Question 235Safety & Environmental - Assistant Engineer

The correct answer is A) convection. The doors to a stair tower must be closed to prevent the spread of fire by convection. Convection is the transfer of heat through the movement of fluids, such as air or gases. When a fire occurs, the hot air and gases rise, creating a convection current that can carry the fire and smoke to other areas of the building. Closing the stair tower doors helps to contain the fire and smoke within the stair tower, preventing it from spreading to other parts of the building through this convection process. The other options are incorrect because: B) Conduction is the transfer of heat through direct contact, which is not the primary mechanism by which fire spreads in this scenario. C) Radiation is the transfer of heat through electromagnetic waves, which is also not the primary mechanism. D) Ventilation refers to the process of providing fresh air, which is not the specific reason for closing the stair tower doors.