Research and development 585 igniter However, in a 20 litre chamber, fully developed explosions were generated even with a kJ chemical igniter The reason for this could be that in the smaller chamber, the initial combustion and expansion of the dust cloud was directly supported by the ignition source The pressure and temperature in the unburnt cloud ahead of the flame would then have increased significantly above ambient when the flame eventually propagated without support from the ignition source Consequently the self-sustained flame propagation, if any, would then occur in an adiabatically pre-compressed dust-cloud, rather than in a cloud of normal ambient temperature and pressure These results suggest that great care must be exercised whenever comparatively small chambers, in particular closed ones, are used for any explosion limit determination Matsuda and Itagaki (1994), compared dust explosions in a 30-litre explosion bomb with explosion in a m3 vessel They found that the ranges of explosible concentrations in the 30-litre vessel were considerably wider than those in the m3 vessel for the same dust A marked increase of the explosible range was found in the 30-litre bomb when increasing the ignition energy from to 10 kJ This effect was practically absent in the m3 vessel, in the ignition energy range 4-20 kJ Tian Renqu et al (1994), using a 20-litre explosion bomb, found that the minimum explosible concentrations of coal dusts decreased by a factor of two or more when the ignition energy was increased from 2.5 to 10 kJ Xu Tianrui et al (1994) also arrived at the conclusion that the apparent minimum explosible dust concentration determined in a 20-litre bomb depends markedly on the ignition energy It was found that 10 kJ would be too high to yield realistic results All this suggests that limiting conditions for flame propagation should be determined in apparatuses of sufficient volumes to prevent significant influence of even quite strong ignition sources, on the main phase of flame propagation In Europe the standardization organization CEN will probably adopt the m3 I S standard bomb for this kind of tests Zhou Congzhang et al (1994) proposed an alternative procedure for determining the minimum explosible dust concentration in closed-bomb explosion experiments Their experimental evidence indicated that at the minimum explosible concentration, the time interval from ignition to the pressure peak has its highest value They proposed that this criterion be used instead of some arbitrary pressure rise criterion of explosion 8.4.4 MISCE LLAN EOUS Tian Renqu et al (1994), using a 20-litre explosion bomb, found that, when using a 2.5 kJ igniter, and adding vol % methane to the air, the minimum explosible dust concentration dropped by at least a factor of two, compared with the values for dust in air This ‘hybrid’ effect has been studied previously by several other workers (see Chapter 1.) Pu et al (1991) concluded that the turbulence structure of experimental dust clouds in a standard 20-litre spherical dust explosion test bomb had little resemblance to turbulence structures in dust clouds in accidental dust explosions in industry Mintz (1995) discussed some further problems with 20-litre bomb experiments Dahoe et al (1995) constructed a 20-litre spherical dust explosion vessel allowing variation of the initial pressure between atmospheric and 14 bar overpressure, and initial temperatures between below 0°C and 250°C Experiments could also be conducted in 586 Dust Explosions in the Process Industries enriched oxygen atmospheres, up to pure oxygen The problem of ensuring constant turbulence of the dust cloud at the moment of ignition, with varying dust concentration, and pressure and temperature of the gas phase, was investigated Hertzberg et al (1992a) determined a range of dust explosibility parameters for nine different dusts of solid explosives when dispersed as clouds in air in a closed bomb In the low-concentration range (d 400g/m3) the dusts behaved as dusts of normal carbonaceous and plastic materials At higher concentrations they became more hazardous, starting to exhibit genuine explosives properties Wang and Zhang (1994) determined the minimum ignition energy, the minimum explosible concentration, and the maximum explosion pressure for clouds of TNT dusts in air The values are similar to those of natural organic materials The results confirm that dilute clouds of dusts of explosives not exhibit explosive properties, but behave as clouds of ordinary combustible dusts Similar conclusions were drawn by Li et al (1994), who studied the dust explosion properties of dry ‘powder emulsion explosive’ powders 85 EXPERT SYSTEMS - F R I E N D S O R ENEMIES? Expert systems may be defined as computer-based decision-making tools that make relevant expert knowledge accessible for non-specialist users by means of ‘if-then’-rules and ‘class/object’ structures During the last few years there has been an increasing interest in developing sophisticated computer-based expert systems for evaluation of dust explosion hazards and assessment of optimal safety design features Haefen and Schecker (1993) presented such a system for assessment of dust explosion hazards in industry and selection of appropriate means of prevention and mitigation The system is in all essentials based on the German protection philosophy Wach (1993) presented another expert system designed for the same purpose, but the technical and philosophical basis was not explicitly stated A comprehensive expert system developed in UK was presented by Tyldesley (1993) and the need for Quality Assurance of such systems was emphasized Hesener and Schecker (1995) presented an expert system for the safety analysis of drying plants The systematic procedure implied in the system consists of four consecutive steps, viz hazards identification, hazard assessment, development of a protection concept, and selection of specific protection methods/technology The system presented was regarded as a prototype, rather than a final product The development of this kind of expert systems is a natural consequence of two main factors The first is the almost ‘explosive’ development of the performance of personal computers The second is the steadily increasing knowledge about ignition and explosion phenomena which demands a steadily more differentiated and complex approach for solving the practical design problems As long as this development is conducted by people who are not only experts on computers but also on the physics and chemistry of the phenomena treated, expert systems should indeed be welcomed However, there may be a possibility of the future market place being offered software that is not up to acceptable standards with respect to the physics and chemistry As long as the interior of the system is not fully exposed deficiencies in t h e basics may not be obvious to the user A need may emerge for establishing some internationally recognized body of experts that can ensure that expert Research and development 587 systems offered in the area of dust explosion prevention and mitigation are up to acceptable standards 8.6 THE HUMAN HAZARD FACTORS The present survey deals with the chemistry physics and technology of dust explosion prevention and mitigation However a briefmentionshould also be madeofthe importance ofthe human factor sin thiseffort Thisaspectwasdiscussed by Fernando( 1993) 8.7 JOINTRESEARCH EFFORTS IN EUROPE, R S A C AND EE R H DEVELOPMENT IN P R CHINA During the early 1990s potential for organizing joint European research efforts emerged within the EU/EFTA/EUREKA system This also applied to dust explosion research British Materials Handling Board (BMHB) in the UK played a central role in this process (Middleton 1992) A number of parallel research programmes were conducted within the European Union’s ‘CREDIT Project’ Gibson (1991) summarized the areas requiring consideration under the headlines: 0 Combustion processes in dust clouds (experiments, theoretical models) Identification and control of ignition sources Design of methods to prevent/protect against dust explosions The results of this important research effort were published as conference proceedings (CREDIT 1995) containing about ten papers covering a wide range of topics such as initiation of smouldering combustion in powder deposits by localized heat sources measurement of dust cloud characteristics in industrial plants, measurement of laminar burning velocities of dust clouds, partial inerting of dust clouds, measurement of dust flame structures, measurements of blast effects and fireball sizes from vented dust explosions and last but not least, a start on a development of a comprehensive CFD-based (Computational Fluid Dynamics) numerical computer code for simulating the development of dust explosions in complex systems An overview was given by Gibson (1996) Wang Dongyan (1994), characterizing P R China as a developing country, emphasized the need for increasing the efforts to prevent dust explosion accidents in China’s rapidly growing industry Of the number of dust explosions recorded in this country during the decade 1980-1989, 65% were in the grain industry, 17% in the textile industry 12% in the coal industry and 6% in the metallurgical industry With the rapid development of the chemical and metallurgical industries, the annual number of explosions can easily raise if adequate precautions are not taken There is a strong need for education and training on all levels, and for adequate safety technology The -6th International Colloquium on Dust Explosions’ in Shenyang, P R China in August/September 1994 (see section 8.1.2) demonstrated that research and development on dust explosion prevention and protection, in this enormous country is growing at great pace 588 Dust Explosions in the Process Industries 8.8 CONCLUSION Initiation and propagation of industrial dust explosions are, from a fundamental scientific point of view, extremely complex phenomena Comprehensive mathematical theories for predicting ignition and combustion of dust clouds in industrial environments from fundamental physical and chemical principles in general are, at present, beyond reach It is not surprising, therefore, that the vast amount of existing knowledge on dust explosion-related phenomena is to a large extent fragmented It is believed, however, that more and more fragments will, step by step, become tied together, and that steadily increasing domains of coherence will emerge Comprehensive mathematical models and powerful computers are invaluable tools in this process But experiments will remain indispensable for calibration of the mathematical models, because such models will remain approximate and require careful tuning in the foreseeable future It is necessary to continue the execution of realistic industrial-scale experiments A t the same time, the more basic research and mathematical modelling should continue at full pace Much of the research that needs to be undertaken is very demanding, and international co-operation in joint research programmes should be encouraged 8.9 ACKNOWLEDGEMENT Sincere thanks are due to Aaslaug Mikalsen for typing the manuscript of the entire book REFERENCES Alexander, C G., Harbaugh, A S , Kauffman, C W., Li, Y C., Cybulski, K., Dyduch, Z , Lebecki, K., Sliz, J., Klemens, R., Wolanski, P., and Zalesinski, M (1993) The Establishment of Dust Detonations Proc 5th Internat CON Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 365-381 Alfert, F., and Fuhre, K (1992) Venting of Dust Explosions in Filters and Integrated Systems Report 92-A25021, Chr Michelsen Institute Dept of Science and Technology, N-5036 Fantoft Norway Alfert, F (1993) ‘PC-Vent’: A software solution to control explosion hazards Paper given at the European Summer School on Dust Explosion Hazards: Their Assessment and Control, Cambridge, UK, organized by IBC Technical Services Ltd in association with BMHB and IELG Austin, P J., Girodroux, F., Li, Y C., Alexander, C G , Kauffman, C W., and Sichel, M (1993) Recent progress in the study of dust combustion phenomena at The University of Michigan Proc 5th Internat CON.Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 211-214 Bakke, J R., and Wingerden, K van (1992) Guidance f o r Designing Offshore Modules Evolving from Gas Explosion Research Society of Petroleum Engineers Inc., Richardson, Texas, USA SPE 24617 pp 763-770 Research and development 589 Bartenev, A M., Gelfand, B E., and Frolov, S M (1993) The Rupture of Vessels Containing Explosive Mixtures Proc 5th Internat Coll Dust Explosions (April 19-22), Pultusk near Warsaw, pp 465472 Bartenev A M., Medvedev, S P., and Polenov, A N., e t a l (1994) The Effect of Dust Filler on the Rupture of High Pressure Vessels Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2) Shenyang, P R China pp 116-124 Barth, U Siwek, R., Suter, G., and Kubainsky, Ch (1995) Explosion Protection of Small Mills In Loss Prevention and Safety Promotion in the Process Industries: Volume (Ed by J J Mewis, H J Pasman and E E De Rademaeker), Elsevier Science B V pp 255-264 Bartknecht W (1993) Explosionsschutz: Grundlagen und Anwendung Springer-Verlag Berlin ISBN 3-540-55464-5 Boiko V M Papyrin A N., and Poplavski S V (1993) On Peculiarities of Coal Dust Ignition in Incident Shock Waves Proc 5th Internat Coll Dust Explosions, (April 19-22) Pultusk near Warsaw, pp 329-334 Boiko, V M., and Papyrin, A N (1994) Laser Diagnostics Processes of Mixture Formation and Combustion of Dusts in Shock Waves Proc 6th Internat Coll Dust Explosions (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China pp 302-3 05 Boiko V M Kiselyov, V P., and Kiselyov S P., et al (1994) On Gas Parameter Profiles at Non-Stationary Shock Wave Interaction with Dust Cloud Proc 6th Internat Coll Dust Explosions (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2) Shenyang P R China, pp 336-340 Bradley, D Chen, Z and Swithenbank J R (1988) Burning Rates in Turbulent Fine Dust/Air Explosions Proc 22nd Symp (Internat.) on Combustion The Combustion Institute Pittsburgh, USA pp 1767-1775 Bradley, D Chen, Z El-Sherif, S El-Din Habik, S., and John G (1994) Structure of Laminar Premixed Carbon-Methane-air Flames and Ultrafine Coal Combustion Combustion and Flame % pp 8&96 Britan A B Levin V A , and Mitichkin, S Y et al (1994) Investigation of Relaxation Zone under Interaction of Shock Wave with Protective Aqueous Foam Layer Proc Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski) (August 29-September 2) Shenyang, P R China, pp 360-365 Britan A B Levin V A , and Mitichkin, S Y , et al (1994a) Influence of Aqueous Foam Screen upon Propagation of Shock Waves Proc 6th Internat CON Dust Explosions (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2) Shenyang P R China pp 472477 Cashdollar, K L., and Chatrathi, K (1922) Minimum Explosible Dust Concentrations Measured in 20 litre and m3 Chambers Combustion Science and Technology 87 pp 157-171 Cashdollar, K L., Weiss, E S Greninger N B., and Chatrathi K (1992) Laboratory and Large-scale Dust Explosion Research PlantlOperations Progress 11 pp 247-255 Cashdollar, K L (1996) Coal Dust Explosibility J Loss Prev Process Ind Special issue on Dust Explosions, (Ed P R Amyotte), pp 65-76 Chernenko, E V Alfanasyeva, L F and Lebedeva V A (1993) Flame Propagation Along the Surface of Metal Powders and Powdered Mixtures of Metal Oxides Proc Joint Meeting of the Russian and Japanese Sects of The Comb Inst October 2-5, Chernogolovka, Moscow Region pp 124-125 CREDIT (1995) Dust explosions: Protecting People, Equipment Buildings and Environment Proceedings of conference in London (October 11-12) Published by IBC Technical Services London UK Crowhurst, D (1993) Self-heating and Spontaneous Combustion Characteristics of Bulk Powders and Powder Layers Paper given at the European Summer School on Dust Explosion Hazards: 590 Dust Explosions in the Process Industries Their Assessment and Control, Cambridge, UK, organized by IBC Technical Services Ltd in association with BMHB and IELG Crowhurst D (1993a) The Strength of Equipment to be Used for Contained and Vented Explosions Paper given at the European Summer School on Dust Explosion Hazards: Their Assessment and Control Cambridge UK, organized by IBC Technical Services Ltd in association with BMHB and IELG Crowhurst D (1993b) Explosion Protection of Industrial Buildings Paper given at the European Summer School on Dust Explosion Hazards: Their Assessment and Control, Cambridge, UK organized by IBC Technical Services Ltd in association with BMHB and IELG Crowhurst D Colwell S A., and Hoare D P (1994) The External Effects of Vented Dust Explosions Proc 6th Internat Coll Dust Explosions (Ed by Deng Xufan and Piotr Wolanski) (August 29-September 2) Shenyang, P R China, pp 51@525 Cybulski K Dyduch, Z Lebecki K., and Sliz, J (1993) Suppression of Grain Dust Explosions with Triggered Barriers Proc Sth Internat Coll Dust Explosions, (April 19-22) Pultusk near Warsaw pp 437-447 Cybulski K Dyduch Z Lebecki, K and Sliz, J (1994) Weak Coal Dust Explosion Propagation in a Mine Workings Network Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski) (August 29-September 2) Shenyang, P R China pp 371-380 Cybulski K Dyduch Z., Lebecki, K and Sliz, J (1994a) The Tests on Triggered Barriers in Cross-roads of Mining Galleries Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski) (August 29-September 2) Shenyang, P R China, pp 500-509 Dahn, C J Reyes, B N., and Kashani, A (1993) Electrostatic Discharge (ESD) Energy Initiation of Dust Cloud Proc 5th Internat Coll Dust Explosions, (April 19-22), Pultusk near Warsaw pp 87-97 Dahn C J Reyes, B N and Kashani A (1994) Static Electricity Hazards of Flexible Intermediate Bulk Containers Proc 28th AlChE Ann Loss Prev Symp Session No 12 on Electrostatic Hazards (April 17-21) Atlanta USA, American Institution of Chemical Engineers, 345 E Street, New York Dahoe A E Velzen Th J van, Sluijs, L P., Neervoort, F J., Leschonski, S , Lemkowitz S M Wel P G J van der, and Scarlett, B (1995) Construction and Operation of a 20-litre Dust Explosion Sphere At and Above Atmospheric Conditions In Loss Prevention and Safety Promotion in the Process Industries: Volume 11, (Ed by J J Mewis, H J Pasman and E E De Rademaeker) Elsevier Science B V pp 285-302 Dahoe A E Zevenbergen J F., Lemkowitz S M and Scarlett, B (1996) Dust explosions in Spherical Vessels: The Role of Flame Thickness in the Validity of the 'Cube-root Law' J Loss Prey Process f n d Special issue on Dust Explosions, (Ed by P R Amyotte) pp 33-44 Dansk Fire Eater A/S (1992) INERGEN: Anlagsbeskrivelse & Design Report obtained from Dansk Fire Eater A/S Skovlytoften 14, DK-2840 Hoke, Denmark Deng Xufan, Xu Renxian Xie Lin, Dang Junxian, Zang Tingan, Gao Jun and Tan Feng Gui (1993) Explosibility and Ignitability of 16 Types of Dust and Some Opinions on Fundamental Research for Dust Explosions Proc 5th Internat Coll Dust Explosions (April 19-22), Pultusk near Warsaw pp 217-224 Deng Xufan Zang Tingan Dang Junxian and Xie Lin (1993a) Maize Dust Explosion in the 94.4m3 Experimental Silo for Venting of Deflagrations in Low Strength Silos Proc 5th Internat Coll Dust Explosions, (April 19-22) Pultusk near Warsaw, pp 403-41 Deng Xufan and He Jicheng (1994) A Brief Review of Dust Explosion Reaction Engineering Proc 6th Internat Coil Dust Explosions (Ed by Deng Xufan and Piotr Wolanski) (August 29-September 2) Shenyang P R China pp 96-115 Ding Hua and Huang Wanli (1994) On the Chapman-Jouguet Condition of Dust Detonation Proc 6th Internat Coll Dust Explosions (Ed by Deng Xufan and Piotr Wolanski), (August Research and development 59 "-September 2) Shenyang, P R China pp 341-348 Dushin V R Nikitin V F., Smirnov, N N., Zverev, N I Machviladze, G M and Yakush S E (1993) Mathematical Modelling of Particle Cloud Evolution in the Atmosphere After a Huge Explosion Proc 5th Internar Coll Dust Explosions (April 19-22), Pultusk near Warsaw pp 287-292 Eckhoff R K (1991) Generation Ignition, Combustion and Explosion of Sprays and Mists of Flammable Liquids in Air A Literature Survey Report No CMI-91-A25014 from Christian Michelsen Research (Chr Michelsen Institute) N-5036 Fantoft Norway Eckhoff R K (1992) Influence of Initial and Explosion-induced Turbulence on Dust Explosions in Closed and Vented Vessels Research at CMI Powder Technology 71 pp 181-187 Eckhoff R K ( 1993) Dust Explosion Research: State-of-the-art and Outstanding Problems Journal of Hazardous Marerials 35 pp 103-1 17 Also reprinted in Archivum Combustionis 13 (1993) pp 135-147 Eckhoff R K ( 1993a) Influence of Initial and Explosion-induced Turbulence on Dust Explosions in Large Silo Cells Safety Science 16 pp 511-525 Eckhoff R K (1994) Prevention and Mitigation of Dust Explosions in the Process Industries: A Survey of Recent Research and Development Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski) (August 29-September 2) Shenyang, P R China, pp 5-34 Eckhoff R K (1995) Dust Explosion Hazards in the Ferro-alloys Industry Proc 52nd Electric Firrtiace Conference (November 13-16 1994) Nashville TN, USA pp 283-302 Published by Iron and Steel Society, lnc., Warrendale PA USA Eckhoff R K (1996) Prevention and Mitigation of Dust Explosions in the Process Industries: A Survey of Recent Research and Development J Loss Prev Process Ind Special issue on Dust Explosions (Ed by P R Amyotte) pp 3-20 Eckhoff R K (1996a) Dust Explosion Hazards in the Silicon Crushing and Grinding Industry Proc of Conf on Silicon for the Chemical Industry I l l (June 18-20 1995) Sandefjord Norway Fan B C Ding D M and Tang M J (1993) An Aluminium Dust Explosion in a Spherical Closed Vessel Proc (suppl.) 5th Internar Coll Dust Explosions (April 19-22), Pultusk near Warsaw pp 21-31 Fan Xisheng and Wu Jianxing Li Li (1994) The Edge Effect in the Static Bursting of Vent Closure Proc 6th Inrernat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski) (August 29-September 2) Shenyang P R China pp 553-559 Fernando D (1993) Dust Explosion Hazards: The Human Element Paper given at the European Summer School on Dirst Explosion Hazards: Their Assessmenr and Control Cambridge UK organized by IBC Technical Services Ltd in association with BMHB and IELG Frolov S M Mack A , and Roth P (1993) Diffusion Model of Dust Lifting Behind a Shock Wave Proc 5th Itirertiat Coll Dust Explosions (April 19-22), Pultusk near Warsaw pp 30 1-3 IO Gao Guangchun Chen Zhandong Tang Quinghua and Luo Ruquan (1994) New Technique and Equipment for Fire and Explosion-protection of Blast Furnace Bituminous Infection Proc 6th Intertiat Coll Dust Explosions (Ed by Deng Xufan and Piotr Wolanski) (August ?-September 2) Shenyang P R China pp 407-411 Gelfand B Medvedev S Polenov A , , and Bartenev A (1990) Shock Waves From Expansion o f Burning Dust Clouds combustion Explosion and Shock Waves No pp 85-91 Gelfand B and Tsyganov S (1992) Private communication Semenov Institute of Chemical Physics Academy of Sciences of Russia Kosygin Street Moscow 117977 Russia Gelfand B E Khomik S V., and Polenov A (1994) Quenching of Shock Waves in Dusty Medium Proc 6th Interticit Coll Dust Explosions (Ed by Deng Xufan and Piotr Wolanski) (August 29-September 2) Shenyang P R China pp 478-483 Geng J H Tang M J and Gronig H (1993) Pressure Front of an Incident Shock Propagating into ii Combustible Particles-oxidative Gas Mixture Proc 5rh Internat Coli Dust Explosions 592 Dust Explosions in the Process industries (April 19-22), Pultusk near Warsaw, pp 335-344 Geng, J H., Tang, M J., and Gronig, H (1993a) Shock-induced Ignition Delay of Cornstarch Dusts Proc 5th Internat CON Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 321-328 Geng, J H., Liao, S P., and Tang, M J (1994) Dynamics Effects on Ignition of a Dust Suspension Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China, pp 366-370 Geng, J H., Ven, A van de, Zhang, F., and Gronig, H (1994a) A New Setup to Measure Ignition Delay of a Dust Suspension Behind an Incident Shock Wave Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China, pp 309-314 Gibson, N (199a) A Review of Dust Explosion Research Projects for BMHB Research Project Panel: An interim report (November) Gibson, N (1993) Precautions Against Fires and Explosions in Drying Operations Paper given at the European Summer School on Dust Explosion Hazards: Their Assessment and Control, Cambridge, UK, organized by IBC Technical Services Ltd in association with BMHB and IELG Gibson, N (1996) Problems in the control of dust explosions: an overview of the CEC CREDIT project J Loss Prev Process Ind pp 255-258 Gieras, M., Klemens, R., and Wolanski, P (1993) Pyrolysis Processes During Grain Dust-air Mixture Explosions Proc 5th Internat CON Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 137-152 Gieras, M., and Klemens, R (1994) Experimental Study of the Ignition and Mechanism of Flame Propagation in Dust and Hybrid Mixtures Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China, pp 158-178 Gieras, M., Klemens, R., and Wolanski, P., et al (1994) Suppression of Dust Explosion Triggered by Explosive Charge Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China, pp 484-490 Glinka, W., Klemens, R., and Wolanski, P (1993) Experimental and Theoretical Studies on Radiative Ignition of Dust Layer Proc 5th Internat Coll Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 69-86 Glor, M (1993) Static Electricity - Theory Electrostatic Hazards in Powder Handling Operations Papers given at the European Summer School on Dust Explosion Hazards: Their Assessment and Control, Cambridge, UK, organized by IBC Technical Services Ltd in association with BMHB and IELG Glor, M., and Maurer, B (1992) Ziindversuche mit Schiittkegelentladungen Paper presented at VDI Colloquium Sichere Handhabung brennbarer Stiiube, (November 4-6), Niirnberg, Germany Glor, M (1993a) Private communication Ciba-Geigy AG, Basle, Switzerland Glor, M., Maurer, B., and Rogers, R (1995) Recent Developments in the Assessment of Electrostatic Hazards Associated with Powder Handling In Loss Prevention and Safety Promotion in the Process Industries, Volume I (Ed by J J Mewis, H J Pasman and E E De Rademaeker), Elsevier Science B V., pp 219-230 Haefen, E von, and Schecker, H (1993) DUSTEXPERT - An Expert System for the Assessment of Explosion Hazards and the Selection of Explosion Protection Methods for Dust Handling Plants Proc 5th Internat Coll Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 487-496 Harmanny, A (1992) Explosion Effects Proc Ist World Seminar on the Explosion Phenomenon and on the Application of Explosion Protection Techniques in Practice, February 17-21) Arranged by EuropEx, in Brussels Research and development 593 Harmanny, A (1993) Duration of Vented Dust Explosions EuropEx Newslener 23 (December) pp 5-9 Hattwig, M., and Hensel, W (1993) Applicability of the new VDI-guideline 3673 to Silos of Rectangular geometry Proc (suppl.)5th Internat Coll Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 71-81 Hauert, F Vogl A., and Radandt, S (1994) Measurement of Turbulence and Dust Concentration in Silos and Vessels Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China, pp 71-80 Hensel, W., and John, W (1992) Zusammenhang zwischen Glimmverhalten und Staubschichtdicke Paper presented at VDI Colloquium Sichere Handhabung brennbarer Stabe (November 4-6) Niirnberg, Germany Hensel, W., and John, W (1993) The Dependence of Minimum Ignition Temperatures of Dust Layers Upon Layer Thicknesses Proc 5th Internat Coll Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 35-57 Hensel, W., Krause, U., John, W., and Machnov, K (1994) Critical Parameters for the Ignition of Dust Layers at Constant Heat Flux Boundary Conditions Proc 28th AIChE Ann Loss Prev Symp Session No 13 on Dust Explosions (April 17-21) Atlanta, USA American Institution of Chemical Engineers, 345 E 47 Street, New York Hertzberg, M., Zlochower, I A., and Cashdollar, K L (1992) Metal Dust Combustion: Explosion Limits, Pressures, and Temperatures Proceed, 24th Symp (Internat.) on Combustion, The Combustion Institute, Pittsburgh, USA, pp 1827-1835 Hertzberg, M., Cashdollar, K L., Zlochower, I A., and Green, G M (1992a) Explosives Dust Cloud Combustion Proc 24th Symp (Internat.) on combustion The Combustion Institute, Pittsburgh, USA, pp 1837-1843 Hesener, U., and Schecker, H -G (1995) ExTrA - An Expert System for the Safety Analysis of Drying Plants In Loss Prevention and Safety Promotion in the Process Industries, Volume 11, (Ed by J J Mewis, H J Pasman and E E De Rademaeker), Elsevier Science B V., pp 643-653 Hjertager, B H., Fuhre, K., and Bjoerkhaug, M (1988): Gas Explosion Experiments in 1:33 and 1:5 Scale Offshore Separator and Compressor Modules using Stoichiometric Homogeneous FueYair Mixtures J Loss Prev Process Ind, pp 197-205 Hoechst, S., Leuckel, W., and Eibl, J (1993) Experimentelle Untersuchungen zum Ablauf von Staubexplosionen in einer dmckentlasteten Versuchs-Silozelle Chem -Ing -Techn 65 No 12, pp 1488-1490 Holbrow, P., Andrews, S., and Lunn, G A (1996) Dust Explosions in Interconnected Vented Vessels J Loss Prev Process Ind Special issue on Dust Explosions, (Ed by P R Amyotte) pp 91-103 Huang Wanli, Pu Yikang, and Ding Hua (1994) The Electrical Conduction Phenomenon in the Process of Combustion of Aluminium Powder Air Mixtures Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China, pp 201-205 Hu Dong, and Sun Zhumei (1994) Studies of the Behaviour of Aluminium Powder Reaction in the Gas Phase Reaction Environment Proc 6th Internat Coll D s Explosions, (Ed by Deng ut Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China, pp 349-354 Hu Dong, Wang Tianfu, Zhang Guanren and Sun Zhumei (1994) Studies on High Speed Reaction Behaviour of Wheaten Hour Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China, pp 355-359 Itagaki, H., and Matsuda, T (1994) Thermal Ignition of Activated Carbon Dusts Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China, pp 141-145 Jansson, L (1993) Private communication Firefly AB, Huddinge, Sweden 594 Dust Explosions in the Process Industries Kauffman, C W., Sichel, M., and Wolanski, P (1991) Dust Related Detonations In Dynamic Structure of Detonation in Gaseous and Dispersed Media, Kluwer, Boston, USA Kauffman C W., Sichel, M and Wolanski, P (1992) Research on dust explosions at the University of Michigan Powder Technology 71 p 188 Khomik, S V Gelfand, B E and Knyazev, M V (1993) On the Critical Diameter of Detonation Propagation in Dust Suspensions Proc of Joint Meeting of the Russian and Japanese Secs of The Comb Inst., (October 2-5) Chernogolovka, Moscow Region, p 188 Khomik, S V., Gelfand, B E., and Knyazev, M V (1994) Experimental Determination of a Critical Diameter of Detonation Propagation in Dust Suspensions Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China, pp 315-319 Kjaldman, L (1992) Numerical Flow Simulation of Dust Deflagrations Powder Technology 71 pp 163-169 Kleinschmidt, H -P (1992) Private communication Fagus-GreCon Greten GmbH & Co., Postfach 1243, D-W-3220 Alfeld-Hannover, Germany Klemens, R., Teodorczyk, A., Wolanski, P., and Wolinski, M (1993) Detonation Parameters of Hybrid Mixtures Containing Grain Dusts Proc (suppl.) 5th Internat Coll Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 57-69 Klincewicz, M., and Kordylewski, W (1993) A New Explosion Diverter for Pipelines Protection Proc 5rh Internat Coll Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 431436 Korobeinikov, V P (1993) The Analysis of Basic Parameters for Detonation of Dusty Gases Proc 5th Internat Coll Dust Explosions, (April 19-22), Pultusk near Warsaw pp 351-364 Krause, U (1993) A Two-Dimensional Model for the Numerical Simulation of Explosions in Vented Vessels Proc 5th Internat Coll Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 421430 Krause, U , Weinert, D., and Wohrn, P (1993) Diagrams for the Determination of the Limiting Oxygen Concentration of Dust/air Mixtures Proc 5th Internat CON Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 257-266 Krause, U (1994) Numerical Investigation of the Influence of Velocity Fluctuation on Venting of Vessels Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China, pp 441452 Krause, U., and Hensel, W (1994) Hazards Arising from Electrical Devices Surrounded by Deposits of Flammable Dust Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), (August 29-September 2), Shenyang, P R China, pp 146-157 Krishenik, P M., and Shkadinskii, K G (1993) Modeling of Combustion Modes in Bi-size and Bi-material Dust-Air Mixture Proc 5th Internat Coll Dust Explosions, (April 19-22), Pultusk near Warsaw, pp 191-198 Laar, G F M van (1994) Area Classification for Dust Explosion Hazardous Environments Preprints for seminar on Explosion Safety and Related Risk Control (March 23-24) Ghent Belgium, organized by Technological Institute-KVIV, in cooperation with EuropEx (Kontich, Belgium), pp 127-141 L’Abbe, R J (1992) Explosion effects on people Proc Ist World Seminar on the Explosion Phenomenon and on the Application of Explosion Protection Techniques in Practice, (February 17-21) Arranged by EuropEx, in Brussels Lebecki, K., Sliz, J., Dyduch, Z and Wolanski, P (1990) Critical Dust Layer Thickness for Combustion of Grain Dust Publication by American Institute of Aeronautics and Astronautics, pp 51-58 Lee, J H S., Zhang, F., and Knystautas, R (1992) Propagation Mechanisms of Combustion Waves in Dust-Air Mixtures Powder Technology 71 pp 153-162 Li Gang, Deng Xufan, Liu Wenxin, er al (1994) Development of a Quenching Venting Door (QVD) Proc 6th Internat Coll Dust Explosions, (Ed by Deng Xufan and Piotr Wolanski), 636 Index Cork dust: experiments, 405-6 heat conductivity, 403 Corona discharges, 17 Cost comparisons, protection systems, 126 Critical mass, suppressant, 106 Crushing and milling equipment, protection selection, 130-33 ‘Cube-root-law’, 301, 347 Cyclone experiments, 452-5 Damkohler number, 262,392,394 Deagglomeration see dispersion Deflagration-to-Detonation-Transition (DDT), 375, 377, 380 Detonation: defined, 375 theories: Chapman-Jouguet, 378-9 dust cloud, 380-81 ZND theory, 380 Devolatilizationprocess, 29, 31, 265-6, 298-300 Differential scanning calorimetry (DSC), 506 Dispersedness, 204 Dispersibility, 488-93 Dispersion mushroom design, 531,535 Donat vent sizing method, 441 Doors, hinged explosion, 92-3 Drag, partic!e, 219-22 Drag coefficient, viscous, 219-20, 230 Drag velocity, 228 Drop hammer tests, 522-3 Dryers, protection selection, 134 Drying process, 270 Duct flow devices, explosion isolation, 77-9 Ducts, detonation experiments in, 375-7 Dust accumulation, 114 removal of, 115 Dust chemistry, 25-8 Dust clouds: detonation experiments, 375-3 detonation theories, 38&81, 571 electric spark ignition energy, 517-22 experimental generation of, 244-5 in closed circulation system, 248-9 in open circuit system, 249-50 by short air blast, 245-8 explosibility : industrial, 550 laboratory tests, 550-52 formation of, 204-5 generation, 203-4 ignitability: industrial, 550 laboratory tests, 55&52, 565 inerting: by inert dust, 56, 629 by + NZ, 628-9 Initial pressure effects, maximum experiment safe gap, 353-7 minimum ignition energy, 422-3 minimum ignition temperatures: BAM furnace, 509-10 Godbert-Greenwald furnace, 508 industrial, 507 laboratory tests, 508 predictions, 4314 USBM furnace, 511-12 prevention of explosible: addition of inert dust, 74 insertion of inert gas, 67-70 limitation of dust concentration, 70-73 sensitivity to ignition from mechanical impact: industrial, 524 laboratory tests, 525-7 tests at other than normal atmospheric conditions, 549 Dust concentration, 3S5, 23944 controlling, 70-73 explosible, 7-10, 309,369-70 maximum, 318-19 minimum, 310-18, 527-34 theories, 320-25 measurement of, 71 Dust control: by addition of liquids, 11618 by vacuum removal, 115 Dust depositdayers, ignition of industrial, 501 laboratory tests, 502-507 Dust dispersioddiffusion: degree of, 32-3 mechanisms for, 2314 pressure, 52-3 in turbulent gas flow,23944 Dust explosions, literature survey, 481-3 statistical records, 20-21 in F R Germany, 2 grain explosion in US, 24-5 in US, 21-2 Dust fineness, 2-3 Dust free zone, 418 Dust heaps, 564 Dust layers: ignition 565 sensitivity: industrial, 522 laboratory tests, 522-3 thickness experiments, 36%9 Dust removal equipment, 115-16 index protection selection, 135 Dust ridges, 232 Dust sampling (for testing), 485-6 Dust selection data, 603 Dustability, 235 Earthing, need for, 17 Electric spark energy equivalent, 427 Electric spark ignition energy: dust clouds: CMI discharge circuit, 520 direct discharge, 518-20 industrial, 517 international standard, 5%22 laboratory tests, 517-18 dust layers: industrial, 513 laboratory tests, 514 Nordtest Fire 16, 514 Electric sparks: hazards from, 1519,484-5 ignition prevention, 65-6 ignition theories, 4244 Electrostatic discharges: 15-19 ignition prevention, 66 Electrostatic powder coating, 140-41 Electrostatic spark hazard, 15-19 Entrainment experiments, dust: by parallel airflow on dust surface, 228-34 by parallel air flow on particle monolayer, 226-7 i by upwards a r flow, 234-5 ‘Equivalent energy’ concept (spark discharge), 19 Event Tree Analysis, 128 Explosion: definitions, 1, 309,532 primary, secondary, 9-10 Explosion isolation, 74, 577 by active devices, 80 literature survey, 75 by passive devices, 77-9 by rotary locks, 76-7 by screw conveyors, 76 Explosion kinetics, 26-7 Explosion, pressure, maximum, 632 data, 604 in hybrid mixtures, 548-9 industrial, 534 laboratory tests, 53541 Explosion pressure, maximum rate of rise (explosion violence): data, 604, 632 further development, 545 industrial, 543 637 laboratory tests, 343, 543-5 Explosion-pressure-resistant equipment, 80-85 Explosion protection standards, 123-4 Explosion risks, 475-6 ‘worst-case’, 477 Explosion suppression systems, see under Suppression systems Explosion tube facility, 31CL11 Explosion venting, see under Venting Explosion violence, see under Explosion pressure, maximum rate of rise, Explosibility ond Ks,values Explosible dusts, hazard classification, 552-3 Explosibility: laboratory tests, 481-3 philosophy, 483-5 test data tables: BIA, 602-29 USBM, 630-3 see also under KQ values Extinguishing agents, 109-11 water, 63 injection of, 80 see also under Suppression systems Failure Modes and Effects Analysis (FMEA), 127 Fault Tree Analysis, 127-8 Finite element design techniques, 84-5 Fire extinguishing systems, see under Suppression systems Fish meal: explosion in Norway 1975, 175-9 literature survey, 137 thermal behaviour, 410 flame acceleration experiments, 361-3 Flame jet ignition 74, 566 Flame propagation: laminar: in closed vessels, 300-309 in dust clouds, 289-300 gaddust comparisons, 274-5 in premixed gas, 271-3 stationary burner studies, 27-9 non-laminar in vertical ducts, 325-32 tests, 502 theories, 289-300, 371-4 turbulent: in closed vessels, 339-48 models, 3324 overview, 336-8, 569 in unconfined geometries, 348-51 Flame stability systems, 394-5 Flame types: Nusselt , 273 in pre-mixed gas, 273-5 volatile, 273 Flammability tests, 5026, 605 Flexible big bags 574 Flour dusts: explosion in Turin 1785, 159-61 literature survey, 136-7 Fluidized bed experiments, 234-6 FMRF: lift-off apparatus, 491-3 settling velocity apparatus, 490 Frank-Kamenetskii’s constant, 393, 396, 397, 404,408 Friction: as hazard, 14 tests, 523 ‘Friction sparks’, 13, 64,427, 524 Galleries, experiments in, 368-9, 375-7 Gas explosions: risks from heated dust, 499-500 smouldering: Malmo 1989, 183-6 Stavanger 1985, 180 TomyIovo 1988/9, 181-2 Gas flow turbulent, 239-44 Gas inerting systems, 68-9 partial, 69-70 Gaseous product generation risk, 499 Glow temperature, 605 Godbert-Greenwald furnace, 431-3, 508, 512 Grain dust: experiments, 400, 428-9 explosions: Iowa 1980, 172 Kambo 1976, 165-7 Minnesota 1980, 169-71 Missouri 1980, 169 Oslo 1976, 167-8 Oslo 1987, 168 Stavanger 1970, 1624 Stavanger 1988, W Texas 1981, literature survey, 136-7 use of liquid additives, 117-18 Grewer furnace, flammability test, 504-5 Gruber venting theory, 472 Gutterman and Ranz-gas velocity gradient, 229-30 Halons (as suppressants), 109 Hartmann apparatudbomb, 246, 488 Haswell coal mine explosion, 2&21 Hazard analysidsurveys, 126-30 classification system 552-3 reduction possibilities, 60-61, 66-7 Hazard and Operability Studies (HAZOP), 177 I LI Hazardous materials, 57 Heat conductivity, 402-4 Heat flux ignition sources, 399 Heats of combustion, Heinrich and Kowall venting theory, 469 Hot particle detection system, 63 Hot-plate test, Hot spots, as ignition hazard, 426-30 generation of, 524-6 Hot surfaces, as ignition hazard, 13, 61-2, 430-3 Human motivation (in explosion prevention), 121-3 Hybrid mixtures: effect of, 49-53 explosive properties test, 548-9 IC1 Dessicarb (suppressant), 107, 1 Ignitability assessment: by laboratory tests, 481-3 philosophy of, 483-5 test data tables: BIA 602-29 USBM 63&3 Ignition: defined, 392-5 of dust clouds: by electric spark, 424-6 by hot surfaces, 43Ck34 by mechanical rubbing or impact, 426-30 of single particles: aluminium, 256-8 coal, 261-8 magnesium, 258-60 wood, 269-70 zirconium, 260 Ignition delay, 28, 342 Ignition energy, minimum, see Minimum ignition energy Ignition sensitivity, 3-4,35, 357, 421, 427, 429 Ignition sources, 536, 538, 540 electric sparks and arcs, 15-19 electrostatic discharges, 15-19 elimination of, 60-67 heat from mechanical impacts, 13 hot spots, 42630 hot surfaces, 13 open flames, 13, 61-2 smouldering or burning dust, 11-12 Ignition temperature, 296 determination, 396.401, 502, 504 Impact hazard, mechanical, 14, 428-30 Induction times, 371-2, 398, 406 Index Inert dust: in clouds, data, 586 influence of, 5uses of, 74 Inert gases, uses of, - 96 Inerting, intrinsic, Inerting system (coal grinding plant), 113 Integrated process plants, explosion prevention, 1 1-4 International Electrochemical Commission (IEC): hazard classification system, 5hot-plate test, 0ignition temperature experiment, 398,5 minimum ignition energy test, 520-22 resistivity test, 9standards, 4 International Standardization Organization (ISO): Bartnecht system, 246,3 codes and standards, 144 explosion suppression system test, 546,548 Ksl value, 347 m3 closed vessel test, 88,3 MEC r s l s , eut,37 Inter-particle forces: due to liquids, 0-0 electrostatic forces, and strength of bulk powder, 211-17 van der Waals’ forces, Intrinsic inerting, Iron, direct-reduced, corrosion of, 1 Jaeckel theory of explosive concentrations, 3& 22 Jenike cell, 213-14 Jost theory of ignition in pre-mixed gases, 424 639 Linen flax dust explosion, Harbin 1987, 179 8-0 Liquid additives, dust control, 116-18, 20 Liquid bridge regimes, 0Literature surveys: aluminium, 1 cellulose, coal dust, 13940 dust explosion hazards, explosion mitigatiodprevention, magnesium, 1 4metal dusts, 4milk powder, miscellaneous powderddusts, 4peat dust, 3powder for electrostatic coating, self-heating of powderddusts, 395,408-11 silicon, sugar, wood dust, Lutolf s method, 500, 2 Lycopodium, use of, 217,250,2834,416-18, 420 Mach number, 2 Mache-Hebra nozzles, Magnesium; ignition and combustion, 258-60 literature survey, 1 4Magnetic separators, Maisey venting theory, 6Maize starch experiments: bag filters, 456 dust clouds, 367,3 ignition, 2laminar flame, 8Darticle size Millard-le Chatelier thermal diffusion theory, 271,2 K-epsilon theory, 335 Ksr values (measurement of inherent explosibility), 99,347,543-4, 630 data, 604 Kjaldman computer models, 372-4 Kolmogoroff energy spectrum law, 334 Lambert-Beer’s law, Laminar flame propagation 567 Lift-off apparatus, 9Light attenuation measurement systems, 13 Lightning type discharges, Lignite dust, see Coal dust Maximum experimental safe gap (MESG), 353-7 Mechanical accidental impact ignition hazard, 63-5,5 2Mechanical bulk properties, powder, Metal dust: flame studies, 29,276-8,324 literature survey, 4Metal sparks: ignition hazard, 426-30 generation of, 524-6 Methane, effect of, Milk powder: literature survey, thermal behaviour, 410 640 Index Milling equipment, protection selection for, 130-33 Minimum electric spark energy, see Minimum ignition energy (MIE) Minimum explosive dust concentration (MEC) data 576-7 604, 631 experimental determination, 310-18 industrial, 527-8 laboratory tests: GermadSwiss closed bombs, 530 Nordtest Fire 011, 531-2 in USA, 528-30 and particle size, 31 Minimum ignition energy (MIE): data, 605,631 in dust clouds, 424-6 in hybrid mixtures, 51-2 and moisture content, 27-8 in pre-mixed gases, 422 Minimum ignition temperature: dust cloud data, 604 631 dust layer data, 630 Moisture content: role of, 27-8, 342, 494-5 data, 559 Nagy and Verakis venting theory, 471-2 National Fire Protection Association (NFPA): nomograph method, 439,455 standards, 144 vent scaling procedure, 464 Nomograph vent sizing method, 43940,455 Nomura and Tanaka venting theory, 470-71 Nordtest Fire 011 method, 317, 318, 531-2 MEC results, 317 Nordtest Fire 016 method, 514 Norwegian vent sizing method, 441 Nozzle: dispersal of agglomerates by, 236-9 Mache-Hebra type, 276 rebound design, 540-41 Nusselt number, 263, 266 Nusselt type flames, 273 Ohmic energy dissipation, 412-13 Open flame hazards, 13, 61 Open-circuit systems (for dust cloud generation), 249-50 Optical flame detectordsensors, 105 Organic materials: flame studies, 283-8 rates of pressure rise, 26-7 thermal behaviour, 410 see also under specific names Oxidation reaction, cooling of, 59-60 Oxidiser gas, oxygen content of, Oxygen concentration data, maximum 62X-9 632 Oxygen detectordsensors, 69 Particle dislodgementfentrainment: in parallel air flow, 226-7, 228-34 in upwards airflow, 234-5 Particle size, 2-3, 28-32 analysis, 487-8 data, 602, 603 Particles, suspended: drag on, 219-22 movement of, 223-5 terminal settling velocity, 217-19 Passive devices, explosion isolation, 77-9 Peat dust: computer model, 372 literature survey, 139 Personal motivation (in explosion prevention), 121-3 Pipelines, experiments in, 451 Pneumatic pipelines, 451 Pneumatic separators, 65 Polyesterlepoxy powders, literature survey, 140-41 Powderldust conveyors, protection selection, 135 Powderldust mixers, protection selection, 134 Powderddusts: literature survey, 4 mechanical properties, 212-17, 494 see also under specific types Prandtl-Karman relation, 228 Pressure dectectordsensors, 104 Pressure piling, 74, 534 Pressure pulse, 101-2 Pressure vessel design, 83 Pressure waves, large amplitude, 225 Preventive means, 57 ignition source avoidance, 57-67 explosible dust cloud elimination, 67-74 explosion transfer avoidance, 74-80 explosion-pressure-resistant equipment, 80-103 Primary explosions, 9, 80 Process equipment: pressure-resistant design, 83 pressure-shock-resistant design, 83 protection selection, 130-35 Process variables, monitoring, 112 example, 112-14 Protection selection: 123-5 cost considerations, 126 see a h Preventive means Index Publications, see Literature surveys Pulverised coal, 261 PVA flame studies, 283 PVC behaviour, 27 Pyrolysis, 29, 270, 400 Quantitative Risk Analysis, 582 Quenching distances, 279, 283, 287-8 Quenching tube, 99-100, 124 Radandt scaling law, 442, 448 Radiative heat transfer, 274-7, 338 Reactive forces, 100-103 Re-entrainment (of dust), 226-36 Resistivity, electrical, 495-6 Reynolds’ number, 219-20, 326, 334-5, 336 special, 351 Richardson-Zaki equation, 236 Risk analysis, 128 Rosin-Rammler charts, 432 Rotary locks: effectiveness of, 357-8 explosion isolation, 76-7 Rust venting theory, 470 St classification (explosion violence), 88, 604 Safety audits, 128-9 Safety management, 121-3 Safety in Mines Research Establishment (SMRE), 481 Saltation, 231 Sampling techniques, dust, 485-6 Schuber experimental work, 354-8 Screening tests, explosibility, 496-8 Screw conveyors, 76 Secondary explosions, 9-10 Self-heating, 395, 505 574 in bag filter dust, 411 computer models, 405-8 experiments: deposit on hot surface, 398 heat conductivity, 4 heat flux ignition source, 399 isoperibolic, 3% smouldering combustion, 399401 powder types, 409-1 prevention of, 58-9 theoretical work, 404 Self-ignition, see Self-heating Separators, use of, 65 Settling velocity apparatus, 490 Shear cells, 213-14 641 Shock waves, 225 567 Silicodalloys dust, literature survey, 142-3 Silicon powder explosion, Bremanger 1972, 193-5 Silos, experiments in: large, 443-6 slender, 446-51 Single impact ignition risks, 64 Siwek test (201 sphere), 246-7, 540 MEC results, 317 Smouldering combustion, 11-12, 501 564 experiments, 399-400 extinction, 59-60 prevention of, 59 Smouldering nests, 12, 23, 62-3 Sodium dithionite experiments, 398 Sound, speed of, 224-5 equilibrium, 224 frozen flow, 225 Spark gap length, 422-3 resistance, 412-13 Spark ignitioddischarges, 1617, 19 background, 411 duration effect, 413-21 dust cloud theories, 424-6 ohmic resistance, 412-13 optimum duration, 420-21 time effect, 413-18 Spark kernel, hot, 418, 424 Specific heats data, 224 Specific surface data, 2-3, 28-32, 487 Spinning riffler, 486 Spontaneous ignition, 23 Standards, regulations and guidelines, 144 Statistical records, 20-21 F R Germany 1965-1985, 22-4 grain explosions in USA, 24-5 in USA W , 21-2 Steel, spark-producing experiments with, 429 Stefan-Boltzmann Law, 266 Stokes’ theory for laminar flow, 217, 221 Stone dust, inerting effect of, 56 Stored capacitor energy criterion, 415-16 Structural response analysis, 84-5 Sugar, literature survey, 137 Suppressant agents, types of, 59-60, 109-11 Suppression systems, automatic: design, 108-9 efficacy of, 546 general concept, 103-8 literature survey, unacceptability situations, 124 Suppressor units, 103 Swedish vent sizing method, 441 Swift venting theory, 472 Systems reliability analysis, 127 642 Index Tchen theory of diffusion, 242-3 Temperature, effect of initial, 44-5 Tensile strength testers, 214-15 Terminal settling velocity, 217-19 Test results (for ignitability and explosibility,), correlation with real hazards, 483-5 Thermite reaction, 14, 64 Three-element flame propagation theory, 305-307 Three-zone flame propagation theory, 304 Titanium experiments, 429 ‘Top events’, 127 Tramp metal, risks of, 178-9 Turbulence, 35-8, 332-6 562 explosion studies, 352 intensity of, 333 mixing effect, 239-44 Turbulence intensity experiment, 465-6 Turbulent dust explosions (in large diameter enclosures), 359-71 Turbulent dust flames, 336-8 experiments with, 33947 Turin warehouse explosion, 20 Ural venting theory, 472-3 US Bureau of Mines (USBM), 481 201 vessel, 529, 541 drop hammer tests, 522-3 flammability test, 504 furnace, 511-12 laboratory test methods, 630-2 spark ignition tests: for dust clouds, 517-18 in dust layers, 514 Vacuum cleaners: explosion-proof, 115-16 protection selection, 135 Valves: fast-closing, 80 vented, 79 Vent covers, 78, 88-93 reversible, 93-4 Vent ducts, 95-9 580 Vent sizing, 87-8 current developments: bag filters, 463 basic’approach, 461, 464-5 cyclones, 462-3 elongated enclosures, 463 intermediate enclosures, 463 large empty enclosures, 461 large slender enclosures, 461 limitations of, 461 mills, 463 NFPA scaling procedure, 464 other shapes and dusts, 464 small slender enclosures, 462 European and US methods: modified Donat method, 441 nomograph, Norwegian method, 441 Radandt scaling law, 442 Swedish method, 441 vent ratio, 439 full scale experiments: bag filters, 455-8 cyclones, 452-5 large silos, 443-6 others, 459-60 pneumatic pipelines, 45 slender silos, 446-51 probabilistic nature of problem, 474-6 Ventex valves, 79 Venting, 86, 467-8 hazards, 94-5 blast effects, 100-103 unacceptability of, 94-5, 124 methods: flame free, 124 quenching tube, 99-100 vent covers, 88-94 vent ducts, 95-9 theories: Gruber, 472 Heinrich and Kowall, 469-70 Maisey, 468-9 Nagy and Verakis, 471-2 Nomura and Tanaka, 47&71 Rust, 470 Swift, 472 Ural, 472 Venting system in coal grinding plant, 113-14 Verein deutscher Ingenieure (VDI) 3673: explosiod pressure guidelines, 452, 454, 456, 458, 460 namographs, 440 recunmendations, 45 vent siziz: 87, 445, 461, 463 standards, 144 Volatile flame type, 273-5 Weiss-Longwell criterion, 240 Wheat flourldust experiments, 365-6, 378, 444,446, 452 ‘Whirling’ chamber, 246 Wood flourldust: experiments, 365-7, 399, 400 literature survey, 138 Index 643 Wood particles, ignition and combustion, 29, 269-70 ‘Worst credible explosion’ criterion, 476 7xhr’s combustion bomb, 319 Zehr’s theory of explosive concentrations, 321-2 Zero gravity conditions, 290-92 Zircaloy dust, precautions with, 4 Zirconium particles, ignition and combustion, 260 ZND model, 380 Plate 18.5 m3 vented explosion vessel connected to a straight vent duct (Courtesy of Health & Safety Executive, UK) Plate Coal dust explosion in 18.5 m3 vessel vented through a duct with a 90" bend at the end (Courtesy of Health & Safety Executive, UK) Plate High-turbulence maize starch explosion in 500 m3bolted steel plate silo at Vaksdal, Norway, in April 1982 (Photographer: A M Fosse, Vaksdal) Plate Experimental site outside Bergen, Norway, with 236 m3 steel silo, dust injection system and instrumentation cabins Enclosed winding staircase along the silo wall to the left Vented maize starch explosion in 236 m3 steel silo in Norway Plate Plate Maize starch explosion in 5.8 m3 experimental bag filter unit in Norway Vent area 0.16 m2 Static opening pressure of vent cover IO bar(g) Maximum explosion pressure 0.15 bar@) Plate Silicon dust explosion in the welding torch ignition test apparatus used in Norway Plate 10 Ignition of a dust cloud in the Codbert-Creenwald furnace ... were in the grain industry, 17% in the textile industry 12% in the coal industry and 6% in the metallurgical industry With the rapid development of the chemical and metallurgical industries, the. .. , u) continued I Appendix 615 continued 16 Dust Explosions in the Process Industries Table A l , a > Table A l , continued Appendix 617 61 continued Dust Explosions in the Process Industries. .. , continued Appendix 619 620 Dust Explosions in the Process Industries Table A l , continued + I Table A l , continued Appendix 621 I s m continued 622 Dust Explosions in the Process industries