Which factors influence water supply design for a new sprinkler system?

• A. Design density, area of coverage, pipe friction losses, elevation changes, and residual pressures.
• B. Elevation changes and residual pressures only.
• C. Design density and area alone.
• D. Number of doors.

Answer: (C)

Water supply design is driven by the system’s hydraulic demand, which comes from how much water the sprinkler system must deliver to control a fire across the protected area. The core factors that set this demand are the design density (the required flow per unit area) and the area of coverage (the total space to protect). Multiply density by area to get the total flow the water supply must be able to deliver, and that figure guides sizing of pumps, mains, and storage to meet that need at the required pressures.

Elevation changes, friction losses in the piping, and residual pressure requirements aren’t used to determine the basic demand; they’re part of the hydraulic calculations used to verify that the supply can actually meet the demand across the system and to determine required pump head and pressure at different points. The number of doors has no bearing on the water supply calculation.