Bulking Brush Discharge

A partial surface discharge created during bulking of powder in containers, appearing as a luminous, branched channel flashing radially from the wall toward the center of the container. Its maximum effective energy with respect to dust ignition is believed to be 10–20 mJ (less than the MIE of Lycopodium). May ignite flammable gas, hybrid mixtures and some fine dusts in air. Owing to large size of phenomenon the effective energy cannot be measured directly but instead must be inferred from accident case histories where dust of known spark MIE was ignited with proper grounding in place.