30 C.F.R. § 57.8531 Construction and maintenance of ventilation doors.
Title 30 - Mineral Resources
Ventilation doors shall be— (a) Substantially constructed; (b) Covered with fire-retardant material, if constructed of wood; (c) Maintained in good condition; (d) Self-closing, if manually operated; and (e) Equipped with audible or visual warning devices, if mechanically operated.
Title 30: Mineral Resources
PART 57—SAFETY AND HEALTH STANDARDS—UNDERGROUND METAL AND NONMETAL MINES
Subpart G—Ventilation
Underground Only
§ 57.8531 Construction and maintenance of ventilation doors.
