What is the minimum residual pressure required at the hydraulically most remote 2 1/2 inch hose connection in a standpipe system?

What is the minimum residual pressure required at the hydraulically most remote 2 1/2 inch hose connection in a standpipe system?

• A. 20 psi
• B. 100 psi
• C. 50 psi
• D. 150 psi

Answer: (B)

In standpipe design, you must guarantee a minimum residual pressure at the hydraulically farthest 2-1/2 inch hose connection when water is flowing. This ensures the firefighter’s handline will still have enough pressure to deliver an effective flow at the nozzle, even after all the friction losses along the longest piping run. The standard minimum remaining pressure at that remote outlet is 100 psi. This value is chosen because it provides a practical margin so the nozzle can perform as expected under typical firefighting conditions, despite the friction losses in long runs, fittings, elevation changes, and valve losses. It keeps the system from under-delivering water to the most remote point. Why the other numbers aren’t the right fit: 20 or 50 psi would not reliably provide adequate nozzle pressure after losses in a long standpipe run, risking poor flow or inability to control the stream. 150 psi is more than necessary for the minimum design and could introduce undue stress or complications in the system’s components, without added benefit for the standard scenario.

In standpipe design, you must guarantee a minimum residual pressure at the hydraulically farthest 2-1/2 inch hose connection when water is flowing. This ensures the firefighter’s handline will still have enough pressure to deliver an effective flow at the nozzle, even after all the friction losses along the longest piping run.

The standard minimum remaining pressure at that remote outlet is 100 psi. This value is chosen because it provides a practical margin so the nozzle can perform as expected under typical firefighting conditions, despite the friction losses in long runs, fittings, elevation changes, and valve losses. It keeps the system from under-delivering water to the most remote point.

Why the other numbers aren’t the right fit: 20 or 50 psi would not reliably provide adequate nozzle pressure after losses in a long standpipe run, risking poor flow or inability to control the stream. 150 psi is more than necessary for the minimum design and could introduce undue stress or complications in the system’s components, without added benefit for the standard scenario.