Frequently Asked Questions

There isn’t a specific legal requirement to have airflow indicators or similar fitted to an extraction. But as an employer you do by law have to make sure your LEV system keeps working properly. One of main reasons why LEV doesn’t do what it should is because the airflow falls for some reason (eg build-up of material, damage to ducting etc), becomes inadequate and effective control is lost.

One simple way of checking this is the use of airflow indicators at the hood and this will provide you reassurance that the flow-rate is maintained,that the protection for employees is there and that you’re not wasting money. There are other ways of checking airflow such as using anemometer, or a dust-lamp or smoke tracer (with the work process running). However, an airflow indicator is currently the only method that will show the operator or supervisor immediately if there’s a problem, and HSE’s LEV guidance HSG 258 recommends these are fitted.

It is not possible to gauge effectively the speed (velocity) of the air entering an LEV hood ‘by hand’. A suitable airflow indicator should make it easy to see whether airflow is adequate.

It is not a specific legal requirement, but you should have some way of checking that adequate airflow is being maintained. If you decide to get airflow indicators, you should identify which LEV systems or parts of systems need to be addressed first.

Factors to consider in your decision include:

• The risk of exposure
• Whether the operator has to set the hood airflow
• Whether other checks are practical
• The cost
• New LEV systems will soon be fitted with airflow indicators as standard.

Health and safety law says you must assess the risks to your workers from hazardous substances – dusts, fumes, vapours, etc. – and decide what measures to use to protect their health.

If the measures you adopt include extraction systems (LEV) to remove the dusts, fumes, vapours etc. produced by your work processes or activities, then you must maintain the LEV in efficient working order so it continues to provide the necessary protection. You should also have a periodic thorough examination and test (at least every 14 months) and must keep this record for at least 5 years. In addition, you should have information on the installed LEV system to confirm it provides adequate protection, which should be kept for the life of the equipment.

It is a check that your LEV is still working as effectively as originally intended and is helping to protect your employees’ health. To be able to tell if it is still working as it should, you should be able to provide the examiner with information about the intended or designed performance of your system e.g. hood type and position relative to the process, airflow and other measurements.

This information might be in the form of an initial appraisal or commissioning report, if one was carried out, or for simple ‘stand alone’ systems it could have been provided as standard operating data by the suppliers of extraction equipment. Alternatively, it might be found in recognised guidance (including that from HSE) on simple processes/systems. For examples CLICK on this link http://www.coshh-essentials.org.uk/. If none of this is available, you could consider getting someone competent to advise you.

To assess if the LEV is still working properly, the examiner ideally needs to know what it was originally intended to do. When you obtained the LEV equipment, the supplier should have tested it on installation (or ‘commissioned’ it) to check it was working effectively and providing the necessary protection, as specified. If this did not happen then other sources of information may be available. See ‘What is the purpose of a thorough examination and test?’.

The person doing the examination should let you know whether the information you provide is adequate for assessing whether the LEV is working as intended. Many examiners can help you identify intended performance information.

The law says that a record of the thorough examination and test should be kept. The HSE Approved Code of Practice gives practical advice on what the report should contain, which includes details of the system’s intended operating performance. It is strongly recommended that you get a report that follows this guidance. If you do so you will probably be doing enough to comply with the legal requirement to keep a record.