Research on the accuracy of electrostatic testing in the feeding process of energetic materials

The electrostatic safety of materials is commonly assessed using the charge-to-mass ratio (CMR) obtained from the standard chute test. However, this method suffers from two critical limitations. The unclear influence of initial charge on the CMR value, and its questionable applicability for risk evaluation in large-quantity feeding. This study systematically examines the accuracy and applicability of the electrostatic test specified in the GJB 5891.8-2006 standard. Experimental results reveal that the initial charge of 3 mm polyoxymethylene particles contributes 17.5–18.1 % of the net charge after feeding, introducing a measurement error of 10–20 %. For kilogram-scale sodium chloride particles of 1 mm in diameter, the CMR does not increase proportionally with feeding rate due to non-uniform charging. Moreover, only the bottom layer of material actively participates in tribocharging within the chute, with sufficiently charged particles accounting for merely 37.1 % of the total volume. These findings demonstrate that using CMR alone is not a scientifically robust metric for electrostatic hazard assessment. Instead, the increasing electrostatic potential associated with accumulated charge provides a more reasonable criterion. When the proportion of sufficiently tribocharged particles exceeds 85 %, both CMR and electrostatic potential can serve as reliable indicators for evaluating the electrostatic level during chute feeding.