Investigation on Effectiveness of Water Mist Fire Extinguishing System on Wet Bench
CHEN PAO CHU
The occurrences of the fire accident of Advanced Semiconductor Engineering Inc. (ASE Inc.), explosion accident of Motech Industries Inc. and gas explosion accident of Tuntex Distinct Corp. in recent years reveals that there still exists a lot of room for improvement in preventing fire and explosion incident from occurring inside the plants or fabs for the industrial circles. In addition, according to the experiences of fire accidents that previously occurred in electronic companies, such as Winbond, UICC, Advanced Microelectronic Products Inc. etc., it shows that the key for preventing hazardous occurrence is aiming at the characteristics of production process and contents inside the plant or fab with systematically sieving out. It recognizes the condition and consequence of major potential hazardous events, as well as uses the application of engineering tools to conduct the simulation and analysis to the occurring course of accidents. After that it can apply the analyzed results as the basis for carrying out the engineering improvement and establishing the emergency response system. Thus, it is able to reduce the occurring seriousness and scale of the hazardous events to the minimum level. Currently, while we’re experiencing the economic depression, the occurrence of unexpected accidents may cause enterprises to mistakenly lose many business opportunities and that will result in enormous loss to our economic development; therefore, the effective fire risk control and the complete planning of disaster prevention system become more important. The construction cost of high-tech plants and fabs is very expensive, and most manufacturing process equipment is the high-tech apparatus or machinery equipment specifically produced for related manufacturing process; in addition, various types and large volume of chemicals are used inside the plants and fabs, thus it is relatively important for the fire prevention and management. This work adopts the hazard risk as its core concept and along with the approaches of risk assessment to identify the machinery equipment with higher risk in the high-tech plants and fabs (LED plants/fabs) as the main subject of fire prevention. Furthermore, after implemented the a series of risk assessment and reviewed the historic experiences, it found that due to its manufacturing process characteristics, the cleaning solution used in wet bench usually is flammable and it usually operates along with heat source; therefore, the fire risk of wet bench is enormously high. Additionally, in order to prevent the metal corrosion, the machinery part of wet bench is usually made of plastic case, which contains a high fire load; as a result, the web bench has become the hazardous source with higher fire risk for semiconductor fabs commonly. According to the statistical data of FM (1977-1997), the highest occurring frequency of the accident inside the semiconductor fabs is the wet bench. As a result, in this work, the subject is focused on the wet bench and conducts an investigation on the application of water mist system to the fire extinguishing efficiency and feasibility for the wet bench.