U.S. Code of Federal Regulations

Regulations most recently checked for updates: Oct 19, 2019

§ 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 spaces60
Accommodations spaces95
Voids95
Consumable liquid tanks 1 95 or 0
Other liquid tanks 2 95 or 0
Cargo (completely filled)60
Cargo (empty)95
Machinery85

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.