Electrification of toluene flowing in large-diameter metal pipes

Data are given on the electric currents generated by the flow of toluene (ρ=2 × 10 12 Ω cm) and toluene containing Shell Anti-static Additive No3 (ρ=5 × 10 11 Ω cm and 5 × 10 10 Ω cm) in large stainless-steel pipes (length 29 m, diameters 1·62, 2·88, 5·39, 8·35 and 10·90 cm). It is shown that the effect of changes in flow velocity and pipe diameter on charging current can be calculated using empirical equations of the form i infinity = KV m d n when ρ>10 11 Ω cm and V =100 to 1000 cm s −1 . The data are also used to test the validity of the Koszman and Gavis equation for the electrification of liquids during pipeline flow. The evidence suggests that, when G <10 −6 , the power dependence of i infinity on d for large-diameter pipes differs from the value 0·88, predicted and found to be true for small-diameter pipes. After modification to have a diameter power of 1·4, the equation could be used to calculate the order of magnitude of i infinity.