46 CFR 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)

Storeroom spaces 60

Accommodations spaces 95

Voids 95

Consumable liquid tanks 1 95 or 0

Other liquid tanks 2 95 or 0

Cargo (completely filled) 60

Cargo (empty) 95

Machinery 85

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.