Flow and Spraying

        If the surface of a liquid is changed, the electric double layer has to be formed or destroyed. These processes are supposed to have a certain inertia, which implies that it is possible to separate the charges of the double layer by mechanical action on the liquid. 

        If a liquid is flowing through a tube, there is a tendency for the outer charge of the double layer to be given off to the tube and the inner charge to be carried along with the flow. The effect of the charging increases with the resistivity of the fluid (and depends on several other parameters). Consequently, only highly insulative liquids (r > ca. 107 W•m) will show charging by flow. Water, therefore, will not charge by flow.

Electrification by fluid of liquid

        Although charging of liquids by flow can only occur with highly insulative liquids, charging by spraying can happen with almost any liquid.

Electrification by spraying of liquid