Learning lessons from five electrostatic incidents

It is well known that electrostatic discharges can ignite mixtures of flammable gases with air and suspensions of combustible dust in air. For this reason, the prevention of electrostatic discharges is an essential part of measures to prevent explosions and fires. Incendive electrostatic discharges occurred in five cases in various chemical plants.The incidents involved were:

• 1.Spark type electrostatic discharges from a leaking steam pipe.
• 2.Spark type electrostatic discharges inside a charging chute for a solid.
• 3.A spark type electrostatic discharge whilst transferring a solid powder from a bin, which led to ignition of the powder.
• 4.A propagating brush discharge during pneumatic transfer of solid, which caused a severe electric shock to a process operator.
• 5.A brush discharge inside an electrostatic precipitator which caused ignition of an aerosol of hydrocarbon.

To avoid explosions and fires it is important to prevent incendive electrostatic discharges from occurring in industrial facilities. To help managers of chemical plants to do this, the incidents above are presented in the form of learning lessons including:

• •the mechanism of the generation and separation of electrical charges,
• •the mechanism of the electrostatic discharge,
• •the root causes of the incident,
• •the safety measures which are necessary to avoid a repetition.