§ 33.125. Splitting air current.

 When more than 75 persons are working in any mine, the Department or its authorized representative will determine from the air conditions in the mine whether it is necessary to split the air current to supply a sufficient amount of pure air for all persons employed in the mine. The inlet and outlet air passages for any particular district shall be separated by a pillar if the thickness and dip of the bed, seam or vein will permit, unless it becomes necessary to cut through the pillar for the purpose of ventilation, traffic, or damage, in which case doors or brattices shall be provided.