Hong Kong Regulations

MERCHANT SHIPPING (INSTRUCTIONS TO SURVEYORS) (PASSENGER SHIPS) REGULATIONS - REGULATION 33

Classes of watertight doors

The permissible classes of doors are: Class 1.-Hinged doors fitted with
catches workable from each side of the bulkhead. Class 2.-Sliding doors
operated by hand gear only. Class 3.-Sliding doors with brass rubbing faces
operated by hand gear only. Class 4.-Sliding doors with brass faces operated
by a releasing arrangement above the bulkhead deck as described in paragraph
35, and by hand gear. Class 5.-Sliding doors with brass rubbing faces operated
by power from a central control, as described in paragraph 36, and by hand
gear.