Fume Extraction Systems
Extraction Systems · Extraction Systems overview
Fume extraction systems capture airborne fumes, vapours, mists and process emissions at source and remove them from the workplace before they enter operators' breathing zones. They are used across engineering, fabrication, laboratories, chemical processing, electronics and manufacturing — anywhere a process releases volatile or particulate emissions that need to be controlled at source rather than diluted across the room.
What fume extraction systems are used for
Fume extraction is the engineering control used wherever a workplace process generates an airborne emission that is hazardous, irritating or simply objectionable to operators downwind. Typical applications include soldering and electronics assembly, chemical handling and decanting, laboratory benches and fume cupboards, paint and adhesive use, hot-work processes, plating and surface treatment, and a wide range of industrial reactions and process equipment.
The aim is the same as any source-capture system: draw the emission into a hood or enclosure faster than it can drift into the breathing zone, transport it through ductwork, clean it through filters or scrubbers as required, and discharge cleaned air to a safe location. Where the substance is covered by COSHH, fume extraction is the engineering control that demonstrates exposure is controlled.
Fume, vapour, mist, smoke and process emissions
The word 'fume' is used loosely on the shop floor, but the distinction matters for extraction design.
- Fume — fine solid particles formed by condensation of a vapour, typically from a hot process. Welding fume, soldering fume and metal-vapour condensation are classic examples.
- Vapour — the gas phase of a substance that is normally liquid at room temperature. Solvent vapours, fuel vapours and many process chemicals fall into this category.
- Mist — small liquid droplets suspended in air, generated by atomisation, spraying or condensation. Metalworking fluid mist, paint spray and cooling-tower drift are common examples.
- Smoke — combustion-derived aerosol containing fine particulate, water vapour and gaseous combustion products. Generated by burning, oxy-fuel cutting and some plastics processing.
- Process emissions — a broader category covering anything released from process equipment, reactors, vessels or pipework during normal operation, sampling, decanting or maintenance.
Source capture, enclosure, filtration and discharge
Fume extraction systems are normally designed around source capture or enclosure. A capture hood is positioned close to the emission point — over a soldering iron, beside a chemical vessel, across the front of a fume cupboard — so that the emission is drawn into the inlet before it can drift. Full or partial enclosure of the process is preferred wherever it is practical, because it allows much lower extraction volumes for the same level of control.
Air cleaning depends on the emission type. Particulate fume is normally controlled by bag, cartridge or HEPA filtration. Vapours are controlled by activated carbon or other sorbent media, or by wet scrubbing for water-soluble or reactive vapours. Some emissions require a combination — pre-filter for particulate followed by carbon for the vapour fraction.
Discharge is just as important as capture. Cleaned air discharged near a fresh-air intake, an open door or a downwind window can re-enter the workplace and undo the work of the extraction system; discharge stack height, direction and proximity to neighbouring buildings all need to be considered.
Typical workplaces using fume extraction
Fume extraction systems are found across UK industry. Engineering and fabrication workshops use them for welding, soldering and hot-work processes. Laboratories rely on fume cupboards and benchtop extraction for chemical handling. Chemical and pharmaceutical processing depends on enclosed extraction at reactors, dryers, mills and dispensing booths. Electronics assembly uses local fume extraction at soldering stations. Surface treatment, plating, painting and adhesive bonding all generate airborne emissions that need extraction at source.
The common factor across all these sectors is that the emission is hazardous or irritating, and dilution alone cannot reliably keep individual operator exposures below the workplace exposure limit. Fume extraction at source converts an uncontrolled emission into a controlled one.
How fume extraction performance is reviewed
Where a fume extraction system is provided to control exposure to a substance covered by COSHH, it falls within Regulation 9 and must be examined and tested at suitable intervals — at least every 14 months — following the HSG258 methodology. The review confirms capture or face velocity at the hood, total extracted volume, condition of filters and air-cleaning equipment, integrity of ductwork, and how the system is used in practice.
Beyond the statutory test, a broader engineering review is sensible whenever the process changes, when new substances are introduced, when operators report symptoms or detectable odour, or when the existing extraction was designed for a different application. The review identifies whether the current system is the right answer for the current process and what targeted improvements would restore or extend its effective life.
Common fume extraction problems
Fume extraction systems tend to fail in recognisable ways across very different industries.
- Capture hood too far from the source, so the emission plume escapes into the room before reaching the inlet.
- Fume cupboard sash worked above the design opening, dropping face velocity below the level needed for safe containment.
- Carbon or HEPA filters left in service beyond their useful life, raising resistance and reducing extracted volume.
- Ducted systems extended or re-routed without re-balancing, leaving some hoods over-served and others starved of airflow.
- Discharge points relocated or new fresh-air intakes installed nearby, allowing re-entrainment of contaminated air.
- Operators bypassing the system because it is noisy, in the way, or perceived as unnecessary for short tasks.
Frequently asked questions
What is the difference between a fume extraction system and an LEV system?
In UK regulatory terms they describe the same thing: a powered system that captures a contaminant at source and removes it from the workplace. 'Fume extraction' is the common shop-floor phrase where the emission is fume, vapour or mist; 'LEV' is the HSE's preferred regulatory term, used throughout HSG258 and COSHH guidance.
Do laboratory fume cupboards count as fume extraction systems?
Yes. A fume cupboard is a form of partial enclosure with integral extraction, and where it is used to control exposure to a substance covered by COSHH it is examined and tested under the same Regulation 9 framework as any other LEV.
Can one fume extraction system serve multiple processes?
It can, provided the system is designed for the combined duty and the substances are chemically compatible inside the ductwork and filter. Adding new branches to an existing system without re-balancing, or mixing incompatible substances in shared ductwork, is a frequent cause of underperformance.
How often should fume extraction be tested?
Under COSHH Regulation 9, at suitable intervals and at least every 14 months for most applications. Some processes — particularly those with very low workplace exposure limits or high fume loading — benefit from more frequent statutory examination and in-house user checks between visits.
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