Local Exhaust Ventilation System Cleaning

What is Local Exhaust Ventilation?

The Health and Safety Executive (HSE) report that, every year, thousands of employees contract occupational asthma and other lung diseases. They develop them because they breathe in too much dust, fumes and other airborne contaminants at their workplace.

An (LEV) local exhaust ventilation system uses extract ventilation to prevent, or substantially reduce, the level of these airborne hazardous substances. It draws pollutants, dust and noxious fumes away from a process or operation that would be harmful to operatives’ health. It usually consists of an extract inlet such as a hood, slot, booth or cabinet placed around or close to the point of release of the potentially harmful substance.

Typically it is connected by ducting via an extract fan to exit to atmosphere or returned elsewhere in the workplace having first been cleaned to make it safe for release.

Why must LEV’s be tested and maintained?

The HSE is mandated by the Government to reduce the incidence of work related respiratory disease and to achieve this by promoting better understanding and enforcement of COSHH Regulations relating to airborne particulates. They require that where, as a result of industrial and commercial operations, substances are produced which could be harmful to health by inhalation or contact they must be either contained or safely disposed of by a Local Exhaust Ventilation system.

The Regulations contain statutory requirements for the undertaking of formal examination and testing of LEV systems. Now premises which use LEV’s to control exposure are subject to inspection by HSE Inspectors to ensure the systems are properly designed and installed and subjected to thorough annual inspection by the premises owners or managers (more frequently for high hazard processes) to ensure they are operating to maximum efficiency. They should be given a visual check at least once a week. Failure to ensure compliance will result in enforcement notices being issued.

What does LEV testing involve?

Indepth will carry out a thorough inspection of all parts of the LEV installation and report on its performance and effectiveness. Where necessary, and with your agreement, we will carry out remedial work to restore the system to 100% extract effectiveness.

A Thorough Examination & Test of an LEV system in accordance with HSG258 carried out by us shall include:

Stage 1 Thorough visual & structural examination

This may include, as appropriate:

  • thorough external examination of all parts of the system for damage, wear and tear;

  • internal duct & hatch seal examinations;

  • checks that any filter cleaning devices work correctly;

  • inspection of filter fabric, check pressure guages;

  • check of water flow and sump condition in wet scrubbers;

  • checks that monitors and alarms are working;

  • inspection of the fan drives mechanisms;

  • checks for indications of effectiveness such as significant deposits of dust around the LEV hood or noisy fan operation.

Stage 2 Measure technical performance
  • measure air velocities in main & branch ducts, hood faces;

  • static pressures in ducts, hoods and air cleaners;

  • checking fan speed, motor speed and power consumption;

  • checking the replacement or make-up air supply;

  • testing alarms by simulating a failure and the alarms ability to detect a failure;

  • measuring air temperatures;

  • testing the air cleaner performance in recirculating systems.

Stage 3 Assess control effectiveness
  • careful observation of processes and sources;

  • assessment of how effective the LEV is at controlling operators' exposure;

  • smoke tests to determine leakages, eddying and the breathing zone;

  • dust lamp tests to check for escape of dust or mists;

  • observation on operators' method of work to ensure that these are suitable.

The above are contained within a report with schematics of the systems showing test points and components, photographs of the faults found, testing data, an executive summary, conclusions and recommendations.

LEVs and Fire Hazard

Some LEVs extract inflammable materials, for example from woodworking operations. These can accumulate in the extract ducting and will constitute a potential fire hazard to employees. Ensuring the safety of building occupants is a primary requirement of the Fire Safety Order (The Regulatory Reform [Fire Safety] Order 2005) and business owners and managers have a responsibility under this legislation to have removed, or at the very least minimised, conditions which are potential fire dangers.

As part of the Indepth service we not only check on the efficient extraction of substances which could be hazardous to health, but also inspect the internal condition of the extract ducting for the presence of inflammable deposits which could be a potential fire hazard to all building occupants. As part of our service we will then remove any fire hazardous material to ensure your compliance with the law.

On completion of our services we will provide you with a certificate confirming work carried out which can be used as evidence of compliance.

The results of all checks, tests, and records of any remedial work or repairs carried out on LEV systems must be kept available for a minimum of 5 years.