30 C.F.R. § 57.22215 Separation of intake and return air (I-A, II-A, III, and V-A mines).
Title 30 - Mineral Resources
Main intake and return air currents shall be coursed through separate mine openings and shall be separated throughout the mine, except— (a) Where multiple shafts are used for ventilation and a single shaft contains a curtain wall or partition for separation of air currents. Such wall or partition shall be constructed of reinforced concrete or other noncombustible equivalent, and provided with pressure-relief devices. (b) During development of openings to the surface— (1) Ventilation tubing approved by MSHA in accordance with 30 CFR part 7 or previously issued a BC or VT acceptance number by the MSHA Approval and Certification Center may be used for separation of main air currents in the same opening. Flexible ventilation tubing shall not exceed 250 feet in length. (2) Only development related to making a primary ventilation connection may be performed beyond 250 feet of the shaft. [52 FR 24941, July 1, 1987, as amended at 54 FR 30508, July 20, 1989]
Title 30: Mineral Resources
PART 57—SAFETY AND HEALTH STANDARDS—UNDERGROUND METAL AND NONMETAL MINES
Subpart T—Safety Standards for Methane in Metal and Nonmetal Mines
Ventilation
§ 57.22215 Separation of intake and return air (I-A, II-A, III, and V-A mines).
