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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.

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.

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.