Local Exhaust Ventilation

What is Local Exhaust Ventilation? Why do we use it?

   Local exhaust ventilation is a way to remove any contaminates in the air away from an individual's breathing zone.  These machines take away a large part of the hazardous particles so that the workers can do their job safely.  Without this equipment, the employees are being exposed to harmful materials that can cause major health problems.  What's different about this type of ventilation is that the contaminates are being removed directly from the source.  They are being contained or stored and then discarded properly.  Local exhaust ventilation is one of the many ways to remove vapors, mists, dusts, and other hazardous particles from one's breathing zone. Although these are very effective, they have to be used properly to work the way that they are designed to work.  Failure to correctly use these machines, can lead to damage of the worker's health.  The most important thing is to make sure that the workers have proper training and understand how to effectively use these machines.

How does it work?

   There are five main parts on local exhaust ventilation systems: hood, duct, air cleaner, fan, and stack.  Initially, there has to be a contaminate that the ventilation system will interact with.  The contaminate first travels through the hood.  The hood is where the contaminate is first captured from the source.  The next location for the contaminate is the duct.  The duct is where the air travels through the system to the step.  The duct is then connected to the air cleaner.  The air cleaner, as it sounds, is where the air is cleaned of contaminates. After it flows through the air cleaner, the fan propels the air through the next step, the stack.  The final step of ventilation is where the cleaned air is now ready to be put back into a safe environment through the stack pipe.  This process is the way that air is removed, cleaned, and then reintroduced into the environment.  The local exhaust ventilation system is a very effective way to remove hazardous air from a specific emission location.  

Sources:

  Center for Occupational Health and Safety

     http://www.ccohs.ca/oshanswers/prevention/ventilation/introduction.html

  Health and Safety Authority 

 http://www.hsa.ie/eng/Publications_and_Forms/Publications/Occupational_Health/Local_Exhaust_Ventilation_LEV_Guidance.pdf