Dust Extraction Systems
Extraction Systems · Extraction Systems overview
Dust extraction systems are engineered ventilation installations that capture airborne particulate at source and remove it from the working environment. They are the primary engineering control for woodworking, stone and ceramic processing, metal grinding, pharmaceutical handling, food and bulk-material industries — anywhere a process generates dust that operators would otherwise breathe in.
Why workplace dust extraction matters
Airborne dust is one of the most common occupational health hazards in UK industry. Respirable crystalline silica, hardwood and softwood dust, flour dust, welding-related metal dust, pharmaceutical actives and many process powders all have workplace exposure limits set under COSHH, and several are linked to chronic respiratory disease and cancer.
Industrial dust extraction is the control that converts a dusty process into a controlled one. Where dust is generated by cutting, grinding, sanding, sieving, transfer, bagging or cleaning operations, extraction at source captures the particulate before it can disperse into the room and into operators' breathing zones.
Capturing dust at source
Effective workplace dust extraction depends on capture velocity at the point the dust is released. The capture hood, enclosure or booth must draw air in fast enough to overcome the energy of the process itself — a high-speed grinding wheel throws dust outwards far more aggressively than a slow weighing operation, and the hood arrangement must reflect that.
Wherever practical, the most effective arrangement is partial or full enclosure of the dust-generating process, with the operator working through a controlled opening. Open hoods placed close to the source can work well for small, localised dust release; for larger or more energetic processes, enclosure is normally the only reliable option.
Inhalable, respirable, visible and settled dust
Workplace dust is not a single thing, and the type of dust influences both the health risk and the extraction design.
- Inhalable dust — the fraction that can be breathed in through the nose and mouth. Larger particles, but capable of depositing in the upper airways.
- Respirable dust — the much finer fraction that can penetrate deep into the lungs and reach the alveoli. This is the fraction of greatest concern for silica, hardwood dust and many metal dusts.
- Visible dust — what operators can see in the air or on surfaces. Visible dust is a warning sign but absence of visible dust does not mean exposure is controlled; the respirable fraction is essentially invisible.
- Settled dust — accumulated dust on horizontal surfaces, ledges and inside ductwork. Settled dust is a secondary source: any disturbance, sweeping or compressed-air cleaning re-suspends it into the breathing zone.
Hoods, ductwork, filters and housekeeping
Particulate extraction systems share the same building blocks as any LEV system but require particular attention to the things that go wrong when dust is involved. Duct transport velocity must be high enough to prevent dust dropping out and accumulating inside the ductwork — typically much higher than the velocities used for fume or vapour extraction. Bends, horizontal runs and dead-legs are common locations for build-up.
Filtration is normally provided by bag filters, cartridge collectors or, for heavier material, cyclone pre-separators feeding a finer secondary filter. Filter selection must match the dust loading, particle size and any combustion risk. Combustible dusts (wood, flour, metal fines, sugar) carry an explosion hazard and require additional engineering measures such as explosion venting, suppression or isolation.
Housekeeping interfaces directly with extraction. A system that runs cleanly will still produce some settled dust; cleaning should be by vacuum extraction connected to a suitable filter, not by sweeping or compressed air, both of which return dust to the breathing zone.
Common dust extraction problems
Workplace dust extraction tends to fail in predictable, recognisable ways.
- Poor capture — hood too far from the source, hood opening too large, or hood positioned so that draughts pull dust away from the inlet.
- Blocked or end-of-life filters raising resistance and reducing extracted volume, often masked by automatic damper compensation until performance collapses.
- Damaged or modified ductwork — flexible hose crushed, rigid duct dented, branches added without re-balancing.
- Wrong hood position relative to the operator's stance, so that contaminated air passes through the breathing zone before reaching the hood.
- Users bypassing the controls — switching off extraction to reduce noise, removing booth panels for access, or sweeping rather than vacuum cleaning.
COSHH, LEV testing and practical exposure control
Where dust extraction is the chosen control for a substance covered by COSHH, the system must be examined and tested at least every 14 months under Regulation 9, following the HSG258 methodology. The test confirms capture velocity, airflow, filter condition, system integrity and user practice, and produces a defensible record that exposure is being controlled.
Statutory testing is one element of a wider COSHH programme. Practical exposure control also depends on selecting suitable extraction in the first place, training operators to use it correctly, maintaining filters and ductwork on a planned schedule, and reviewing the arrangement whenever the process changes.
Frequently asked questions
What is the difference between dust extraction and general ventilation?
General ventilation reduces room-average dust by introducing fresh air, but it cannot prevent high local concentrations at the source. Dust extraction captures particulate before it disperses, and is the normal control for any process generating significant or hazardous dust.
Do dust extraction systems need a LEV TExT?
If the system is provided to control exposure to a substance covered by COSHH — and most dust extraction is — it falls within Regulation 9 and must be examined and tested at suitable intervals, normally at least every 14 months.
Can a workshop vacuum count as dust extraction?
A vacuum captures already-settled dust. Source-capture dust extraction prevents the dust becoming airborne in the first place. Some on-tool extraction units combine both functions, but a general workshop vacuum is not a substitute for an engineered extraction system on a dust-generating process.
How often should extraction filters be changed?
Filter life depends on dust loading, particle size and operating hours. Many systems include pressure indicators or differential-pressure alarms that signal when the filter has reached the end of its useful life; planned filter changes based on these indicators are normally more reliable than a fixed time interval.
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