LEV Testing

LEV testing should only be carried out by a competent person at regular intervals. Call us today to find out how we can help you comply with COSHH Regulation 9.

01782 614236

There are three different stages to the LEV test.

Stage 1 – Thorough visual and structural examination.

A visual examination of the system to check that all parts of the system are in good condition and clean. This check can comprise of all, or some, of the following parts.

An external examination of the entire system for damage and wear of the parts.
An internal examination of the ductwork.
Checks on the filter cleaning devices such as dust shakers or reverse air pulse systems to ensure they operate correctly.
Inspection of the actual air cleaner. For example, damage to the filter fabric can make it ineffective.
A check on the differential pressure gauges that measure the pressure drop across the filter material.
Checks on the water flow to wet back booths and wet scrubbers.
Checks on any alarms that the system may contain.
An inspection of the fan. Such as whether it is operating in the correct direction, and whether the drive belts are working effectively and if it is vibrating or noisy.
A check for settled dust around the hood.

Picture of containers showing the importance of visual examination

Stage 2 – A technical Test of the LEV’s performance.

A check of the technical performance to show if the system still meets with the commissioning data or other sources of relevant information.

Observations of the process and the hazard source.
Smoke to examine the airflow into the hood. This can also include the capture distance of capture hoods or air leakage from enclosures.
Dust lamps used while the process is operating to check for capture of the hazard by capture hoods or leakage from enclosures.
Measurements of the ventilations’ performance, such as
- Airflow velocity measurements from the hood and ductwork.
- Also, the calculation of the overall flow rate.
- Measurements of the static pressure behind the hood, in the ductwork and across the filter media.
- A check of the makeup air supply to ensure that it is efficient.
Checks of fan speeds and direction.
Checks of air cleaner performance for air that the LEV returns to the workplace.
Simulation of failures to ensure that alarms work correctly.
Synergy can also measure the levels of discharges to atmosphere through its stack emission monitoring service.

How the technical test is used

After the LEV Tester takes the measurements, they compare the results to the system design criteria. This can be in the commissioning report, the user manual or the requirements of HSG 258. It may then also be possible to make simple alterations to return the ventilation to full working order. An example of this is a system has become out of balance because of the position of its dampers. If the ventilation is not working correctly, then the owner should stop the system until its performance has been corrected.

Stage 3 – A test of the LEV’s effectiveness to control the hazard.

The purpose of the Test is to ensure that the ventilation continues to contribute to the control of exposure. Synergy uses

the visual and structural examination.
observations of the process and the way that the operator uses the system.
the technical measurements.
including workplace air monitoring to make this assessment.

If the ventilation is able to control the contaminant in all circumstances, then the technician issues a certificate (in a report) to show this.

Marking hoods

Synergy marks each of the hoods and test points on a system with a label. Where appropriate, the technician also marks it with the capture distance. The system is also labelled with a certificate to show that it has been checked and to show operators and supervisors when the LEV next needs a test.

If a system fails then Synergy attach a red fail label to show that the ventilation is not working effectively. For example, the reasons a system could fail are:

if the airflow is insufficient.
If the hood fails to capture, receive or contain the hazard effectively.

The technician may also use a red label for individual parts of the system that are not working correctly.

Report of LEV thorough examination and test

Report of LEV Thorough Examination and Test.

When the test is complete, Synergy’s examiners will judge whether the ventilation is assisting in the control of the hazard.

If the ventilation is not working correctly, then the report will give reasons why. It will also contain a list of prioritised remedial actions. This provides our customers with the actions that they must complete to return the system back to a state where they can be sure that control is effective.

Synergy’s reports contain:

- The name and address of the company owning the LEV.
- The date of the work.
- The date of the last test.
- The identification of each LEV and its location.
- The hazardous substances that it is controlling.
- The conditions during the examination.
- A schematic diagram of the system showing test points and hoods.
- Photographs of parts.
- The general condition of the LEV.
- Intended performance of the LEV for adequate controlling the hazards to COSHH Regulation 7 If there is no information available for this, then this shows the need for further assessment to meet regulation 6 to show that COSHH Regulation 7 is met.

Information to show if the plant is still meeting the recommended performance, or Details of adjustments and repairs that are needed to make the LEV meet these criteria.

Testing the Performance of an LEV

Testing the Performance of an LEV.

How the technician achieves their judgement about the performance:

Smoke tests.
Tyndall lamp check results.
Static pressure measurements.
Velocity measurements.
Air sampling Results.
Checks of the filter performance.
Details of the way that the operators use the LEV.
System defects.

The technician also notes adjustments and parts that need changing before the next LEV Test.

The report must be kept by the employer and be available for at least five years after the test. If there was no previous information about the LEV, the report should also contain enough detail to form the basis of a User Manual and LEV Logbook.

Test Methods

LEV Testing Methods.

There are numerous qualitative and quantitative methods that the LEV Tester can use to assess a system’s performance.

Full enclosures

The tester should measure the differential pressure across the envelope of the enclosure. Also, the pressure inside the hood should be less than the pressure outside it. That is to say, that the flow of air will always be into the enclosure.

Partial enclosures

For booths and fume cupboards Synergy measures the face velocities of partial enclosures. These should be in a grid pattern in the shape of the hood. These must not vary significantly across the face.

Receiving hoods including canopies and capturing hoods

The LEV Tester must measure the face velocity must in the same way as capture hoods. The examiner measures air velocities must at regular intervals along the slot length and should not vary significantly.

Hood Static Pressure

The technician measures the static pressure behind the hood. If there is a pressure gauge the LEV examiner uses this to check it is working correctly.

Plenum

The tester measures the static pressure of the plenum should along with the hood duct measurements.

Ducts

They measure the gas velocity in the duct behind each hood. This should be in a straight section of ductwork and away from any parts such as dampers, fans or changes in duct diameter. This will help avoid areas of turbulence. They calculate the flow of the gas using the diameter of the duct.

Fans

If there is a sufficient length of ductwork, then the technician makes measurements of the static pressure and gas velocity before and after the fan.

Where possible the direction of the fan and its RPM should be measured with a tachometer. We measure Air velocity at a series of points across the face of the booth. The tester places the anemometer should at the centre of a series rectangles.

Filters

The technician measures the static pressure before and after the filter, so that the pressure drop across the filter can be determined.

Where the system has a shakedown mechanism for cleaning the filter, the technician activates it before checking the pressure drop. If the air flow through the filter is the same as the fan, then it is not necessary to determine the flow rate across the filter. The technician checks the function and accuracy of any manometers (such as magnehelic gauges) in the system.

Special filter

Filtration of hazardous substances require a high-performance filter such as a HEPA filter Wet scrubber Measure the static pressure at the inlet and outlet to the scrubber. It may also be necessary to measure the pH if it is relevant to the performance of the air cleaner.

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