| 摘要 |
The draught box comprises a work table forming a bottom in a shaft with gastight side walls extending upwards from the table. In the shaft wall is an aperture providing access to the work table, and the arrangement is connected to a suction system for withdrawal of gases from the shaft. - Suction is produced through the work table which is shaped as a box, with gas and fluid-tight side walls and base, and whose upper flat limiting wall is at least on one part gas permeable. The table is connected to an evacuation channel separate from the shaft for suction of gas from the shaft through its upper limiting wall. |
