NFPA 14 Standpipe and Hose Systems
Classes and demands
NFPA 14 standpipes are Class I (2½-in. fire department outlets), Class II (1½-in. occupant hose stations), or Class III (both). Class I and III systems are designed for 500 gpm through the hydraulically most remote 2½-in. outlet, with 100 psi residual at the topmost outlet. Class II is designed for 250 gpm at 65 psi at the topmost 1½-in. outlet. Where multiple standpipes are required, add 250 gpm for each additional standpipe, up to the NFPA 14 maximum. The IBC commonly requires Class I standpipes where the occupied floor is more than 30 ft above the lowest fire department access.
Layout rules
- Hose connections must be located so that all portions of the floor are within the hose reach allowed by the code; stairwells and horizontal exits are common locations.
- Standpipes need control valves, drain valves, pressure-reducing valves where pressures exceed limits, and fire department connections.
- Manual standpipes depend on the fire department pumper; automatic standpipes have a water supply. Do not size the pipe from the pumper alone.
- PRVs must be sized for the actual flow and not just static pressure.
Worked example
A six-story building has two Class I standpipes. Demand = 500 gpm for the remote standpipe + 250 gpm for the second = 750 gpm. The topmost 2½-in. outlet must see 100 psi. Add friction loss in the 6-in. main and risers, plus 0.433 psi per foot of elevation. A pump selection that supplies 750 gpm at the resulting pressure is required.
Traps
Using 65 psi for a 2½-in. outlet; forgetting the additional-standpipe flow; omitting PRVs on lower floors; and designing a manual standpipe as if it had an automatic supply.