MSHA - Code of Federal Regulations - 30 CFR 7.24
30 CFR § 7.24
Technical requirements.
(a) Brattice cloth shall be flame resistant when tested in accordance
with the flame resistance test in §7.27.
(b) Flexible ventilation tubing shall be manufactured using an
MSHA-approved brattice cloth. If a supporting structure is used, it shall be
metal or other noncombustible material which will not ignite, burn, support
combustion or release flammable vapors when subjected to fire or heat.
(c) Rigid ventilation tubing shall be flame resistant when tested in
accordance with the flame resistance test in §7.28.