Combustion and explosion characteristics of dusts

Status:

completed 06/1997

Aims:

Knowledge of the characteristics of dusty or pulverous substances or substances which release dust, and which are handled in companies, is essential for the avoidance of fires and explosions. The combustion and explosion characteristics are of major importance for both preventive measures and for engineered explosion protection measures. Uncertainty often arises in practice regarding whether and to what extent the substances being handled are flammable, or explosive when mixed with air. The BG Institute for Occupational Safety (BIA) supports the German Institutions for Statutory Accident Insurance and Prevention and their member companies with expert advice on these issues. This often also entails assessment of the combustion and explosion characteristics of the substances under consideration. The data which have been collected as a result over the years may also represent a valuable resource for experts for the assessment of hazards and risks involved in the handling of flammable substances and substances capable of facilitating dust explosions. A solution was therefore sought by which the available characteristic data could be made available to workers in the field. Such a resource would indicate the substances for which the explosive characteristics are already known, and the anticipated order of magnitude of the values for these substances. The project therefore contributes substantially to practical implementation of Council Directive 89/391/EEC (EC Framework Directive for occupational health and safety), and is intended, in conjunction with the anticipated ATEX 118a Directive, as a tool for experts which permits assessment of the hazards presented by flammable dusts in individual cases, and where applicable also permits the selection and rating of protective measures.

Activities/Methods:

The combustion and explosion characteristics of approximately 800 dust types were initially compiled in 1980 and published by the BIA in the form of a research report entitled "Dust Explosions", and subsequently in expanded form (with approximately 1900 dust types) in the BIA Manual entitled "Safety and Health Protection at the Workplace" (1987). Based upon this existing collection of data, further combustion and explosion characteristics of dusts detected by the BIA were reviewed, assessed, and included in a database created especially for the purpose, in consideration of data protection concerns. In addition to the BIA's comprehensive data, numerous other data records were supplied by other test institutes and incorporated.

Results:

The database currently encompasses the combustion and explosion characteristics of approximately 4300 dust types, and is available to fire and explosion prevention experts in the form of BIA Reports 12/97 (German edition) and 13/97 (English edition). The database provides in the first instance an approximate guide to whether or not a substance should be regarded as facilitating dust explosion. The known relationship between the characteristics of fineness and moisture is generally easily recognized, in particular for substances for which a large number of discrete results are available. It is also evident, however, that a single substance may exhibit a broad range of values in some cases. This in turn demonstrates that despite the useful guidance provided by the tables, a study of the dusts actually present is essential in many cases for precise specification of measures for explosion protection, and that consideration should always be given to suitable safety reserves and distances. The database is to be published on the Internet in the near future. Regular updates, in particular of the Internet version, are also planned.

Further informations:

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