Sensitivity Of Explosives Research Articles

Finding a way through the “misty” evaluation of the flammability and explosivity of kerosene aerosols

• JetA1 mist flammability and explosivity are assessed in a confined explosion vessel. • Influence of initial conditions on explosion sensitivity and severity is studied. • JetA1 mists with a small droplet size have a higher rate of pressure rise. • The MIE of JetA1 mist may be lower than that of vapors at low temperatures. • The vapor/liquid ratio of a mist is a key parameter of its explosion severity. In the context of assessing hydrocarbon mist ignition sensitivity and explosion severity, an original test method is proposed, focusing on kerosene JetA1 mists but is applicable to other hydrocarbons. Experiments were carried out in a modified apparatus based on the 20L explosion sphere. Fine control of the gas/liquid ratio and flow rates, the mist concentration, and the ignition energy and duration, was ensured by a specifically customized control system guaranteeing the flexibility and compliance of the test apparatus. The droplet size distribution (DSD) and the level of turbulence of the JetA1 mist cloud were first determined by an in-situ laser diffraction sensor and by Particle Image Velocimetry, respectively. The lower explosive limit (LEL), the minimum ignition energy (MIE), the limiting oxygen concentration (LOC), the maximum explosion overpressure (P max ), and the maximum rate of pressure rise (dP/dt max ) were then determined for different mist concentrations, ambient temperatures, initial turbulence levels, energies, and DSD. Tests showed that the LEL mist of JetA1 mists of an average diameter of 8 µm is around 94 g/m 3 , a value which increases to 220 g/m 3 with increasing DSD. This value also tends to decrease considerably with increasing temperatures. Moreover, at a JetA1 concentration of 125 g/m 3 , P max and dP/dt max as high as 6 bar and 192 bar/s respectively were reached, the latter increasing to about 480 bar/s at T = 60 °C. These mists were shown to be ignitable using energies as low as 200 mJ, which is lower than that of vapors at low temperatures, and a limiting concentration of oxygen of 15.8 % v/v . The potential presence of hydrocarbon mist should therefore be an element that requires reconsidering the classification of hazardous areas. Finally, to stress the influence of the vapor-liquid ratio present in the cloud before ignition on the combustion kinetics, an evaporation model based on the d 2 -law was developed estimating the evaporation time and the vapor quantity at different initial temperatures or droplet diameters. Findings were shown to be well coherent allowing the proposition of a new technique for determining hydrocarbon mist safety criteria. Finally, results have shown that JetA1 mists can ignite at temperatures below the liquid’s flashpoint under varying turbulence levels and droplet size distributions.

Hydrogen bond and 3D frameworks to reconcile the conflict between safety and detonation performance in energetic metal–organic frameworks

Energetic metal–organic frameworks (EMOFs), which combine energetic ligands with metal ions, hold promise as novel energetic materials to balance the sensitivity and safety of explosives. The coordinating solvent molecules have a significant effect on the energetic properties of EMOFs. Two EMOFs, [K(AFTO)·H2O]n (1) and solvent-free [K(AFTO)]n (2), were obtained at different reaction temperatures. EMOFs 1 and 2 exhibit excellent thermal stability (Td,1 = 569 K, Td,2 = 574 K), insensitivity to mechanical stimuli (FS ≥ 360 N, IS ≥ 40 J for 1; FS ≥ 360 N, IS = 35 J for 2) and satisfactory detonation performance (D1 = 8291 m s−1, P1 = 31.9 GPa; D2 = 8415 m s−1, P2 = 32.7 GPa) due to their different 3D framework structures and strong hydrogen bond networks.

Preparation of Core-Shell-Structured RDX@PVDF Microspheres with Improved Thermal Stability and Decreased Mechanical Sensitivity.

Reducing the sensitivity of high-energy simple explosives is the key technology in improving the practical application of high-energy insensitive powder. As the most widely used high-energy explosive, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is limited in application due to its high sensitivity. In this work, polyvinylidene fluoride (PVDF) was used as an energetic binder. Core-shell-structured RDX@PVDF microspheres are produced using electrospray assembly technology and fully characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, and mechanical sensitivity. Their thermal stability and mechanical sensitivity are directly related to the weight fraction of the added PVDF. Moreover, core-shell-structured RDX@PVDF microspheres with RDX and PVDF in the proportion three to one possess a spherical-like morphology, the lowest impact sensitivity, the lowest friction sensitivity, and the highest thermal stability. This work provides a facile method for the positive design energetic materials and the prediction of their environmental adaptability.

Identifying the Molecular Properties that Drive Explosive Sensitivity in a Series of Nitrate Esters.

Energetic materials undergo hundreds of chemical reactions during exothermic runaway, generally beginning with the breaking of the weakest chemical bond, the “trigger linkage.” Herein we report the syntheses of a series of pentaerythritol tetranitrate (PETN) derivatives in which the energetic nitrate ester groups are systematically substituted by hydroxyl groups. Because all the PETN derivatives have the same nitrate ester-based trigger linkages, quantum molecular dynamics (QMD) simulations show very similar Arrhenius kinetics for the first reactions. However, handling sensitivity testing conducted using drop weight impact indicates that sensitivity decreases precipitously as nitrate esters are replaced by hydroxyl groups. These experimental results are supported by QMD simulations that show systematic decreases in the final temperatures of the products and the energy release as the nitrate ester functional groups are removed. To better interpret these results, we derive a simple model based only on the specific enthalpy of explosion and the kinetics of trigger linkage rupture that accounts qualitatively for the decrease in sensitivity as nitrate ester groups are removed.

Explosion dynamics and sensitivity analysis of blended LPG/DME clean fuel promoted by H2 in a confined elongated space

The involvement of highly chemically reactive H2 greatly increases the fuel explosion risk. In order to reveal the elevated explosion risk of LPG/DME blended gas due to the participation of H2, the explosion-promoting dynamics of H2 and its sensitivity characteristics are investigated based on a combination method of numerical simulation, experimental verification and theoretical analysis. The results show that the participation of H2 increases the explosion overpressure and the shockwave propagation velocity by 147.9% and 90% respectively to the greatest extent. The explosion temperature shows five typical combustion stages, with the participation of H2, the maximum temperature rise range of the shock wave adiabatic compression heating period and the combustion period is significantly increased, the adiabatic holding time is prolonged, the peak flame temperature is increased, and the flame propagation velocity is also significantly improved. The addition of H2 causes the relative distance between the explosion shock wave and the flame front first increases, then decreases and then increases in the shape of “half-morning glory”. The number and sensitivity coefficients of the new explosion-promoting elementary reactions brought by H2 are larger than that of the new explosion-inhibiting elementary reactions, which explains and confirms the explosion-promoting nature of H2 in terms of the reaction mechanism.

Spun of improvised cis‐1,3,4,6‐tetranitrooctahydroimidazo‐[4,5‐d]-Imidazole (BCHMX) in polystyrene nanofibrous membrane by electrospinning techniques

Development of ultra-fine fiber technology and nano-sized materials are widely taking place to enhance the characteristic of different materials. In our study, a newly developed technique was used to produce improvised nano energetic fibers with the exploitation of cis‐1,3,4,6‐Tetranitrooctahydroimidazo‐[4,5‐d] imidazole (BCHMX) to spin in a polystyrene nanofiber membrane. Scanning electron microscopy (SEM) showed the synthesized nanofibrous polystyrene (PS)/BCHMX sheets with clear and continual fiber were imaged with scanning electron microscopy (SEM). Characterization of the produced nanofiber was examined by Fourier Transform Infrared (FTIR), and X-ray diffractometer (XRD). Explosive sensitivity was also evaluated by both BAM impact and friction apparatus. Thermal behavior for the synthesized PS/BCHMX fiber and the pure materials were also investigated by thermal gravimetric analysis (TGA). The results show enhancement in the fabrication of nano energetic fibers with a size of 200–460 nm. The TG confirms the high weight percentage of BCHMX which reaches 60% of the total mass. PS/BCHMX fiber was confirmed with the XRD, FTIR spectrum. Interestingly, XRD sharp peaks showed the conversion of amorphous PS via electrospinning into crystalline shape regarding the applied high voltage. The synthesized PS/BCHMX nanofiber was considered insensitive to the mechanical external stimuli; more than 100 J impact energy and > 360 N initiation force as friction stimuli. PS/BCHMX is considering a candidate tool to deal with highly sensitive explosives safely and securely for explosives detection training purposes.

Understanding Explosive Sensitivity with Effective Trigger Linkage Kinetics.

We present a simple linear model for ranking the drop weight impact sensitivity of organic explosives that is based explicitly on chemical kinetics. The model is parameterized to specific heats of explosion, Q, and Arrhenius kinetics for the onset of chemical reactions that are obtained from gas-phase Born-Oppenheimer molecular dynamics simulations for a chemically diverse set of 24 molecules. Reactive molecular dynamics simulations sample all possible decomposition pathways of the molecules with the appropriate probabilities to provide an effective reaction barrier. In addition, the calculations of effective trigger linkage kinetics can be accomplished without prior physical intuition of the most likely decomposition pathways. We found that the specific heat of explosion tends to reduce the effective barrier for decomposition in accordance with the Bell-Evans-Polanyi principle, which accounts naturally for the well-known correlations between explosive performance and sensitivity. Our model indicates that sensitive explosives derive their properties from a combination of weak trigger linkages that react at relatively low temperatures and large specific heats of explosion that further reduce the effective activation energy.

Iron dust explosion characteristics with small amount of nano-sized Fe2O3 and Fe3O4 particles

Iron powder, as one of the most abundant metal fuels that can be used as recyclable carriers of clean energy, is a promising alternative to fossil fuels in a future low-carbon economy. It may pose a potential explosion hazard during the process of processing, storage, transport, and reduction/oxidation (redox). The explosion characteristics of iron dust in air were undertaken via a 20 L spherical explosion chamber with an emphasis on minimum explosion concentration (MEC) of iron dust. The alternative method of combustion duration time (tc) was used to determine MEC and compared with the standardized over pressure method. Two kinds of nano-sized iron oxides (Fe2O3 and Fe3O4) were used as inertants to determine the inhibition effect of different oxidation products. The iron dust explosion products with various shapes and sizes were found to be able to grow up 4–6 times of the iron dust for the first time. Adding small amount of Fe2O3 or Fe3O4 could reduce the explosion severity and sensitivity of iron dust. The MEC data determined by both methods were comparable. The addition of 5 % oxide has obvious inhibition effect under 1500 g/m3 concentration. With the increase of oxide concentration to 10 %, the inerting effect increases, and the MEC of iron dust increases more than 3 times. The increase of dust concentration will weaken the inerting effect. When the concentration increases from 500 g/m3 to 3000 g/m3, the weakening effect of 10 % Fe2O3 on the explosion pressure decreases from 38.45 % to 2.24 %, and 10 % Fe3O4 decreases from 46.21 % to 10.63 %. Unlike coal, biomass or aluminum dusts, the iron dust explosion was found to have a unique secondary acceleration of pressure rise rate for the first time. These results provide a fundamental basis to mitigate the iron dust explosion via solid inerting method without adding extra elements.

Effect of CaCl2, Al(OH)3 and NH4H2PO4 on the explosion sensitivity of pulverized coal

ABSTRACT In this paper, the effects of 30 wt%, 50 wt% aluminum hydroxide, calcium chloride and ammonium dihydrogen phosphate three explosion inhibitors on the two sensitivity parameters of the minimum explosion concentration and the minimum ignition energy of pulverized coal were investigated. It was found that for the same explosion inhibitor, the higher the content of explosion inhibitor, the higher the increase of MEC and MIE of pulverized coal-explosion inhibitor. At the same time, dust reduction measures should be taken in time when the coal dust concentration will be close to 70 g/m3. It was found that for the same explosion inhibitor, the higher the content of explosion inhibitor, the higher the increase of MEC and MIE of pulverized coal-explosion inhibitor. In the meantime, dust reduction measures should be taken in time when the coal dust concentration will be close to 70 g/m3. Furthermore, 150 g/m3 was the critical concentration of the ignition energy of pulverized coal. In order to prevent the occurrence of coal dust explosion accidents, it was necessary to resolutely prevent the concentration of pulverized coal from approaching this value on site. In addition, when the pulverized coal-explosion inhibitor concentration was 100 g/m3-250 g/m3, whether it was 30 wt% NH4H2PO4 or 50 wt% NH4H2PO4, the ignition energy required for mixing with pulverized coal was greatly increased. Overall, in the concentration range of 30–50 wt%, 50 wt% NH4H2PO4 was more advantageous in the suppression of coal dust explosion.

Relationship of the Impact Sensitivity of Explosives with the Thermal Decomposition Reaction

Relationship of the Impact Sensitivity of Explosives with the Thermal Decomposition Reaction

Predicting explosive properties of chemicals accounting for thermodynamic and kinetic factors

A novel modelling platform, the Merck Explosive Prioritisation Scheme, is introduced. It’s dependent on neither atom types nor the chemical class of the assessed molecule. The thermodynamic layer includes simulation of chemical decomposition with further estimation of the enthalpy of the decomposition and the volume of released gases. A new algorithm, the “Greedy” method, is used in calculating decomposition enthalpy. The heats of formation are estimated by quantum-chemical calculations. The enthalpy of decomposition and volume of released gases are used to predict the Power Index (PI) of the chemicals estimated as the ratio of the explosive power of the analysed substance towards the reference chemical picric acid. Based on regulatory defined thresholds for the enthalpy of explosion and volume of released gases, a threshold for the PI is defined. Chemicals are classified as “explosive” if their PI values are higher than the threshold. The performances of the algorithms in the thermodynamic layer showed good predictability. Given the nature of the Greedy algorithm, the thermodynamic model tends to slightly overpredict experimental power indices but never underestimates the explosive properties of chemicals. The kinetic layer estimates the explosive sensitivity by applying the COREPA model based on quantum-chemical and physicochemical parameters. The COmmon REactivity PAttern (COREPA) modelling system performs well for the impact sensitivity dataset. Given the limited number of chemicals used to derive the model, its current applicability domain is narrow.

Novel method to control explosive shock sensitivity: A mesoscale study to understand the effect of thermally expandable microsphere (TEM) inclusions in high explosives (HE) microstructure

When the void content and/or void structure of a high explosive (HE) is altered by some means (i.e., bulk heating or mechanical damage), the shock initiation behavior of the material changes. The ability to precisely predict the change in shock sensitivity after an HE has undergone microstructural changes is a crucial capability in multi-scale reactive flow models. Here, we utilize thermally expandable microspheres (TEMs) as a dopant in a polymer bonded explosive (PBX) matrix to alter the shock initiation properties in a controlled fashion. Using a mesoscale modeling approach, we evaluated how a single TEM (before and after thermal expansion) behaves under shock compression, as well as how the matrix PBX in the direct vicinity of the TEM is affected. We first examined the effect of an unexpanded TEM in the explosive matrix and found that its presence does not significantly perturb the bulk flow and by extension will not affect bulk sensitivity. Next, we examined the effect of an expanded TEM and found that its presence significantly perturbs the flow via hydrodynamic jetting, which causes a secondary shock wave with a strength that exceeds that of the incident wave. Finally, we showed that this secondary shock interacts with the downstream porosity to ignite a larger fraction of the overall pore volume, commensurate with the secondary shock strength and the affected volume, increasing the global (bulk) shock sensitivity.

Improved stability of picric acid: 1-aminopyrene’ charge-transfer complex: Synthesis, characterization, energetic performance and molecular docking study with B-DNA

Green energy materials are being developed with an eye on environmental friendliness, safety, and performance enhancement. Therefore, designing and synthesizing innovative, energetic salts for a new generation of ecologically conscious products is vital. In the present study, a charge-transfer complex (PIC:1APYRN) was synthesized via solvent evaporation by combining picric acid (PIC) with 1-aminopyrene (1APYRN). The structural characterization of the target compound was performed through single-crystal X-ray diffraction, and its impact sensitivity was determined using the BAM method. Accordingly, the X-ray diffraction technique was applied to examine the solid-state structural characteristics of the novel energetic salt, and it was found that the π-stacking and hydrogen-bonding interactions, which promote tighter packing, might increase explosive impact sensitivity. The obtained PIC:1APYRN energetic salt displayed a moderate value of heat of formation (-71.035 kJ.mol−1), high decomposition temperature (Td: 319.3 °C), moderate detonation performance (Dv= 4.85 km.s−1, P = 9.66 GPa), and excellent sensitivity towards outer stimuli. Furthermore, the structure-property relationship was also revealed from the experimental results and supported by the subsequently performed quantum chemical calculations. Experimental and density functional theory (DFT) studies reveal that the newly formulated energetic salt provides a viable balance between strong detonation quality, insensitivity, and appropriate thermal stability. Furthermore, the interaction of pristine molecules and PIC:1APYRN with B-DNA was investigated using a rigid docking technique via HEX software to foresee its potential detectability through nanobioprobes.

Effect of stearic acid coating on the explosion characteristics of aluminum dust

To explore the effect of stearic acid coating on the explosion characteristics of aluminum dust, the flame propagation characteristics, minimum explosion concentration and explosion overpressure characteristics of aluminum (Al) and stearic acid coated aluminum dust (SA-Al) were studied by using the synchronous thermal analyzer, the improved Hartmann tube explosion test device, and 20 L explosion test device. Then micro morphology and composition of the explosion products were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), and a physical model of stearic acid coated aluminum dust explosion was established. The results showed that the combustion intensity and flame propagation velocity of SA-Al dust cloud in the semi-closed pipe were lower than that of Al dust cloud, and the flame propagation was weak in the initial stage of explosion. The minimum explosion concentration (MEC), the optimal explosion concentration, the maximum explosion pressure (Pmax) and the maximum explosion pressure rise rate ((dP/dt)max) of SA-Al dust cloud were greater than that of Al dust cloud, and its products contained the incomplete combustion products AlO2, indicating that the stearic acid coating could abate the explosion sensitivity of Al dust cloud, and weaken the degree of oxidation of Al dust. In case of explosion, stearic acid coating could significantly enhance the explosion hazard of Al dust, resulting in a higher explosion risk.

Comparing the shock sensitivity of insensitive energetic materials

We present a tabletop method to study the shock sensitivity of plastic-bonded explosives that are considered shock insensitive using high dynamic range optical emission spectroscopy with laser-launched km/s flyer plate impacts (2, 3, and 4 km/s), which measures the spectral radiance (the emission spectrum vs a calibrated intensity standard) every 0.8 ns in the nanosecond and microsecond regimes. The explosives were TATB (1,3,5 trinitro, 2,4,6 triamino benzene), FOX-7 (1,1-diamino-2,2-dinitroethylene), LLM-105 (2,6-diamino-3,5-dinitropyrazine-1-oxide), and NTO (nitrotriazolone), all with 20% Sylgard 182 binder. Time resolving emission from shocked explosives produces a unique fingerprint at each shock pressure, and the emission temporal profile can be used to understand each material's shock response and the underlying mechanisms within the framework of the well-known shock ignition and growth models. Ignition was characterized by the emission intensity during nanosecond hot spot ignition. The growth process, which occurs after the shock has unloaded, was characterized by the time derivative of microsecond emission intensity. Singular-value decomposition was used to determine a characteristic spectral radiance over the entire time range, and this radiance was fit to a graybody model to determine a characteristic temperature Tc. Even though these insensitive explosives have similar shock sensitivities, our method can clearly distinguish their shock response. FOX-7 and NTO were the most sensitive, with FOX-7 having the greatest shock ignition sensitivity, growth rate, and Tc. LLM-105 was much less sensitive than FOX-7 and NTO, and TATB consistently showed the lowest sensitivity by any measure.

Quantitative prediction and ranking of the shock sensitivity of explosives via reactive molecular dynamics simulations

A deep understanding of explosive sensitivities and their factors is important for safe and reliable applications. However, quantitative prediction of the sensitivities is difficult. Here, reactive molecular dynamics simulation models for high-speed piston impacts on explosive supercells were established. Simulations were also performed to investigate shock-induced reactions of various high-energy explosives. The fraction of reacted explosive molecules in an initial supercell changed linearly with the propagation distance of the shock-wave front. The corresponding slope could be used as a reaction rate for a specific shock-loading velocity. Reaction rates that varied with the shock-loading pressure exhibited two-stage linearities with different slopes. The two inflection points corresponded to the initial and accelerated reactions, which respectively correlated to the thresholds of shock-induced ignition and detonation. Therefore, the ignition and detonation critical pressures could be determined. The sensitivity could then be a quantitative prediction of the critical pressure. The accuracies of the quantitative shock sensitivity predictions were verified by comparing the impact and shock sensitivities of common explosives and the characteristics of anisotropic shock-induced reactions. Molecular dynamics simulations quantitatively predict and rank shock sensitivities by using only crystal structures of the explosives. Overall, this method will enable the design and safe use of explosives.

The danger of initiating explosives by electrostatic discharge. Checking the level of sensitivity of explosives to electrostatic discharges

Explosives designed for civil uses can be, in some cases, be triggered by accident due to electrostatic discharge. Static electricity, as a source of electrostatic discharge, is a common phenomenon in the explosives manufacturing industry. Explosives designed for civil uses are substances, materials and accessories that present a high-risk factor during their production, packaging, storage, transport, use and disposal. In order to establish essential safety requirements for civilian uses explosives, national legislation has been harmonized with European legislation, respectively with Directive 2014/28/EU of the European Parliament and of the Council regarding the placing on the market and control of explosives for civil use, for handling with minimal risk to the safety of human life and health, to prevent damage to property and the environment, and to ensure the safety and health of persons coming into contact with civil uses explosives. In this context, it is necessary to apply high-performance test methods to determine the safety parameters for assessing the conformity of explosives for civil use with the safety requirements set out in the specified directive. This paper describes some aspects regarding the implementation of the testing method for checking the level of sensitivity to electrostatic energy of explosives within the Laboratory of Non-Electrical Ex Equipment, Electrostatics, Materials and PPE within INCD INSEMEX Petroșani [1, 2].

Effect of Nano-Sized Energetic Materials (nEMs) on the Performance of Solid Propellants: A Review.

As a hot research topic, nano-scale energetic materials have recently attracted much attention in the fields of propellants and explosives. The preparation of different types of nano-sized energetic materials were carried out, and the effects of nano-sized energetic materials (nEMs) on the properties of solid propellants and explosives were investigated and compared with those of micro-sized ones, placing emphasis on the investigation of the hazardous properties, which could be useable for solid rocket nozzle motor applications. It was found that the nano-sized energetic materials can decrease the impact sensitivity and friction sensitivity of solid propellants and explosives compared with the corresponding micro-sized ones, and the mechanical sensitivities are lower than that of micro-sized particles formulation. Seventy-nine references were enclosed.

Recruiting Perovskites to Degrade Toxic Trinitrotoluene.

Everybody knows TNT, the most widely used explosive material and a universal measure of the destructiveness of explosions. A long history of use and extensive manufacture of toxic TNT leads to the accumulation of these materials in soil and groundwater, which is a significant concern for environmental safety and sustainability. Reliable and cost-efficient technologies for removing or detoxifying TNT from the environment are lacking. Despite the extreme urgency, this remains an outstanding challenge that often goes unnoticed. We report here that highly controlled energy release from explosive molecules can be accomplished rather easily by preparing TNT–perovskite mixtures with a tailored perovskite surface morphology at ambient conditions. These results offer new insight into understanding the sensitivity of high explosives to detonation initiation and enable many novel applications, such as new concepts in harvesting and converting chemical energy, the design of new, improved energetics with tunable characteristics, the development of powerful fuels and miniaturized detonators, and new ways for eliminating toxins from land and water.

Methods to predict variations of lower explosion limit associated with hybrid mixtures of flammable gas and dust

In order to study variations of the lower explosion limit associated with hybrid mixtures of flammable gas and dust, four hybrid mixtures of methane/lycopodium, methane/polyethylene, ethylene/lycopodium, and ethylene/polyethylene with various concentration ratios were constructed. The lower explosion limits of these mixtures were measured in a 20 L spherical explosion vessel. According to the experimental results, it was obtained that the lower explosion limits of these hybrid mixtures were decreased by increasing the flammable gas concentration. The two-dimensional coordinate system was divided into explosion area and non-explosion area using the lower explosion limit curve. For different hybrid mixtures, the proportions of the explosion area were different in the two-dimensional coordinate system. The larger the proportion, the greater the explosion sensitivity. Based on this proportionality relationship, a dimensionless parameter called sensitivity index was defined as the ratio of the explosion area to the non-explosion area. The greater the sensitivity index, the greater the explosive sensitivity of the hybrid mixture. According to the relationship between the sensitivity indices of different hybrid mixtures, the influencing factors for the sensitivity index were established, including combustion heat of the flammable gas and dust, chemical reactivity of the flammable gas, as well as dimensionless parameters of dust decomposition characteristics. Considering these influencing factors, a calculation method for the sensitivity index was established using maximum explosion pressure as well as explosion indices of the flammable gas and dust. Through this comprehensive study, a new predictive approach for determining variations of the lower explosive limit of hybrid mixtures with the newly proposed sensitivity index was established. The predictive performance of this newly developed approach was verified using data from other hybrid mixtures.