What is the minimum flow rate for the hydraulically most remote standpipe?

• A. 100 gpm
• B. 500 gpm
• C. 250 gpm
• D. 750 gpm

Answer: (C)

When designing a standpipe system, the determining factor for minimum flow is the hydraulically most remote outlet—the farthest point from the water source. You must ensure that, even with the greatest friction losses along the longest run, this outlet can still deliver a practical firefighting flow. The standard specifies a minimum flowing rate of 250 gallons per minute for that hydraulically most remote standpipe. This value reflects a balance: high enough to provide an effective handline flow through the longest, most restrictive path, yet not so high that it imposes unnecessary demands on pumps and piping in typical buildings. Higher numbers aren’t required by the minimum, though they can occur in higher-demand designs.