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Free fire protection calculators and guides
Quick browser calculators with the method explained. Nothing you type leaves your browser.
Hazen-Williams friction loss calculator (sprinkler pipe)Free online Hazen-Williams friction loss calculator for fire sprinkler pipe: psi per foot, total loss, elevation and velocity.Open calculatorHow to do a fire alarm battery calculation (with free calculator)Step-by-step fire alarm battery calculation with a free calculator: standby and alarm amp-hours, safety margin and battery size.Open calculatorHow to calculate NAC voltage drop (with free calculator)How to calculate fire alarm NAC voltage drop with the end-loaded method, plus a free calculator with pass/fail and max circuit length.Open calculatorHow to check a fire pump curve against demand and water supply (with free calculator)Check a fire pump against your sprinkler demand and water flow test: supply curve, pump curve at demand, margin, churn and 150% flow checks, with a free calculator.Open calculatorHow to do a sprinkler density/area flow calculation (with free calculator)How to estimate sprinkler system demand with the density/area method: design flow, number of flowing sprinklers, remote head pressure from the K-factor, and hose allowance, with a free calculator.Open calculatorHow to read a hydrant flow test (with free calculator)Turn a static/residual hydrant flow test into available flow at any residual pressure with the N^1.85 formula, plus a free browser calculator.Open calculatorFire alarm secondary power calculator (standby + alarm)Estimate fire alarm secondary (battery) capacity from standby and alarm currents and required durations, with a free browser calculator. Educational only.Open calculator
Need the whole calculation, not just one check?
The Excel workbooks handle full flow paths, 40-device battery tables and 30 circuits per sheet.