30 CFR Part 57Public Domain
§ 57.8531 — Construction and maintenance of ventilation doors
Subpart G — Ventilation
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.
Public Domain: 30 CFR Part 57 (MSHA Safety and Health Standards — Underground Metal and Nonmetal Mines) is a U.S. government publication and is not subject to copyright. Text extracted from the official source ↗. Figures are served from the eCFR; if one does not load, use the link in its place.