What is the minimum operating pressure for any sprinkler head in a residential (13D) system?

In a residential fire sprinkler system designed under the NFPA 13D standard, the minimum operating pressure for any sprinkler head is set at 7 PSI. This pressure ensures that the sprinkler heads can reliably activate and deliver the required water flow to effectively control or extinguish a fire. Maintaining this minimum pressure is crucial for the proper functioning of the system, as it allows for adequate water distribution throughout the designated coverage area of the sprinklers. Effective performance at this specified pressure contributes to the safety and protection provided by residential fire sprinkler systems. Higher pressures would not only be unnecessary but could also potentially lead to damage or inefficiencies in the sprinkler system.