Electrostatic ignition hazards in road tanker loading: Part 1. Review and experimental measurements

Abstract Electrostatic ignition hazards may occur during the loading of road tankers with hydrocarbon fuels. The hazards arise when the charge density in the liquid entering the tank (the “inlet charge density”) exceeds a critical threshold that depends on the loading conditions. In this paper, the first in a series of three, both the inlet charge densities that occur in commercial filling operations and the threshold values for the relevant conditions are determined. The charge densities and thresholds are established by combining critical reviews of the existing measurements with the results of some hitherto unreported work. The thresholds obtained at different laboratories agree to within ±20%. The maximum inlet charge densities are less than half the thresholds. The new inlet charge density measurements that are presented here provide sufficient data for a statistical analysis of the risk of exceeding the threshold in a commercial loading operation. This analysis is described in the second paper of the series. The third paper examines how the risks are influenced by a variety of precautions and practices including the use of anti-static additives, reduced or increased filling velocity, slow starts and splash-loading.