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Abstract

For drum filling, a demarcation of 50 pS/m (below which a liquid may accumulate hazardous static in a grounded drum) is conservative and takes account of the effects of temperature and/or charge density on relaxation rate. The worst-case conductivity as regards static accumulation rate is about 0.5 pS/m, but in practice this should not correspond to the worst-case charge generation rate. Published forms of the Schon equation are not conservative for smooth-bore pipes and hoses; a new equation is proposed. Certain rough-bore hoses containing an inner grounding spiral can generate almost as much charge as a microfilter. Theory and experiment are discussed with reference to published Codes and Guidelines; attention is given to filter placement and drum linings.