(a) The master shall ensure that:

1. (1) Hold and interbarrier spaces on a vessel with full secondary barriers are inerted so that the oxygen concentration is 8 percent or less by volume when flammable cargoes are carried;

2. (2) Hold and interbarrier spaces contain only dry air or inert gas on:

   1. (i) A vessel with partial secondary barriers;
   2. (ii) A vessel with full secondary barriers when non-flammable cargoes are carried; and
   3. (iii) A vessel with refrigerated independent tanks type C;
3. (3) When cargo tanks containing flammable vapor are to be gas freed, the flammable vapors are purged from the tank by inert gas before air is admitted; and
4. (4) When gas free cargo tanks are to be filled with a flammable cargo, air is purged from the tank by inert gas until the oxygen concentration in the tank is 8 percent or less by volume before cargo liquid or vapor is introduced.