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Dust explosion poses a significant hazard in industry. An explosion of dispersed dust can be ignited by an improvised explosive device. The article deals with the study of explosion parameters of representative samples of dispersed dust ignited by an improvised explosive device. Hexamethylene triperoxide diamine was used as an igniter. Lycopodium clavatum spores were used as a standard sample. Furthermore, dust samples were selected from those types of operations that may be endangered if an improvised explosive device is used as an igniter. Wheat flour and beech wood dust were selected as representative samples. The achieved parameters of explosion pressure and explosion constant Kst were on average by 5–15% lower than the parameters achieved when using a commercial igniter. The Pmax value and the inflection point of the explosion record were reached 7–12 ms earlier than those achieved with a commercially available igniter. The findings may be relevant in the design of explosion prevention devices. New types of explosion prevention devices can be designed to reduce the risk of explosion of dispersed combustible dust caused by improvised explosive devices, e.g. in a case of terrorist attack on the objects with the occurrence of dust clouds.

EN 14034 standard defines the requirements for igniter, to determine the properties of dust clouds. The standard specifies the conditions for occurrence of explosions of dust clouds. According to the standard, equipment with a volume of 1m3 and 20L can be used to determine the explosion parameters of dispersed dusts. The equipment has the time parameters of dispersing and the ignition system defined in the Standard. Experimental determination of time parameters is required for a different chamber volume. The article therefore deals with the determination of parameters for dispersing system in the 291 litre chamber. Determination of igniter delay was performed on the base of setting the time relay. Activation of pressurised air flow was determined by calculation, and it was subsequently experimentally verified in laboratory conditions. A video camera recording was selected for measuring the rate of nitrocellulose ignition from the resistance wire. The result of this study is determination of the igniter timing in dependence of the explosion chamber volume. The time delay of the nitrocellulose igniter is 320 ms.

Dust is a product or by-product in many industries. To ensure effective measures of explosion prevention, it is necessary to know the fire properties of dispersed and settled dust. These parameters cannot be calculated, but can be determined on the base of measurements in standard equipment. The article deals with the measurement of fire properties of polyethylene. The values of the minimum ignition temperature of settled and dispersed dust (MIT) and the values of explosion characteristics of polyethylene dust cloud lower explosion limit (LEL), maximum pressure Pmax and maximum rate of pressure rise (dp/dt)max were measured. The measurements were performed on the equipment according to the STN EN 80079-20-2: 2016 Standard Explosive atmospheres - Part 20-2: Material characteristics - Combustible dust test methods and according to the STN EN 14034 + A1: 2011 Standard Determination of explosion characteristics of dust clouds. The MIT of the settled dust was not determined (the sample melted), the MIT of the dispersed dust was 435 °C. The maximum explosion pressure Pmax reached 7.0 bar, and the maximum rate of pressure rise dP/dt was 37.5 bar.s−1.

A standardized device with a volume of 1 m3 or 20 L is used to determine explosion parameters. An explosion chamber where explosion takes place is of a spherical or cylindrical shape that suits the shape of a cubic container. In the case of a cylindrical vessel, the diameter and depth of the vessel are 1: 1. In this case, it is a spherical vessel with a volume of 365 liters. Time parameters of the disperser in the spherical vessel are compared with those of a truncated spherical vessel with a volume of 291 liters. Comparison of the measurement results showed that the optimal delay time of the explosion chamber with a volume of 291 liters is 290 ms, while the delay time of the explosion chamber with a volume of 365 liters is 350 ms.

Floating coal dusts are always produced during coal mining process in the underground mines. In a coal mine and other coal processing or utilizing industries, there are always some potential safety problems, such as coal dust explosion accidents.[1,2] During lignite mining and processing, flammable coal dust is produced. Fire properties of coal dust depend on the particle size. The article deals with the measurement of explosion characteristics of lignite in dependence of particle size at three various concentrations. The measurements were carried out according to EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds. Tests of the lignite dust clouds explosions showed that the maximum value of the pressure was reached at the concentrations of 500 g.m−3 and the particle size between 0 – 56 µm. At this concentration, the highest explosion pressure of 8.25 bar was reached.

The article deals with the determination of fire characteristics of industrial dust samples. Particle size granulometry and determination of explosion parameters according to EN 14034 (Lower Explosion Limit LEL, Pmax, Kst) are presented. The minimum ignition temperatures of the dust layer and dispersed dust from the hot surface according to EN ISO / IEC 80079-20-2: 2016 were measured. It was found that LEL is 60 g.m−3, Pmax is 8.61 bar, and Kst is 89 bar.s−1.m. The minimum ignition temperature (MIT) of dust layer is 280 ° C and the minimum ignition temperature of dispersed dust is 400 ° C.

Fire protection is an important part of the industry where flammable and explosive dusts are found. Production, storage and transport of food powders such as flour can be very dangerous in terms of explosiveness. The article deals with the measurement of explosion characteristics of wheat flour dust. The measurements were carried out according to EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds and the maximum rate of explosion pressure rise according to EN 14034-2+A1:2012 Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds. A sample of wheat flour with a median particle size 84 μm exhibits the maximum explosion pressure 7.00 bar at the concentration of 600 g.m−3 and then explosion constant is 16.9 bar.s−1.m. A sample of wheat flour with a median particle size 50 μm exhibits the maximum explosion pressure 7.97 bar at the concentration of 1000 g.m−3 and the explosion constant 54.9 bar.s−1.m.Based on the results of the measurements, we found that the particle size distribution has a significant influence on the explosion parameters of the wheat flour samples.

Dust explosions are a major hazard in many industrial processes. In operations such as crushing and grinding, conveying, classifying and storage, an explosion may occur in the presence of combustible dusts or powders. Such explosions can result in loss of production, process equipment and quite possibly human life. This paper is oriented on design of dust dispersion system for explosion chamber KV-150 M2. The explosion chamber KV-150 M2 is designed to measure the explosion parameters of dispersed dusts.

Wood and its processing are associated with significant fire hazards. In the past, there were many significant fires of wood clouds that caused property damage and human lives. The study of flammable wood clouds fire characteristics is the basis for fire and explosion protection. The article deals with the study of the influence of particle size on the ignition temperature of settled and swirled beech wood dust. Measurement of fire characteristics was performed according to EN ISO/IEC 80079-20-2 in GG oven and heated surface. The sample was dust from beech wood with different particle sizes. By measuring, it has been found that with decreasing particle size, the flammability of the samples improves and the minimum ignition temperature (MIT) also decreases.

The use of additive technologies keeps growing. Increasingly, flammable powder materials are also used in additive technologies, and there is a risk of explosion or fire when using them. The current article deals with the determination of fire parameters of a powder sample of polyamide Sinterit PA12 Smoth in accordance with the EN 14034 and EN ISO/IEC 80079-20-2 standards. For that purpose, a sample at a median size of 27.5 µm and a humidity of 0% wt. was used. The measurements showed that the maximum explosion pressure of the PA12 polyamide sample was 6.78 bar and the value of the explosion constant Kst was 112.2 bar·m·s−1. It was not possible to determine the MIT value of the settled dust, since the melting point of polyamide sample is low. The MIT of the dispersed dust was 450 °C. Based on the measured results, it can be stated that the powdered polyamide PA12 poses a risk in terms of explosions and fires. Therefore, when using polyamide PA12 in additive technologies, it is necessary to ensure an effective explosion prevention.

The article deals with the measurement of explosion characteristics of wood dust. The measurements were carried out according to STN EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds and the maximum rate of explosion pressure rise according to STN EN 14034-2+A1:2012 Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds. On the basis of measurements, we found that the distribution of the particles has a significant impact on the parameters of wood dust samples.

The article deals with the measurement of explosion characteristics of wheat flour. The measurements were carried out according to STN EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds, the maximum rate of explosion pressure rise according to STN EN 14034-2+A1:2012 Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds and LEL according to STN EN 14034-3+A1:2011 Determination of explosion characteristics of dust clouds: Determination of the lower explosion limit LEL of dust clouds. The testing of explosions of wheat flour dust clouds showed that the maximum value of the pressure was reached at the concentrations of 600 g/m3 and its value is 8.32 bar/s. The fastest increase of pressure was observed at the concentration of 750 g/m3 and its value was 54.2 bar/s.

Chemical igniters are used in the study of dispersed dusts. Energy released during their use is defined by EN 14034 at 2 x 5 kJ. The Standard does not define the exact composition of the pyrotechnic mixture. The condition of using the igniter is to release energy according to the Standard. This article is focused on pyrotechnic composition with magnesium powder. It deals with various ways of activating, preparing and sealing the pyrotechnic mixture in the igniter. These values are important for setting up a device for studying the explosive properties of dispersed dusts. Chemické zažehovače jsou používány pro studium zážehu prachových disperzí. Energie uvolněná zažehovačem je definována normou EN14034 na velikost 2x 5 kJ. Citovaná norma však neuvádí jasnou specifikaci pyrotechnické směsi použitelné pro zažehovač. Jssou pouze určeny podmínky pro hoření zažehovače. Tato práce se zabývá studiem použitelnosti pyrotechnické slože obsahující hořčíkový prášek. Jsou studovány různé podmínky aktivace a uspořádání konstrukce a utěsnění zažehovače na hoření směsi v zažehovači. Tyto hodnoty jsou důležité pro nastavení zařízení pro studium výbušných vlastností prahových disperzí.

The aim of this paper is to approximate danger of dust clouds normally occur by determining their explosion characteristics. Nowadays, dusty environment is phenomenon in the industry. In general, about 70% of dust produced is explosive. Dust reduction in companies is the main purpose of the national and European legislative. Early identification and characterization of dust in companies may reduce the risk of explosion. It could be used to identify hazards in industrial production where an explosive dust is produced. For this purpose several standards for identification and characterization of explosion characteristics of industrial dust are being used.

In order to achieve relevant and exact value in measurement of vibrations, it is necessary to add the corresponding value of deviation to the result of measurement. As the topic of determining the deviation is too complex and the scope of article is limited, we focus on the characteristic features and mathematical description of the basic types of deviations and some partial deviations which should betaken into account in measurement.

The article deals with the measurement of maximum explosion pressure and the maximum rate of exposure pressure rise of wood dust cloud. The measurements were carried out according to STN EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds and the maximum rate of explosion pressure rise according to STN EN 14034-2+A1:2012 Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds. The wood dust cloud in the chamber is achieved mechanically. The testing of explosions of wood dust clouds showed that the maximum value of the pressure was reached at the concentrations of 450 g / m3 and its value is 7.95 bar. The fastest increase of pressure was observed at the concentrations of 450 g / m3 and its value was 68 bar / s.

The article deals with assessing the impact of the heat flux on the flammability of wood materials with application of fire retardants potassium hydrogen carbonate (KHCO3) and azanium dihydrogen phosphate (NH4H2PO4), which can limit or slow down the combustion of the material. After application of fire retardants on samples time to ignition increased and thus confirmed the retardation effect. Retarding effect was observed depending upon the concentration of the solution applied to the sample.

FTAe is software tool for Fault Tree Analysis in Microsoft Excel. This paper is focused on short description of created FTAe. A brief description of Fault Tree Analysis is in the first part of paper. The Structure, Logic and Minimal Cut Sets in Fault Tree analysis is described too. Next part of this paper is focused on the choice of algorithm for cut set calculation and brief description of structure of FTAe. Finally, advantages of FTAe software in Microsoft Excel are described in conclusions.

The article is devoted to incident investigation, specifically to one of its aspects: the satisfactory identification of root causes. Management Oversight and Risk Tree (MORT) technique is exploited as a tool that helps to fulfill the task. However, since the application of traditional MORT diagrams was not considered satisfactory, a new software tool MORT WorkSheet was developed to make the MORT analysis easier. The article explains what led to the development of the software tool, how the tool works, and what results it is able to provide. An incident example is used in the article that illustrates how the new tool is applied during the investigation and how the results of its application look. Final comparison shows how different the obtained results may be with support of the MORT WorkSheet from the results of conventional incident investigation.