46 CFR §154.1200

1. (a)Each cargo compressor room, pump room, gas-dangerous cargo control station, and space that contains cargo handling equipment must have a fixed, exhaust-type mechanical ventilation system.
2. (b)The following must have a supply-type mechanical ventilation system:
   1. (1)Each space that contains electric motors for cargo handling equipment.
   2. (2)Each gas-safe cargo control station in the cargo area.
   3. (3)Each gas-safe space in the cargo area.
   4. (4)Each space that contains inert gas generators, except main machinery spaces.