what is a Local Exhaust Ventilation (LEV) System?

An LEV system is not a simple extract system but is mainly used for the removal of harmful fumes and dust. This video below prepared by the Health and Safety Executive explains in more detail. As I often find people confusing normal ventilation systems with Local Exhaust Ventilation, LEV for short when they are very different pieces of equipment with different maintenance and legislation.

Transcript :-

Lots of different jobs across different industries involve work processes that create dust and

fumes. If these are not controlled properly people can breathe them in and develop diseases

such as asthma, lung scarring and cancer.

Every year thousands of people in Great Britain die as a result of breathing in harmful dusts

and fumes at work. The common way businesses can control dust and fumes is by using local

exhaust ventilation systems or LEV, also called extraction or fume control.

LEV systems can be very effective at controlling dust and fumes but it is vital that people

understand how LEV works so that they buy the right LEV and use it properly.

LEV systems all work in the same way.

In this example 2 hoods are used to enclose the saw blade, one above the table and one

below. The LEV airflow into these hoods carries the wood dust away. The contaminated extracted

air is transported through the duct work to the filter and fan unit. The filter removes

the dust from the air. The fan creates the airflow. It’s the motor that moves air through

the system.

An LEV system will often provide extraction at more than one machine. Getting the right

type of LEV hood is the most critical step. If the hood design is right for the process

then it is possible to control the dust and fume. Soldering work produces fume which can

cause asthma.

Here the worker is protected by the LEV hood and system but how does it work. The hot fume

cloud rises but is prevented from reaching the woman’s breathing zone by the enclosing

hood. The LEV airflow draws the fume filled air away. The enclosure and the airflow act

together to protect the worker’s health. Enclosures can be very effective but in practice

LEV hoods come in all shapes and sizes, from ones which are large enough to stand in to

others that are tiny and built into tools.

LEV hood design is critical to controlling dust and fumes. For almost any dusty or fumy

process there is an LEV hood and system design that will provide effective control.

Make sure your LEV is the right sort and is properly applied. Well designed and applied

LEV systems can really protect your workers’ health.

Professional advice is widely available.

You can get competent help from your trade association or a professional adviser.

Printed guidance on how to choose and use LEV is available from the HSE and a range

of information and links can be found at the HSE LEV website.