In order to prevent dust explosions caused by electrostatic discharges in a silo during loading of particulates in a pneumatic transport system, a passive-type electrostatic eliminator without a power supply has been newly developed. The eliminator consists of nozzle-type ionizers mounted on the outside of an insulating short pipe that is installed at the end of the loading pipe inside the silo. The ionizer is equipped with a grounded needle electrode within the insulated metal nozzle. The elimination ability depends on the electrification of the insulating pipe with the same polarity as the charge on the products during the loading. The nozzle is also electrified due to electrostatic induction and discharge from the charged insulating pipe and induces corona discharges at the needle electrode. The air ions generated by corona discharges are blown into the pipe to neutralize the static charge of the products before entering the silo. Improvement of the eliminator was attempted, and its effectiveness was examined using a real-sized pneumatic powder-transporting facility. (C) 2003 Elsevier B.V. All rights reserved.