Safety Design in Explosives Testing Laboratories. Some examples at CERCHAR

AbstractFor more than forty years, CERCHARCentre d'Etudes et Recherches de Charbonnages de France. 's activities on explosives and related items have employed a staff of 10 to 20 people including 3 to 5 engineers. This staff, called LSEVLaboratoire des Substances Explosives de Verncuil , acts as the official French laboratory for testing and performing a variety of studies. The main research topics concern the safety in manufacturing of explosives, their transport, storage, and use, particularly in gassy and dusty mines. The same holds for hazardous chemicals that are potentially explosive or otherwise unstable. Related to these activities is the safety of the personnel involved in testing, which requires special attention to be paid to adapted procedures and instructions and to special devices or equipment, desiged for the most part by CERCHAR itself. Three examples of such designe are presented. Their objectives and advantages are disscussed.The first one is an explosion chamber for firing confined explosive charges up to 2 kilograms. This facility has the possrommy of being highly instrumented. Fragments formed in the detonation of deflagration regimes are totally stopped by the walls of the chamber.The second one is a cell device for daily storage of explosives. This device led to a very important reduction in the quantity of explosives handled by people in the same room. This avoids a possible catastrophic mass explosion when large samples are needed such as for modern, insensitive mining explosives. the design of the cell structure, based on ful scale experiments, limits an unexpected explosions to the contents of a single cell without propagation to the other cells.The third and last example presented is a movable wood barrier, located in areas where explosives are fired in the open. This barrier ensures a significant reducation in the blast effect. It allows the worker to stay in the immediate vicinty of charge during the final preparation stages i.e the connection of the detonator wires to the firing circuit.