During a recent inspection of a woodworking LEV system, our engineers identified a series of serious faults that had been missed in a previous examination — just one month earlier. The system, used for extracting fine hardwood dust, had been operating well below safe performance levels and presented both occupational hygiene and explosion safety risks to the workforce.
Background
Wood dust — particularly from hardwoods such as oak and beech — is a known carcinogen under COSHH (HSE EH40/2005). Prolonged exposure can lead to nasal cancer, asthma, and chronic respiratory illness. In addition, the accumulation of fine combustible dust poses a significant fire and explosion hazard if not properly controlled.
Maintaining LEV systems in full working order is therefore not only a compliance requirement under COSHH Regulation 9 but also critical to employee safety and business continuity.
Findings
Our inspection went beyond a standard pass/fail TEXT report. Through detailed mechanical assessment and performance testing, we uncovered multiple underlying issues:
- Corroded door seals on the filter housing, allowing moisture ingress.
- Over-caked filters, reducing airflow by approximately 40%.
- Failure of the shaker mechanism due to lack of maintenance.
- Over 50kg of wood dust and shavings accumulated in the ducting, restricting flow and creating a serious fire risk.
- Three split flexible hoses leaking directly into the workspace.
- No duct velocity test points, meaning proper testing had never been carried out.
- Explosion relief doors had been sealed shut by a previous maintenance operative in an attempt to stop moisture ingress — rendering the explosion relief system non-functional.
Root Cause
Moisture ingress through the corroded seals caused filters to over-cake and choke the system. As airflow dropped, dust began to fall out of suspension, blocking ductwork and worsening velocity depletion. The sealed explosion relief doors meant the system could no longer safely vent pressure in the event of a deflagration — a potentially catastrophic modification that compromised the entire safety design of the extraction unit.
Actions Taken
- Replaced all corroded door seals and split flexible hoses
- Overhauled the shaker mechanism and carried out a complete duct and filter clean-down
- Removed the sealed explosion panels and reinstated the correct explosion relief doors to ATEX-compliant specification
- Installed permanent duct velocity test points for future verification
- Restored airflow performance to design standard
- Delivered user and supervisor training on system checks and maintenance responsibilities
Results
Following the remedial works, the system achieved capture and transport velocities in accordance with HSG258 guidance values. The occupational exposure risk to hardwood dust was significantly reduced, and the explosion safety design was reinstated to manufacturer and ATEX requirements. A structured maintenance plan and inspection schedule have since been implemented to maintain compliance.
Key Takeaway
This case highlights the risks of incomplete or superficial LEV inspections. A recently “signed-off” system can still conceal major performance and safety issues if the inspection lacks technical depth. In this instance, our engineers prevented potential health, fire, and explosion hazards through a thorough, standards-based approach to testing and engineering control verification.
