What are the Major causes of static electricity build up during liquid cargo operations ?

OIL FLOW

Flow in the pipeline is turbulent, this turbulence scoops up an inner layer of charged molecules and distributes it throughout the bulk of the petroleum in the pipe,whilst leaving the outer layer at the interface with the pipe wall. Thus the charge layers are seperated and the petroleum in and emerging from the pipeline becomes charged. The faster the flow in the pipe the greater the turbulence and the greater the charging. Due to the turbulence if there is build up of charge difference-voltage then spark may be produced due to static electricity

AIR FLOW

The passage of air will not generate static electricity, but if air is passed into the bottom of the tank and then releases water to the surface with it present in the oil in very small quantity the subsequent settling of water back through a low conductivity distillate can result in powerful electro-static charging which will persist until the disturbed water has settled.