Local exhaust hood capture velocity

modified2026-07-21statusfinished

ACGIH Industrial Ventilation Manual — exhaust flow required to achieve a capture velocity at a set distance from an unflanged plain opening.

[4.3] Governing equation

$$Q=v_x\left(10X^2+A_{\text{hood}}\right)$$

Imperial units: $v_x$ in fpm, $X$ in ft, $A$ in ft², $Q$ in cfm. Source: ACGIH Industrial Ventilation Manual.

FIG. 01 — capture velocity vx decays with distance X from an unflanged opening

Capture velocity vx (fpm) Distance X (ft) Hood face area A (ft²)

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