30 CFR § 57.14114
Air valves for pneumatic equipment.
A manual master quick-close type air valve shall be installed on all
pneumatic-powered equipment if there is a hazard of uncontrolled movement
when the air supply is activated. The valve shall be closed except when the
equipment is being operated.
[53 FR 32528, Aug. 25, 1988; 53 FR 44588, Nov. 4, 1988]