Workshop on unconfined vapor cloud explosions

The purpose of this paper is to summarize the principle points made during the course of the workshop, identify (to whatever extent is possible) a consensus position of the panel members on key issues, and to review research needs as identified by the panel. No attempt will be made to summarize each panel members' individual presentation, as such, since there was considerable overlap both in the presentation topics and in the subsequent discussions.     

Dust entrainability and its effect on explosion propagation in elongated structures

Two apparatuses have been developed to characterize the entrainability of dust deposits. The minimum aerodynamic wall shear stress required for dust removal (Critical Shear Stress), measured by the first apparatus, is an indicator of the ease with which dust particles can be removed from a layer. The second apparatus measures the settling velocity distribution of dust clouds, which is an important factor controlling the extent of dispersion as well as the time period during which the entrained dust cloud can remain suspended. Testing has shown that the critical shear stress depends not only on the nature of the dust, but on the way the dust deposit is formed. Therefore, a portable version of this apparatus was developed to allow field testing of dust deposits. This methodology has also been used to evaluate the effect of oil treatment sometimes used in the grain handling industry to reduce dust emission. Simulated explosion tests have demonstrated the importance of critical shear stress on dust entrainability. A simple model calculating unsteady dust concentration in elongated structures has been developed. The model shows that flammable dust concentrations induced in a gallery by a primary explosion exist over a finite length and time period. Therefore, the probability of a secondary explosion depends not only on the dust and layer properties, but on the details of the primary explosion and of the enclosure geometry. A simple criterion for transmission of a primary explosion into an adjoining elongated structure is discussed in the paper.     

Inherently safer plants: An update

Instead of adding on protective equipment to control hazards, in an inherently safer plant we avoid them by using less of the hazardous material. Another option is to implement safer alternatives. Though the chemical industry has been slow to adopt such designs there has been some progress.     

BOOK REVIEWS

Dynamics and Conflict in Regional Structura1 Change—Essay in Honor of Walter Isard Volume 2 Practical Methods of Regional Science and Empirical Applications—Selected Papers of Walter Isard, Volume 2 Department of Economics Loughborough University Export Promotion Strategies—Theory and Evidence from Developing Countries Commonwealth Secretariat Export Market Development Division Human Development Report 1990 for the United Nations Development Programme (UNDP) (New York and Oxford: University of Nottingham The World Bank and the Environment—First Annual Report Fiscal 1990, The World Bank (New York: The World Bank, 1990 London Environmental Economics Centre University College London The European Communities' Single Market: The Challenge of 1992 for Sub-Saharan Africa Loughborough University     

ENVIRONMENTAL FINANCE: VALUE AND RISK IN AN AGE OF ECOLOGY

Environmental issues are restructuring markets and redirecting capital flows throughout the world. An outline is provided of concerns facing the development of an environmentally responsible or ‘environmental finance’ perspective. It reviews the major ways in which organizations are responding to environmental threats and opportunities in the three major branches of finance — corporate finance, investments and financial institutions — highlighting in particular novel programs and initiatives. In the past, financial concerns have exacerbated the degradation of the natural environment; in the future, they probably hold the key to their preservation.