The arrangement of two fire closures o

The arrangement of two fire closures of multi blade design according to D.4.1.4 in a common
frame is acceptable, if the following requirements are fulfilled:
 The total free cross sectional area of the entire ventilation opening is at least 3 m2
 The cross sectional area of each single blade is at least 0.5 m2
 The two fire closures are to be separated from each other. For this purpose an intermediate frame is
to be provided
 The closing mechanism of the two fire closures shall be independent from each other
D.4.1.6 Weather tight closures of a recognized standard are accepted as fire closures. In that case
weathertight closures are to be permanently attached irrespective of the length of the ship.
D.4.1.7 GL approved weather tight closures of multi-blade design, which are use rubber as sealing
material, may be accepted as fire closures if the following requirements are fulfilled:
 The closure is located in a position, where in accordance with Load Line Convention weather tightness
is required
 The closure consist of not more than 5 single blades
 The total clear height of each blade shall be at least 200 mm
 Each blade shall have a thickness depending on its cross section as specified in