LEV - 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^[1] 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

LEV suppliers can fit airflow indicators if requested.

Not for all LEV. For instance, a manometer, measuring static pressure across the filter unit, can provide sufficient indication, for a simple LEV system consisting of a fan, an air-cleaner (eg filter), a duct and a hood.

It depends on the level of potential health risks. If risk is low, a simple indicator will be appropriate. More hazardous substances and circumstances may require more sophisticated, and potentially more costly, indicators eg with an alarm if airflow drops too low.

Whatever indicator is chosen, it will need to show clearly whether the airflow is adequate.

Example of a simple airflow indicator display

Green - Adequate airflow

Red - Inadequate airflow

'Tell-tales' such as pieces of paper or plastic hung to bend in the LEV hood airflow, do not provide an effective indication of airflow and they are delicate and easily damaged.

In all but very simple systems, extracting low hazard substances, they will not be effective, adequate or suitable.

No - there is no specific legal requirement on employers or examiners to label LEV.

The law is that the employer must maintain LEV system performance and should also arrange a thorough examination and test at least every 14 months.

The employer needs to know whether or not an examination has been done or when it's due, and so do supervisors and operators. Critically, they also need to know when a hood (or LEV system) has failed. Attaching labels is an effective way of easily providing this information.

HSE guidance recommends examiners label each hood with a test record. Alternatively, the test record label could alternatively be placed nearby, for instance, close to the system on-off switch. It should be clearly visible to the supervisor and operators.

Example of an LEV test record label

HSE guidance recommends that a red 'Failed' should be put on any hoods (or system) that has failed, to warn supervisors and operators directly and explicitly. This could be done by the examiner with agreement from the employer (client). Or, the label could be issued to the employer's responsible person.

With the label should come a short 'emergency' written report containing a clear description of what's wrong and a list of practical remedial actions.

Example of a "Failed" label

Once the employer has had the LEV hood or system repaired, a competent person needs to check that it is effective and adequately controls exposure. The 'Failed' label can then be removed.

Labels are recommended as a means of providing clear and simple indication that a hood/system is not functioning satisfactorily. Other means can be used, as long as it is clear to the employer and to the operators that the equipment requires rapid attention.

Competence is a combination of knowledge, skills and application experience that enables a person to do an effective and reliable job.

You have a legal responsibility to ensure that employee exposure to dust/fumes etc. is minimised and well controlled. LEV is an excellent way of doing this. People who supply, examine and maintain LEV need to be competent otherwise your LEV may not work properly, putting people's health at risk.

Competent people have the right mix of skills, knowledge and experience to do a good job. Ask about relevant qualifications and training, experience and previous work. A competent supplier will be able to supply references or testimonials - ask for them. If the cost is high, it might be worth visiting other sites and viewing other LEV installed by the supplier. A good supplier should also be able to train your staff to maintain the LEV.

Some trade associations keep lists of members who claim LEV competence - see LEV useful links page^[2]. Prepare a simple description of the work you want the person to do and give it to them. Ask them what qualifications, experience and types of LEV system they have designed or supplied before. Always get more than one quote.

No. A training course by itself will not make a person competent. Competence comes from a combination of knowledge, skills and experience. Some people with lots of experience, but with no formal qualifications, may be competent.

No. HSE mentions certain training courses in its guidance, as examples, but does not require suppliers to have these qualifications.

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 eg 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 COSHH Essentials ^[3]). If none of this is available, you could consider getting someone competent to advise you.

Carrying out a thorough examination and test of LEV equipment requires specialist skills and although it is possible to undertake this on your own, most businesses engage someone with specialist knowledge, experience and skills (See LEV Competence FAQs - what is competence?). It is important that the person who undertakes the thorough examination and test is competent to do so.

The examiner will use information about your equipment's intended performance to undertake the necessary examinations, tests and measurements to verify whether it is still meeting this level of performance. The report that they provide for you should clearly show whether this is the case and if it isn't, the report should clearly show what is wrong and what needs to be done to correct it.

It is important that you:

1. Read and understand your thorough examination and test report
2. Ask the examiner questions if you don't understand anything that it says
3. Make sure you act on the recommendations in the report.

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.

The person who undertakes your thorough examination and test must be competent to do so. See - Why do I need to employ or use competent people? for more information on competence. If you don't understand what the examiner is saying or what the report means, then ask. A good examiner will be able to tell you beforehand whether they have enough information for them to be able to check if your LEV system is working as intended.

For more information, see INDG408 - Clearing the air^[4].

A thorough examination and test is a detailed and systematic examination sufficient to ensure that the LEV can continue to perform as intended by design and will contribute to adequate control of exposure.

The employer (ie your client) has the duty in law to ensure control equipment is always working properly/to correct specification. LEV TExT is part of this. The purpose of the LEV and the TExT is to help to ensure that control of exposure is adequate and protects worker' health. You will have been engaged to provide the necessary competent support the employer's need to do this, and they will expect you to provide adequate service and advice. You should make sure you have sufficient information to be able to do this work.

Examples of the information which should be available in respect of the main components of the LEV system include:

• enclosures/hoods: maximum number to be in use at any one time; location or position; static pressure behind each hood or extraction point; and face velocity
• ducting: dimensions; transport velocity; and volume flow
• filter/collector: specification; volume flow; static pressure at inlet, outlet and across filter
• fan or air mover: specification; volume flow; static pressure at inlet; and direction of rotation
• systems which return exhaust air to the workplace: filter efficiency; and concentration of contaminant in returned air

In the case of simple LEV systems, often available for purchase 'off the shelf' and with known performance capability, the employer (ie your client) should be advised to obtain information on its intended operating performance, such as performance data (volume flow and static pressure at inlet etc) and other information from the equipment suppliers. HSE guidance such as COSHH essentials sheets and users' own COSHH risk assessments may be useful in comparing with current performance. If such information is not available, you may, in the case of unmodified, single-point, standard systems, be able to use your own knowledge to refer to information about expected performance for this type of equipment and use this in your report. Many design criteria are standard and should be known and used by competent examiners.

Where no information is available for non standard and multipoint LEV systems, then coming to a judgement on whether it meets its initial design and performance standards may be more difficult and, in some cases, not possible. In such cases, you can still undertake a TExT which will provide information on the current performance of the system.

Paragraphs 186, 187 and 189 of the COSHH Approved Code of Practice (ACOP) give guidance on what to cover and ways of making an examination assessment. However, it is possible that your report may not fully meet the advice in the ACOP to record performance with reference to the intended operating performance. If this is the case, you should indicate this in your report as well as providing information about how you have reached a judgement on whether the performance you have reported is effectively contributing to adequate control. Your examination should also identify any adjustments or repairs that you believe are needed.

Further guidance on the methods and techniques to use in conducting your examination can be found in HSE's publication HSG258 'Controlling airborne contaminants at work'^[5].

On-tool extraction is a specialised type of local exhaust ventilation (LEV) system. It has similar parts to a fixed LEV system (ie hood, hoses and the extraction unit with filtration). Unlike fixed LEV systems, however, these parts can be interchangeable – eg the same extraction unit and hose might be used with an angle grinder for one task and then a circular/chop saw for another. The flexible nature of on-tool extraction means that it can be used in a number of work situations. These can be subdivided into:

• 'fixed' system: where the same on-tool extraction system is regularly used for specific applications – eg in a car repair or joinery workshop.
• 'variable' system: where an extraction unit is used with a number of different tools / hoses for a variety of work tasks or activities – eg on a construction site.

This interchangeable nature means that all parts have to work together for the on-tool extraction to be effective. Some manufacturers/ suppliers provide complete 'harmonised' systems but parts from different makes and models can be used together providing they are compatible. Also check that the parts are fit for purpose – ie right for the work / substances involved. Poor design or performance of any part can significantly reduce the effectiveness of the system and the level of protection it gives. The most critical factors are to ensure the substance(s) involved is captured or contained by the hood and subsequently diverted into the extraction unit. If the hood is ineffective for any reason (eg it is incompatible with the tool design, damaged or weakened by deterioration) then control will be lost. You can find detailed information about on-tool extraction in CIS69^[6].

Yes. On-tool extraction is a form of local exhaust ventilation (LEV). The TExT ensures that the LEV system continues to meet its intended operating performance and effectively contributes to achieving adequate control as required under regulation 7 of COSHH^[7]. However, the TExT for on-tool extraction equipment is only necessary for the extraction unit itself. Other items are covered by your maintenance checks – see below.

The extraction unit should be thoroughly examined and tested at least every 14 months. More frequent testing may be required if regular wear and tear could prematurely reduce the unit's effectiveness. Keep a copy of the report issued by the examiner. Address any critical defects immediately. Putting a test label on an extraction unit is a quick and effective way of indicating to users that the unit has undergone a TExT, that it has passed and the next examination due date. This is particularly the case for situations where different people may regularly use the extraction unit such as the construction or hire industries.

You, as the employer, need to arrange for this if you own an on-tool extraction unit that will be used as part of an LEV system (eg with a tool with in-built hood and hose). Remember it should be carried out by someone who has the correct knowledge, skills and practical experience to ensure an effective and reliable job. Contact the manufacturer or supplier for more information if you are unsure.

When hiring, check with the hire company that the extraction unit has been appropriately tested. They own the equipment and have the responsibility to ensure the TExT has been carried out. Pay particular attention to the expiry date of the TExT when hiring extraction equipment for long periods. You will be responsible for ensuring that this equipment is not used after the TExT has expired if it is still on hire to you. Contact the hire company before this date and arrange for the equipment to be re-tested or delivery of an alternative with an up to date TExT.

Hire companies should provide you with information on how to use the equipment plus the inspection and maintenance requirements. The HSE website contains further information on the duties of hirer and suppliers^[8].

Yes. It's important to note that as well as a TExT, you need to regularly check the equipment is in good working order. This involves pre-use checks and more detailed maintenance inspections (eg weekly) to ensure the whole control system (ie hood, hoses and extraction unit) continues to provide satisfactory performance. Typical checks involve ensuring:

• any airflow indicator and built-in cleaning mechanism is properly working (eg by simulating a blockage)
• filters are replaced when necessary
• the equipment is regularly cleaned to stop dust building up
• the hood is correctly positioned and any connections are secure (this is particularly important where equipment is being interchanged)
• there is no damage or blockages to parts of the system
• the correct collection bags are fitted to the extraction device
• parts are compatible or suitable for the task being done

Follow the manufacturer's recommendation and instructions.

The principles for conducting a TExT for on-tool extraction are the same as for fixed LEV systems and outlined in 'Controlling airborne contamination at work' HSG 258^[9]. However, it is only necessary to thoroughly examine and test the extraction unit itself. This is because the interchangeable nature of on-tool extraction and the range of tasks it is used for make it impractical to test all the potential combinations. The condition and performance of the other components (ie hood and hoses) should be regularly checked by visual inspection as stated under COSHH^[10] Regulation 8. They should be replaced or repaired where there is damage or deterioration. It is the responsibility of the employer to ensure the extraction system is functioning properly and providing effective control each time the equipment is used.

The TExT of the extraction unit should consist of:

Stage 1: Thorough visual examination - of individual parts for presence, damage or wear that could affect control performance. This may include checking the:

• unit is complete with its standard items, correct signage and identification
• extraction unit body for damage that may indicate leakage (eg latches, seals, connections and any staining around the exhaust port)
• gauge(s) and indicator(s) if fitted are correctly working
• correct filter is used, properly fitted and its condition
• filter cleaning method is working correctly (where fitted)
• collection bags can be correctly fitted and removed
• unit is approved for explosive dust according to the ATEX Directive 94/9.EC if required

Stage 2: Measuring technical performance – of the extraction unit(s). This involves:

• measuring the performance of the extraction unit to make sure it is adequate (eg air velocity in a test hose adjacent to the inlet or calculating this from another measurement such as volume flow – use the LEV calculator^[11])
• checking the effective performance of any indicators fitted (eg by restricting the airflow in the test hose such that the velocity falls below 20m/s)

Both ought to be done in respect to the largest diameter tubing supplied by the manufacturer.

eg For dust class M or H machines this means checking against BS EN 60335-2-69 that the air velocity is greater than 20m/s (or the equivalent volume flow etc) and that the alarm / indicator operates when it falls below this.

• the extent of any general wear and tear
• if the unit still meets the minimum performance standards (eg that specified in standards or by the manufacturer)
• the condition of the filter and whether it needs replacing
• any other action required

Any suitable equipment can be used provided the results are accurate, reliable and repeatable. Examples include:

A Pitot static tube - This can be used in conjunction with a 'test piece' of smooth walled duct or pipe attached to the extraction unit inlet. Pre-drill a small hole into this test piece. Locate the Pitot static tube through this hole ensuring that it sits in the centre of the ducting. It should sit at least 7 times the diameter away from the opening not attached to the extraction inlet (eg 350 mm for a 50mm diameter duct). This allows the airflow to develop and provide more accurate/stable readings. The air velocity in circular ducts is not uniform, the centreline velocity is typically 1.2 times the average velocity. Simply divide the centreline velocity by 1.2 to give an estimate of the average velocity.

Manometer: Make sure that you have the correct information from the manufacturer (eg the pressure at which any low flow indicator fitted should operate). Take care when selecting analogue devices to ensure that the gauge can provide an accurate reading (ie is not subject to significant deflection).

A record should normally contain all of the information outlined in the Approved Code of Practice to the COSHH^[12] regulations. However, some of this is not practical for on-tool extraction; particularly where it may be used with a number of different tools / hoses for a variety of work tasks. Below is an outline of the information which should be collected: