Which statement accurately describes hydraulic calculations in NFPA 13?

• A. They estimate the number of occupants in a building.
• B. They determine the required water supply and pressure to reliably deliver water to all sprinklers during a fire event.
• C. They assess the structural fire resistance of building elements.
• D. They size electrical components for the fire pump.

Answer: (B)

Hydraulic calculations in NFPA 13 are used to confirm that the water supply and system pressure are capable of delivering the required water to every sprinkler head during a fire. This involves calculating the flow and pressure demands of the entire sprinkler network, accounting for pipe sizes, lengths, fittings, elevations, and the simultaneous operation of multiple heads. The goal is to ensure that, under fire conditions, the water flow and pressure at the most hydraulically demanding sprinkler meet the design requirements, which may also dictate pump sizing, pipe sizing, or additional water supply as needed. This focus is distinct from estimating occupant numbers, assessing structural fire resistance, or sizing electrical components for a fire pump.