ventilation 通风 - ohlearning.ppt

Routine Maintenance Appraisal日常维护与评估 Ensure that the LEV is always running when hazardous substances are being emitted or are likely to be emitted 当有害物质正在排放或可能排放时，始终要确保局部排气通风处于运行状态 Observe the condition of the suction inlet such as the hood, booth, etc to see whether it has moved or has been damaged 观察进气口，如烟尘罩、管腔等的状况，看看是否有移动或已损坏 Observe the condition of any visible ductwork and dampers by the inlet 从送气口观察可见的管道系统和节气闸的所有情况 Routine Maintenance Appraisal (cont)日常维护与评估（续） Observe any evidence of control failure, for example noticing if there are unusual dust deposits or a stronger odour than normal immediately outside the LEV 观察任何控制失效的迹象，例如，注意在紧靠局部排气通风系统外，是否有异常的粉尘沉积，或是否有超乎正常的刺鼻气味 Observe any local instrument that has been fitted to the LEV to show its performance, such as a pressure gauge on a filter or an airflow device on a fume cupboard 观察已经安装在局部排气通风上的所有本机仪器，并显示其性能，如过滤器上的压力表，或通风橱上的气流装置等 Undertake any minor servicing such as emptying filter bins 进行细微的维护作业，如排空过滤箱 Limitations of LEV Systems 局部排气通风系统的局限性 Need to be purpose designed for a process, making process changes difficult if the same level of control is to be maintained 如果要保持同样程度的控制，需要进行专门的工艺设计，才能使工艺不会改变 High capital and operating cost. All LEV systems require energy for the fan, making operating costs an added expense 投入和运行成本高。所有局部排气通风系统都需要为风扇提供电源，这样就会增加运行成本 High levels of noise are common with LEV system, resulting in them being turned off by operators in many cases 局部排气通风系统常伴有高分贝噪音，从而导致操作人员在很多情况下要关闭该系统 Limitations of LEV Systems (cont) 局部排气通风系统的局限性（续） Many are of a fixed structure design making flexibility within the workplace difficult 许多局部排气通风系统具有固定的结构设计，使其在工作场所的灵活性不够 Many require the installation of an air supply system. Supplied air may need to be heated in cold climates or during winter months in temperate climates 许多局部排气通风系统需要安装一个供风系统。供应的空气在寒冷的气候，或在冬季月份的气候条件下可能需要加热 Not practical for large disperse contaminant clouds that have multiple sources 这对有多种污染源的大量分散污染云团而言，是不切合实际的 Limite