The Importance Of Local Exhaust Ventilation [LEV] And Why You Need It

Is Your Aircon System Working Safely And Efficiently

Dust and contaminants in the workplace are a cause of thousands of fatalities each year in Britain. Mist from sprayers in paint shops, flour dust that circulates around many bakeries or fumes created by welding processes cause lung disease and asthma. Other causes could be vapour from evaporating paint solvents and even carbon monoxide created in furnaces.

Businesses can tackle this problem by buying local exhaust ventilation (LEV) to protect the health of their workforce. But the problem is choosing the correct type of LEV, installing it correctly and maintaining it.

LEV ventilation systems extract gases, dusts, mists and fumes from the ambient air. The process works by collecting the contaminated air, containing the contaminants and leaving the clean air to flow out safely.

Typical LEV systems consist of a hood to collect the contaminants in the air, preferably close to their source such as the welding operation, furnace or paint sprayer and a duct system that carries these contaminants away from the source to a filter where the air is cleaned.

The main requirement here is a powerful fan that has to create a large enough force to effectively suck the contaminated air towards the filter, clean it and then discharge the clean product.

Local Exhaust Ventilation

Local Exhaust Ventilation System 1

One of the most common reasons for LEV not working correctly is that the hood does not catch all of the contaminants. Here, the solution is to match the size of the hood to the source of the dust or fumes. Businesses should avoid buying an off the shelf system that cannot catch the contaminants and opt for a bespoke model. LEV systems are not standardised for any specific industrial process. The LEV supplier can provide a good system only when he receives specifications from a client.

Such specifications should include a description of the industrial process in question, together with the contaminants produced and any other hazards that need to be controlled. It is vital that any chemical or flammable processes are fully explained.

The LEV system should be easy to run so that the workforce can become familiar with its features. It needs indicators at various stages that show the system is operating correctly. Cleaning should be able to be carried out without the danger of causing any skin irritation to the workforce. It should be possible to remove filters and dispose of the waste without the release of the contamination.

Regular checks and maintenance are vital tasks to be carried out by both the supplier and the client. A user manual provided by the supplier should explain all testing and maintenance processes, performance benchmarks are provided and the firm schedule of replacement of parts.

Filter shakers and fan bearings are moving parts that could suffer wear and tear frequently. Ductwork, hoods, seals and other non-moving parts may be damaged by any contact with water and chemicals as well as wear and tear. Flexible ducts and filters will also deteriorate as they are used. Filters in particular need regular attention to check if they need replacing.

All results of checks, tests and maintenance should be recorded in a logbook.

Local Exhaust Ventilation System Image Source –

by Louise Burke