細水霧系統應用於通風環境下之研究

Abstract

中文摘要 細水霧系統自船舶使用而發展以來，逐漸成為各種消防防護領域的新技術，隨著美國國家防火標準訂定NFPA750為細水霧標準，在1996年首版到2006年第四版頒行後，2007年歐盟安全法規委員會也訂定TS14972為細水霧在歐盟設計標準，2008年在中國大陸許多省或直轄市都已公告細水霧標準。雖然細水霧系統是重要的選項，但在通風或排煙環境中能否適用，水霧粒子是否會被排煙機所抽離，大空間中局部放射的水霧粒子，在□有受到圍壁空間包覆時，會不會造成嚴重離散，造成因通風狀態而失效。透過國內外文獻收集分析後，本研究決定以高壓細水霧系統為主，進行實場驗証，實驗情境設為機械排煙與自然通風二種，機械排煙情境中選擇變化參數為火源種類、風量大小、撒水對照、排煙口位置等，實驗進行中將監測火場溫度、一氧化碳、二氧化碳、煙濃度等生命安全指數變化情形，除了確認滅火性能外，還可確認人員能否安全。在開放空間部份採用了FM及IMO中有關局部防護Local Application實驗設定，分別於室外及室內針對油類火源執行油盤及立體噴濺燃燒，過程中將確認在自然通風環境下，能否有效撲滅火源，實驗的過程與結果，令人十分滿意。研究結果顯示，細水霧在排煙的情況下，亦能有效的撲滅油盆火災。但滅火時間會受到排煙風量大小的影響，當排煙風量愈大，其滅火時間就愈長，並能有效降低火場的煙濃度、CO2、CO和溫度，降低了火場內部的危害，可以延長火場內人員避難逃生的時間；在木堆火源的實驗中，細水霧對於火場的抑制能力和火場內部的降溫效果，以及對氣體濃度的影響，都比傳統撒水頭還要好，對於人員的避難逃生也較為有利。

Abstract Since the water mist system has been developed and used in the watercraft fields, gradually it becomes a cutting-edge technology for the today’s fire protection systems. Following with the 1996 edition of NFPA750 standard and its 4th revised version in 2006, European Union Safety Committee in 2007 also regarded TS14972 as a water mist design standard for European Union. In 2008, many China provinces and direct-controlled municipalities bulletined the water mist standards. These make the water mist system to become an important fire suppression option. However, could the water mist system be suitable in the ventilated environment or influenced by de-smoke system that the water mist granules could be pulled out and not reach the fire? Also could such system be capable of emitting water mist granules in a big space without fully walled that might be resulted in failure due to serious granule divergence in a ventilated situation? After intensive literature review, this research adopts the high-pressure water mist system as the primary target for the onsite fire tests. Experiments were designed for the mechanical de-smoke and the natural ventilation situations. The selected parameters in the former situation were various types of fire, exhaust capacity, comparison with traditional sprinkler, and smoke vent position, etc. In fire tests, the variations of safety index, such as temperature and concentrations of carbon monoxide, carbon dioxide and smoke, were measured to justify the fire extinguishment and also the occupant egress safety. In the natural ventilation situation, the Local Application experiment was set up by using FM and IMO standards, which focused in hazardous level of liquid fire in indoor and outdoor environments. They are carried out by using the pool fire and the jet fire as the fire sources. The purposes were to confirm whether these fires can be suppressed effectively under the natural ventilation environment. The experiment process and results were very quite satisfied. From the experimental results, it was found that water mist system even under the desmoking condition still can effectively put out the pool fire. However, the fire extinction time is greatly affected by the mechanical de-smoke capacity. The extinction time becomes longer as the capacity is higher that also can reduce the smoke density, CO2 and CO concentrations, and temperature simultaneously. In other words, it can mitigate the fire hazard and extend the occupant egress time. In the crib fire tests, water mist system was found to be able to control the fire and reduce the field temperature. It was also found that the toxic gas concentration is reduced comparing to that of regular sprinkler system so that the occupancy evacuation becomes safer.