Accidental fuel spillages into ports and inland waterways is the cause of serious pollution. This type of pollution amounts to millions of litres of fuel per year. One litre of fuel pollutes 2000 m² of surface water. Floating barriers and dispersants are used to combat accidental pollution, however, the associated costs, for local authorities for instance, are costly. WHY DOES THIS POLLUTION OCCUR ?
When filling tanks, blow backs from the fuel tank occur when the liquid level reaches full capacity and consequently causes overspill. For technical reasons, air evacuation is obligatory on boats. Every port is equipped with automatic switch off dispenser nozzles
(same principle as service stations) This is the reason why, when filling up a jerrican, the automatic switch off dispenser nozzle is activated and overspill is avoided. To fill up a tank, one fills up at a rate of flow of roughly 1 litre/second into a pipe of 50mm in diametre. Air evacuation happens at the same time by the vent hole. When the tank is full, it is no longer air which is circulated but fuel which then escapes without the automatic switch off dispenser nozzles being activated because there is noblow back to stop the flow. Given that the vent hole on pleasure boats is generally 16mm in diametre and for professional crafts identical to the size of the filler cap : spillage always occurs!
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