What is A class divisions as per SOLAS ?

As per SOLAS chapter II-2, regulation 3

Accommodation spaces are those spaces used for public spaces, corridors, lavatories, cabins, offices, hospitals, cinemas, game and hobby rooms, barber shops, pantries containing no cooking appliances and similar spaces

‘‘A’’ class divisions are those divisions formed by bulkheads and decks which comply with the following criteria:

1. They are constructed of steel or other equivalent material;
2. They are suitably stiffened;
3. They are insulated with approved non-combustible materials such that the average temperature of the unexposed side will notrise more than 140 degree C above the original temperature, nor willthe temperature, at any one point, including any joint, rise more than 180 degree C above the original temperature, within the time listed below:
   • class ‘‘A-60’’ 60 min
   • class ‘‘A-30’’ 30 min
   • class ‘‘A-15’’ 15 min
   • class ‘‘A-0’’ 0 min
4. They are so constructed as to be capable of preventing the passage of smoke and flame to the end of the one-hour standard fire test; and
5. The Administration required a test of a prototype bulkhead or
6. deck in accordance with the Fire Test Procedures Code to ensure that it meets the above requirements for integrity and temperature rise.

‘‘B’’ class divisions are those divisions formed by bulkheads, decks, ceilings or linings which comply with the following criteria: