在二氧化碳空体焊作业中,局部排风罩必须同时符合下列条件;(1)从周围吸入到罩子的空气流不干扰CO_2气体层。(2)能有效地排除所发生的烟尘。(3)罩子的形状要做得既有效而又不降低操作效率。一个具有环形吸入口的罩子是能满足要求的,定名为环形罩,如图1所示。附表列出了环 In the carbon dioxide airbody welding operation, the local exhaust hood must meet the following conditions at the same time; (1) The airflow sucked into the hood from the surroundings does not interfere with the CO2 gas layer. (2) It can effectively eliminate the smoke that occurs. (3) The shape of the hood is made to be effective without reducing the operating efficiency. A cover with a circular suction inlet is sufficient to meet the requirements. It is called an annular cover, as shown in Figure 1. Schedule lists rings