2.2. Conflicts of interest
Measures are often taken for reasons of environmental protection, occupational safety, quality assurance, productivity, etc. which are instrumental in achieving objectives in these areas, but result in increased ignition hazards due to the accumulation of electrostatic charge. Typical examples of these are as follows:
- Solvent-laden exhaust air, which in the past was discharged into the atmosphere as diluted as possible, is today collected in as concentrated a form as possible. This potentially explosive mixture is then led, often through plastic piping, to a central off-gas treatment system.
- For reasons of occupational hygiene and environmental protection there is a growing trend to collect dust in local filters, in which clouds of fine dust particles can form a potentially explosive atmosphere, especially during filter shaking. If there is inadequate grounding of components such as the filter support elements, the dust cloud can be ignited by the electrostatic charge accumulated in the
shaking operation.
- The concrete surfaces of filling station forecourts, which actually conduct electricity quite well, are often provided with an insulating layer to protect the ground water against contamination in the case of a fuel spillage. Although car wheels are usually conductive, this insulating layer in the concrete means that grounding of the vehicles is not assured. When the pump nozzle is moved towards the car’s filler pipe, a spark discharge can take place in exactly that location where a potentially explosive mixture may be present.