See how far a soldering fume extraction nozzle actually reaches. Enter airflow, target capture velocity, and nozzle geometry to draw the isovelocity capture-zone contour, based on the Dalla Valle capture-velocity equations used throughout industrial ventilation design.
A fume extraction nozzle does not create a wall of suction. Velocity drops off very fast with distance from the face -- roughly with the square of distance for a round nozzle. The Dalla Valle equations (used throughout ACGIH's Industrial Ventilation manual) model this falloff and let you solve for X: the maximum distance at which the air is still moving at your required capture velocity.
Open pipe for a bare flex-arm hose end, flanged pipe if it has a disc or cone around the tip, or slot hood for a narrow rectangular extraction slot (common on bench-mounted rail extractors).
0.5 m/s is the commonly cited minimum capture velocity for low-toxicity soldering flux fumes with low momentum release (ACGIH-style guidance). Raise it toward 0.75-1.0 m/s for more aggressive fluxes, hotter irons, or when the source is farther from the hood.
Use the measured or rated volume flow at the nozzle, not the fan's free-air rating -- hose length, filters, and bends all reduce real delivered airflow.
The shaded contour is the outer boundary where air is still moving at your required velocity. The soldering point needs to sit inside that boundary, not at its edge, to allow a safety margin for cross-drafts.