At a minimum, the water supply must deliver the required volume of water to the highest sprinkler in a building at a residual pressure of how many psi?

At a minimum, the water supply must deliver the required volume of water to the highest sprinkler in a building at a residual pressure of how many psi?

• A. 10 psi
• B. 15 psi
• C. 20 psi
• D. 25 psi

Answer: (B)

The key idea is ensuring the water supply can deliver the required flow to the farthest sprinkler with enough pressure to make it operate properly. The highest sprinkler in a building loses pressure along the way due to friction and elevation, so the system must keep a minimum residual pressure at that point. That minimum is 15 psi, which NFPA 13 design criteria use to guarantee there’s enough pressure to achieve the correct flow and reliable activation at the most hydraulically remote sprinkler. Pressures as low as 10 psi risk inadequate discharge, while 20 or 25 psi would go beyond the required minimum and isn’t needed to meet the standard.

The key idea is ensuring the water supply can deliver the required flow to the farthest sprinkler with enough pressure to make it operate properly. The highest sprinkler in a building loses pressure along the way due to friction and elevation, so the system must keep a minimum residual pressure at that point. That minimum is 15 psi, which NFPA 13 design criteria use to guarantee there’s enough pressure to achieve the correct flow and reliable activation at the most hydraulically remote sprinkler. Pressures as low as 10 psi risk inadequate discharge, while 20 or 25 psi would go beyond the required minimum and isn’t needed to meet the standard.