Fire Flow Calculator Guide – NFF Examples, Decision Triggers, and Demand vs Supply Planning
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Fire flow estimates are best used as a planning compass: they help you estimate demand, then compare it to supply options. Use the Fire Flow Calculator alongside Hydrant Flow, Hydrant Finder, and fallback tools like Tanker Shuttle.
Jump to:Inputs · Examples · Decision triggers · What to do next
Open Fire Flow CalculatorWater Supply & Hydraulics PillarHydrant Flow
Training note: Fire flow formulas vary. Use your department’s preferred approach where applicable. The purpose is decision discipline, not perfect math.
Inputs (What Matters Most)
- Building size and construction: larger/heavier buildings generally increase demand and complexity.
- Involvement: demand grows quickly as involvement increases.
- Exposures: when exposures are threatened, demand can rise even if the main body isn’t fully involved.
Examples (How to Think, Not Just Compute)
- Small residential: demand may be manageable with one strong hydrant and stable hose package.
- Medium commercial / strip mall: demand often outpaces a single hydrant—plan redundancy and larger supply.
- Rural / fringe hydrants: demand can exceed supply quickly—set relay/shuttle triggers early.
Decision Triggers (Demand vs Supply)
- Demand > supply: improve supply (relay/shuttle), reduce demand (tactics/strategy), or transition based on SOP/SOG.
- Long lays + high demand: check stability with Friction Loss and compute PDP with PDP.
- Unknown hydrant reliability: verify primary/secondary hydrants (Hydrant Finder guide + field check).
What to Do Next
- Plan primary/secondary hydrants: Hydrant Finder
- Sanity-check supply: Hydrant Flow
- Stabilize delivery: Friction Loss → PDP → Pump Chart
- Fallback planning: Tanker Shuttle
