Engineering Methods

How FireCalc Pro
performs calculations

Industry-standard solver methodology with full traceability — every result referenced back to the applicable clause of AS2118, AS2419, AS4587, or NFPA.

Solver Methodology

Newton-Raphson primary solver

FireCalc Pro uses a Newton-Raphson iterative solver as its primary algorithm, with Hardy Cross as an automatic fallback. Both solvers converge to a residual tolerance of 0.001 L/min — significantly tighter than industry practice and well within the requirements of all supported standards.

01

Initialise network

All node pressures are seeded with reasonable initial estimates based on elevation and supply pressure.

02

Compute flows

Hazen-Williams or Darcy-Weisbach friction loss is applied across each pipe segment to determine flow distribution.

03

Check continuity

Flow balance residuals are calculated at every node. If any residual exceeds 0.001 L/min, the iteration continues.

04

Newton-Raphson correction

The Jacobian matrix of partial derivatives is assembled and solved for the pressure correction vector.

05

Hardy Cross fallback

If the Newton-Raphson system becomes ill-conditioned, the solver switches to Hardy Cross loop correction automatically.

06

Convergence & report

Once all residuals are below 0.001 L/min, results are finalised and the PDF report is generated.

Convergence tolerance0.001 L/min residual flow
Primary solverNewton-Raphson (Jacobian matrix)
Fallback solverHardy Cross loop correction
Friction methodsHazen-Williams & Darcy-Weisbach
Network topologiesTree, looped, gridded, combined
Node limitUnlimited (plan-dependent)
System Types

What can be calculated

Sprinkler System Hydraulics

AS2118NFPA 13

Tree, looped, and gridded pipe networks. Each node solves for pressure, flow demand from attached sprinklers, and residual pressure margin.

Input Parameters

  • Pipe material and C-value (Hazen-Williams)
  • Sprinkler K-factor and minimum operating pressure
  • Remote area size and hazard classification
  • Water supply static and residual pressures
  • Pump curves (if applicable)

Outputs

  • Node pressures and flows at each junction
  • Pipe velocities and friction losses
  • Design flow rate and residual supply pressure
  • Pass / fail determination with margin
Hazen-Williams · Newton-Raphson

Fire Hydrant Systems

AS2419NFPA 14

Hydrant main sizing from supply point to most remote outlet. Simultaneous outlet selection and booster pump verification.

Input Parameters

  • Pipe diameter, material, and run lengths
  • Number of simultaneous hydrant outlets
  • Town main available flow and pressure (C-factor test data)
  • Booster pump duty and standby curves
  • Elevation differences across the site

Outputs

  • Pressure at each hydrant outlet
  • Velocity through each pipe segment
  • Required pump duty point
  • Compliance assessment per AS2419 clauses
Hazen-Williams · Newton-Raphson

Hose Reel Calculations

AS2441

First-aid hose reel hydraulics including hose friction loss and nozzle back-pressure. Standalone and combined system configurations.

Input Parameters

  • Hose length, diameter, and friction coefficient
  • Nozzle type and minimum flow rate
  • Supply pressure at reel connection point
  • Combined load with sprinkler or hydrant system

Outputs

  • Available flow and pressure at nozzle tip
  • Friction loss through hose run
  • Minimum supply pressure required
  • Pass / fail per AS2441 requirements
Hazen-Williams

Water Mist Systems

AS4587NFPA 750

High-pressure water mist hydraulics using Darcy-Weisbach friction method, appropriate for the small-bore pipework and elevated pressures typical of mist systems.

Input Parameters

  • Pipe internal diameter and absolute roughness
  • Fluid viscosity (temperature-dependent)
  • Nozzle flow coefficient and operating pressure
  • Protection area and nozzle spacing

Outputs

  • Reynolds number and friction factor per segment
  • Pressure distribution across protection zone
  • Minimum operating pressure at each nozzle
  • Compliance with AS4587 / NFPA 750 density requirements
Darcy-Weisbach · Newton-Raphson

Combined Systems

AS2118AS2419AS2441

Simultaneous load analysis for buildings with multiple fire protection system types sharing a common water supply.

Input Parameters

  • Each system's individual demand (flow and pressure)
  • Shared riser pipe sizing
  • Total simultaneous demand on the water supply
  • Supply capacity (pump, tank, or town main)

Outputs

  • Combined demand at the supply connection
  • Worst-case scenario identification
  • Residual margin of the water supply
  • Complete pipe schedule for the combined network
Hazen-Williams · Newton-Raphson

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