What is the duration of water supply required for NFPA 13D systems?

The correct answer reflects the requirement for the duration of water supply in NFPA 13D systems, which specifies that the water supply should be designed to provide a flow for 10 minutes in relation to the total system demand. This is crucial because NFPA 13D systems, which are typically used in residential fire sprinkler systems, are designed to effectively control or suppress a fire until the fire department arrives.

By using the system demand multiplied by a time frame, it ensures that the system is adequately equipped to manage potential fire scenarios adequately. The idea is to not only consider how much water is needed but also to ensure that the designed water supply can sustain that demand for an adequate period to effectively combat a fire.

This specific understanding allows for practical application in residential settings and is in alignment with design criteria for smaller scale systems where the structure’s layout and expected occupancy can affect the demand on the fire suppression system.

The other choices do not reflect the NFPA guideline quantitatively or qualitatively, as they present arbitrary figures that do not adequately factor in system demand, which is essential for the effective operation of the sprinkler system in emergency situations.