§ 185.608 § 185.608 Fuel shutoff valves. Remote fuel shutoff stations must be marked in clearly legible letters at least 25 millimeters (1 inch) high indicating purpose of the valve and direction of operation.
46 CFR §185.608
46 CFR Part 185
TL;DR
Remote fuel shutoff stations must be marked in clearly legible letters at least 25 millimeters (1 inch) high indicating purpose of the valve and direction of operation.