泡沫消防系統(tǒng)外文翻譯

1、<p>　　Fire Prevention and Foamsystem</p><p>　　The selection of the proper storang tanks,their spacing and proper design,is the best safeguard against fire hazards.There are three basic conditions that m

2、ust be for fire to start:</p><p>　　(1)Fuel must be present in dispersed form as a vapor.</p><p>　　(2)Air (supplying oxygen for combustion) must be presernt in the right proportion with the fuel

3、vapor to form a maxture that can be ignited.</p><p>　　(3)A source of ignition (high temperature and energy sufficient to initiate the chemical action of combustion) must be present.</p><p>　　Sta

4、rting a fire requires all three essentials existing at the same time and at the same place. Extinguishment usually requires that either the fuel or air be eliminated.</p><p>　　When water is applied directly

5、to an oil fire it often does more damage than good, since burning oil f;oating on the water surface may actually spread the fire. Water is of assistance in keeping adjacent tanks and buildings cool. Water fog,a finely di

6、vided spray, is useful in shutting off air from burning oil surface and cooling it below ignition temperature.Water fog is effective on viscous oils or high flash oils in areas that are within the range of the spray.<

7、/p><p>　　A standard fire stream is rated at about 250 gpm using a 1.125 in. nozzle and 2.5 in. smooth rubber lined hose. This standard stream will require a nozzle pressure of about 45 psi with a hydrant pressu

8、re of 105 psi using 400 feet of hose between hydrant snd nozzle. A main distribution pressure of 125 psi for hose streams and foam generation is adequate.</p><p>　　When pressure is inadequate, fire pumps are

9、 installed. Pumps in the 500 to 1500 gpm are normally used. Standby pumps, usually diesel engine driven are provided for use in large facilities or when electrical power may be lost during a fire.</p><p>　　A

10、.Foam Fire Fighting Systems</p><p>　　The principal of foam application is to cover a burning oil surface with abblanket that will exclude air and smother the. Here are some basic definitions.</p><

11、p>　　(1)Foam Concentrate-a chemical which when mixed with water can be acrated and expanded to form foam.</p><p>　　(2)Foam Solution-the mixture of foam concentrate and water in proper proportions, usually

12、about 3-10% foam concentrate.</p><p>　　(3)Foam – the aerated mixture of foam solution that is made up of air filled bubbles that form a blanket to smother fire.</p><p>　　The most pertinent devel

13、opments with respect to types of foam include the following:</p><p>　　(1)protein foam concentrate</p><p>　　(2)fluoroprotein foam</p><p>　　(3)aqueous film forming foams(AFFF)</p&g

14、t;<p>　　AFFF was developed by the U.S. navy for crash fires and is very effctive on spill fires.When AFFF is combined with dry chemcial powder (Purple K) it is very effective in extinguishing spill fires.</p>

15、;<p>　　Mechanical foam is made when its three parts: water, air and foam concentrate (chemical compound) are brought together in proportionate and thoroughly and turbulently mixed. The basic method of combining th

16、ree components is with a “foam maker”. Water under pressure via pipeline or hose is proportioned by an internal orifice. The water moving at high velocities draws the foam concentrate into the water stream resulting in a

17、 soluting of 3%-10% foam. This solution also moving at high velocities cre</p><p>　　The effective use of foam requires its placement on the burning liquid surface as a stable blanker, and it must therefore p

18、ossess certain desirable physicl properties for this object to be achieved.</p><p>　　1. Fluidity</p><p>　　An important property of foam is that of being able to flow easily over the surface of o

19、il and around any obsturctions which may be in its path and so exclude air. An index of fluidity is given by a torsional vane type of viscometer which measures the shear stress of the foam (in bynes per square centimeter

20、). A “stiff” foam would have a shear stress of around 1000 dyness/ sq cm, whereas a foam produced by the normal foam-making branch pipe would have a shear stress within the range of 150 to 250</p><p>　　2.Exp

21、ansion</p><p>　　Mechancical aeration of the aqueous foam solution expands the solution into a foam which is less dense than oil, so that the foam can float on the oil surface. Expansion ratios of 6:1 to 12:1

22、 represent the normal range obtained from conventional foam-making equipment, depending upon the appliance and foam solution used. The expansion ratio is measured by comparing the volume of foam produced with the volume

23、of solution required to produce it. Thus assuming an expansion ratio of 10, one unit volu</p><p>　　3. Drainage rate</p><p>　　The heat-resistance of a foam blanket is dependent upon the stability

24、 of the bubble formation and the retention of water in the foam. Liquid drains away in time from the foam as a result of bubble breakdowm and gravitation between the bubble walls. The time taken in minutes for 25 per cen

25、t of the total liquid content to drain away under standard conditions of test is known as the 25 per cent drainage rate.</p><p>　　Since it is not possible to produce a foam which has all the desired properti

26、es, the experienced fire-fighter will utilize his foam-making appliances to the best effect according to the cirumstances. For example, varying the amount of foam compound introduced into the water stream will affect the

27、 expansion ratio, shear atress, and drainage rate, and formulations of foam compounds can be selected to give low (6 to 7 ), intermediate (8 to 12 ) or high expansion (12 to 16) foams.</p><p>　　There are thr

28、ee main ytpes of foam extinguishment systems. The fixed system consists of storage tanks of the foam concentrate, foam pumps and proportioning system, as well as pipelines to various equipment or structures, and foam dis

29、charge devices. It is a centralized foam solution system, that will produce foam only at specified locatoins. The fixed systems have been used where large storage tanks are in use such as large marine terminals or bulk s

30、torage plants. The advantages of a fixed system</p><p>　　(1)It is fast to operate.</p><p>　　(2)It requires low manpower.</p><p>　　(3)It makes efficient use of foam.</p><p

31、>　　The disadvantages include the following:</p><p>　　(1)low flexibility</p><p>　　(2)no mutual aid back-up</p><p>　　(3)high maintenance costs and high initial capital investment&l

32、t;/p><p>　　The semi-fixed system is the same as the fixed system with respect to foam discharge devices except that there is no central foam solution production and storage. Instead, mobile foam-proportioning t

33、rucks or trailer mounted units are used to produce the foam solution. A back-up truck is usually used for resupplying the units with foam concentrate.</p><p>　　The advantages of this system are as follows:&l

34、t;/p><p>　　(1)flexibility to cover the entire plant</p><p>　　(2)mutual aid possible</p><p>　　(3)low maintenance costs</p><p>　　(4)low capital investment</p><p&g

35、t;　　The disadvantages of this system are as follows:</p><p>　　(1)a time delay to operate of 5 to 15 minutes</p><p>　　(2)manpower requirements are in the 2-4 man range</p><p>　　Porta

36、ble systems may be a combination of mobile and hand transportable equipment. The foam discharge devices may be foam towers, monitor nozzles or foam nozzles. This ststem is especially suited for spill fires. Some of the a

37、dvantages of this system are:</p><p>　　(1)flexibility</p><p>　　(2)mutual aid</p><p>　　(3)low maintenance costs</p><p>　　The main disadvantages are:</p><p>

38、　　(1)high manpower requirements</p><p>　　(2)not effective for large cone tanks.</p><p>　　B. Foam Making Devices</p><p>　　Both the fixed and semi-fixed methods use the same foam maki

39、ng devices, usually at the base of the tank. One system consists of a pipeline called a foam lateral, starting outside the dike and running ti the base of the tank. Then a foam maker, that is, an aerator for the foam sol

40、ution, is situated at the tank base. The expanded foam is then piped up the outside of the tank through foam riser piping to a foam chamber.</p><p>　　On cone roof tanks, chambers are installed to introduce t

41、he cirumference of the shell just below the roof angle. Typical chamber requirements are as follows:</p><p>　　Tank Diameter Chambers</p><p>　　65 ft or less 1&

42、lt;/p><p>　　65 ft-117 ft 6 in 2</p><p>　　117 ft-140 ft 3</p><p>　　140 ft and over 4</p><p>　　Another method of ap

43、plying foam is subsurface or base injection</p><p>　　Floating roof tanks are a special case of fire extinguishment system application. Fires in this type of tank are and when they do occur, they are limited

44、to a flash fire around the circumference between the seal and tank shell. Usual practice is to rely on portable systems to extinguish these fires. However, with the installation of tanks in the 300 ft diameter range, por

45、table systems are less efficient. The general procedure is to install a foam dam about a foot or so from the seal area and the</p><p>　　Experience from past tank fires has led to the following conclusion:<

46、;/p><p>　　(1) It appears that subsurface injection is viable for extinguishing fires in large light fuel cone roof tanks.</p><p>　　(2) Large amounts of foam concentrate are needed to fight a fire i

47、nvolving several tanks, so mutual aid planning may be warranted between other tank farms, munic-ipalities and foam manufacturers.</p><p>　　(3) Water supply systems for tank farms are basic to successful fire

48、 fighting operations.</p><p>　　(4) Mutual aid planning with respect to the following is essential for efficient operations:</p><p>　　1) all parties to use a common radio frequency</p><

49、;p>　　2) logistics planning for fire fighting personnel and equipment, i. e. food and fuel</p><p>　　3) a fire control center for coordinating purposes</p><p><b>　　泡沫消防系統(tǒng)</b></p&

50、gt;<p>　　選擇合理的油罐、油罐間距和正確的設計，這是最好的防火安全措施?；馂牡陌l(fā)生必須三個基本條件：</p><p>　　(1)燃料必須以分散狀態(tài)存在，如蒸氣。</p><p>　　(2)空氣（提供燃料用的氧氣）必須以恰當?shù)谋壤c燃料構(gòu)成能引燃的混合物。</p><p>　　(3)必須存在引燃源（足以引起燃燒這種化學反應的高溫和能量）。<

51、/p><p>　　起火需要的上述三個基本條件必須同時存在。切斷燃料或空氣通常就能滅火。</p><p>　　如果直接將水潑于油類火災上，非但無益，反而有害，因為浮在水面上燃燒著的油實際上只能使火災蔓延。水有助于保持鄰近油罐和建筑物的冷卻。水霧，即細分散狀的水花有助于使燃油表面于空氣隔絕，并使油冷卻到燃點以下。水霧僅對水霧覆蓋范圍內(nèi)的粘性油或高閃點油有效。</p><p>

52、;　　當使用9/8英寸噴嘴和5/2英寸光滑橡膠襯里軟管時，標準滅火水流流量是250加侖/分。該標準水流要求噴嘴壓力約為45磅/英寸，若噴嘴于消防栓間采用400英寸軟管，則要求消防栓壓力為105磅/英寸。為滿足軟管水流和泡沫的生產(chǎn)，干管的分配壓力達到125磅/英寸便足夠了。</p><p>　　壓力不夠時，就要安裝消防泵。通常泵流量在500～1500加侖/分之間。大型站庫或火災中有可能斷電時，常采用由柴油機驅(qū)動的備

53、用泵。</p><p><b>　　A、泡沫滅火系統(tǒng)</b></p><p>　　應用泡沫的原理是在燃油表面上覆蓋一層能 隔離空氣并窒息火焰的覆蓋物。以下是某些基本定義：</p><p>　　1.泡沫劑：一種于水混合后能充氣并膨脹生成泡沫的化學劑。</p><p>　　2.泡沫溶液：泡沫劑與水按恰當比例混合的混合液，通常

54、含有3%～10%的泡沫劑。</p><p>　　3.泡沫：泡沫溶液內(nèi)充空氣后的充氣混合物，能形成窒息火災的覆蓋層。</p><p>　　泡沫類型方面最實際的發(fā)展包括：</p><p>　　1.蛋白泡沫劑；2.氟蛋白泡沫；3.水成膜泡沫（AFFF）。</p><p>　　水成膜泡沫時美國海軍為撲滅突發(fā)性火災而開發(fā)的，對流散火災非常有效。當水成膜

55、泡沫與化學干粉（Purple）聯(lián)合使用時，對于撲滅流散火災非常有效。</p><p>　　當把水、空氣和泡沫劑（化合物）按一定比例混合，并充分攪拌就可生成機械泡沫。將這三種成分混合在一起的基本方法是使用“泡沫產(chǎn)生器”。在壓力下通過管道或軟管的水用內(nèi)部孔板來調(diào)節(jié)比例。高速流動的水將泡沫劑吸入水流中形成比例為3%～10%的泡沫溶液。這種溶液仍以高速流動形成真空吸入空氣后，泡沫溶液膨脹8到10倍。泡沫本身是一種夾帶氣泡

56、的粘稠混合物。</p><p>　　有效地使用泡沫要求泡沫以一種穩(wěn)定的覆蓋層覆蓋在燃燒液體的表面。為達到這一目的泡沫必須具有某些所希望的物理性質(zhì)。</p><p><b>　　a.流動性</b></p><p>　　泡沫的一個重要性質(zhì)就是能很容易的在油表面上流動，并繞過流道上的任何障礙物，以隔絕空氣。用一種測量泡沫剪切應力（以達因/厘米表示）的

57、扭片型粘度計可測得粘動性指標。“流動性差”的泡沫剪切應力約為1000達因/厘米，而普通泡沫槍生成的泡沫的剪切應力在150～250達因/厘米范圍內(nèi)。</p><p><b>　　b.膨脹性</b></p><p>　　水成泡沫劑溶液經(jīng)機械充氣后，使溶液膨脹形成一種比油輕的泡沫，從而使泡沫能浮在油面上。根據(jù)所采用的器械和泡沫劑溶液，常用泡沫生產(chǎn)設備獲得的膨脹比范圍為6：1

58、至12：1，比較所生產(chǎn)的泡沫體積與生產(chǎn)該體積泡沫所需溶液體積就可測出膨脹率。若假設膨脹率為10，單位體積溶液將充氣膨脹為十倍的泡沫體積。</p><p><b>　　c.析水率</b></p><p>　　泡沫覆蓋層的隔熱性能與泡沫層的穩(wěn)定性及水在泡沫中的存留量有關。泡沫的破滅和泡沫壁間的引力作用導致液體不時從泡沫中析出。在標準試驗條件下，總液量中25%液體析出所需時

59、間（以分表示），稱為“25%析水率”。</p><p>　　由于不可能生產(chǎn)一種能全面滿足上述所有性能泡沫，所有有經(jīng)驗的消防人員會根據(jù)環(huán)境條件，使泡沫生產(chǎn)器械發(fā)揮最高效能。例如，改變吸入水流中的泡沫計量將影響膨脹率、剪切應力和析水率，并能通過選擇泡沫劑的分子式來生產(chǎn)低（6～7），中（8～12）會或高（12～16）膨脹率的泡沫。</p><p>　　有三種主要形式的泡沫滅火系統(tǒng)。固定式系統(tǒng)包括

60、泡沫劑儲罐、泡沫泵、比例混合系統(tǒng)，以及接至設備和構(gòu)件的管線和泡沫排放裝置。這是一種集中的泡沫溶液系統(tǒng)，只能在特定地點產(chǎn)生泡沫。固定系統(tǒng)應用在設有大型儲罐的地方，如大型海上轉(zhuǎn)輸站或散裝儲油庫。</p><p>　　固定式系統(tǒng)的優(yōu)點是：1.啟動快捷；2.人力需求少；3.泡沫利用率高。</p><p>　　其缺點是：1. 靈活性差；2.不能互相支援；3.初始投資打，維修費用高。</p>

61、;<p>　　辦固定式系統(tǒng)除了沒有集中的泡沫溶液生產(chǎn)和儲存部分外，泡沫排放裝置與固定式系統(tǒng)一樣。它采用泡沫比例車或裝在拖車上的裝置生產(chǎn)泡沫溶液。用輔助卡車為比例車提供泡沫劑。</p><p>　　這種系統(tǒng)的優(yōu)點是：1.具有靈活性，能照顧到整個站庫；2.能互相支援；3.維修費用低；4.投資少。</p><p>　　其缺點是：1.啟動時間要延遲5～15分鐘；2.需要約2～4人。&

62、lt;/p><p>　　移動式系統(tǒng)可以由車載和人工移動設備組合而成。泡沫排放裝置可以是泡沫炮、水槍管和泡沫噴管。該系統(tǒng)特別適用于撲滅流散火災。</p><p>　　這種系統(tǒng)的優(yōu)點是：1.靈活性高；2.能互相支援；3.維修費用低。</p><p>　　其缺點是：1.需要的人力多；2.對大型錐頂罐無效。</p><p><b>　　B、泡沫

63、發(fā)生裝置</b></p><p>　　固定式和辦固定式系統(tǒng)都是有同樣的泡沫發(fā)生裝置，一般安裝在油罐基礎處。系統(tǒng)中具有泡沫支管，它從防火堤外接至油罐基礎處。還有泡沫發(fā)生器，即：膨脹后的泡沫通過罐外的泡沫立管送至泡沫室。</p><p>　　在錐頂罐上，往罐內(nèi)導入泡沫的泡沫室安裝在低于灌頂角鋼的管壁四周。所需泡沫室的典型數(shù)據(jù)如下：</p><p>　　罐徑

64、 泡沫室數(shù)</p><p>　　小于等于65英寸 1</p><p>　　65～117英寸 2</p><p>　　117～140英寸 3</p><p>　　大于等于140英

65、寸 4</p><p>　　另一種供給泡沫的方法是液下輸入法或底部注入法。</p><p>　　浮頂油罐是應用滅火系統(tǒng)的特殊情況。這種油罐發(fā)生火災，一旦真的發(fā)生，也僅局限在密封與罐壁間的圓周內(nèi)發(fā)生閃燃。常用移動式系統(tǒng)來撲救這種火災。但當油罐直徑達到300英尺左右，移動式系統(tǒng)效果很差。一般的工藝是在離密封區(qū)約一英尺處安裝環(huán)狀泡沫堰板，并在圍繞罐壁的背板

66、上安裝小型泡沫發(fā)生器及排放裝置。</p><p>　　從過去油罐火災的經(jīng)驗教訓中已經(jīng)得到了以下結(jié)論：</p><p>　　1.為撲滅大型輕質(zhì)燃料油錐頂罐的火災，看來液下注入法是可行的。</p><p>　　2.撲救幾個油罐的火災需要大量的泡沫劑，所有可在各個油庫、市政當局和泡沫制造廠之間應有相互支援的計劃。</p><p>　　3.油庫區(qū)的供