Probable Peak Demand (WSFU to GPM)

Hunter's-curve probable peak flow in GPM from total water-supply fixture units, for flush-tank or flush-valve systems.

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Formula and source

gpm = interpolate(curve, wsfu): piecewise-linear between published [WSFU, GPM] breakpoints for the selected system type (flush tank or flush valve). Flush-valve systems peak higher at low WSFU.

Hunter's curve (NBS BMS65, Methods of Estimating Loads in Plumbing Systems) and IPC 2021 Appendix E (Table E103.3(2)) by name; the curve ships as editable breakpoints, not a transcribed table.

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