Learn how local exhaust ventilation works, its benefits and risks, and safety considerations when operating and maintaining them.
Published 13 Feb 2023
| By Tiffany Argent, Leizel Estrellas
Local Exhaust Ventilation (LEV) is an engineering control system used to capture and remove airborne contaminants at their source before they can spread throughout the site. It’s an essential part of workplace health and safety programs, as it aims to protect workers from exposure to hazardous dust, mist, vapor, and fumes. LEV systems are used in various industries, such as manufacturing, construction, and healthcare.
LEV systems offer numerous advantages. First, they improve indoor air quality by collecting, containing, and filtering harmful particulates at the place where they are emitted. This ventilation system is also instrumental in limiting exposure to hazardous substances (e.g., silica dust, nanomaterials), minimizing safety risks, and improving work environments for employees in high-risk settings (e.g., welding).
Moreover, a well-maintained LEV system allows for sufficient ventilation in a building. This measure helps decrease the risk of spreading airborne infections and avoid health hazards associated with poor air quality, such as:
A local exhaust ventilation system operates in a similar fashion to a household vacuum cleaner. It follows the following process:
An LEV system typically consists of the following elements:
Components of an LEV system
The hood, also called the inlet or closure, serves as the entry point for contaminated air in the LEV system. It takes a reverse funnel-like shape that gathers harmful particles straight from where it originates. This part comes in the following types, which usage will depend on the work to be performed and the substance to be collected:
After getting pulled in by the hood, contaminants pass through a hollow-shaped channel called the duct system. This channel facilitates a seamless flow of air through the LEV system until it arrives at the exit. Ideally, it should have no sharp corners and be easily accessible for cleaning and maintenance.
Located in the interior of the LEV system, the air filter traps hazardous particles to clear out any impurities in the extracted air before it goes out of the system. While it adds a protective layer, it’s not a requirement, as some systems can work without the cleaning function.
For optimal performance, it’s best to choose a filter that works best against the contaminants you’re working with.
Considered a power source of the extraction process, the fan pushes the air from the ducts to the exhaust stack. By creating a negative pressure in the system, it ensures that hazardous substances are not released into the environment.
The exhaust stack discharges air outside the LEV system. Also called an air discharge outlet, this valve is typically placed on the roof or outer wall of the building, away from air conditioning units and public spaces, to release extracted air in a safe manner.
For an LEV system to work at its optimal state, it must be installed correctly and maintained regularly. Here are some things to keep in mind when performing these processes:
Installing a local exhaust ventilation system is a complex process that requires the expertise of a competent and qualified professional. Proper installation is vital to ensure that the LEV system is effective in removing hazardous substances from the air.
The installation process typically involves the following steps:
Aside from correct installation, an LEV system also requires regular maintenance to ensure that they are working properly and efficiently. This process involves scheduled maintenance checks, periodic inspections, and thorough testing.
First, periodic maintenance should be carried out to check for any signs of wear and tear and see if the system is operating correctly. It includes:
Next to maintenance checks are regular inspections. In this procedure, a qualified professional examines the system for malfunctioning parts or potential problems and makes the necessary repairs or adjustments.
Eliminate manual tasks and streamline your operations.
Lastly, local ventilation exhaust testing is performed to see if the system is meeting the required safety standards. It must be conducted on a regular basis—at least every 14 months in the UK, for example—to ensure that the system is operating safely and correctly.
Local exhaust ventilation systems may have several benefits, especially for workplace safety, but sometimes, they have drawbacks. Here are 5 common risks and challenges associated with LEV systems:
Local exhaust ventilation systems must meet specific laws and standards to safely and effectively function. They may vary depending on the country in which a business operates. This section walks you through some of the prominent regulations for LEV systems around the world.
The Occupational Safety and Health Administration (OSHA) sets the standards for designing, installing, operating, and maintaining LEV systems. Here are the laws and regulations to refer to for LEVs in the US:
In the United Kingdom, the Health and Safety Executive (HSE) is responsible for establishing guidance documents and regulations for local exhaust ventilation systems. Listed below are the laws and regulations that govern these systems:
In Australia, the laws, regulations, and guidelines for LEV systems fall under the responsibility of Safe Work Australia. The following laws and standards generally apply to Australian territories:
Ventilation systems come in three basic types:
Both general and local exhaust ventilation systems are used in industrial settings, but there’s a key difference between them.
General ventilation refers to systems that partially control indoor air particles, making it ideal for standard use. On the other hand, LEV works for locally-controlled zones, as it takes a more targeted approach to handle airborne contaminants.
LEV systems are typically used in areas where hazardous dust, fumes, and vapors could be present, such as the following:
The price of local exhaust ventilation systems can range from $1,000 to $3,000, but this can vary depending on the LEV’s size and complexity. Generally, the cost will cover the equipment, installation, and maintenance. There may also be additional costs for services, such as permits, inspections, other regulatory requirements, and the disposal of hazardous materials.
Local exhaust ventilation systems are vital for keeping workers safe during operations. For them to continue working in their best condition, they must be regularly checked for wear and tear and accumulation of debris.
Businesses can optimize their inspection and maintenance tasks with the help of digital tools like SafetyCulture. With the world’s leading mobile inspection app, LEV operators and safety officers can:
Browse the following checklists for maintaining and inspecting local exhaust systems:
Tiffany is the Head of Customer QSHE Services at SafetyCulture, a chartered member of IOSH and an IOSH mentor with 17 years of health and safety management experience in freight forwarding, warehouse operations, science and manufacturing.
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