What is the maximum delay in seconds for an automatic-closing fire door to close after smoke detection?

Automatic-closing fire doors are critical components in fire safety systems within commercial buildings. They are designed to close automatically in the event of smoke detection to prevent the spread of fire and smoke between different areas. The maximum delay for these doors to close after smoke is detected is set at 10 seconds.

This timeframe allows for any unintended triggers, such as temporary smoke from activities like cooking, to dissipate, while still ensuring that the door effectively aids in containing smoke and fire. A longer delay could compromise safety by allowing more time for smoke to spread, which could put occupants at risk.

Thus, the standard of a maximum delay of 10 seconds strikes a balance between minimizing false alarms and maintaining immediate response to genuine fire situations. This is why this specific answer is the correct choice. Other options, which suggest longer delays, do not align with the established safety protocols and standards for fire door operations.