Hands on explosives: Safety testing of protective measures

Several attempts have been made to test the suitability of protective measures for the handling of explosives. We investigated the suitability of safety gloves and a combined safety helmet and face shield. In the presented studies, three different experimental setups were used to simulate the effects of an explosion of a primary explosive in a glass flask on the glove or helmet protected body. Depending on the experimental setup, the fragment effects were evaluated and compared. Furthermore, the fragment distribution of an explosion inside a glass flask was investigated. The explosion of 1 g of lead azide in a 10 mL flask yielded approximately 14,000 glass fragments. However, most of the shards were accelerated down- and side-wards and only few upwards. Holding a flask on its neck (instead of its bottom) is therefore a simple but effective way of diminishing the risk of injury, when handling explosives. The safety helmet/face shield performed very well, by shielding the face from all fragments. Furthermore, it could be proven that DIN and EN standard testing procedures for gloves are unsuitable to simulate the effects of a respective explosion.In this article, the progress in the development of realistic testing procedures for the testing of gloves for the protection against fragmentation effects of glassware in situations involving explosions is reported and the results and methods of previous tests are summarized.     

Evaluating safety management and culture interventions to improve safety: Effective intervention strategies

The Dutch Ministry of Social Affairs and Employment provided subsidy over the period 2004–2008 to a number of companies to introduce changes aimed at reducing accidents by changing their safety culture and aspects of their safety management. As part of the programme a scientific evaluation was set up to assess the effectiveness of the interventions in 17 of the projects, covering 29 companies. Before and after studies were made of the companies, documenting the state of their safety management and risk control efforts and their accident rates before the intervention, the changes made over the study period and the resulting changes in a range of measures aimed at assessing the success of the changes. The analysis led to a categorisation of the projects according to their degree of success.This paper describes the patterns of interventions distinguishing between successful and not successful projects and discusses the mechanisms lying behind them. Interventions bringing about constructive dialogue between shop-floor and line management, providing motivation to line managers and strengthening the monitoring and learning loops in the safety management system (SM) appeared more successful. The amount of energy and creativity injected by top managers and, above all, by the coordinator (safety professional) appeared also to be a distinguishing factor.     

Effect of varying two key parameters in simulating evacuation for subway stations in China

With the rapid development in economics, subway systems have been constructed in many big cities of China. Computer evacuation models developed overseas are commonly applied in working out safety management scheme. However, input evacuation parameters are not compiled from surveying passenger behavior in China. In fact, very few studies were conducted on justifying such parameters. Staircases in subway stations, particularly those connecting the platform and the ticket hall, are identified as the ‘bottleneck’ during evacuation in the subway stations. The maximum upstairs speed and the average minimum width of staircase utilized per person are the two key parameters affecting the evacuation through the staircase. Effect of varying these two parameters will be studied in this paper by taking two subway stations in China as examples. Evacuation performance is predicted with the software buildingEXODUS. The default values in the software are used and adjusted through field survey. Effect of varying either or both of the two parameters is discussed. The possible causes on the differences and the factors to affect such effect are explored. It is found that changing both parameters simultaneously would reduce the overall evacuation time by 50%. The effect of varying the two parameters on the overall evacuation performance of the whole station depends also on the occupancy density in the station; and the travel distance from the outlet of the staircase between the platform and the ticket hall to the inlet of the staircase between the ticket hall and the ground surface.     

Modeling the heat transfer in acetylene cylinders during and after the exposure to fire

In this paper two different approaches for predicting the heating-up of an acetylene cylinder involved in a fire and the afterward cooling with water are presented. In the simulations polynomial functions were used to describe the temperature dependency of the thermal properties of the cylinder interior, which is a complex system composed by a solid porous material, a solvent (typically acetone) and acetylene dissolved in it. Model equations covered heat conduction in the cylinder interior and at its walls. In the first approach the cylinder surroundings were simulated as a further domain constituted by CO₂, during the fire exposure, and for water, during the cooling. In this domain the coupled heat transfer (convection and conduction) and the momentum equation (Navier–Stokes) were solved. In the second approach no further domain was considered but boundary conditions were set directly on the cylinder walls. Results of the calculations performed with both approaches are presented. This work could prove helpful in predicting to which extent the interior of an acetylene cylinder exposed to fire reaches temperatures capable of initiating the decomposition of acetylene and to determine how long a water cooling should be applied, so that the system is brought again under non-critical conditions.     

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Prenatal diagnosis of endocardial fibroelastosis

In a case of fetal heart failure caused by endocardial fibroelastosis, prenatal echocardiography clearly demonstrated; a thickened endocardium. We therefore suggest that an abnormal endocardium may be detected in utero by ultrasound, thus representing an important clue in the differential diagnosis of fetal nonimmune hydrops and in the evaluation of pregnancies at risk for endocardial fibroelastosis.     

Prenatal diagnosis of pericentric inversion of chromosome no. 17 in a twin pregnancy

Although prenatal genetic diagnosis can usually provide prospective parents with information as to whether their fetus is affected with certain genetic conditions, the presence of twins and the uncertainty about the phenotype of some chromosome variations pose a major dilemma and make genetic counselling very difficult. Here, a case report of an unusual chromosome aberration (pericentric inversion of chromosome no. 17) in a twin pregnancy which was originally suspected to be monoamniotic but later proved to have two sacs was presented.