Airflow is the engine of dust extraction, but more flow is not always better. What matters is the velocity at the point of release and the ability of the system to maintain that velocity under load while moving dust through the duct without settling.

Capture velocity falls with distance

Air speed drops quickly as you move away from a hood or tool shroud, so doubling the hood distance can cut capture dramatically. The practical answer is to get the hood close and shape the inlet to pull air uniformly. A bellmouth or flanged hood reduces entry losses so more of the extractor’s capacity reaches the plume.

Under-load airflow beats free-air numbers

Filters, hoses, bends, and tool-mounted shrouds add resistance. As filters load, airflow falls. Size equipment using realistic under-load figures and keep resistance low: use the shortest feasible hose, smooth-bore ducting, and large-radius bends. Monitor differential pressure across filters to know when cleaning or replacement is needed.

Keep dust moving in the duct

Airflow must be high enough to carry dust to the hopper or collection bag. Too low and material settles; too high and you waste energy and create noise. Balance hood capture needs with conveying needs. Seal joints to stop leaks that rob flow, and avoid long runs of flexible hose which increase friction.

Simple site checks and adjustments

• Verify hood performance with smoke or tissue tests; adjust distance and angle until the plume is drawn in.
• Close unused branches with blast gates; fix leaks at joints and tool shrouds.
• Shorten hoses, reduce sharp bends, and avoid tight reducers that choke flow.
• Track filter loading with a gauge; clean or change before flow drops below target.
• Confirm improvements with a particulate monitor or air quality meter.

From a compliance standpoint, keep exposure below relevant WELs (e.g. 0.1 mg/m³ for respirable crystalline silica under HSE EH40). In practice, you hit that by protecting capture velocity at the task and maintaining airflow as the system loads.