Gas explosion characteristics and spray control mechanism in underground square

The spray system mechanism during a gas explosion in an underground square pipeline is complex. In this paper, the underground square of Fuxin City is selected as the research object. FLACS numerical simulation software is used to analyze the spatial and temporal distribution characteristics of a gas explosion in an underground square pipeline with an unopened spray system using combustion and combustion rate models. Different spray pressures were compared and analyzed to determine the optimal spray control pressure, and the spray system mechanism was clarified. The results revealed that the gas explosion overpressure is divided into the overpressure gentle, overpressure rising, and overpressure decay stages, corresponding to a trend of rapid growth and slow decline. The influence of spray pressure on the gas explosion exhibits a promotion-inhibition-promotion trend, corresponding to 0-0.2 MPa, 0.2-0.6 MPa, and 0.6-1.6 Mpa, respectively. The peak overpressure and overpressure propagation rates are the lowest at 0.6 MPa, and the explosion suppression effect is the most pronounced. The spray system mechanism varies with the explosion overpressure stages. Generally, the time to peak value, that is, the peak time, the overall duration of the explosion, and the duration of the explosion stage decrease, whereas the peak explosion overpressure decreases.

Fuzzy multi-criteria decision-making framework for controlling methane explosions in coal mines

The structure of underground coal mines is vulnerable to many mishaps because of the challenging conditions of production and the unique features of the earth. These incidents could cause significant financial and production losses for the mines in addition to worker injury, disability, or death. In coal mines, methane explosions are a frequent threat. Establishing a safe work environment requires managing these problems with an accident control method. The current study used the fuzzy TOPSIS and fuzzy AHP techniques for this aim. The framework was used to tackle the four-alternative problem of underground coal mine explosion control method selection. To identify potential risks of a methane explosion, a data gathering survey was conducted as part of the suggested hybrid methodology. The fuzzy AHP was used to compute the fuzzy weights of the hazards. "Improper ventilation system" is ranked highest out of the 34 sub-risk factors. The fuzzy TOPSIS was then utilized to rank the explosion control methods using the weights. To assess the viability of the study's conclusions, a sensitivity analysis was carried out. The findings indicate that "improving safety technology" and "financial investments" are the best ways to reduce such events. The results additionally indicate that the fuzzy TOPSIS approach in combination with the fuzzy AHP provides a helpful framework for dynamically assessing mine methane explosion accidents.

FRAM-based causal analysis and barrier measures to mitigate dust explosions: A case study

Both the number of dust explosion accidents and the resulting number of casualties have increased dramatically in recent years. To reduce this risk of dust explosions, we use the functional resonance analysis method (FRAM) to analyze the cause of the dust explosion accident at the Kunshan factory and propose barrier measures to prevent such accidents. The functional units that changed in the production system during the accident and how these functional units coupled to eventually cause the dust explosion were examined and explained. In addition, barrier measures were developed for functional units that changed during production and emergency systems defined to block the propagation of changes between functions and prevent resonance. Through case study, the identification of key functional parameters in both triggering the initial explosion and in then allowing its spread are key to define barriers to prevent a recurrence of such an event. FRAM uses system function coupling instead of traditional linear causality to explain the accident process, and develops barrier measures for changing function units, providing a novel thinking strategy and method for the analysis of accidents and their prevention.

Combustible wood dust explosions and impacts on environments and health - A review

Wood dust is the major wastes from timber and wood-based panel processing, including wood sawing, sanding, chipping, flaking, etc., which easily causes fire and explosions. The fine wood dust had risks of inhaling the dust air, causing problems to the respiratory system of workers, as well as the explosive risk of the wood dust-air mixture. Wood dust explosions occur worldwide, which have caused massive damages to equipment, buildings, and environments, killed people, and threatened human health. This study was aimed at exploring the causes, affecting factors, mechanisms, models of wood dust explosions, and their environmental/health impacts through reviewing and analyzing the collected data in order to minimize wood dust explosion risks by improving of safety procedures in the wood processing industry. To better understood and prevent wood dust explosion cases in the future, this review collected the explosion reports and analyzed the accident information through the following aspects: 1) Summarization of published review articles regarding wood dust explosions in Introduction, 2) Scrutinization of wood dust explosion cases and design of testing device, 3) Exploration of effects of wood dust properties and surrounding conditions on explosion and their mechanisms, 4) Investigation of methods for reducing wood dust explosion risks, 5) Modeling and simulation of wood dust explosions, 6) Examination of environmental and health impacts of wood dust explosions. Finally, the findings in this review were summarized in Conclusions. By collecting dust explosion reports, reviewing literature, and analyzing the collected data, wood dust explosions can be better understood. The results of this study can be useful for the design of equipment and dust absorption systems, as well as further suggestion of safety improvement procedures to minimize or eliminate risks of wood dust-related fire and explosion in the wood processing industry and mitigate its impacts on environments and health.

Encouraging Firework Safety Through Public Service Announcements

A dramatic increase in firework-related blast injuries to the hand and upper extremity resulted in record-setting numbers at our institution over the July 4, 2018, holiday. This led our hand and upper extremity department to create a public service announcement (PSA) campaign regarding firework safety and injury prevention. This PSA was broadcast in advance of the next July 4 holiday via several media platforms including television, radio, and the internet. The following year only 4 patients required surgery for firework-related blast injuries to the hand and upper extremity over the same 10-day period, including the weekends before and after the July 4, 2019, holiday. This represented a considerable reduction compared with the 14 patients seen within the same time frame in 2018. The purpose of this article was to outline the process and report the impact of creating and disseminating a public service announcement for firework-related blast injury prevention.

Fireworks and the Eye

A prospective study involving all casualty departments in Trent Region and 81% of the major eye units in UK was performed to determine ocular morbidity from the use of fireworks during 1986. A serious injury was defined as involving admission to hospital and/or intraocular damage. Of all the injuries from fireworks, 16.7% seen at major eye units were serious and were caused by rockets or exploding fireworks ( P< 0.001). Only 53% of all injuries and 12.5% of serious injuries involved children, and in contrast to the 1950s and early 1960s, young adults appear at greatest risk in the 1980s. Legislation to reduce ocular morbidity should concentrate on restricting the use of rockets and exploding fireworks and encouraging the use of suitable eye protection.

Comparison of the CAS-POL and IOM samplers for determining the knockdown efficiencies of water sprays on float coal dust

Float coal dust, generated by mining operations, is distributed throughout mine airways by ventilating air designed to purge gases and respirable dust. Float coal dust poses an explosion hazard in the event of a methane ignition. Current regulation requires the application of inert rock dust in areas subjected to float coal dust in order to mitigate the hazard. An alternate method using water sprays, which have been effective in controlling respirable dust hazards, has been proposed as a way to control float coal dust generated on longwall faces. However, the knockdown efficiency of the proposed water sprays on float coal dust needs to be verified. This study used gravimetric isokinetic Institute of Occupational Medicine (IOM) samplers alongside a real-time aerosol monitor (Cloud Aerosol Spectrometer with polarization; CAS-POL) to study the effects of spray type, operating pressure, and spray orientation on knockdown efficiencies for seven different water sprays. Because the CAS-POL has not been used to study mining dust, the CAS-POL measurements were validated with respect to the IOM samplers. This study found that the CAS-POL was able to resolve the same trends measured by the IOM samplers, while providing additional knockdown information for specific particle size ranges and locations in the test area. In addition, the CAS-POL data was not prone to the same process errors, which may occur due to the handling of the IOM filter media, and was able to provide a faster analysis of the data after testing. This study also determined that pressure was the leading design criteria influencing spray knockdown efficiency, with spray type also having some effect and orientation having little to no effect. The results of this study will be used to design future full-scale float coal dust capture tests involving multiple sprays, which will be evaluated using the CAS-POL.

Pacemaker Explosions in Crematoria: Problems and Possible Solutions

The number of artificial cardiac pacemakers is increasing, as is the number of bodies being cremated. Because of the explosive potential of pacemakers when heated, a statutory question on the cremation form asks whether the deceased has a pacemaker and if so whether it has been removed. We sent a questionnaire to all the crematoria in the UK enquiring about the frequency, consequences and prevention of pacemaker explosions. We found that about half of all crematoria in the UK experience pacemaker explosions, that pacemaker explosions may cause structural damage and injury and that most crematoria staff are unaware of the explosive potential of implantable cardiac defibrillators. Crematoria staff rely on the accurate completion of cremation forms, and doctors who sign cremation forms have a legal obligation to provide such information.

Is There a Threat Towards Medical Institutions, and What to Do?

Unfortunately the reality of today is that a terrorist threat in Europe has become evident. With increasing frequency we are confronted with attacks all across Europe, at least this is the perception. So is there a Threat? If look at the paper of Wolf et al (1), this describes an increase of terrorist attacks from 1999- 2006, the amount of victims due to these attacks increased exponentially. This means the attacks are getting more effective. The perpetrators are getting better and are learning how to injure or kill more victims. The techniques are getting more sophisticated. For example if we look at the Bali Bombing in 2002, here a second hit technique is used. The terrorist placed first a small bomb in a tourist area, knowing that this eventually will attract many people who rush in to help the victims. Then a second hit was done with a much larger bomb killing and wounding even a larger group of people. This is the goal of the terrorist, introducing terror, shocking the world, introduce fear. If we look at the attack in Nice, South France. They used a truck driving through a large tourist crowd, knowing that there would be many children and young people. This is their ultimate goal, shock the world. With that mindset, just imagine how shocking would it be to primary attack a medical institution. Our weakness as medical people is that we want to help people, In fact we gave a Hippocratic oath that we will always help other people, that is our job. We find it hard to believe that medical relief institutions will be attacked. If we look at the London bombing in 2005, one of the terrorists detonated the bomb in a bus. By coincidence this happened right in front of the British Medical Association with many doctors in the building at that time. All of them immediately went to the exploded bus to provide medical relieve, did they even think for a second that there maybe would be a second hit? We are to nice, and the terrorists know this. Historyhas proven to us that medical institutions are a potential goal. 2008 a terror attack in Mumbai, eight series of attacks were done between 26-29th of November. Eventually the terrorist where heading for the CAMA hospital. However because the hospital was alerted and were able to perform a complete lock down they were able to prevent additional casualties in the hospital itself. Are these rare incidents?

A novel method of fuzzy fault tree analysis combined with VB program to identify and assess the risk of coal dust explosions

Coal dust explosions (CDE) are one of the main threats to the occupational safety of coal miners. Aiming to identify and assess the risk of CDE, this paper proposes a novel method of fuzzy fault tree analysis combined with the Visual Basic (VB) program. In this methodology, various potential causes of the CDE are identified and a CDE fault tree is constructed. To overcome drawbacks from the lack of exact probability data for the basic events, fuzzy set theory is employed and the probability data of each basic event is treated as intuitionistic trapezoidal fuzzy numbers. In addition, a new approach for calculating the weighting of each expert is also introduced in this paper to reduce the error during the expert elicitation process. Specifically, an in-depth quantitative analysis of the fuzzy fault tree, such as the importance measure of the basic events and the cut sets, and the CDE occurrence probability is given to assess the explosion risk and acquire more details of the CDE. The VB program is applied to simplify the analysis process. A case study and analysis is provided to illustrate the effectiveness of this proposed method, and some suggestions are given to take preventive measures in advance and avoid CDE accidents.

Comparison of coarse coal dust sampling techniques in a laboratory-simulated longwall section

Airborne coal dust generated during mining can deposit and accumulate on mine surfaces, presenting a dust explosion hazard. When assessing dust hazard mitigation strategies for airborne dust reduction, sampling is done in high-velocity ventilation air, which is used to purge the mining face and gallery tunnel. In this environment, the sampler inlet velocity should be matched to the air stream velocity (isokinetic sampling) to prevent oversampling of coarse dust at low sampler-to-air velocity ratios. Low velocity ratios are often encountered when using low flow rate, personal sampling pumps commonly used in underground mines. In this study, with a goal of employing mine-ready equipment, a personal sampler was adapted for area sampling of coarse coal dust in high-velocity ventilation air. This was done by adapting an isokinetic nozzle to the inlet of an Institute of Occupational Medicine (Edinburgh, Scotland) sampling cassette (IOM). Collected dust masses were compared for the modified IOM isokinetic sampler (IOM-MOD), the IOM without the isokinetic nozzle, and a conventional dust sampling cassette without the cyclone on the inlet. All samplers were operated at a flow rate typical of personal sampling pumps: 2 L/min. To ensure differences between collected masses that could be attributed to sampler design and were not influenced by artifacts from dust concentration gradients, relatively uniform and repeatable dust concentrations were demonstrated in the sampling zone of the National Institute for Occupational Safety and Health experimental mine gallery. Consistent with isokinetic theory, greater differences between isokinetic and non-isokinetic sampled masses were found for larger dust volume-size distributions and higher ventilation air velocities. Since isokinetic sampling is conventionally used to determine total dust concentration, and isokinetic sampling made a difference in collected masses, the results suggest when sampling for coarse coal dust the IOM-MOD may improve airborne coarse dust assessments over "off-the-shelf" sampling cassettes.

Suppression of methane/air explosion by ultrafine water mist containing sodium chloride additive

The suppression effect of ultrafine mists on methane/air explosions with methane concentrations of 6.5%, 8%, 9.5%, 11%, and 13.5% were experimentally studied in a closed visual vessel. Ultrafine water/NaCl solution mist as well as pure water mist was adopted and the droplet sizes of mists were measured by phase doppler particle analyzer (PDPA). A high speed camera was used to record the flame evolution processes. In contrast to pure water mist, the flame propagation speed, the maximum explosion overpressure (ΔP(max)), and the maximum pressure rising rate ((dP/dt)max) decreased significantly, with the "tulip" flame disappearing and the flame getting brighter. The results show that the suppressing effect on methane explosion by ultrafine water/NaCl solution mist is influenced by the mist amount and methane concentration. With the increase of the mist amount, the pressure, and the flame speed both descended significantly. And when the mist amount reached 74.08 g/m(3) and 37.04 g/m(3), the flames of 6.5% and 13.5% methane explosions can be absolutely suppressed, respectively. All of results indicate that addition of NaCl can improve the suppression effect of ultrafine pure water mist on the methane explosions, and the suppression effect is considered due to the combination effect of physical and chemical inhibitions.

[Causation, prevention and treatment of dust explosion]

With the development of industrial technology, dust explosion accidents have increased, causing serious losses of people's lives and property. With the development of economy, we should lay further emphasis on causation, prevention, and treatment of dust explosion. This article summarizes the background, mechanism, prevention, and treatment of dust explosion, which may provide some professional knowledge and reference for the treatment of dust explosion.

Methane bioattenuation and implications for explosion risk reduction along the groundwater to soil surface pathway above a plume of dissolved ethanol

Fuel ethanol releases can stimulate methanogenesis in impacted aquifers, which could pose an explosion risk if methane migrates into enclosed spaces where ignitable conditions exist. To assess this potential risk, a flux chamber was emplaced on a pilot-scale aquifer exposed to continuous release (21 months) of an ethanol solution (10% v:v) that was introduced 22.5 cm below the water table. Despite methane concentrations within the ethanol plume reaching saturated levels (20-23 mg/L), the maximum methane concentration reaching the chamber (21 ppm(v)) was far below the lower explosion limit in air (50,000 ppm(v)). The low concentrations of methane observed in the chamber are attributed to methanotrophic activity, which was highest in the capillary fringe. This was indicated by methane degradation assays in microcosms prepared with soil samples from different depths, as well as by PCR measurements of pmoA, which is a widely used functional gene biomarker for methanotrophs. Simulations with the analytical vapor intrusion model "Biovapor" corroborated the low explosion risk associated with ethanol fuel releases under more generic conditions. Model simulations also indicated that depending on site-specific conditions, methane oxidation in the unsaturated zone could deplete the available oxygen and hinder aerobic benzene biodegradation, thus increasing benzene vapor intrusion potential. Overall, this study shows the importance of methanotrophic activity near the water table to attenuate methane generated from dissolved ethanol plumes and reduce its potential to migrate and accumulate at the surface.

Ocular injuries from shake and bake methamphetamine labs

PURPOSE

To review ocular injuries resulting from "shake and bake" methamphetamine labs.

METHOD

Retrospective case series of 4 patients with ocular injuries sustained from "shake and bake" lab explosions.

RESULTS

Four men ages 20-39 underwent complete ophthalmologic examination after an injury from a "shake and bake" methamphetamine lab explosion.The mechanism of injury was initially misrepresented in each case; the physical findings were suggestive of thermal and alkali injury. Visual acuity ranged widely from 20/20 to light perception only. Treatment in the acute setting included irrigation, pH monitoring, and intraocular pressure lowering.

CONCLUSION

Methamphetamine production by means of the"shake and bake" method can result in combined thermal and alkali ocular injury. Patients who sustain this type of injury may not accurately report the mechanism of exposure. Increased awareness of this type of ocular injury may increase the rapidity of diagnosis, avoid early misdiagnosis, and ultimately improve outcomes.

Characterization of partially reduced graphene oxide as room temperature sensor for H2

Reduced graphene oxide (RGO) was synthesized under H(2)/Ar treatment from 100 °C to 900 °C. RGO-300 shows excellent sensitivity to H(2) and a dual sensing mode was observed. The balance between the chemical adsorption capacity and electronic conductivity, and the dominance of either electrons or holes are the key factors.

Accident investigation reporting deficiencies related to organizational factors in machinery space fires and explosions

Careful accident investigation provides opportunities to review safety arrangements in socio-technical systems. There is consensus that human intervention is involved in the majority of accidents. Ever cautious of the consequences attributed to such a claim vis-à-vis the apportionment of blame, several authors have highlighted the importance of investigating organizational factors in this respect. Specific regulations to limit what were perceived as unsuitable organizational influences in shipping operations were adopted by the International Maritime Organization (IMO). Guidance is provided for the investigation of human and organizational factors involved in maritime accidents. This paper presents a review of 41 accident investigation reports related to machinery space fires and explosions. The objective was to find out if organizational factors are identified during maritime accident investigations. An adapted version of the Human Factor Analysis and Classification System (HFACS) with minor modifications related to machinery space features was used for this review. The results of the review show that organizational factors were not identified by maritime accident investigators to the extent expected had the IMO guidelines been observed. Instead, contributing factors at the lower end of organizational echelons are over-represented.

Modeling solid thermal explosion containment on reactor HNIW and HMX

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaaza-isowurtzitane (HNIW), also known as CL-20 and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), are highly energetic materials which have been popular in national defense industries for years. This study established the models of thermal decomposition and thermal explosion hazard for HNIW and HMX. Differential scanning calorimetry (DSC) data were used for parameters determination of the thermokinetic models, and then these models were employed for simulation of thermal explosion in a 437L barrel reactor and a 24 kg cubic box package. Experimental results indicating the best storage conditions to avoid any violent runaway reaction of HNIW and HMX were also discovered. This study also developed an efficient procedure regarding creation of thermokinetics and assessment of thermal hazards of HNIW and HMX that could be applied to ensure safe storage conditions.

Experimental determination of self-heating and self-ignition risks associated with the dusts of agricultural materials commonly stored in silos

Agricultural products stored in silos, and their dusts, can undergo oxidation and self-heating, increasing the risk of self-ignition and therefore of fires and explosions. The aim of the present work was to determine the thermal susceptibility (as reflected by the Maciejasz index, the temperature of the emission of flammable volatile substances and the combined information provided by the apparent activation energy and the oxidation temperature) of icing sugar, bread-making flour, maize, wheat, barley, alfalfa, and soybean dusts, using experimental methods for the characterisation of different types of coal (no standardised procedure exists for characterising the thermal susceptibility of either coal or agricultural products). In addition, the thermal stability of wheat, i.e., the risk of self-ignition determined as a function of sample volume, ignition temperature and storage time, was determined using the methods outlined in standard EN 15188:2007. The advantages and drawbacks of the different methods used are discussed.

Determination of parameters used to prevent ignition of stored materials and to protect against explosions in food industries

There are always risks associated with silos when the stored material has been characterized as prone to self-ignition or explosion. Further research focused on the characterization of agricultural materials stored in silos is needed due to the lack of data found in the literature. The aim of this study was to determine the ignitability and explosive parameters of several agricultural products commonly stored in silos in order to assess the risk of ignition and dust explosion. Minimum Ignition Temperature, with dust forming a cloud and deposited in a layer, Lower Explosive Limit, Minimum Ignition Energy, Maximum Explosion Pressure and Maximum Explosion Pressure Rise were determined for seven agricultural materials: icing sugar, maize, wheat and barley grain dust, alfalfa, bread-making wheat and soybean dust. Following characterization, these were found to be prone to producing self-ignition when stored in silos under certain conditions.

Mitigation of TNT and Destex explosion effects using water mist

The effects water mist has on the overpressures produced by the detonation of 50 lb equivalent of high explosives (HE) TNT and Destex in a chamber is reported. The overpressures for each charge density were measured with and without mist preemptively sprayed into the space. A droplet analyzer was placed in the chamber prior to the detonation experiments to characterize the water mist used to mitigate the explosion overpressures. The impulse, initial blast wave, and quasi-static overpressure measured in the blast mitigation experiments were reduced by as much as 40%, 36%, 35% for TNT and 43%, 25%, 33% for Destex when water mist was sprayed 60s prior to detonation at a concentration of 70 g/m(3) and droplet Sauter Mean Diameter (SMD) 54 microm. These results suggest that current water mist technology is a potentially promising concept for the mitigation of overpressure effects produced from the detonation of high explosives.

Molecular simulation studies on chemical reactivity of methylcyclopentadiene

Molecular simulations are important to predict thermodynamic values for reactive chemicals especially when sufficient experimental data are not available. Methylcyclopentadiene (MCP) is an example of a highly reactive and hazardous compound in the chemical process industry. In this work, chemical reactivity of 2-methylcyclopentadiene, including isomerization, dimerization, and oxidation reactions, is investigated in detail by theoretical computational chemistry methods and empirical thermodynamic-energy correlation. On the basis of molecular simulations, an average value of -15.2 kcal/mol for overall heat of dimerization and -45.6 kcal/mol for overall heat of oxidation were obtained in gaseous phase at 298 K and 1 atm. These molecular simulation studies can provide guidance for the design of safer chemical processes, safer handling of MCP, and also provide useful information for an investigation of the T2 Laboratories explosion on December 19, 2007, in Florida.

Explosion protection for vehicles intended for the transport of flammable gases and liquids--an investigation into technical and operational basics

In Europe, the transport of flammable gases and liquids in tanks has been impacted by new developments: for example, the introduction of the vapour-balancing technique on a broad scale and the steady increase in the application of electronic components with their own power sources; furthermore, new regulatory policies like the ATEX Directives are being enforced in the European Union. With this background in mind, the present investigation aims to provide a basis for future developments of the relevant explosion protection regulations in the safety codes for the transport of dangerous goods (RID/ADR). Specifically, the concentration of gas in the air was measured under various practical conditions while tank vehicles were being loaded with flammable gases or liquids. These spot-test data were supplemented by systematic investigations at a road tanker placed in our test field. With respect to non-electrical ignition sources, a closer investigation of the effect of hot surfaces was carried out. With regard to improving the current regulations, the results of our investigation show that it would be reasonable to implement a stronger differentiation of the characteristics of the dangerous goods (gaseous/liquid, flashpoint) on the one hand and of the techniques applied (loading with and without vapour-balancing system) on the other hand. Conclusions for the further development of the current international regulations are proposed.

The simulation of air recirculation and fire/explosion phenomena within a semiconductor factory

The semiconductor industry is the collection of capital-intensive firms that employ a variety of hazardous chemicals and engage in the design and fabrication of semiconductor devices. Owing to its processing characteristics, the fully confined structure of the fabrication area (fab) and the vertical airflow ventilation design restrict the applications of traditional consequence analysis techniques that are commonly used in other industries. The adverse situation also limits the advancement of a fire/explosion prevention design for the industry. In this research, a realistic model of a semiconductor factory with a fab, sub-fabrication area, supply air plenum, and return air plenum structures was constructed and the computational fluid dynamics algorithm was employed to simulate the possible fire/explosion range and its severity. The semiconductor factory has fan module units with high efficiency particulate air filters that can keep the airflow uniform within the cleanroom. This condition was modeled by 25 fans, three layers of porous ceiling, and one layer of porous floor. The obtained results predicted very well the real airflow pattern in the semiconductor factory. Different released gases, leak locations, and leak rates were applied to investigate their influence on the hazard range and severity. Common mitigation measures such as a water spray system and a pressure relief panel were also provided to study their potential effectiveness to relieve thermal radiation and overpressure hazards within a fab. The semiconductor industry can use this simulation procedure as a reference on how to implement a consequence analysis for a flammable gas release accident within an air recirculation cleanroom.

[Stop the annual firework disaster--a plea for medical scientific associations to take a clear-cut position]

Every year people sustain serious injuries when they let off fireworks on New Year's Eve. Public education and protective eye wear do not solve this problem. Experience from other countries shows that the number of injuries decreases dramatically when fireworks are handled only by experienced specialists. Medical scientific associations are invited to promote a ban on ordinary citizens letting off fireworks and for fireworks to be reserved for firework specialists only.

Correlation between self-ignition of a dust layer on a hot surface and in baskets in an oven

Evaluation of self-ignition hazard of bulk materials requires experimental determination of self-ignition temperatures as a function of volume. There are two standardised methods: (1) determination of the self-ignition temperature of dust samples in oven and (2) measurement of the self-ignition temperature of a dust layer deposited on a hot surface. Sometimes, the sample behaviour during these tests makes the second method difficult to apply. The self-ignition phenomena in these two tests rely on the same principles. Their results are interpreted with the help of theoretical relations. The correlation described in this paper can be considered acceptable to deduce self-ignition temperature of a dust layer, based on results of self-ignition of the same dust in heating ovens, if the Biot number (alpha) can be estimated. Uncertainty on the correlation is near 30K. This uncertainty is on the same order of magnitude as the difference in the self-ignition temperature on a hot surface for thickness between 5 and 15 mm.

Numerical investigation of explosion suppression by inert particles in straight ducts

This paper is devoted to the mitigation of explosions in long galleries by means of an inert dust cloud. In practice, this technique bases on mounting shelves under the roof, on which the inert dust is distributed. This issue was numerically investigated in this research. The medium was assumed to be a two-phase mixture consisting of a fast flowing gas (representing the explosion) and a cloud of solid particles (representing the dust phase). The model makes use of the Eulerian-Lagrangian approach, where the solid particles are modelled as moving points, interacting with the gas flow. The objective was to analyse the suppression process and compare with experimental findings.

MIKE 3 versus HARTMANN apparatus: comparison of measured minimum ignition energy (MIE)

In this study, MIE values measured with two different explosion tubes, HARTMANN and MIKE 3, are compared. Generally, MIKE 3 apparatus provides MIE results, which are equal or lower to those measured with the HARTMANN apparatus; this is particularly true for the energy ranges between 1 and 10mJ and higher than 100mJ. Differences observed can modify samples classification according to their sensitivity to electrostatic ignition sources. Nevertheless, ignition of a dust cloud by an electrostatic discharge is complex, and implies a different mechanism from that occurring during MIE tests. Thus, it seems difficult to synchronise dust dispersion and spark triggering to obtain optimal concentration in the spark area. Moreover, spark characteristics such as duration or energy feeding rate of spark cannot reproduce exactly industrial-world ones. On this point, it is not possible to conclude if characteristics of MIKE 3 electric circuit, e.g., resistance and inductance, are more relevant than HARTMANN circuit ones.

[Firework injuries in Denmark in the period 1995/1996 to 2006/2007]

INTRODUCTION

The purpose of this study was to observe the occurrence and character of firework injuries on the two days around New Year in Denmark over the last decade.

MATERIALS AND METHODS

Since 1995/1996 all Accident and Emergency Departments in Denmark have registered all contacts where fireworks were the cause of injury on 31st December and 1st January. Data comprised hospital, sex, age, type of firework, diagnosis and final treatment. Follow-up and reminder by phone secured a 100% response rate. The total number of injured patients was 4,447.

RESULTS

The number of firework injuries on the 31st of December and 1st of January was reduced by half over the 12-year period. Furthermore, the number of firework injuries caused by illegal fireworks in 2006/2007 was only 10% of the number in 1996/1997. Only 8% of injuries on last New Year's Eve were caused by illegal firewoks compared to almost 50% at the beginning of the period. A similar halving is seen in serious injuries. Roughly one quarter sustained injuries to the eyes, one quarter to the head/neck and 38% to hands.

CONCLUSION

Firework injuries are now half of the level in 1996/1997. Injuries caused by illegal fireworks and serious injuries have shown a downward tendency throughout the period. The actual number of severe injuries from illegal fireworks is now only 10% of the level in the mid-1990s. This reduction can be attributed to preventive campaigns, greater knowledge of the risk of fireworks in general as well as legislation. Continued focus on preventive campaigns, control of fireworks for the general public and control of firework distribution to professionals is recommended.