Electrostatic Ignitions

Toluene – An Underestimated Fire Hazard

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Cause of Fire

The filling nozzle was electrostatically charged by the flowing toluene. This charge was capable to drain off to earth via the conductive hose but not via the isolating PVC hose. Unfortunately the worker was wearing isolating safety gloves which prevented the charge to be drained off via the handheld filling nozzle and the person.

Providing Conductive Hoses is Highly Recommended

It is not always known whether a liquid is isolating and thus electrostatically chargeable. Therefore it is recommended always to provide conductive hoses when handling flammable liquids. When working in explosion endangered areas only conductive safety gloves should be worn. So it will be ensured that electrostatic charges from handheld parts can be drained off to earth via the person.

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3. Filling Toluene Into Small Metal Drums

Toluene was delivered in a composite-IBC (1000 litres volume) and had to be filled via the drain cock into 60 l metal drums. For this task the IBC was placed onto a concrete pedestal of such height that the drum fit below the drain cock. As the drums were transported on a drum trolley the drum did not reach the drain cock at its side. Therefore a metal extension of 500 mm length was taken but it did not show an appropriate thread to the drain cock. A transition piece was made that fit and now action could start.

First the worker attached earthing clamps to the drum and the housing grating of the IBC and afterwards opened the drain cock. When the drum was almost filled, suddenly the toluene inside was on fire. The worker could not reach the drain cock to close it unchallenged but he could escape to safety. So the entire content of the IBC could outflow into the fire and caused a devastating conflagration.

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