Title 30
SECTION 57.22205
57.22205 Doors on main fans (I-A, II-A, III, and V-A mines).
§ 57.22205 Doors on main fans (I-A, II-A, III, and V-A mines).In mines ventilated by multiple main fans, each main fan installation shall be equipped with noncombustible doors. Such doors shall automatically close to prevent air reversal through the fan. The doors shall be located so that they are not in direct line with explosive forces which could come out of the mine.