Causes of Static Charge from Liquid Flow and the Precautions Needed
Typical examples of accumulation Electrostatic charge formation in tanks and vessels in which hydrocarbons or chemicals are pumped or stirred is widely recognized as a serious hazard. This electricity, which is generated in tanks during these normal operations, occasionally causes a spark in a tank vapor space. As statistics show, during 10 years in one state and one oil company only, 18 fires have been attributed to static electricity, causing damage and product losses of millions of dollars. Knowledge of particular chemical’s or hydrocarbon’s resistivity and the current generated by pumping or gravity flow into tank to calculate the voltage difference will help in deciding the likelihood of self-ignition or explosion. The method to calculate the current is given in detail in article written by Adam Zanker for Hydrocarbon Processing (March 1976). The precautions generally taken to avoid the static charge are to reduce the velocity of inflow to the tanks by providing one size larger di...