Maximum Explosion Pressure Research Articles

Effects of ethylene addition and dilution on the explosion characteristics of ethane-ethylene mixtures

The properties of an ethane-ethylene mixture were analyzed under varying equivalence ratios (ranging from 0.58 to 1.4) and ethylene volume fractions (ranging from 0% to 100%) with varying dilution ratios, using a 20-liter apparatus. The study aimed to understand the explosion characteristics of the mixture and to identify the elementary reactions that have the most significant impact on the rise in pressure and ethylene consumption during the explosion process. The results showed that adding ethylene increases the maximum explosion pressure and broadens the flammability limit range. In addition, the work investigated the effects of diluting the mixture with either nitrogen or carbon dioxide. It was found that carbon dioxide has a higher specific heat capacity compared to nitrogen, which enhances the heat absorption capacity of the mixture. The collision of carbon dioxide molecules with the activated radicals in the reaction transfers energy from the radicals to carbon dioxide, reducing the radicals' activity and causing a more significant dilution effect than nitrogen. Finally, a chemical kinetics analysis of the premixed gas using the UC San Diego mechanism revealed that the production rate of key free radicals gradually increases with the addition of ethylene, enhancing the explosion reaction intensity.

Preparation of modified fly ash-based, core–shell inhibitor and its effect on suppression of Al-Mg alloy dust explosion

Dust explosions caused by energetic metals pose a significant risk to process industries, making it crucial to develop high-performance explosion inhibitors. In this study, the modified power plant solid waste fly ash (FA) was confirmed as a raw material for the preparation of core–shell inhibitors to efficiently suppress dust explosion of Al-Mg alloy. The interfacial compatibility of FA was dramatically improved by using alkali hydrothermal modification and organic modification. It formed a well-coated nano-Mg(OH)2 cladding layer on the surface of modified FA by the heterogeneous nucleation method. In a vertical combustion pipe and a 20 L spherical explosion device, the suppression effect of this novel core–shell inhibitor (FA-2@Mg(OH)2) was investigated. The experimental results showed that the addition of 60 wt% of FA-2@Mg(OH)2 reduced the maximum flame velocity (Vmax), velocity to the top of the pipe (Vtop), and average pulsation degree (Vap) by 87.9 %, 92.5 %, and 87.7 %, respectively, and the peak flame temperature (Tp) declined to 298 °C. The maximum explosion pressure (Pmax) and the maximum explosion pressure rise rate ((dp/dt)max) were reduced by 86.1 % and 92.9 %, respectively. Combining the analysis results of SEM, EDS, XRD, and TG-DSC, the suppression mechanism of FA-2@Mg(OH)2 was explained in depth, mainly from the heat absorption, coating effect, gas dilution, and radical adsorption. This work not only sheds new light on the design of dust explosion suppression functional materials but also broadens the application of industrial solid waste FA.

Montmorillonite Powder and Its Hydroxyl Modified Powder Experimental Study on the Inhibition of Lycopodium Powder Explosion

ABSTRACT In order to seek a better inhibitor to suppress the explosion of lycopodium powder, this paper used Hartmann experimental system and 20 L spherical explosion experimental system to conduct the flame propagation and explosion pressure suppression experiments of lycopodium powder explosion, respectively, to study the suppression effect of lycopodium powder explosion under the conditions of adding different proportions of montmorillonite powder and hydroxy modified montmorillonite powder, combined with the FTIR curves before and after the explosion of lycopodium powder as well as the reaction involving it and inhibitors, the inhibition mechanism of montmorillonite powder and hydroxy- montmorillonite powder on the explosion of lycopodium powder was analyzed. The experimental results show that: with the increase of the addition ratio of the two inhibitor powder, the flame brightness becomes darker, the flame propagation speed gradually decreases, and the maximum explosion pressure and the maximum explosion pressure change rate gradually decreases. By the analysis of inhibition mechanism: montmorillonite powder blocks and absorbs thermal radiation and has basically no chemical inhibition effect whose inhibition effect is relatively weak; hydroxy-montmorillonite powder in addition to the basic physical inhibition with montmorillonite powder, but also decomposition at high temperatures to generate a large number of hydroxyl radicals, the radicals generated can make the reaction of the explosion in the reverse direction, and nearly can block the explosion chain reaction continues, playing a key role in chemical inhibition. Research results show that: montmorillonite powder and hydroxyl modified montmorillonite powder on lycopodium powder explosion have a certain inhibition effect, and modified hydroxyl montmorillonite powder than montmorillonite powder on the lycopodium powder explosion inhibition effect is better.

Spray and explosion characteristics of methanol and methanol-benzene blends near azeotrope formation: Effects of temperature, concentration, and benzene content

The explosion hazard of flammable liquids leaking to form spray in storage and transportation at ambient temperature has not been systematically investigated. This work presents new results from experimental investigations of the atomization and explosion characteristics of methanol, and methanol-benzene blends forming near the azeotrope under different initial conditions (initial temperature (298.15–318.15 K), methanol concentration (198–514.8 g/m3) and benzene content (41–81%)) in a 20-L spherical vessel. The empirical formulas for Sauter Mean Diameter (SMD) of the droplets and the maximum explosion pressure with respect to the initial temperature and methanol concentration were obtained from the quantitative analysis. Compared to the explosion hazard of pure methanol and methanol-benzene blends spray, the results showed that the maximum rate of pressure rise and maximum explosion temperature of methanol-benzene blends were relatively low. Furthermore, the effect of carbon soot formation on the explosion hazard during explosion development was analyzed.

Explosion characteristics of shale gas in air

In this work, explosion characteristics of stoichiometric shale gas were studied employing a standard 20-L explosion bomb. Shale gas was represented by methane/ethane, methane/propane, and methane/ethane/propane mixtures, and the effect of fuel compositions, the volume fraction of ethane (or propane) increases from 0 to 0.42, on explosion parameters was examined. Results show that the maximum explosion pressure, the maximum explosion pressure rising rate, and the laminar flame speed increase with the volume fraction of ethane (or propane). The reason is that the increment of ethane (or propane) volume fraction increases the mole fraction of [H + O + OH]max. For a given volume fraction, propane provides more heat and H, O, and OH radicals, and consequently, propane shows a more robust incentive function on explosion parameters. Finally, the CH ratio, which is defined as the ratio of total carbon atoms and hydrogen atoms, is used to further study the explosion characteristics of various fuel compositions. There is a robust linear relationship between the CH ratio and explosion parameters. For laminar flame speed, however, the global fit curve provides poor accuracy while the local fitting curves coincide well with the data. This indicates that the laminar flame speed is more sensitive to the gas species.

Inhibition effects of aluminum dust explosions by various kinds of ammonium polyphosphate

In this work, vinyltriethoxysilane (A151) and 3-aminopropyltriethoxysilane (KH550) were used to modify ammonium polyphosphate (APP), showing that the dispersibility of APP could be improved remarkably by A151 and KH550. The maximum explosion pressure of aluminum dust explosion decreased with the addition of APP, A151-APP (APP-A) and KH550-APP (APP-B), with the exception of the case where the inerting ratio (α) of APP-A was less than 0.4. After the addition of APP-B, there was little difference in flame propagation behavior and explosion pressure compared with that of adding APP, indicating that APP-B could retain the inhibition performance of APP compared with APP-A. When the inerting ratios of APP, APP-A and APP-B were 1.2, 1.4 and 1.4, respectively, the aluminum dust explosion could be completely inhibited. The explosion residues of aluminum dust/APP mainly consisted of Al2O3, P-containing and N-containing compounds. It could be analyzed that APP exerted the inhibition effect through both chemical and physical effects.

Flame propagation characteristics of premixed hydrogen–air deflagration with low concentration in a pipeline

This study used a visualized explosion propagation experimental system to investigate the flame propagation and hydroxyl (OH·) spectral radiation characteristics of hydrogen deflagration at the hydrogen concentration range of 7–17 vol%. The experimental results indicated that maximum flame propagation velocity, maximum explosion pressure, maximum flame temperature, and maximum relative spectral intensity of OH· gradually increased with hydrogen concentration. When concentration increased from 13 vol% to 17 vol%, the time to reach the maximum flame propagation velocity, the formation time of tulip flame, and the duration of the spectral radiation signal of OH· decreased by 52.9%, 55.6%, and 48.2%, respectively. In addition, flame propagation velocity oscillated when the tulip flame appeared, and maximum explosion pressure appeared later than the maximum temperature. Maximum flame propagation velocity, maximum explosion pressure, and maximum flame temperature positively correlated with maximum relative spectral intensity in the reaction system. These findings may serve as an essential reference for the safe and effective use of hydrogen and the research and development of radical targeted explosion suppressants.

Effect of combination of explosion venting and chemical barrier on starch explosion suppression in a large scale connected vessels

The explosion of starch poses a potential threat to the process safety of food and energy enterprises in product processing and storage. To control explosion, a 5 m3 columnar tank with a 10 m long connecting pipe at one end and a 700 mm diameter explosion vent at the other end was built as an experimental device. Combined controlled explosion experiments were conducted using a rupture disc with a static activation pressure of 10 kPa and a chemical barrier containing ABC powder with nitrogen as the driving gas to investigate the pressure and flame change characteristics inside the vessel and piping. The experimental results show that the maximum explosion pressure in the connected vessel without explosion venting is 41.21kPa and the maximum pressure rise rate is 5.20 bar/s. Explosion venting reduces the maximum explosion pressure and pressure rise rate in the vessel by 52.31 % and 21.92 %, respectively, and reduces the flame propagation speed in the pipeline, so that the chemical barrier device can effectively isolate the flame when the installation distance is more than 6 m. The N2 and ABC dry powder two-phase explosion suppressant produced an effective inhibition effect through the physical effects of oxygen insulation, heat absorption, and thermal transmission weakening, as well as the chemical effect of eliminating explosive radicals. The explosion venting provides an initial defense by releasing any remaining pressure and heat of the explosion, while the chemical barrier provides a secondary layer of protection by extinguishing the flame and suppressing the explosion in the pipe to prevent further damage. This combination can greatly reduce the risk of equipment damage, injuries, and fatalities caused by explosions in industrial settings.

Investigation of C2H6, C2H4, CO and H2 on the explosion pressure behavior of methane/blended fuels

The introduction of other combustible gases to methane could change accident consequences. This work aimed to experimentally compare the effects of blended fuels (C2H6, C2H4, CO, and H2 mix in different proportions) on the explosion pressure behavior of methane and blended fuels in air. The explosion pressure properties of the mixtures were tested. Principal component analysis was employed, and multiple regression models were developed to predict the influences of principal components on the maximum explosion pressure of CH4. In addition, the software was used to analyze and compare the sensitivity analysis. For the fuel-lean CH4-air mixture(φ = 0.72), the results demonstrated that the value of Pmax and (dP/dt)max of the mixed gases increased, as the volume fraction of the blended fuels increased. The effects of other gases followed the order C2H6>C2H4>H2>CO. For stoichiometric concentrations (φ = 1), the order of the influence degree was H2>CO > C2H6>C2H4, and the value of Pmax and (dP/dt)max of the mixed gases tended to decrease slightly. As the volume fraction of the blended fuels was increased to 2%, the Pmax and (dP/dt)max of CH4 showed a decreasing trend for the fuel-rich CH4-air mixture. The effects of blended fuels on the equivalence ratio of φ = 1.1 followed the order C2H4>H2>CO > C2H6. The sensitivity variation analysis and normalized sensitivity variation analysis indicated that the chain branching reaction 2CH3(+M)<=>C2H6(+M) was the most sensitive reaction under various conditions. However, it was not very susceptible to changes in the blended fuel ratio. Most reactions were susceptible to changes in the blended fuel ratio. The 10 most sensitive reactions were generally much more susceptible to changes in the blended fuel ratio in the 2% blended fuels than they were in the 0.4% blended fuels.

Effects of CaCl2, Al(OH)3, And NH4H2PO4 on the Explosion Intensity of Pulverized Coal

ABSTRACT Herein, the ability of three explosion inhibitors (Al(OH)3, CaCl2, and NH4H2PO4) to prevent the occurrence of coal-dust explosions was compared at mass fractions of 30 wt% and 50 wt%. The effects of the three explosion inhibitors on the parameters characterizing the explosion intensity of pulverized coal, such as the maximum explosion pressure, pressure rise rate caused by the explosion, and the explosion index, were investigated. The results demonstrate that with increasing mass fractions of CaCl2 and NH4H2PO4, the explosion intensity of pulverized coal decreases. Notably, an increase in the mass fraction of Al(OH)3 did not reduce the explosion intensity. Furthermore, 50 wt% NH4H2PO4 content considerably decreased the values of both the maximum explosion pressure during a single explosion (Pex) and the maximum rate of explosion pressure rise in a single dust explosion experiment [(dp/dt)ex]. The maximum decrease in Pex after adding NH4H2PO4 was observed to be 62.79%, which is 35.87% and 47.70% higher than that obtained after adding CaCl2 and Al(OH)3, respectively. Furthermore, the maximum decrease in (dp/dt)ex after adding NH4H2PO4 when compared with the pulverized coal was 93.07%, which is 10.23% and 45.51% higher than that obtained after adding CaCl2 and Al(OH)3, respectively. Therefore, the order of the explosion suppression performance was as follows: NH4H2PO4 > CaCl2 > Al(OH)3.

Making hybrid mixture explosions a common case

Explosions of gas-dust hybrid mixtures have long been considered as particular cases encountered in specific industrial contexts. However, it should be reminded that during the explosion of an organic powder, the presence of a hybrid mixture composed of the dust itself and its pyrolysis gases is compulsory. On these premises, an experimental study to determine the role of cellulose pyrolysis products (gaseous, condensable and solid) on the global phenomenon is presented. Hybrid mixture explosion tests were exploited to carry out the investigation. The G-G furnace and the 20 L sphere were employed. Several experimental strategies were chosen to demonstrate the impact of pyrolysis reaction on the explosion of organic powders: i) the fuel equivalence ratio of the reactive mixture (case 1), or ii) the mass of reactants (case 2) were respectively kept constant, iii) the effects of water vapor, char and tar were tested. They were next compared to identify the most suitable one. The two first experimental approaches lead to significantly different results: only case 2 keeps the maximum explosion pressure almost constant, but maximum rate of pressure rises and deflagration index greatly decrease when the pyrolysis gases concentration decreases, which highlights the importance of the pyrolysis reaction on the explosion kinetics. It should also be stressed that the maximum explosion severity is not obtained for the pure gases but when a small dust content is added. The same evolution is observed when a small amount of char is introduced to pyrolysis gases, which underlines the influence of the radiative transfer. Adding small amounts of tar to cellulose tends to increase its explosion severity. However, this impact is less than that generated by the addition of pyrolysis gases.

Effect of N2 and CO2 on explosion behavior of hydrogen-air mixtures in non-premixed state

In this paper, the suppression effects of non-premixed inert gas (N2, CO2) on hydrogen-air explosion behaviors are experimentally studied. The effects of N2 and CO2 addition on flame propagation, explosion pressure and flame length are analyzed. The results show that N2 and CO2 can effectively reduce the explosion hazard in non-premixed state. The mixing process of non-premixed gases leads to the development of turbulent flame, but the suppression of inert gas on explosion exceeds the promotion of turbulent flame. Under the action of N2 and CO2, the energy of the flame decreases, and the front contour becomes blurred. When the fuel zone is only set at the ignition end, with the suppression of N2 and CO2, the maximum explosion pressure is reduced by 35.1% and 50.6%, respectively. It is worth noting that the high-frequency periodic oscillation and pressure soaring appear in the pressure histories, which are attributed to the rapid phase transition of water. Furthermore, the two inert gases can significantly reduce the chemical reaction rate and heat release rate during the explosion, which is reflected in the decrease of the maximum flame length. It is found that N2 and CO2 have different explosion suppression effects and mechanisms, but CO2 has better suppression performance on hydrogen-air explosion.

Effect of concentration, obstacles, and ignition location on the explosion overpressure of hydrogen-air in a closed-vessel

The report deals with the investigation of explosion safety parameters of hydrogen-air mixtures in a 17.17 L cylindrical closed-vessel with different concentrations, obstacles, and ignition locations. The experimental data including the maximum explosion pressure, laminar burning velocity, and corresponding flame radius were confirmed by using GASEQ code and theoretical calculation, respectively. The report shows the orifice plate reduced the maximum explosion pressure of the low-concentration hydrogen (φ＜20% v/v), while the maximum explosion pressure of high-concentration hydrogen (φ＞20% v/v) was increased, and the oscillation of the explosion pressure in the closed-vessel was obvious. The effect of the ignition location on the maximum explosion pressure was related to the interaction between the flame instability and the orifice plate for the φ = 30% v/v hydrogen-air mixture.

Investigation of the Suppression of Methane Explosions by N2/CO2 Mixtures in Different Proportions.

To characterize the inerting effect of N2/CO2 mixtures containing various proportions on methane-air explosions, a series of experiments were conducted in a 20 L spherical vessel under the normal temperature (25 °C) and normal pressure (101 kPa). Six concentrations (10, 12, 14, 16, 18, and 20%) of N2/CO2 mixtures were selected to analyze the suppression of methane explosion by N2/CO2 mixtures. The results indicated that the maximum explosion pressure (p max) of methane explosions was 0.501 MPa (17% N2 + 3% CO2), 0.487 MPa (14% N2 + 6% CO2), 0.477 MPa (10% N2 + 10% CO2), 0.461 MPa (6% N2 + 14% CO2), and 0.442 MPa (3% N2 + 17% CO2) in the presence of the same N2/CO2 concentration, and similar decreases in the rate of pressure rise, flame propagation velocity, and production of free radicals were observed. Therefore, with the increase of CO2 concentration in the gas mixture, the inerting effect of N2/CO2 was enhanced. Meanwhile, the whole process of the methane combustion reaction was affected by N2/CO2 inerting, which was mainly attributed to heat absorption and dilution of the N2/CO2 mixture. N2/CO2 with a greater inerting effect leads to lower production of free radicals under the same explosion energy and a lower combustion reaction rate at the same flame propagation velocity. The findings of the current research provide references for the design of safe and reliable industrial processes and the mitigation of methane explosions.

Dynamic characteristics of methane explosion flame propagation in three types of pipe

In process industries, the pipe connecting the various process units has complex structures. An experimental system was established to examine the flame propagation in premixed methane explosions given various methane concentrations. Three types of vented pipe, a horizontal pipe, a vertical pipe, and a T-shaped pipe, were investigated. When the methane concentration was 10 vol%, the flame propagation velocity was maximised, and the time to reach maximum flame propagation velocity (ta) was the shortest, vmax in the T-horizontal pipe was higher than that in the T-vertical pipe. The attenuation coefficient of the velocity for the vertical part was 1.16. When the methane concentration was closer to 10 vol%, the maximum flame temperature Tmax and maximum explosion pressure Pmax were higher, and the response time differences among thermocouples at different positions were more minor. The vertical bifurcation structure enabled shunting of the methane explosion shock wave and energy, and the attenuation on T and P reached up to 49.08% and 13.91%. The attenuation coefficients for the Tmax and Pmax in the vertical part were 1.50 and 1.08, respectively. The findings can provide theoretical basis for reducing and controlling the risk of pipeline accidents involving natural gas explosions.

Explosion hazards of mixed aluminum/aluminum hydride dust cloud in a closed vessel

Aluminum (Al) and aluminum hydride (AlH3) powders are important energetic materials but show an explosion risk when suspended in air. The explosion hazard of mixed dust forms the basis of safety design in industrial processes. In this work, the explosion characteristics and mechanism of Al/air, AlH3/air, and Al/AlH3/air were investigated by experiments and simulations. The results show that the induction time of Al dust explosion is longer than that of AlH3, but the explosion severity of Al dust is smaller than that of AlH3. For the three-component Al/AlH3/air system, the addition of AlH3 dust can shorten the explosion induction time of the mixed system. The maximum explosion pressure (Pmax) of the dust mixture first increases and then decreases with mixed concentrations. At a mixed concentration of 900 g/m3 and an AlH3 content of 80%, the Pmax of the mixed dust is reached.

A novel dry water with perfluorohexanone for explosion suppression of AlH3

AlH3 is a promising candidate for hydrogen storage, but has high explosion risk. To prevent the accident of AlH3, the novel dry water (DW) was applied to the suppression of AlH3 explosion, and the addition of perfluorohexone improved the suppression effect significantly. When the mass fraction of 16.70wt% perfluorohexanone-modified dry water (PMDW) was added with 700 g/m3, the maximum explosion pressure decreased by 54.37 %, and the maximum explosion pressure rising rate dropped by 98.80 %. The 3-dimensional network structure of silica, adsorbing flame radicals and preventing heat transfer, was proved to play a pivotal role in the explosion suppression by HRTEM and NMR. The evaporation and decomposition of the internal solution would greatly improve the cooling effect. CF2 captured H, O, and OH radicals in the flame and interrupted the free radical chain reaction. Our work is a step towards the application of eco-friendly DW in the field of explosion suppression.

Experimental study on CO2/CF3I suppression of methane-air explosion and flame propagation

To explore the inhibitory effects of CF3I and CO2 gas on the explosion pressure and flame propagation characteristics of 9.5% methane, a spherical 20 L experimental explosion device was used to study the effect of the gas explosion suppressants on the maximum explosion pressure, maximum explosion pressure rise rate and flame propagation speed of methane. The results indicated that with a gradual increase in the volume fraction of the gas explosion suppressant, the maximum explosion pressure of methane and maximum explosion pressure rise rate gradually decreased, and the time taken to reach the maximum explosion pressure and maximum explosion pressure rise rate was gradually delayed. At the same time, the flame propagation speed gradually decreased. Additionally, the time taken for the flame to reach the edge of the window and the time taken for a crack as well as a cellular structure to appear on the flame surface was gradually delayed. The fluid dynamics uncertainty was suppressed. The explosion pressure and flame propagation processes were markedly suppressed, but the flame buoyancy instability was gradually enhanced. By comparing the effects of the two gas explosion suppressants on the pressure and flame propagation characteristics, it was found that at the same volume fraction, trifluoroiodomethane was significantly better than carbon dioxide in suppressing the explosion of methane. By comparing the reduction rates of the characteristic methane explosion parameters at a volume fraction of 9.5%, it was observed that the inhibitory effect of 4% trifluoroiodomethane on the maximum explosion pressure was approximately 4.6 times that of the same amount of carbon dioxide, and the inhibitory effect of 4% trifluoroiodomethane on the maximum explosion pressure rise rate and flame propagation speed was approximately 2.7 times that of the same amount of carbon dioxide. The addition of 0.5%–1.5% trifluoromethane to 4% and 8% carbon dioxide can improve the explosion suppression efficiency of carbon dioxide. This enhancing phenomenon is a comprehensive manifestation of the oxygen-decreasing effect of carbon dioxide and the trifluoroiodomethane-related endothermic effect and reduction in key free radicals.

Explosive properties of selected aerosols determined in a spherical 5-L test chamber

Combustible liquids in the form of aerosols are important for many industrial processes. Therefore the problem of explosion hazards posed by the aerosols becomes increasingly more prominent. To correctly assess the explosion risk and fulfil the requirements of the ATEX directive, it is necessary to obtain information regarding the flammable and explosive properties of the aerosols. Unlike in the case of gases and dusts, no standard procedures aimed at obtaining quantitative information of this type exist. Factors that influence the explosion dynamics of aerosols include: concentration, droplet size, temperature etc. Some of these factors are strongly dependent on the aerosol generation methods. A prototype apparatus was designed and constructed to address that dependence. The apparatus was used in an attempt to determine the basic explosion parameters of liquid flammable aerosols. The device consisted of a 5-L spherical vessel equipped with a pump-injection system that generated aerosols as well as a spark ignition source. A wide variety of injection settings were tested to select the most suitable conditions over a broad range of concentrations and fluid properties. A measurement procedure was developed for operating the device. Prototype tests were carried out with fluids commonly used in industry: isopropanol and kerosene. The tests demonstrated the significant influence of the vessel wall temperature on the result accuracy. Correct temperature control made it possible to obtain relationships between the aerosol concentration and the following explosion parameters: maximum explosion pressure and maximum rate of pressure rise.

Study of dust cloud behaviour in the modified Hartmann tube using the image subtraction method (ISM)

A dispersion of fine particles in the air is needed for a dust explosion to occur since an explosion is the fast combustion of particles in the air. When particles are poorly dispersed, agglomerated, or their concentration is low, the combustion velocity decreases, and deflagration would not occur. The combustion rate is strictly related to dust concentration. Therefore, the maximum explosion pressure rise occurs at dust concentration close to stoichiometric. Conversely, Minimum Explosion Concentration (MEC) is the lower limit at which self-sustained combustion and a pressure rise are possible. Dust explosion tests are designed to reproduce the dispersion and generation of dust clouds in industrial ambiences by using dispersion devices activated by pressurised air pulses. The resulting dust cloud, which has a marked transient character, is considered representative of real clouds by current standards. Over time, several studies have been carried out to optimise these devices (e.g. to reduce the inhomogeneity of the cloud in the 20 L sphere). The Minimum Ignition Energy (MIE) of dust is measured using the Mike3 modified Hartmann tube, where the ignition attempt is made 60–180 ms after dust dispersion regardless of dust characteristics.This work investigates the dust clouds’ actual behaviour inside the modified Hartmann tube before ignition using high-velocity video movies and a new image post-treatment method called Image Subtraction Method (ISM). Movies are recorded with high-speed cameras at a framerate of 2000 fps and elaborated with an on-purpose developed LabVIEW® code. Concentration (mass per volume) and dispersion pressure are varied to evaluate their effect on dust clouds. Maise starch, iron powder and silica powder are chosen to investigate the effect of particle density and size on the cloud structure and turbulence. This approach will help to investigate the structure of the dust cloud, the shape and size of the particle lumps and the change in dust concentration over time. In addition, information on the actual concentration and cloud turbulence at the ignition location and delay time were obtained, which may help identify the local turbulence scale and widen the characterisation of the cloud generated in the Hartmann tube.