Fume cupboard testing and LEV testing are essential when it comes to protecting your personnel from hazardous or noxious vapours, gases and dust produced inside fume cabinets.

It is because of the toxic nature of many of the processes carried out within fume cupboards that the Control of Substances Hazardous to Health (COSHH) 2002 Regulations apply. These regulations impose a duty on employers to manage the exposure of their employees to hazardous substances and, where it is not reasonably practicable to prevent exposure, to employ control measures to reduce it to an appropriate level, and fume cupboards are a common means of partially containing hazardous chemicals and preventing their release into the workplace environment.

COSHH requires all Local Exhaust Ventilation (LEV) systems, including fume cupboards, to be maintained in effective and efficient working order and they are also subject to inspection and fume cupboard testing and LEV testing every 14 months – or more frequently when risk assessments have identifed a high risk of exposure.

The COSHH Approved Code of Practice 5th edition 2002 and the HSE publication ‘Maintenance, Testing and Examination of Local Exhaust Ventilation’ provide detailed guidance for employers to help ensure fume cupboard testing and maintenance is carried out as required by the regulations to demonstrate LEV is operating as it is designed to and that it is adequately controlling exposure to hazardous substances.

LEV Testing – Fume cupboard and LEV testing by Tecomak.

How Fume Cupboards Work

There are two main types of fume cupboard – ducted, and recirculating (ductless). Both work with the same objective – to draw air away from the open end of the cupboard and either expel it into the outside environment or pass it through filters and back into the room.

Ducted Fume Cupboards

Ducted fume cupboards have externally located fan units connected to the fume cupboard via duct work. These fume cupboards generally pull air from their front aperture, through ducts to vent to a safe position on the roof of the building. This point of discharge is normally three metres above the roof line and from here the hazardous fumes can be safely diluted in the atmosphere.

Recirculating or Ductless Fume Cupboards

Recirculating fume cupboards are self-contained units that draw contaminated air away from the aperture, passing it through a filtration system and discharging it back into the room.

The type of filter used is dependent upon the class of the chemicals being worked with and all filters have a limited absorbency capacity. It is vital to ensure that the limit is not exceeded, as this can result in the release of hazardous substances into the work environment.

Recirculating fume cupboards are not suitable for work involving radioactive, highly toxic, carcinogenic or sensitising substances. In fact the Health and Safety Executive (HSE) do not recommend using these fume cupboards for exposure control of vapours or carbon nanotubes (HSE Control Guidance note 201 and HSE Risk Management of Carbon Nanotubes 2009).

The selection and fitting of recirculating systems must be carefully reviewed. Consideration should be given to whether such a unit can provide adequate, reliable control of the anticipated hazards and that the resources and a safe system of work are in place to ensure the unit is monitored and maintained.

Fume Cupboard Testing Standards

There are two main fume cupboard and LEV testing standards – British Standards BS EN 14175 for industrial ducted systems, and British Standard BS7989:2001 for recirculating or ductless units.

These two standards specify the safety and performance requirements for general purpose fume cupboards and also outline the technical specifications required for their design, manufacture, installation and containment. While historically, face velocity measurements have been used to demonstrate fume cupboard performance, current emphasis is on demonstrating containment, which is done by establishing a programme of regular tracer gas containment testing. The test methodologies suitable for fume cupboards are detailed in the British and European standard (BS EN 14175-2:2003), available from the British Standard Institute (BSI).

Test Criteria

The maintenance required for fume cupboards varies by manufacturer and they should be maintained within the performance thresholds, including expected face velocity and containment values, recommended and confirmed by them at the time of commissioning.

If you are using older units, or if you cannot find the manufacturer’s performance specifications, best practice velocity guidelines for ducted fume cupboards carrying out standard work with hazardous substances are that the face velocity should be 0.5m/s ±10% with the sash set to 500mm height, and if face velocities fall below 0.45m/s the unit should be removed from use until remedial work has been completed.

If you are using your fume cupboard to work with radioactive materials that could result in a gaseous or aerosol release, these may require a higher airflow velocity, usually 0.7 m/s or an average SF6 containment of 0.01ppm.

Fume Cupboard and LEV Testing Requirements

When it comes to fume cupboard and LEV testing, the HSE have updated their guidance in the second edition of their publication HSG 258 – ‘Controlling airborne contaminants at work: A guide to local exhaust ventilation (LEV)’.

While a variety of qualitative and quantitative methods may be employed for LEV testing, HSE guidance for fume cupboard testing states the need to measure face velocity and that any further testing should be carried out in accordance with BS EN 14175.

Testing of recirculating fume cupboards must also include particular filter and seal integrity testing and gaseous phase filter capacity testing as outlined in BS 7989:2001.

Before starting any testing, the equipment to be used must be appropriately calibrated and maintained and the performance specifications for the fume cupboard to be tested must be checked to ensure the correct ones are being used.

A visual inspection of the fume cupboard should then be carried out in accordance with BS EN 14175-4:2004 and HSG 258.

Fume Cupboard Testing Methods

Offering a wide range of services to meet the needs of our clients across the industries, at Tecomak for every test that we carry out we issue a routine test report. This will include the fume cupboard identification number, the date of the test, the type of test that has been carried out, the general room conditions at the time of the test, the results of our inspection and of the performance test, and any remedial actions that were needed. The tests we may carry out include:

Face velocity measurements

Measuring the average rate at which air is drawn through the opening of the fume cupboard, face velocity measurements are the conventional method for measuring fume cupboard performance. This is not, however, a direct measure of the containment ability of the fume cupboard.

Containment testing using tracer gas

Providing a quantitative measure of fume cupboard containment under normal working conditions, containment testing using tracer gas analyses the escape of sulphur hexafluoride – the tracer gas – from within the fume cupboard. This type of testing is particularly recommended for newly installed equipment and following any major repairs.

Tecomak’s LEV Testing Service

At Tecomak we believe in delivering a quality service in everything that we do. Whether you choose to work with us in a contract arrangement, allowing us to take the headache out of your scheduling with our timely reminders of your servicing needs, or whether you’d prefer to work with us on an ad hoc basis, our qualified engineers are trained to all relevant standards, including COSHH and BOHS, and they are CRB checked for school and healthcare environments. Offering a full end to end service we can act immediately on your test results carrying out maintenance, repairs and replacements to ensure your down time is minimised.

Fume Cupboard Testing – LEV and fume cupboard testing to meet all of your regulatory obligations.