LEV System Design

Designing an Effective LEV System: Protecting Health at the Source

Local Exhaust Ventilation (LEV) systems are critical in controlling airborne contaminants at the source, preventing them from spreading into the workplace. A well-designed LEV system not only ensures regulatory compliance but also protects worker health and improves operational efficiency.

Here are key principles for effective LEV system design:

🔍 1. Understand the Hazard
Start with a thorough risk assessment. Identify the nature of the contaminant (dust, fumes, mist, gas, vapor), its toxicity, and the process generating it. This informs capture efficiency and airflow requirements.

🛠 2. Capture at the Source
The most effective LEV systems capture contaminants as close to the point of generation as possible. This can involve hoods, enclosures, or slotted vents designed specifically for the process layout.

📐 3. Proper Hood Design
Hood selection is critical—whether it's a receiving hood, enclosing hood, or capture hood, it should suit the task. Poorly designed hoods can drastically reduce system performance, no matter how powerful the fan is.

🌬 4. Maintain Adequate Airflow
Airflow must be sufficient to carry contaminants away. This involves calculating duct velocity, static pressure, and fan performance. Undersized fans or oversized ducts can render systems ineffective.

🔄 5. Minimize Resistance and Leakage
Smooth duct design with minimal bends, sealed joints, and appropriate materials reduces static pressure loss. This enhances system efficiency and reduces energy use.

📊 6. Include Monitoring and Controls
Pressure gauges, flow indicators, or alarms help ensure the system is functioning correctly. Automation can assist with fan speed control based on usage patterns or contaminant levels.

📅 7. Design for Maintenance
Easy access for inspection, filter changes, and duct cleaning is essential. A system that’s hard to maintain is likely to fail over time.

📜 8. Comply with Standards
Ensure the system meets local occupational health and safety standards (e.g., HSE COSHH in the UK, OSHA in the US) and recognized LEV guidance (e.g., HSG258).

A well-designed LEV system isn’t just an engineering solution—it’s a health safeguard. 

Getting it right from the start can mean the difference between long-term worker safety and chronic exposure issues.

Need help with LEV design or assessment? Drop us a line!