Hydrant Flow Test & Rated Capacity Calculator (NFPA 291)

Compute discharge GPM from orifice diameter, pitot pressure, and coefficient, then project available fire flow at standard 20 PSI residual pressure.

🚨 Active Fireground Emergency For active structural fires or life hazards, dial immediate emergency dispatch Call: 911 / 112

📋 Standard Operating Guidelines & Verification Protocol

Verified Standards

Verify full PPE compliance and secure personal accountability tags prior to entry. Confirm primary water supply established and verify uninterrupted supply line integrity. Coordinate tactical ventilation with interior fire attack nozzle advancement. Designate Rapid Intervention Team (RIT) equipped with dedicated hose line and rescue air pack. Execute regular Personnel Accountability Reports (PAR) every 15-20 minutes or after tactical shifts.

NFPA 291 Hydrant Testing Methodology

Hydrant flow testing determines municipal water main capacity and identifies localized tuberculation or valve bottlenecks. Test procedures involve recording static pressure, residual pressure on a designated pressure hydrant, and flow pitot pressure on one or more discharge hydrants.

NFPA Hydrant Color Classifications (Rated at 20 PSI)

Class AA (Light Blue): 1,500 GPM or greater — Ideal for heavy industrial complexes and high-capacity master streams.
Class A (Green): 1,000 to 1,499 GPM — Standard for commercial districts and multi-story multi-family housing.
Class B (Orange): 500 to 999 GPM — Common throughout single-family suburban subdivisions.
Class C (Red): Less than 500 GPM — Inadequate for simultaneous interior attack and exposure protection; requires immediate secondary supply establishment.