46 CFR § 78.47-53
Automatic ventilation dampers
April 15, 2021
(a) The manual operating positions for automatic fire dampers in ventilation ducts passing through main vertical zone bulkheads shall be identified by red day light-reflecting letters at least 1⁄2 inch high “VENTILATION FIRE DAMPER.” In addition, the open and closed positions shall be similarly marked.
(b) [Reserved]
[CGFR 65-50, 30 FR 16955, Dec. 30, 1965, as amended by CGD 67-87, 32 FR 19181, Dec. 20, 1967]