Vertical openings for escalators may be protected by a draft curtain and closely spaced sprinklers if the area of the opening does not exceed how many times the horizontal projected area of the escalator?

In the context of vertical openings for escalators, the use of draft curtains and closely spaced sprinklers is a safety measure aimed at controlling smoke and heat movement during a fire. The effectiveness of these protective features depends on the size of the vertical opening relative to the horizontal projected area of the escalator.

When the area of the opening is limited to no more than two times the horizontal projected area of the escalator, it allows for effective management of smoke and heat, as the smaller opening minimizes the potential for rapid fire and smoke spread. This is particularly critical in maintaining occupant safety and ensuring that the fire suppression system is adequately capable of controlling fire dynamics.

In this case, adhering to a limitation of two times the horizontal projected area ensures compliance with fire safety standards while promoting enhanced protection in commercial buildings. Larger openings would require additional protective measures, highlighting the importance of maintaining appropriate dimensional ratios in fire protection design.