VOC - volatile organic compounds describes gaseous and vaporous substances of organic origin in ambient air. For example hydrocarbon, alcohol, aldehyde and organic acid. VOCs can occur while processing dissolvent, paint, glue, liquid fuel and many other organic compounds and possibly be released into the environment.

VOCs can be quite health damaging in closed rooms.  That’s why emissions are legally limited and the limit value has been tightened several times. A possible source for VOC emissions is while fueling tank wagons, road tankers or oil tankers. The same risk arises while fueling tank farms with gasoline in refineries or storages and at gas stations. Regulations to limit VOC emissions during decanting and storing automotive gas, fuel mixtures or straight-run gasoline regulate the refueling process. To collect the suppressed gas from the target storage it‘s actively sucked and thanks to the recovery refed to recycling. Flow rate is measured during this process for safety reasons and to calculate efficiency which led Germany to greatly decrease its VOC emission.

Measuring backflowing gas and comparing it to the inflowing fuel can help recognise a leak in refineries and therefore also increase the tank farm’s safety. The measurement also helps showing how much of the gas mixture is fed to gas recovery. That way the extent of gas recovery and the facility’s efficiency can be determined. Without those measures, VOC emissions from fuelling processes with automotive gas alone would still be at close to 100,000 t/a instead of the current 2,500 t/a.