Guide to Local Exhaust Ventilation Systems

LEV systems (local exhaust ventilation) capture and filter welding fumes at the source, protecting workers from harmful nanoparticles and carcinogens. Welding extract systems range from central ducted setups to mobile fume‑on‑gun units, each engineered to remove dust, vapours, and fumes before they disperse into the workspace. Proper design—selecting the right hood, ducting, filter, fan, and exhaust stack—ensures compliance with HSE WL3 guidelines and reduces reliance on respiratory protective equipment.

What Is Local Exhaust Ventilation (LEV systems)?

Local exhaust ventilation (LEV) is an engineering control that removes airborne contaminants at their point of origin by drawing polluted air through an extraction hood into a filtered system. It protects health by preventing dust, mist, vapour, and welding fumes from spreading into the general workplace atmosphere.

Why Welding Extract Systems Are Crucial

Welding fumes contain nanoparticles that can bypass respiratory defenses, enter the bloodstream, and travel to the brain, potentially causing long‑term damage. Carcinogenic metals like cadmium, chromium, and nickel in welding fume make effective extraction essential to minimize health risks. Also Read: Why You Need A Welding Fume Extraction System

Key Components of LEV Systems

A robust LEV system comprises five main parts:

1. Hood or Nozzle – Captures contaminants close to the source.

2. Ducting – Channels contaminated air to the filter or exhaust point.

3. Air Cleaner/Filter – Removes harmful particles before releasing air.

4. Fan and Motor – Creates the vacuum to draw air through the system.

5. Exhaust Stack – Safely discharges cleaned air away from work areas.
   

Types of Welding Extract Systems

• Central Extraction with Ducting and Arms: A fixed network serving multiple workstations, ideal for high‑intensity welding areas.
  

• Mobile Filter Units with Fume‑on‑Gun: Portable systems that attach directly to welding torches, offering flexibility for sporadic tasks.
  

• Canopy and Downdraft Hoods: Suitable for larger booths or table‑based work, capturing fumes as they rise or fall.
  

Best Practices and Compliance

HSE’s WL3 guidance categorizes welding exposure into high‑intensity, low‑intensity, regular, and sporadic, recommending LEV as the primary control for all indoor welding processes. Where LEV alone cannot reduce exposure below Workplace Exposure Limits, respiratory protective equipment (RPE) should supplement extraction. Regular maintenance—inspection of hoods, cleaning filters, and checking duct integrity—is vital to ensure continued effectiveness.

Conclusion

Implementing well‑designed LEV systems and welding extract systems is the most effective way to safeguard welders from hazardous fumes. By following HSE guidelines, selecting appropriate components, and maintaining equipment, workplaces can minimize health risks and ensure regulatory compliance. Related Post: Local Exhaust Ventilation and Welding Extract Systems: Essential Guide for Workplace Safety