49 CFR § 229.93
Safety cut-off device
November 18, 2020
The fuel line shall have a safety cut-off device that—
(a) Is located adjacent to the fuel supply tank or in another safe location;
(b) Closes automatically when tripped and can be reset without hazard; and
(c) Can be hand operated from clearly marked locations, one inside the cab and one on each exterior side of the locomotive.