Vent Pressure Research Articles

Experimental investigation on the vented flame and pressure behaviour of hydrogen-air mixtures

To explore the changes in pressure and flame propagation inside and outside the vessel when the pipe diameter does not match the vent diameter, and to check the conservatism of standards NFPA 68 and EN 14491 for this case, an experimental apparatus was utilized to investigate the influences of static activation pressure (0.7–1.75 bar) and vent diameter (30–70 mm) on the deflagration behavior of hydrogen–air mixtures (Φ: 0.6–1.4). The vented pressure, flame propagation, and pressure–flame interaction characteristics of hydrogen–air mixtures were observed and analyzed. Additionally, the conservatism of the calculated venting area under the experimental conditions of NPFA 68 and EN 14491 was verified. The results indicated that under an equivalence ratio of 0.6, the pressure-time curve inside the container exhibited only one peak (Pmax11). In the stoichiometric and fuel-rich states, the pressure-time curve inside the container exhibited two peaks attributed to the decrease in venting efficiency due to the secondary explosion inside the pipe, increasing the turbulence intensity within the container. When the static activation pressure is 0.7 bar, the pressures of the three vent diameters of 30, 50 and 70 dropped by 11.34%, 24.38% and 26.86% respectively. And the Pmax11 at Φ = 1.0 and Φ = 1.4 are similar, while this phenomenon is not observed for other vent diameters. When the vent diameter was inconsistent with the duct diameter. the calculations of both standards were conservative. However, under these testing conditions (vent diameter: 30–70 mm, static activation pressure: 0.7–1.75 bar), the NPFA 68 calculations yield a conservatism range of 3.3–11, whereas EN14491 ranges from 1.6 to 15.7. The NPFA 68 results were more stable and concentrated, making these conditions more suitable for industry safety design in hydrogen venting.

Effects of Vent Size and Pressure on Hydrogen Explosion Dynamic Characteristics.

Explosion venting is an effective method to reduce the explosion damage; in order to study the mechanism of an explosion venting process in internal and external space, this paper investigates the influence of vent parameters on hydrogen-air explosion in a rectangular duct through numerical simulation. The model including the internal and external space is first constructed, and then the explosion dynamic behaviors of the full flow field are analyzed under different vent pressures and sizes. The study aims to reveal the coupling effect of the flame, pressure, and flow field on hydrogen explosion venting. The results indicate that the explosion intensity increases with the growth of the vent pressure and the reduction of the vent size. The maximum external overpressure increases to 2.6 and 2.3 times as the vent pressure increased to 10 times or vent size reduced by 90%. The flame and combustible gas mixture evolve from a mushroom cloud into a jet form as the vent size decreases, and vortexes formed at the flame front suppress flame propagation. However, the flame speed increases significantly as the flame passes the vent under the impact of larger pressure gradient, which results in a more violent turbulence intensity and secondary external explosion.

Flameless venting characteristics and design model of micro-nano PMMA dust explosion

The effects of Fe–Ni foam thickness and dust size on flame propagation, reduced overpressure, and venting efficiency in 30 μm and 150 nm polymethyl methacrylate (PMMA) dust explosions were investigated. The flame quenching mechanism was revealed by coupling the heat transfer and flow of the dust flame within the Fe–Ni foam. It is found that micron dust is more prone to quenching than nano dust, and the differences in the quenching process of micro-nano dust are explained by combining the dust combustion kinetics and the theory of inter-particle heat transfer. The pressure venting mechanism of micro-nano dust was analysed under different thicknesses of Fe–Ni foam, and the thermal expansion effect of the flame passing through the Fe–Ni foam and its flow resistance significantly increased the reduced explosion overpressure. The flow continuity of the micro-nano dust was classified by means of the Knudsen number (Kn), which elucidates the effect of dust size differences on the pressure evolution. A prediction model for the maximum reduced explosion overpressure is proposed based on the explosion pressure venting of micro-nano dust. Changes in vented pressure have a direct impact on the efficiency of flameless venting. Nano-dust has an efficiency of more than 20 % lower than that of micron dust.

Characteristics of dust explosion venting pressure and flame under high activation pressure

A 20 L spherical explosive device with a venting diameter of 110 mm was used to study the vented pressure and flame propagation characteristics of corn dust explosion with an activation pressure of 0.78–2.1 bar and a dust concentration of 400∼900 g/m3. And the formation and prevention of secondary vented flame are analyzed and discussed. The results show that the maximum reduced explosion overpressure increases with the activation pressure, and the vented flame length and propagation speed increase first and then decrease with time. The pressure and flame venting process models are established, and the region where the secondary flame occurs is predicted. Whether there is pressure accompanying or not in the venting process, the flame venting process is divided into two stages: overpressure venting and normal pressure venting. In the overpressure venting stage, the flame shape gradually changes from under-expanded jet flame to turbulent jet flame. In the normal pressure venting stage, the flame form is a turbulent combustion flame, and a secondary flame occurs under certain conditions. The bleed flames within the test range are divided into three regions and four types according to the shape of the flame and whether there is a secondary flame. The analysis found that when the activation pressure is 0.78 bar and the dust concentration is less than 500 g/m3, there will be no secondary flame. Therefore, to prevent secondary flames, it is necessary to reduce the activation pressure and dust concentration. When the dust concentration is greater than 600 g/m3, the critical dust concentration of the secondary flame gradually increases with the increase of the activation pressure. Therefore, when the dust concentration is not controllable, a higher activation pressure can be selected based on comprehensive consideration of the activation pressure and destruction pressure of the device to prevent the occurrence of the secondary flame.

Numerical investigation on explosion hazards of lithium-ion battery vented gases and deflagration venting design in containerized energy storage system

Large-scale Energy Storage Systems (ESS) based on lithium-ion batteries (LIBs) are expanding rapidly across various regions worldwide. The accumulation of vented gases during LIBs thermal runaway in the confined space of ESS container can potentially lead to gas explosions, ignited by various electrical faults. However, a systematic simulation and assessment of the battery vented gases explosion under deflagration venting design still lack. In this work, a three-dimensional combustion model was developed within the frame of open source computational fluid dynamics code OpenFOAM based on a full-scale container, and the LIBs vented gases in realistic proportion were selected as the combustion gas. Coupled boundary conditions were introduced to enable the response of explosion vent doors and top deflagration vent panels on pressure. The internal and external overpressure, flame temperature, and wind velocity fields were employed to assess the gas explosion hazards to ESS container structure and surroundings. The results demonstrate that altering the vent door pressure, without the top vent panel, still leads to serious explosion accidents. There will be unacceptable overpressure for the container structure, as well as serious visible flames and high-speed airflow invading the external environment. Lower vented gas concentrations can reduce explosion hazards, and introducing the vent panel design aids to promote such reduction. The overpressure within the container is significantly decreased by guiding the top external secondary combustion through the vent panel, and the influence range for the environments is also significantly reduced on X-axis. The ignition location can affect the propagation of gas combustion within the container, and the proposed complete vent panel design minimizes the impact on the container structure and surroundings. The findings of this work can offer new references for the safety design of the LIBs ESS.

Influence of vent size and vent burst pressure on vented ethylene-air explosion: Experimental and numerical study

This paper describes the numerical simulation of the vented explosion of ethylene-air mixtures. The influence of concentration, vent size, and vent burst pressure on the vented ethylene-air explosion is investigated by comparing simulation results and experiments. The different phases of external flame propagation are concluded by comparing the experimental photos and the simulation results. The external explosion process is captured by the high-speed camera and simulation. It is found that the unburned mixture expanded to the external atmosphere, which was ignited by the flame. The flow velocity, velocity vector, and turbulence kinetic energy are applied to analyze the mechanism of external flame propagation. The velocity vector is deflected to both sides of the flame front and the reverse flow velocity is captured in the external flow field. The change of ethylene concentration and the venting flow velocity is used to explain the relationship between the pressure rise, chemical reaction rate, and venting flow. Results show that the internal pressure for AV= 0.18 m2 is significantly greater than the internal pressure for AV= 0.55 m2 in this case. The smaller vent size results in higher flow velocity and turbulence kinetic energy inside of the vessel. The vent burst pressure growth promotes the acceleration of the flame front inside of the vessel. The variation curve of ethylene concentration and venting flow velocity has a similar law with different vent burst pressures. The experimental and simulated results can provide technical and theoretical support for the design of gas explosion prevention in the field of process safety and risk engineering.

Vented ethanol-gasoline vapor explosions initiated by two symmetric sparks in a channel

Although accidental fire scenes and explosions are frequently caused by more than one spark, the influencing mechanism of explosion evolution under the case of more than one spark has yet to be determined. Hence a small cuboid channel with two symmetrical sparks was deigned to investigate the effects of spark locations (IpD) and vent coefficient (Kv) on explosion flames propagation and pressures formation, which were simulated to reveal the symmetrical flame fronts and flow field interaction using a large-eddy simulation (LES). Following ignition, two symmetrical flames developed practically simultaneously until they merged to expel, at which moment, due to flow vortexes, a hollow area formed near the channel bottom beneath each configuration. The proposed correlation in this work may adequately explain the trend of experimental flame propagation velocity (v) vsKv following membrane burst. The vent pressure (Pb) and associated peak (dp/dt) remained constant while IpD changed, yet rose as Kv decreased. Surprisingly, the pressure would continue to grow after flame ejection under small IpD and Kv. The increasing trend between the maximum pressure (Pmax) and IpD was found to be met with a sigmoid function, and the Pmax also grew as the Kv climbed, a quadratic relation was discovered. This research can further understand influencing mechanism of explosion evolution in the event of more than one spark.

Experimental and numerical study of the influence of vent burst pressure on venting characteristic of hydrogen-air explosion

Vented explosion is an effective solution to the potential security problem posed by accidental explosions during the operation of storage systems of gaseous fuels. Experimental high-speed photos, pressure histories, and numerical simulation are used to study vented explosion of the hydrogen-air mixture. This work discusses the dynamic of premixed flame propagation and the flame/vortex interaction. Large-eddy simulation turbulent combustion model is adopted to explain the interaction between flame front, turbulent flow, and pressure wave. All experiments and simulations were conducted at 298 K and 1 atm. Numerical simulation reproduces the vented hydrogen–air explosion and provides further understanding of the mechanism of external explosion. The influence of vent burst pressure on the vented explosion is also studied using simulated flame temperature, flow velocity, and pressure history. The simulation result reproduces internal pressure details accurately. Flame front propagation velocity shows four different processes in experimental and simulated flame images. The turbulent flame velocity exhibits a similar trend. The pressure rise mechanism is analyzed using the pressure curve, venting rate, and volume rate of combustion.

Dynamic Pressure Measurements During Vitrectomy in a Model of the Eye.

PurposeTo accurately evaluate pressure changes during vitrectomy in a rigid model of the vitreous chamber and to test the efficiency of the EVA phacovitrectomy system (Dutch Ophthalmic Research Center) in terms of compensation of intraocular pressure variations.MethodsWe tested 23-, 25-, and 27-gauge double-blade vitreous cutters in both vented global pressure control and automatic infusion compensation (AIC) modes in a vitreous chamber model, mimicking the real surgical procedure. Balanced salt solution and artificial vitreous, similar to the real vitreous body, were used. We tested both standard-flow (SF) and high-flow (HF) infusion systems, varying the infusion pressure between 20 and 40 mm Hg. In each experiment, flow rate was also measured.ResultsPressure drop was rapidly and efficiently compensated when 23- and 25-gauge cutters were used in AIC mode, with infusion pressures ranging between 30 and 55 mm Hg. The 27-gauge cutter was less efficient in compensating pressure variations. Pressure fluctuations related to the high-frequency motion of the cutter blade were small compared to the overall pressure variations. The use of the HF infusion system resulted in larger flow rates and lower pressure changes compared to the SF infusion system.ConclusionsDespite the rigid material of the model, the present pressure measurements are in line with previous studies performed on porcine eye. The use of AIC mode compensates intraoperative pressure drops efficiently, with both 23- and 25-gauge cutters. The HF infusion system is more efficient than the SF infusion system.Translational RelevanceThe AIC infusion mode efficiently compensates intraoperative pressure drops, in both 23- and 25-gauge experimental vitrectomy. The HF infusion system resulted in larger flow rate and lower pressure changes.

Experimental and numerical study on pressure dynamic and venting characteristic of methane-air explosion in the tube with effect of methane concentration and vent burst pressure

This paper presents the experiments and numerical simulation of vented methane-air explosion. The influence of methane concentration and vent burst pressure on the internal pressure dynamic and venting characteristic is investigated. The pressure oscillation is hardly noticed in the internal pressure curve as the case of concentration is 7 vol%. But for the case of concentration is from 9 vol% to 13 vol%, the pressure oscillation is obvious in the internal pressure curves. Two internal temperature peaks are found in the three simulated temperature curves. The duration of internal temperature curve will increase with the increase of methane concentration. The methane concentration and vent burst pressure have the influence on the variation curve of the internal fuel concentration. When the methane concentration is 7 vol%, it is worth noting that the internal fuel concentration drops rapidly to zero after vent opening. And when the methane concentration is 9 vol% or 11 vol%, the internal fuel concentration has a dramatic decrease and then maintains a slow descent after vent opening. The internal pressure curves with different concentrations all present two typical pressure peaks. The first pressure peak is more noteworthy than anther one under higher vent burst pressure conditions; the second pressure peak is more important under lower vent burst pressure conditions.

Comparison of two data acquisition protocols for tide gauge sensors at Imbituba port – Santa Catarina State

The Santa Catarina Tide Gauge Network (SCTGN) is a continuous sea level monitoring system to support fishery, aquaculture, and navigation in general. Deployed in the state of Santa Catarina, Brazil, the initiative started in 2012 with one tide gauge at the Santa Catarina Island South Bay to support aquaculture research projects and hydrodynamic numerical modelling. By 2020, the SCTGN was fully operational, consisting of 11 tide gauge stations along the 450km of the Santa Catarina coastal line. The next step is standardizing these tide stations to international data collection protocols. Knowledge of the effects different programming protocols have on data collection are important since they may affect the results. Data from a radar gauge (RG) and a vented (or relative) pressure gauge (VPG) were obtained over six months. The difference between RG and VPG measurements showed a 5.07cm2 variance. Percentage of reading errors was 0.03% and 0.77% for RG and VPG, respectively. This study aims to evaluate the feasibility of the SCTGN data collection protocol in the RG to comply with the Intergovernmental Oceanographic Commission (IOC) recommendations for sea level monitoring. We find that an RG gauge using the SCTGN protocol is adequate to monitor sea levels and has an easier installation and maintenance, and more stable vertical datum control.

Study of the influencing factors of the liquid CO2 phase change fracturing effect in coal seams.

To study the influence of different factors on the cracking effect of the liquid CO2 phase transition, the mechanics of coal rock crack extension based on liquid CO2 phase change blast loading were studied. Through the application of simulation software to analyze the influence of coal seam physical parameters (in situ stress, gas pressure, modulus of elasticity and strength of coal) and blasting parameters (fracturing pore size and peak pressure of detonation)on the effect of liquid CO2 phase change cracking, the simulation results showed that the cracking effect of liquid CO2 phase change was positively correlated with the changes in gas pressure, elastic modulus, fracture hole diameter and peak vent pressure, negatively correlated with the variation in situ stress and compressive strength, and nearly independent of the tensile strength. In addition, by using Gray correlation analysis to analyze the influence degree of six main factors on the cracking effect, the calculation results showed that the effect of blasting parameters was greater than that of physical parameters. The main controlling factor that affected the blasting effect was the peak pressure of blasting release. By conducting comparative engineering trials with different blasting parameters, the test results showed that the crack effect of the coal seam was positively correlated with the change in fracture hole diameter and peak venting pressure, which was consistent with the results obtained from the simulation. The experimental results and simulation results for the effective radius of coal seam fracturing were basically consistent, with the error between the two types of results falling below 10%. Therefore, the reliability of the blasting numerical model was verified. In summary, the research results provide theoretical guidance for applying and promoting liquid CO2 fracturing technology in coal mines.

Experimental and numerical study on the effect of low vent burst pressure on vented methane-air deflagrations

This paper experimentally investigated the effect of low vent burst pressure on the overpressure buildup and flame evolution during the vented methane-air deflagrations in a 1m3 rectangular vessel. CFD software FLACS was assessed in simulation of vented methane-air explosions against the experiment. Experimental results demonstrate that four overpressure peaks of Popen, Pout, Pext and Pacc from the vent failure, flame venting, external explosion and acoustically enhanced combustion, respectively, were observed except for the free venting case, in which only two overpressure peaks of Pout and Pext were monitored. The flame behaviors corresponding to different overpressure peaks were monitored especially at Pacc, where an abrupt increase in flame luminosity was observed on the bottom of the vessel due to the combustion of pockets of flammable mixture. Popen and Pacc increase with the vent burst pressure while Pout and Pext are nearly independent of the vent burst pressure. Double flame accelerations were observed owing to the vent rupture and flame venting. The phenomena of Helmholtz oscillation and the bulk motion of flame bubble always appeared after the vent rupture. The predicted overpressure agrees reasonably well with the experimental data. The discrepancy of the predicted and measured maximum peak overpressures reduces with increasing vent burst pressure. The predicted maximum peak overpressure and external flame length are slightly larger than those in experiment, which would facilitate the safe design in explosion venting and offer a better guidance in risk assessment. The simulation results also show that two overpressure peaks were recorded resulting from the pressure wave propagating above the vessel and the external explosion, respectively.

Experimental Quantification of Vent Mechanism Flow Parameters in 18650 Format Lithium Ion Batteries

Lithium ion batteries have a well-documented tendency to fail energetically under various abuse conditions. These conditions frequently result in decomposition of the electrochemical components within the battery resulting in gas generation and increased internal pressure which can lead to an explosive case rupture. The 18650 format cell incorporates a vent mechanism located within a crimped cap to relieve pressure and mitigate the risk of case rupture. Cell venting, however, introduces additional safety concerns associated with the flow of flammable gases and liquid electrolyte into the environment. Experiments to quantify key parameters are performed to elucidate the external dynamics of battery venting. A first experiment measures the vent burst pressure. Burst vent caps are then tested with a second experimental fixture to measure vent opening area and discharge coefficient during choked-flow venting, which occurs during battery failure. Vent opening area and discharge coefficient are calculated from stagnation temperature, stagnation pressure, and static pressure measurements along with compressible-isentropic flow equations and conservation of mass. Commercially sourced vent caps are used with repeated tests run to quantify repeatability and variability. Validation experiments confirmed accuracy of opening area and discharge coefficient measurement. Further, trials conducted on vent caps from two sources demonstrate the potential for variation between manufacturers.

The effect of vent burst pressure on a vented hydrogen–air deflagration in a 1 m3 vessel

A series of experiments are conducted to investigate the effect of vent burst pressure on stoichiometric hydrogen–air premixed flame propagation and pressure history in a 1 m3 rectangular vessel in this paper. Pressure buildup and flame evolution are recorded using piezoelectric pressure transducers and a high-speed camera, respectively. The results show typical pressure peaks of three different mechanisms for all vent burst pressures in the experiments. The first pressure peak, generated by the rupture of the vent cover, increases with the vent failure pressure, with the subsequent outflow inertia of combustion products giving rise to a negative pressure. The second pressure peak results from the constant bulk motion of the flame bubble (the Helmholtz oscillation), and the third is produced by the interaction between the combustion waves and the acoustic waves. The time interval between the first pressure peak and the second pressure transient remained nearly constant. The Helmholtz oscillation always appears as the vent ruptures and its magnitude increases with the vent burst pressure. Furthermore, the lower the vent failure pressure, the longer the Helmholtz oscillation is sustained. The peak of the acoustically enhanced pressure always occurs within several milliseconds of the flame front touching the vessel. From a theoretical perspective, Rasbash's equation models the relationship between the maximum reduced explosion overpressure and the vent burst pressure precisely. Also, it is observed that the maximum lengths of the external flames were found to be nearly identical in all tests, but the average propagation rate of the flame front increases with the vent burst pressure. It is interesting that a phenomenon of intense oscillation of internal flame bubble was observed with the increase of vent burst pressure.

Vent pipe emissions from storage tanks at gas stations: Implications for setback distances

At gas stations, fuel vapors are released into the atmosphere from storage tanks through vent pipes. Little is known about when releases occur, their magnitude, and their potential health consequences. Our goals were to quantify vent pipe releases and examine exceedance of short-term exposure limits to benzene around gas stations. At two US gas stations, we measured volumetric vent pipe flow rates and pressure in the storage tank headspace at high temporal resolution for approximately three weeks. Based on the measured vent emission and meteorological data, we performed air dispersion modeling to obtain hourly atmospheric benzene levels. For the two gas stations, average vent emission factors were 0.17 and 0.21 kg of gasoline per 1000 L dispensed. Modeling suggests that at one gas station, a 1-hour Reference Exposure Level (REL) for benzene for the general population (8 ppb) was exceeded only closer than 50 m from the station's center. At the other gas station, the REL was exceeded on two different days and up to 160 m from the center, likely due to non-compliant bulk fuel deliveries. A minimum risk level for intermediate duration (>14–364 days) benzene exposure (6 ppb) was exceeded at the elevation of the vent pipe opening up to 7 and 8 m from the two gas stations. Recorded vent emission factors were >10 times higher than estimates used to derive setback distances for gas stations. Setback distances should be revisited to address temporal variability and pollution controls in vent emissions.

Vent Pipe Emissions from Storage Tanks at Gas Stations: Implications for Setback Distances

At gas stations, fuel vapors are released to the atmosphere from storage tanks through vent pipes. Little is known about when releases occur, their magnitude, and their potential health consequences. Our goals were to quantify vent pipe releases and examine exceedance of short-term exposure limits to benzene around gas stations. At two US gas stations, we measured vent pipe flow rates and pressure in the storage tank headspace at high temporal resolution for three weeks. We modeled atmospheric benzene levels based on measured vent emission and meteorological data. For the two gas stations, average vent emission factors were 1.4 and 1.7 lb of gasoline per 1,000 gal dispensed. Modeling suggests that an1-hour Reference Exposure Level for benzene for the general population (8 ppb) was exceeded 160 m away from the gas station. Under stable atmospheric conditions, an occupational 15-minute exposure limit for benzene (1 ppm) was exceeded 27 m downwind from the pipe due to the highest observed 15-minute vent release (6.6 kg of gasoline). Vent emission factors are more than 10 times higher than estimates used to derive setback distances for gas stations. Setback distances should be revisited and account for temporal variability in vent emissions.

Control of laminate quality for parts manufactured using the resin infusion process

Resin infusion is a manufacturing process used to produce fibre-reinforced thermo-set polymer components. This process is utilised in a range of industries such as aerospace, automotive, marine, rail and defense and is a cheaper method when compared to other closed mould or autoclave manufacturing methods, particularly as the size of the parts increases. In this study, wet compaction characteristics and behaviour of three glass fibre reinforcements were analysed, and 2D panels were manufactured with a selection of inlet and vent pressure combinations during both the filling and post-filling stages of the process to achieve control of the final fibre volume fractions. Reinforcement thickness and resin pressure were monitored throughout each experiment and the achieved fibre volume fractions were measured post-manufacture. Void content was analysed microscopically and related to the respective experimental parameters set. The compaction result fairly predicted the achieved fibre volume fraction of the manufactured part. The possibility of controlling the fibre volume fraction through control of the post-filling pressure was demonstrated. Even though there was a risk of increased void content with some post-filling configurations, the fibre volume fraction could still be controlled without creating voids with careful application of post-filling conditions.

Explosion venting of hydrogen-air mixtures from a duct to a vented vessel

Experiments were conducted on the vented explosion of hydrogen–air mixtures from a 150-cm-long duct to a cylindrical vessel with a vent at the center of its side wall to investigate the effects of vent burst pressure and an obstacle in duct on the process of explosion venting. Turbulent pressure oscillation owing to a pressure wave moving back and forth in a duct and vessel was observed for unvented explosions. For explosion venting from duct to vessel, flame acceleration in duct much increases the explosion overpressure in vessel. The maximum explosion in duct is always higher than that in vessel, and both of them increase with an increase in the vent cover thickness. An obstacle installed in duct significantly affected the explosion overpressure, which first increased and then decreased with an increase in the blockage ratio. Three pressure peaks were distinguished in the external pressure-time histories, which were resulted form different pressure waves formed outside the vessel.

Pressure characteristics during vented explosion of ethylene-air mixtures in a square vessel

The vented explosion in a 2 m × 1.1 m × 0.5 m stainless cylindrical vessel with the ethylene-air mixture is investigated as the function of the ethylene concentration, vent area and vent burst pressure. The internal pressure histories measured by two piezoelectric transducers with the vented door of different thickness are used to analyze the effect of vent burst pressure on the whole explosion. It is shown that the peak overpressures are the highest just at the ethylene concentration is 8 vol%. The internal overpressure is grown with the concentration and in turn decreases after internal pressure reached the peak. As the vent burst pressure increases, the same trend that internal peak overpressure is increasing accordingly is found. The dominant peak overpressure will be change with different vent areas. Not only that, it is apparent that venting is more effective on the account of the low ethylene concentrations. The high-speed images demonstrate that the flame is strongly distorted and the unburned mixture is ignited by the external flame. The comparison between experimental results and calculation values has been discussed in consideration of the influences of vent area and vent burst pressure. The predicted overpressures of different theoretical models are relatively conservative than measured peak overpressures.