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Safe standoff distance

Minimum standoff R so the free-field overpressure at the target stays at or below an allowable value, for a given TNT-equivalent charge.

Civil-protection / accidental-explosion scope only (UFC 3-340-02, public release). Weapon-effects and penetration calculations are out of scope.

Inputs

Allowable overpressure ΔPkPa

Common thresholds: ~3.5 kPa glass breakage, ~7 kPa minor structural, ~35 kPa severe.

Equivalent TNT charge Wkg

Ambient pressure P0kPa

Results

Scaled distance Z—

Required standoff R— m

ΔP achieved at R— kPa

Citations

INVKinney-Graham ΔP(Z) inverted by bisection (monotonic), then R = Z·W^(1/3).

VERIFYRound-trip verified: Z=10, W=1000 → R=100 m recovers ΔP=9.99 kPa.

Engine: blast.js v0.1.0 · Method: Kinney-Graham (inverse) · Date:

Peak-overpressure tool

Preliminary calculation tool. Results are for preliminary sizing and cross-check only. Final design, sealed responsibility, and permit submissions require the full official text of the referenced regulations and the review of a licensed engineer.