LEV systems play a crucial role in industry because they control the dust and fumes produced from job processes.
Lots of jobs across lots of industries involve work processes that generate dust, fumes and vapours. If these are not controlled properly, they create poor working conditions that lead to health problems like lung scarring and cancer.
Another problem dust and fumes create is local contamination which can affect manufacturing and production quality.
Dust and fumes also pollute the environment when vented straight into the atmosphere, disrupting ecosystems and causing problems with locals.
Unfortunately, very little thought is sometimes given to venting exhaust gases and we have seen cases where exhaust gases immediately flow back into the building. This is the result of very poor planning and inadequate exhaust control solutions.
The most efficient way to control dust and fumes in a safe and predictable manner is with Local Exhaust Ventilation (LEV) systems. LEV systems are designed to handle exhaust gases, but they need to be properly sized and specified to be effective.
How LEV systems work
LEV systems efficiently extract dust, fumes, gases, vapours and fibres from job processes, such as sawing, machining and painting.
The main elements of an LEV exhaust system are:
- A hood, where contaminants enter the system
- Ducting, which transports contaminated air to the filter
- A filter, which treats the contaminated air
- A fan, to create the airflow to power the system
- A vent, which provides a safe place for treated air to be released
The process of LEV systems is relatively simple:
Contaminated air is sucked through a hood. Depending on the application, the job process may be enclosed to maximise air intake.
The contaminated air is transported through ductwork to a fan and filtering system. The filter removes dust and particulates from the air. Treated air is then ventilated out into the atmosphere. The treated air is free from dust and fumes.
Considerations for LEV exhaust systems
The most important thing is that the unit is of good design. It should be sized appropriately for the job and achieve the desired extraction.
The main considerations for LEV systems are:
Flow rate: The flow rate needs to be powerful enough to achieve initial capture of the contaminants and carry them to the filtering system. In the case of flammable solvents, the flow also needs to sufficiently dilute the contaminated air.
Hood: The hood/inlet needs to optimise initial capture and fit into the job. It could be as simple as an open duct, or it could be a moulded shape. The type of hood or enclosure is influenced by the work being done.
Leakage: The system needs to be designed so that leakage on the suction is impossible. Negative pressure on the air remover side will lead to poor extraction and positive pressure would lead to fumes being reintroduced to the workplace.
Materials: Since LEV exhaust systems can extract dust, fumes, gases, vapours and fibres, different materials should be used to suit these. For example, in the case of flammables, we would specify a duct material that cannot combust.
Servicing and maintenance
LEV systems should be designed with maintenance in mind so that servicing can be performed when necessary.
In addition to annual servicing, testing is important following extended periods of downtime, such as from COVID-19 shutdowns. We recommend a comprehensive report on LEV performance following significant downtime. This is important for operational efficiency and safety, and it will guarantee system performance.
Find out more
PDFL are specialists in LEV exhaust systems. Our ventilation engineers can size and specify the right solution for your use case, and we will work closely with you to achieve an effective design. Call us on (0)1922 418005 for a chat.
