30 CFR § 75.1106-2 - Transportation of liquefied and nonliquefied compressed gas cylinders; requirements.
(a) Liquefied and nonliquefied compressed gas cylinders transported into or through an underground coal mine shall be:
(1) Placed securely in devices designed to hold the cylinder in place during transit on self-propelled equipment or belt conveyors;
(2) Disconnected from all hoses and gages;
(3) Equipped with a metal cap or “headband” (fence-type metal protector around the valve stem) to protect the cylinder valve during transit; and,
(4) Clearly labeled “empty” or “MT” when the gas in the cylinder has been expended.
(b) In addition to the requirements of paragraph (a) of this section, when liquefied and nonliquefied compressed gas cylinders are transported by a trolley wire haulage system into or through an underground coal mine, such cylinders shall be placed in well insulated and substantially constructed containers which are specifically designed for holding such cylinders.
(c) Liquefied and nonliquefied compressed gas cylinders shall not be transported on mantrips.