Fire protection requirements for access doors.

The core of fire protection requirements for building access doors lies in fire resistance limit matching and normally closed state management, and the specific level depends on the installation location and shaft type:

1. Classification of fire resistance Class C fire door (fire resistance limit ≥ 0.50 h): it is suitable for inspection doors of vertical shafts such as cable shafts, pipeline shafts, smoke exhaust ducts, exhaust ducts and garbage passages in ordinary buildings.
2. Class B fire door (fire resistance limit ≥ 1.00 h): it is suitable for the manhole of mechanical pressurized air supply system and the manhole with mechanical smoke exhaust pipe.
3. Class-A fire door (fire resistance limit ≥ 1.50 h): generally, it is not used for conventional tube well access doors, and it may be involved only when there is no horizontal fire separation at the floor of the shaft, or the access door of a specific equipment room, which needs to be determined according to specific design specifications.