Static electricity in pneumatic transport systems: Three case histories



Three incidents, two explosions and one near miss, of electrostatic ignition of dust suspensions in pneumatic transport systems are reported. The incidents actually occurred in three separate systems; but, because of legal implications, they are reported in terms of one generic system. Incident A describes a near miss where there were some ungrounded ducts in the system. Incident B describes an explosion during the filling of an intermediate bulk container with a powdered material. Incident C describes an explosion in a bag filter (bag house) after some two years of operation. The discussions include some basic preventive measures which should be taken in similar systems to prevent the buildup of electrostatic potentials.