Control of VOC Emissions to Atmosphere

Release limits for VOCs are set for either specific components (e.g. benzene, carbon tetrachloride), or as VOCs for organic compounds with a lower environmental impact and classed together and reported, for example, as toluene. 

The problem with eliminating or reducing VOC emissions at source is that the sources of VOC emissions can be many and varied. 

Another way storage tanks can breathe to atmosphere results from the expansion and contraction of the tank contents as the temperature changes between day and night. However, such effects tend to be smaller than those associated with tank filling and emptying. 

Slow leaks from gaskets and from compressor, pump and valve seals can create significant fugitive emissions of VOCs. Such emissions can be reduced at source by better maintenance. However, more sophisticated sealing arrangements are desirable to eliminate the problem at source. 

Many processes involve open operations (e.g. filters, drum handling, etc.) that create VOC emissions. If this is the case, it is often not practical to enclose all such operations, in which case, a ventilation system needs to draw a continuous flow across the operation into a duct and then a vapor recovery system, before being released to the atmosphere. 

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