Reverse-Lay Friction Loss
Single-pump and tandem (parallel) supply friction loss.
Example
You enter
- Hose diameter 2.5_in
- Total flow (gpm) 250
- Length (ft) 600
- Number of pumps 2
You get
- Single-pump friction 75 psi
- Per-pump friction (parallel) 18.8 psi
- Pump count 2
- Coefficient 2
Details, formula, and sources
Single-pump: FL = C × Q² × L. Tandem (parallel): FL_parallel = FL_single / n² where n is the number of parallel hoses (each carrying Q/n).
NFA hose-hydraulics training materials by name.
Free at usfa.fema.gov/training.
Estimate. AHJ and licensed fire protection engineer govern.
Field names used by the API: hose_diameter, gpm, length_ft, n_pumps, single_pump_psi, per_pump_psi, coefficient
- Equal flow split Q / n per parallel hose unless user supplies a measured imbalanceengineering practice