It is more efficient if airborne contaminants are captured as close to the source as possible. According to health and safety organisations “Local exhaust ventilation (LEV) is the principal recommended method of fume control in the welding industry”.
LEV is an extraction ventilation system that takes dusts, mists, gases, vapour or fumes out of the air so that they won’t be breathed in. Properly designed LEV will:
What the right type of LEV is for your specific welding processes depends on all kinds of factors. There may be a standard, ‘off-the-shelf’ system that would be suitable for you. However, it should be fit for purpose and capable of adequately controlling exposure.
If you have to make any changes to a standard system, or if there is no standard system for your industry, a clear specification will help you get what you need, and to avoid any misunderstandings with the LEV supplier. It can help you to write a specification of what you will need. For instance:
The law says that you need to make sure that the LEV carries on working properly, once it is installed. The user manual, logbook and training will help you do this. Most LEV-systems need a thorough examination by a competent person and a test once each year to make sure it works well and continues to protect your employees. Some LEV systems (such as those controlling more critical or high-hazard processes) need more frequent thorough examination and testing. If you have a LEV system that hasn’t been commissioned, you will need to have its performance tested to ensure that it is adequately controlling exposure.
How often you check your LEV and how you do it will depend on how complicated the system is, how likely it is to fail, and the consequences if it does. A complicated LEV where the consequences will have serious if it goes wrong needs more frequent checks and maintenance.
As you gain more experience in running the LEV system you may need to change the frequency of your checks in the user manual.
Checks and maintenance tend to cover four types of parts:
If the LEV can become contaminated with toxic substances, you may need to use ‘permits to work’ and formal method statements when people work on the system.