腐殖層、樹木和灌木的根系、腐朽的木材、泥炭、木屑,通常會形成無焰燃燒。 Ground fuels do not spread fire quickly, but they can pose problems for containing fires.底層可燃物的火勢蔓延速度較慢,但也會對火災的控制造成問題。 Ground fuels burn below the surface of the ground, out of sight, making it difficult to detect. They can burn for extended periods–weeks, and, in some cases, years.底層可燃物的燃燒發生在地面以下,因為難以觀測到,所以很難探測。它們的燃燒會持續數周,甚至一些情況下可以持續數年。 Smoldering ground fuels can burn underneath firelines and cause fires to spread out of containment lines. 底層可燃物的陰燃會發生在防火線以下,導致火災穿過控制線。 Fuels lying on or near the surface of the ground, consisting of leaf, and needle litter, dead branch material, downed logs, bark, tree cones, and low stature living plants. 表面可燃物是指在地面以上或地面附近的可燃物,包括樹葉、針葉層、干枯的樹枝、倒下的木材、樹皮、低矮植物。 Includes most of the material we think about as fuel for wildland fires and are the primary carriers of fire once ignition has occurred. 表面可燃物包括大部分我們所能想到的野外火災可燃物,也是火災發生后主要促使火勢蔓延的可燃物。 The primary fuel to remove to break the fire triangle. 也是滅火過程中首先要移除的可燃物。 Fuels that provide vertical continuity between strata, thereby allowing fire to carry from surface fuels into the crowns of trees or shrubs with relative ease. They help initiate and assure the continuation of crowning.爬梯可燃物為火災在不同高度上蔓延提供連續的可燃物,因此能夠使燃燒較為容易的從地面蔓延到樹冠或灌木的頂部。這些燃料能夠促使形成持續的樹冠火。 Ladder fuels allow fires to move from surface fuels, where firefighters are most effective at stopping fires, to burning in aerial fuels where firefighters are not effective at stopping fire.爬梯可燃物使火災從消防員最擅長撲滅的地面轉移到消防員不能有效滅火的空中。 Standing and supported live and dead combustibles not in direct contact with the ground and consisting mainly of foliage, twigs, branches, stems, cones, bark, and vines.空中可燃物是指不與地面直接接觸,直立和支撐著的活的和死的可燃物,主要由葉子、枝條、樹杈、球果、樹皮和藤蔓組成。 Often referred to as canopy or crown fuels. 經常代指樹冠。 Suppression tactics or tools are not very effective at stopping fires burning through aerial fuels (crown fires). 滅火策略和滅火工具對于控制空中燃料的火災蔓延不十分有效。 Fires moving through aerial fuels (crown fires) can be extremely intense and rapid. Embers from crown fires can travel more than a mile ahead of the fire and perpetuate fire growth. 通過空中可燃物燃燒蔓延的火災火勢強度大、蔓延速度快。樹冠火的飛火可以飄至火頭前方一英里之外,從而加劇火勢的蔓延擴大。 Moisture content is the single most important factor in determining how well a fuel will ignite and burn. 含水量是決定燃料引燃和燃燒難易程度的一個非常重要的因素。 Two categories: 含有的水分分為兩類: Live Fuel – Living plants, such as trees, grasses, and shrubs. The moisture content in live fuels is controlled by plant species, age of the plant, time of year, and drought conditions.活著的可燃物-活著的樹木、草地和灌木叢。活著的植物含水量主要受植物種類、植物年齡、一年中所處的月份以及干旱條件等因素控制。 Dead Fuel – Fuels with no living tissue. The moisture content in dead fuels is controlled by humidity, precipitation, sunlight, wind, and the size, and shape. 枯死的可燃物–每組。枯死的可燃物中的含水量受濕度、降水、日照、風力、大小和形狀等因素的控制。 In general, at the height of the growing season, live fuel moistures will be at their highest and will progressively decrease throughout the fire season, whereas dead fuel moistures can fluctuate frequently throughout the fire season based on immediate precipitation, relative humidity, and sunlight. 一般來說,在生長季節的高峰期,活著的可燃物濕度最高,在整個易發生火險的季節會逐漸減少,而枯死的可燃物濕度在整個易發生火險的季節會根據降水、相對濕度和日照的情況而頻繁波動。 Due to variations in characteristics, as well as size, different fuels located in the same area will have varying moisture levels. 由于自身生長特性、尺寸的差異,在相同區域生長的不同植物,其含水量也會不同。 The drier a fuel is, the more likely it is to catch fire and the hotter it will burn.燃料越干,著火的可能性越大,燃燒的溫度也越高。 For dead fuels, the size and shape of a fuel determines how the fuel reacts to its environment and how long it takes to dry out or absorb moisture. 對于枯死的可燃物,尺寸和形狀決定著其對環境的反應,以及干燥和吸收水分的快慢。 Size and shape classifications are:根據直徑劃分為4級: 0–1/4” diameter 1/4”–1” diameter 1”–3” diameter 3”–8” diameter Fuels within the same size class are assumed to have similar drying and wetting properties, as well as preheating, and ignite at similar rates during the combustion process. 同一級別的可燃物可認為具有相似的干燥和吸潮特性,以及相似的預熱、引燃速度。 Smaller fuels dry out and or absorb moisture faster than larger fuels.小塊可燃物的干燥和吸潮速度大于大塊可燃物。 Size and shape classifications correspond to the time it takes a piece of fuel to change its moisture content to match its environment.大小和形狀分級同時也對應著燃料改變其含水量以適應其環境所需的時間。 This time period is referred to as timelag, which is the rate at which dead fuel gains or loses moisture.這一時間被定義為滯后時間,表征的是枯死可燃物吸收和散失水分的速度。 Timelag rate classifications are: 滯后時間的分級是: Fuels 0–1/4” in diameter = 1 hour. Fuels ?”–1” in diameter = 10 hours. Fuels 1”–3” in diameter = 100 hours. Fuels 3”–8” in diameter = 1000 hours. 舉例: Fuels that are 0-1/4” in diameter take one hour to change moisture content from where it started to that of the surrounding environment. Whereas, fuels that are 1”–3” in diameter will take one-hundred hours. 直徑為0-1/4”的可燃物需要一個小時從起始的含水量調整到與周圍環境濕度一致。而直徑為1”–3”的燃料則需要100小時。 Fuels larger than 8” in diameter are also classified as 1000 hour fuels.直徑大于8”可燃物的滯后時間也認為屬于1000小時的級別。 課后習題 圖中植物根據直徑劃分的尺寸級別屬于? 其滯后時間分級為? 圖中的主要可燃物類型是? 圖中可燃物的分布可以描述為?