One possible location of the hydraulically most remote hose connection in a standpipe system is which of the following?

• A. At the farthest stair tower on the first floor.
• B. At the roof manifold.
• C. At the top of the stairs leading to the roof.
• D. In the basement

Answer: (B)

In a standpipe system, the point that is hydraulically most remote is the one that will experience the lowest pressure when water is flowing. Pressure in a piping system drops with elevation (static head) and with flow through the pipes (friction losses). The location at the roof, where the system’s main hose connections are gathered on the roof manifold, sits at the highest elevation and is farthest from the primary water supply. That combination makes it the point where the pressure is most reduced under operating conditions, so it’s the hydraulic remote point that engineers use when sizing pumps and evaluating performance.

A hose connection on the basement, or on the first-floor stair tower, or at the top of the stairs leading to the roof, would be at lower elevations and closer to the water supply, so they would not experience as great a pressure drop as the roof manifold. Therefore the roof manifold is the hydraulically most remote location.