What is the maximum allowable delay for an automatic smoke-activated door to start closing after smoke detection?

The maximum allowable delay for an automatic smoke-activated door to start closing after smoke detection is 10 seconds. This requirement is based on safety considerations in fire protection systems. The purpose of the delay is to allow for the potential of false alarms or transient conditions that may not necessitate the closing of the door. However, it is crucial for the closing mechanism to activate promptly to ensure that the smoke does not spread and that the door serves its intended purpose of slowing the movement of smoke and fire within a building.

Setting the delay at 10 seconds strikes a balance between accommodating brief incidents that are not indicative of a fire, while still ensuring that the door is responsive enough to protect occupants effectively. Delays longer than this could increase the risk of smoke spreading and compromise the integrity of the safety system.