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发表于 2009-4-16 08:49
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来自： 中国江苏南通
关于各种水喷淋，水雾灭火系统：
之前在我的文章中提到了各种水喷淋灭火系统，很多朋友对这几个系统感到很困惑，现在对它们进行详细的解释。它们分别是：
1.
Water Spray System (Deluge system)
2.
Water Sprinkler Systems
3.
Water Mist Systems
这几个系统有一个共性，它们都是固定灭火系统，都是采用喷水的方式进行灭火。但是它们依然有各自的特点。
先介绍一下water spray system，它相对于其他两个系统来讲，最大的区别在于这个系统要由人工启动，开放式喷嘴（也就是说平时的时候喷嘴里面是没有水的）。主要用于露天危险区域保护。它通常也叫deluge system，deluge的英文意思是洪水，浸没。从字面上的意思就是用大量的水一直对失火区域进行喷淋，以冷却的方式灭火，这一来我们现在就很显然知道为什么它主要用于露天区域灭火。否则，舱室里面排水可能来不及。既然是大量的水，就需要源源不断的水源，这也就这个系统需要用海水作为灭火剂的原因。
系统由海水供给泵，deluge阀，管路，喷嘴，组成。在海洋平台设计中，海水供给泵直接就可以用海水消防泵，也就是说，deluge system实际上是作为消防系统的分支管路，与消防栓不同的是，这里是用的deluge阀和喷嘴。
Deluge系统的喷嘴，对形成的水滴相对很大，下图就是典型的灭火效果。
deluge 阀，事实上是一个减压阀，通过电磁阀控制deluge阀的开关，来控制是否喷水。
这个系统在钻井平台上主要用于一下几个区域的灭火，直升机加油站区域，测井区域，节流压井管汇区域，整个钻台区域。
MODU，USCG，FSS，NFPA这几个规范有对系统设计的要求，摘录几条重要的：
1.
A fixed water spray system is to be installed for the process equipment.
The intent of the water spray system is to keep the process equipment cool and reduce the risk
ofescalation of a fire. Water spray systems are to be capable of beingactuated both automatically by a fire detection system and manually.Installations are generally to be in accordance with NFPA Standard 15,or other equivalent standard such as API RP 2030. Deluge isolationvalves are to be located in a safe area and outside the fire zone theyprotect.
2.
Processequipment, including hydrocarbon vessels, heat exchangers, firedheaters and other hydrocarbon handling systems, are to be protectedwith a water spray system. The system is to be designed to provide awater density of 10.2 liters/min/m2 (0.25 gpm/ft2) of exposed surfacearea for uninsulated vessels, or 6.1 liters/min/m2 (0.15 gpm/ft2) ofexposed surface area for insulated vessels. Process equipment supportstructure, including saddles, skirt, legs, but not secondary deckstructural members, is to be protected with a water spray systemdesigned to provide a water density of 4.1 liters/min/m2 (0.10gpm/ft2).
Alternatively,the use of intumescent coatings may be acceptable in protecting thesupport structure, provided the selection of the fire rating of thecoating is based on the results from a risk analysis and/or fire loadcalculation which must be reviewed and accepted by ABS. The condition(intactness) of the coatings will be the subject of surveyor inspectionduring attendance of the unit following normal survey intervals. Forgas-handling equipment, such as gas compressor skids, where thehydrocarbon liquid inventory is kept minimal, a water spray system isnot required if the equipment is provided with an automatic blowdownupon the process shutdown.
3.
Wellheadswith maximum shut-in tubing pressures exceeding 42 kg/cm2 (600 psi) areto be protected with a water spray system. The water spray system is tobe designed to provide a minimum water density of 20.4 liters/min/m2(0.50 gpm/ft2) based on the protection of wellheads, ESD valves, andcritical structural components including the firewall.
第二个，water sprinkler system,其实全称应该叫做accommodation sprinkler system。看这个名称就知道的用途了，很显然用于钻井平台生活区灭火。如果细心的话，这个与普通写字楼里面的水雾灭火系统相似，抬头看看天花板，在天花板中间可以看到很多均匀分布的小喷嘴。喷嘴里面有玻璃的感应器，一旦破裂，水就自动喷射出来。
显然，sprinkler system的喷嘴是封闭式的，管路平时需要保持，承受一定的压力。这就需要整个系统有蓄能器之类的保压装置。由于用于生活区房间，楼梯间的灭火保护，我们需要的灭火介质是淡水，而海水仅仅只是作为备用的应急水源。
系统由sprinkler控制站，管路，喷嘴，监测报警组成。这个系统比较简单，不做过多描述。
一些要求：
1.
Forexisting fixed installations where passive protection requirements arenot fully met, the accommodation spaces are to be protected by anautomatic wet pipe sprinkler system supplied from the firewater system.Design of the system is to be based on NFPA Standard 13 requirementsfor light hazard occupancies, or other acceptable standards such asChapter II-2, Regulations 12 of SOLAS 1974 and Amendments.
Freshwater is normally to be provided to fill the sprinkler piping. However,the system may be charged with seawater if precautions are taken toeliminate sediment and marine growth in the system.
2.
SVR4-7-3/9.5 requires sprinklers to be placed in an overhead position andspaced in a suitable pattern to maintain an average application rate ofnot less than 5 L/min/m2 (0.12 gpm/ft2) over the nominal area (i.e.,gross, horizontal projection of the area to be covered) covered by thesprinklers. However, the use of sprinklers providing an alternativeamount of water suitably distributed so as to be not less effective maybe considered.
最后一个是water mist system，细水雾灭火系统，这样的翻译就可以看出来和前两个系统的差别，喷嘴里面出来的水滴很细小，同样地，这个系统也是用于室内灭火，淡水（海水应急），自动喷水，可分为高压，中压，低压。
高压---系统的管网工作压力大于或等于3.45MPa 的细水雾灭火系统
中压---系统的管网工作压力大于1.21MPa 且小于3.45MPa 的细水雾灭火系统
低压---系统的管网工作压力小于或等于1.21MPa 的细水雾灭火系统
高压和中压系统可用于配电间的灭火，由于水雾及其细小的缘故。
灭火原理：冷却，水雾切断包覆隔绝空气。
高压系统组成：高压泵组，水柜，控制阀，管路，喷头，高压氮气气瓶（备用），监测报警组成。
也有直接用氮气气瓶作为动力源的water mist system，这里不做介绍
IMO MSC/Circ 668， 728 ，913 ，1165对water mist system 有详细的介绍和规定，我就不再赘述了。
摘录几条：
1．
Inaccordance with paragraph 18 of MSC/Circular 668, systems capable ofsupplying water at the full discharge rate for 30 minutes may begrouped intro separate sections within a protected space. However thesectioning of a system with such spaces must be specifically approved.In addition, paragraph 19 of MSC/Circular 668 indicates that regardlessof the sectioning arrangements, the capacity and design of a system isto be based upon the complete protection of the space demanding thegreatest volume of water. Accordingly, even if sectioning of the systemwithin a particular space is permitted, the system still needs to becapable of supplying all nozzles within that space are the requiredpressure.
2．
Asindicated above, paragraph 19 of MSC/Circular 668 requires that thecapacity and design of a system is to be based upon the completeprotection of the space demanding the greatest volume of water.Accordingly, the calculations should evaluate the most hydraulicallydemanding space, as well as the space demanding the greatest volume ofwater.
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