Common Reasons Local Exhaust Ventilation (LEV) Systems Stop Performing Effectively

A Local Exhaust Ventilation (LEV) system is designed to protect employees by capturing hazardous dust, fumes, vapours and airborne contaminants at source. However, like any engineered system, an LEV installation requires regular maintenance, inspection and testing to continue operating effectively.

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Many businesses assume that once an LEV system has been installed it will continue working indefinitely. In reality, system performance can gradually decline over time, often without obvious warning signs.

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At A-Mac Environmental, we regularly inspect, test and maintain LEV systems throughout Scotland and frequently identify issues that reduce extraction performance and increase employee exposure to hazardous airborne contaminants.

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1. Blocked or Dirty Filters

One of the most common causes of poor LEV performance is blocked filtration.

As filters collect dust and contaminants, airflow becomes restricted, reducing the amount of air the system can extract.

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Signs of blocked filters include:

• Reduced extraction performance

• Dust escaping into the workplace

• Increased fan noise

• Higher energy consumption

• Poor airflow at extraction points

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Routine filter inspections and replacements are essential to maintain system efficiency.

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2. Damaged Ductwork

Over time, ductwork can become damaged through corrosion, vibration, accidental impact or general wear.

Leaks within the ducting allow contaminated air to escape and reduce airflow throughout the system.

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Common ductwork issues include:

• Air leaks

• Loose joints

• Corrosion

• Damaged flexible hoses

• Dust build-up inside ductwork

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Regular inspections help identify problems before they significantly affect system performance.

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3. Worn or Failing Fans

The extraction fan is the heart of every LEV system.

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If the fan becomes worn, damaged or incorrectly maintained, airflow throughout the entire system can be reduced.

 

Potential issues include:

• Worn bearings

• Damaged impellers

• Incorrect fan speed

• Motor faults

• Belt wear

• Excessive vibration

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Routine servicing helps extend equipment life and maintain reliable performance.

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4. Poorly Positioned Capture Hoods

Even a perfectly functioning extraction system will struggle if the capture hood is positioned too far away from the contaminant source.

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Small changes to machinery, production layouts or working practices can significantly reduce capture efficiency.

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Effective capture relies on:

• Correct hood positioning

• Adequate airflow

• Good operator practices

• Suitable hood design

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Sometimes simply repositioning the extraction point can dramatically improve performance.

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5. Lack of Maintenance

Like any industrial equipment, LEV systems require regular servicing.

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Without preventative maintenance, small problems gradually develop into larger failures that reduce efficiency and increase repair costs.

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Routine maintenance should include:

• Filter inspections

• Fan servicing

• Belt checks

• Ductwork inspections

• Airflow monitoring

• Cleaning of extraction equipment

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Preventative maintenance helps maximise system lifespan while reducing unexpected breakdowns.

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6. Changes to Production Processes

Many businesses expand production or introduce new machinery without reviewing whether their existing LEV system remains suitable.

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Examples include:

• Additional welding bays

• New CNC machines

• Increased production rates

• Different materials

• New chemical processes

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An LEV system designed ten years ago may no longer provide sufficient extraction for today's operation.

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7. Poor Original System Design

Unfortunately, not every LEV system is designed correctly.

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Common design problems include:

• Undersized ductwork

• Incorrect fan selection

• Poor hood design

• Insufficient airflow

• Inadequate filtration

• Poor system balancing

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These issues often result in ongoing performance problems, high running costs and repeated maintenance issues.

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8. Failure to Carry Out Regular LEV Testing

Many businesses only discover problems when their LEV system undergoes a Thorough Examination and Test (TExT).

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Regular LEV testing helps identify:

• Airflow reductions

• Filter problems

• Fan performance issues

• Damaged ductwork

• Capture failures

• Maintenance requirements

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Most LEV systems require testing at least every 14 months under COSHH Regulations, although some applications require more frequent examinations.

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Warning Signs Your LEV System May Be Failing

You should arrange an inspection if you notice:

• Dust collecting around machinery

• Welding fumes remaining in the workshop

• Strong odours lingering in the workplace

• Reduced suction at extraction arms

• Increased cleaning requirements

• Filters blocking more frequently than expected

• Higher energy consumption

• Excessive fan noise

• Employees complaining about air quality

• Previous LEV test failures

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Ignoring these warning signs can increase health risks and reduce workplace safety.

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How A-Mac Environmental Can Help

Our qualified P601 and P602 engineers provide complete LEV support, including:

• LEV inspections

• Thorough Examination and Test (TExT)

• Airflow testing

• Fault diagnosis

• LEV servicing

• Preventative maintenance

• Repairs and upgrades

• System redesign where required

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We help businesses identify problems early, improve extraction performance and extend the life of their LEV systems.

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Frequently Asked Questions

 

How can I tell if my LEV system isn't working properly?

Common signs include reduced extraction, visible dust or fumes escaping into the workplace, increased fan noise, poor air quality and failed LEV inspections. If you notice any of these issues, arrange a professional assessment.

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Can an old LEV system be repaired?

Yes. Many older systems can be upgraded with new filters, fans, ductwork or capture hoods rather than being completely replaced. We'll assess your existing installation and recommend the most cost-effective solution.

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How often should LEV systems be serviced?

Although Thorough Examination and Test is usually required every 14 months, routine servicing should be carried out much more frequently. The ideal maintenance schedule depends on the type of system, how often it is used and the contaminants being controlled.

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Does a failed LEV test mean the whole system must be replaced?

Not necessarily. Many failures are caused by issues such as blocked filters, damaged ductwork or poor airflow, which can often be repaired or adjusted without replacing the entire system.

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Keep Your LEV System Performing at Its Best

Regular maintenance, servicing and testing are the best ways to ensure your LEV system continues to protect your workforce and meet COSHH requirements.

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If you're concerned that your extraction system isn't performing as it should, A-Mac Environmental can help.

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Our experienced engineers provide professional inspections, LEV testing, maintenance, repairs and upgrades for businesses across Scotland, helping you maintain safe, efficient and fully compliant extraction systems.