172.240 Permeability of spaces.§ 172.240 Permeability of spaces.
When doing the calculations required in § 172.225,
(a) The permeability of a floodable space, other than a machinery or cargo space, must be assumed as listed in Table 172.240;
(b) Calculations in which a machinery space is treated as a floodable space must be based on an assumed machinery space permeability of 85% unless the use of an assumed permeability of less than 85% is justified in detail; and
(c) Calculations in which a cargo space that is completely filled is considered flooded must be based on an assumed cargo space permeability of 60% unless the use of an assumed permeability of less than 60% is justified in detail. If the cargo space is not completely filled, a cargo space permeability of 95% must be assumed unless the use of an assumed permeability of less than 95% is justified in detail.
Table 172.240 - Permeability
|Spaces and tanks||Permeability (percent)|
|Consumable liquid tanks||1 95 or 0|
|Other liquid tanks||2 95 or 0|
|Cargo (completely filled)||60|
1 Whichever results in the more disabling condition.
2 If tanks are partially filled, the permeability must be determined from the actual density and amount of liquid carried.