Our LEV Test and Service Engineers recently visited a local company in Hampshire, specialising in wood working and joinery.

The wood working company were due their 14 monthly LEV Test and Service on their wood dust extraction system and contacted us to carry our the LEV thorough examination.

Their system consisted of a large dust collector with multiple dust sock filters and with a compressed air cleaning system.

Wood dust is created during all stages of wood processing such as sawing, routing, sanding and other operations. Workers can also be exposed when the dust becomes airborne such as when removing dust from furniture, maintenance activities or when cleaning equipment (e.g emptying the bag from a dust extraction system or vacuum).

Whilst on site, the LEV Test and Service engineers used a number of calibrated measurement instruments to identify airflow levels across the extraction system. These instruments included a manometer with pitot tube – used for measuring in-duct airflow and static pressure. The engineers looked to achieve an in-duct velocity of around 15m/s for wood dust.

A hotwire anemometer was used to test the face velocities at the small hoods, such as articulating flexible arms and hoods above table saws.

For larger areas, such as partial and full enclosures, which may be found at sanding benches, chop saw locations. A Rotating Vane Anemometer (RVA) is used to measure intake velocity.

Further qualitative tests were carried out using high powered beam lamps and smoke release to verify capture and filter efficiency.

The data is then evaluated and compared to HSE industry standards to prove effective control and safe working environment.

LEV test and service report

What is Airflow Velocity?

Air Velocity is measurement of the rate of displacement of air or gas at a specific location

  • Flow is a measure of air output in terms of volume, per unit of time
  • Velocity refers to how fast the air is moving in distance, per unit of time
  • Pressure is the measure of force applied in an area

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LEV test and service velocity table

What was the outcome from the LEV Test and Service?

Whilst being on site the Engineers were able to advise the customer on improvements on their extraction system, in this case they identified two major factors that would contribute to the system to fail.

  1. Operator Interaction
    • As good as the system may perform, without the operators appropriately using the measures put in place, would automatically determine that the system may not pass its annual LEV Test.
    • Typically things our Engineers found on site were that the operators simply were not switching the extraction on or were working outside the extraction zone.
  2. Machinery
    • Quite often machinery is not designed with extraction in mind. Manufacturers do not always think about extracting dust caused during a process when designing wood working machines
    • Machinery such as a table saw sometimes has no extraction – this was the case at this company, which has again failed its test. This has resulted in the requirement for a capture hood or canopy to be installed.

Quite often incorrect hoods are used for a process. Hoods should be designed for a particular purpose in mind to ensure the best possible results are achieved, such as a capture hood for a table saw, unlike a canopy where the extraction would not control contaminant due to the force of the release.

Mixed contaminants can also be another issue with local exhaust ventilation. This can be where purpose designed systems are being used for other processes. For example a system designed for fumes and vapours is being used for powders. This can be very damaging to the system, particularly the fan, as contaminants should be filtered to avoid drop out and potential of a fire .

What is an advantage of using R&B Industrial?

As a company that specialises in reducing and controlling hazardous areas in workplaces, R&B Industrial Ltd can help with the design, supply and installation of bespoke capturing hoods, receiving hoods, small enclosures, walk in booths, partial and full enclosures for a wide range of processes.

R&B Industrial Ltd not only have a fully qualified LEV testing and design team, we can also provide Occupational Hygiene with our in house consultancy team. We can offer guidance on workplace monitoring, noise monitoring and DSEAR and ATEX consultancy services.

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Our dedicated team will be happy to help with any of your extraction and ventilation requirements.