Master LEV Best Practice in 10 minutes

Understanding what Local Exhaust Ventilation (LEV) is and how it works.

Local Exhaust Ventilation (LEV) is an engineering control designed to prevent hazardous contaminants spreading within the workplace. LEV captures and removes airborne, hazardous contaminants such as dust, fume, mists, vapours or gases.

For a local exhaust ventilation system to be considered thorough and effective, it should include the following 5 key components:

1. Hood – Where the contaminant enters the LEV system
2. Ducting – Carries the contaminant from the hood to the air cleaner and onto the discharge point
3. Air filter – Cleans contaminants from the extracted air
4. Fan – Pulls contaminated air into the hood, through the cleaning system and away from the work area to the discharge point
5. Discharge point – Releases the newly filtered air to a safe place

The image below shows how this looks in practice, but as LEV systems are often modular and feature different components, final set ups can come in all different shapes and sizes.

Typical applications for LEV systems

As mentioned above, LEV is used to extract different types of hazardous particles and because of this, it is used for a wide range of projects and has many different applications. Below are some of the most common and typical works we supply temporary LEV systems for.

Construction

• Office and commercial fit‑outs: Applied to prevent the spread of construction dust and odours within partially occupied or sensitive working environments.

• Healthcare, education or public buildings: Used to create negative pressure environments, minimising the risk of hazard migration and protecting vulnerable occupants during refurbishment or alteration works.

• Retail, leisure or hospitality refurbishments: Supports dust and vapour control during works carried out in live, customer‑facing environments.

• Data centre works: Prevents dust contamination of live IT equipment during installation or refurbishment.

• Concrete cutting, masonry and surface preparation: Used for source capture of high‑risk dusts, such as respirable crystalline silica, particularly in enclosed or sensitive areas.

Infrastructure

• Rail or station refurbishments: Used to control dust and fumes during cutting and drilling works in live passenger or operational environments.

• Tunnel or underground works: Deployed to remove dust and exhaust fumes where natural ventilation is limited and permanent systems are not yet available.

• Bridge or highway structure repairs: Applied to manage hazardous dusts and fumes during surface preparation and repair activities in confined zones.

• Water or wastewater facility upgrades: Provided to control airborne contaminants during refurbishment of enclosed process areas such as water tanks.

• Utilities and services diversions: Used for source capture during excavation, cutting or drilling in constrained urban locations.

Industry

• Plant shutdowns or turnarounds: Used to manage airborne contaminants during short‑duration maintenance and repair activities.

• Food and pharmaceutical manufacturers: HEPA‑filtered systems are used to maintain hygiene and air quality during works in controlled environments.

• Energy or power generation facilities: Supports effective dust and fume management during upgrade works in confined or high‑risk areas.

Defence

• Naval vessels during refit or maintenance: Used to control fumes during hot works, surface preparation and coating activities in enclosed onboard spaces.

• Dockyard and shipyard refurbishments: Applied to manage dust and vapours during structural repairs and fit‑out works within covered docks or workshops.

• Submarine or specialist marine platforms: Used to maintain air quality during refurbishment works in highly confined and sensitive internal compartments.

• Marine engineering workshops: Provides local extraction during machining, welding or composite repairs where fixed systems are unavailable or unsuitable.

• Operational waterfront facilities: Supports dust and fume control during maintenance or upgrade works while maintaining safe conditions for ongoing operations.

What hood should I be using?

Choosing the correct hood for your LEV system is vital to achieving effective control. There are 3 different types of hoods to choose from:

1. Enclosed - Surrounds the source of contaminants preventing any release into the wider space.
2. Receptor - Uses the natural buoyancy or velocity a contaminant has to move them towards the hood.
3. Capture - One of the most common used and is positioned next to the source, with a strong airflow from a fan that captures and extracts the contaminant.

What filter should I be using?

Particulate filters

Designed to trap heavy particulates such as particles created from cement dust and wood cutting. A medium grade filter like this is also 80% effective at removing smaller particulate matter down to 1 micron in size (PM1 - 1 μm) including some finer dust particles, industrial fumes, and bacteria spores.

They are often used as a pre-filter to remove the bulk of larger dust particles and protect the finer filters from being blinded by heavy dust loading during the extraction process. Without this, other filters would block and quickly become ineffective.

Fine filters

Good for visible dust removal and designed mainly for low-toxicity dusts or where the system is venting to a safe area.

Acts as a protective layer when using highly efficient filters up to HEPA standard.

High Efficiency Particulate Air (HEPA)

The most efficient filter available on the market, designed to give virtually clean air. Welding fume, burning fume, smoke and even airborne bacteria such as COVID can be caught with a filter of this efficiency.

To put the efficiency into perspective, HEPA filters an impressive 99.97% of 0.3-micrometer air particles, only 3 of every 10,000 particles make it through.

Gas filters

A particulate filter will not prevent gas from passing through it. Work that requires gas to be captured needs a filter with specific materials such as activated carbon. When gas passes across these filters, a chemical reaction causes the gas molecules to stick to the surface of the filter.

Local exhaust ventilation regulations

Uncontrolled dust and fumes are governed by the Health and Safety at Work Act 1974, The Dangerous Substances and Explosive Atmospheres Regulations 2002 and the Control of Substances Hazardous to Health Regulations 2002. These regulations are in place to protect teams like yours from hazardous exposure and the pressure doesn’t end with finding any solution, it ends with finding the right solution.

All the parts that make up LEV is required to have a Thorough Examination and Test (TExT) at least every 14 months within the UK. Here at RVT Group, we have a rigorous maintenance programme in place to ensure that every product is serviced between each hire, including carrying out a TExT. Read more about our TExT service here >

If a HSE inspector visits, they may request evidence of your TExT. It would be down to the site to ensure the tests have been done.

Top 5 requirements for a successful LEV system

1. The positioning of the hood

Positioning of the hood is vital for optimal capture of contaminants. For successful extraction, the hood should be placed as close to the contaminant as possible.

2. Airflow

Using an incorrect airflow would reduce the effectiveness of the LEV system. It must be strong enough to draw the contaminants away.

3. Design

Considerations for design include ensuring no kinks are within the ducting or sharp bends that could slow down the airflow, and ensuring the capture hood is suitable for the works being carried out.

4. Maintenance

All the parts that make up LEV is required to have a Thorough Examination and Test (TExT) at least every 14 months within the UK. Here at RVT Group, we have a rigorous maintenance programme in place to ensure that every product is serviced between each hire, including carrying out a TExT.

5. Training

Workers on site should fully understand how to use the LEV system, and the long-term health risks associated with exposure to the contaminants being extracted.

This information has been taken from our best practice guide for effective LEV use, download the full LEV whitepaper here >

Temporary LEV systems available to hire with RVT Group

RAVEX® Wandafilta Plus – Extraction & Filtration Kit

This LEV system is designed to capture both fume and dust with optimum efficiency. Powerful airflow means fumes from a wide range of activities can be extracted and filtered effectively, even from hard-to-reach areas. Includes capture hood, air filter, fan and ducting – all you need to find is the suitable discharge point.

DUSTEX®Superfilta

The DUSTEX® Superfilta is designed to capture dust at the source and, if required, can help create positive or negative pressure, helping protect sensitive work environments from dust and fume migration risks.

DUSTEX® Clearblast® 900G

Specialist dust extraction equipment designed specifically for abrasive blasting and fine dust filtration. Reliable, ATEX certified dust and debris containment with filtration up to HEPA standard, suitable for sensitive environments.

RAVEX® D1200

The RAVEX® D1200 can be used as a centralised vacuum system, extracting both dust and fumes via long duct runs and high duct velocities across multiple storeys. The unit has 8 extraction ports which can be split into further extraction points depending on project requirements.

The right local exhaust ventilation for dust or fume will depend on the work taking place and application. Our LEV engineers and technical consultants have undertaken extensive training to help ensure the LEV system in place is suitable for works taking place, protects the team effectively and is installed correctly.

If you need advice on which LEV system is best suited for your project, would like to book a free site survey or would like pricing for commercial sized local exhaust ventilation, speak with a consultant today