ABSTRACT
Build-up of static electricity is intrinsically related with most industrial processes. Static electricity may cause nuisance or damage and it may represent a fire or explosion hazard when flammable gases, liquids and powders are handleds. Thus, it is of great concern in chemical, plastics, pharmaceutical, foodstuff, printing and paint industries. The decisive factor for assessing the risk of accidents due to static electricity is the probability of coincidence in space and time between a flammable atmosphere and a high level of charge accumulation. The probability of a coincidence of this kind is greatest when the handling of a product gives rise both to high electrostatic charge densities and to a flammable atmosphere. This is especially true when dealing with flammable, non-conducting liquids such as fuels and apolar solvents or with flammable substances in powder form. Ignition sources may occur in practice due to human errors, technical malfunctions or they are intrinsically related to a process. In contrast to most types of other ignition sources static electricity belongs to all categories. Therefore, it is considered to be the ignition source least amenable to control. Fires and explosions attributed to static electricity have ranged from filling a plastic bucket with toluene, washing of cargo tanks of 200,000 tons oil tankers to the transfer of combustible powder into large silos. Typical other accident reports include the filling of dryers with solvent wet powders and emptying intermediate flexible bulk containers filled with flammable powder. The reports of phenomena due to static electricity date back to the 61h century BC when the ancient philosopher and scientist Thales of Milet observed the attraction and repulsion between amber and light particles. In the last centuries these phenomena have been shown on market places, in saloons and clubs for the amusement and amazement of people. With the industrialization and the frequent use of petroleum products in the present century the phenomena of static electricity became more frequent and obvious. Industry and academia started to investigate these phenomena. This research resulted in industry based (1-5), national and international (6-9) guidance to industry on safe manufacturing practices.
