What is the door closing speed requirement for non-structural closures under NSTM 600?

• A. 6 to 8 seconds
• B. 2 to 4 seconds
• C. 10 to 15 seconds
• D. 1 to 2 seconds

Answer: (A)

The speed is set to six to eight seconds to balance safety with effective containment. Closing a non-structural door within this range slows the motion enough to prevent dangerous air pressure surges and door slam injuries, while still sealing promptly to limit smoke, heat, or flood from moving between compartments. If it closed much faster, doors could slam or whip shut, injuring someone or failing to align properly; if it closed much slower, smoke or flood could spread longer before being contained. Non-structural closures are intended to compartmentalize without bearing structural loads, so the goal is a controlled, predictable closure that protects occupants and maintains isolation.