Welding LEV Testing
Ventilation & LEV · Ventilation & LEV overview
Welding LEV testing is the structured examination of local exhaust ventilation equipment used to capture welding fume at source. In UK workplaces it sits at the heart of COSHH compliance for welding, providing the documented evidence that on-torch extraction, hooded extraction, downdraft benches and central welding fume extraction systems are still capturing fume effectively enough to keep welder exposure adequately controlled.
What welding LEV testing checks
Welding LEV testing — sometimes called LEV examination, LEV TExT or simply welding extraction testing — is a planned engineering review of the whole extraction system serving welding tasks. It is not a single airflow reading. The objective is to confirm that fume produced at the arc is being drawn into the capture hood, transported through the ductwork, treated by the filtration stage and discharged or recirculated safely, and that the system is performing as the original commissioning specification intended.
In practice a welding LEV examination follows the framework set out in HSE guidance HSG258 (Controlling Airborne Contaminants at Work) together with the manufacturer's commissioning data. It documents the equipment, its intended use, the welding processes it serves, and the measured performance compared with the benchmark established when the system was first installed or last verified.
Why welding LEV testing matters
Under COSHH Regulation 9, engineering controls provided to limit exposure to a substance hazardous to health must be subject to a Thorough Examination and Test at least every 14 months. For welding fume, which is now classified by IARC as a Group 1 human carcinogen and treated by HSE as a carcinogen for enforcement purposes, the credibility of that examination is central to demonstrating adequate control.
A welding LEV test that is reduced to a tick-box airflow check at the fan does not satisfy the duty. The examination is expected to evidence that capture is effective at the welder's working position, that the system is fit for the current pattern of welding work, and that any deterioration since the previous examination has been identified and is being managed.
Welding LEV testing, LEV examination and welding fume monitoring
These three activities are routinely confused and it is worth separating them clearly. Welding LEV testing — used here interchangeably with LEV examination and LEV TExT — assesses the extraction equipment itself: hoods, ducts, fan, filter, discharge, and the operator's use of the system. Welding fume monitoring, covered in detail under welding fume monitoring and welding air sampling, measures the welder's actual breathing-zone exposure to fume and metals against the Workplace Exposure Limits in HSE EH40.
The two are complementary. LEV testing answers the question 'is this extraction system still working as designed?'. Personal welding fume monitoring answers 'is welder exposure being adequately controlled in practice?'. A defensible welding fume risk management programme normally relies on both, with each informing the other when results drift outside expectation.
What is typically reviewed during welding LEV testing
The scope of a welding LEV examination is matched to the system and the work. The following elements are commonly reviewed against original commissioning data and HSG258 expectations.
- Hood type, position and proximity to the welding arc and fume plume.
- Capture velocity and capture envelope at the working position.
- Face velocity for hooded extraction, downdraft benches and walk-in booths.
- Duct condition — leaks, blockages, sharp bends, abrasion, deposits, dampers.
- Filter condition, pressure drop, cleaning cycle and replacement history.
- Fan performance, motor condition, drive belts and inverter set points.
- Discharge arrangement, recirculation safeguards and make-up air provision.
- User practice — how welders position the arm or torch and whether the system is switched on.
- Visible defects, damage, modification, missing components and informal repairs.
Common welding LEV problems in fabrication settings
Recurring issues seen in UK fabrication and engineering workshops include capture hoods left more than around 300 mm from the fume plume on movable arms, on-torch extraction disconnected or bypassed because of weight or fume gun damage, central systems running with overloaded filters and reduced flow, and downdraft benches partly obstructed by workpieces or parked tooling. Cross-draughts from open doors, fan dilution units and shop air mover fans can pull fume out of an otherwise adequate capture zone.
These are not unusual failures — they are normal wear, drift and operational pressure on systems that were specified for a tighter range of work than they now serve. The role of welding LEV testing is to identify them honestly and feed them into the COSHH review.
How testing evidence supports COSHH risk management
A welding LEV examination report provides documented evidence that the engineering control is being maintained and is performing as intended. Used alongside welding fume monitoring data and the COSHH welding risk assessment, it supports decisions about whether existing controls remain adequate, whether welder RPE assumptions are still valid, and whether changes in process, consumables or workload should trigger an early review.
The same report often informs capital decisions — for example whether an ageing central welding extraction system should be refurbished, replaced or supplemented with on-torch extraction for particular tasks. Linking LEV examination findings back to welding risk assessment and welding compliance is how the documentation becomes a working control tool rather than a filing exercise.
When welding LEV should be reviewed
Beyond the statutory 14-month interval, an earlier welding LEV examination is appropriate after any material change that could affect capture: relocation of equipment, change of welding process (for example moving from MIG to FCAW), introduction of stainless steel or coated metal work, an increase in welding duty, modification of ductwork, replacement of fans or filters, or any incident that suggests fume is escaping into the breathing zone. Welder-reported symptoms, visible fume drifting past the welder's helmet, or unexpected results from welding fume monitoring are also legitimate triggers.
Frequently asked questions
How often does welding LEV need to be tested?
Under COSHH Regulation 9, engineering controls used to limit exposure to substances hazardous to health must be subject to a Thorough Examination and Test at least every 14 months. For welding fume, earlier review is appropriate after process, consumable or layout changes, or where exposure or symptom evidence suggests control has drifted.
Is a fan airflow reading enough for welding LEV testing?
No. HSG258 expects a structured examination of hood, duct, fan, filter and discharge together with evidence that capture is effective at the welder's working position. A single fan reading does not demonstrate that fume is being captured at source.
Does welding LEV testing replace welding fume monitoring?
No. LEV testing examines the extraction equipment. Welding fume monitoring measures the welder's breathing-zone exposure against EH40 Workplace Exposure Limits. They answer different questions and are normally used together in a COSHH welding fume programme.
Who should carry out welding LEV examination?
The examination should be carried out by a competent person familiar with HSG258, the welding processes involved and the specific extraction equipment in use, with access to the original commissioning data or an equivalent benchmark.
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