TAN Ying-xin， WANG Hai-bin， REN Rui-e

(School of Chemical and Environmental Engineering, North University of China, Taiyuan 030051, China)

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Experimental study on gas explosion to kill and injury mouse

TAN Ying-xin， WANG Hai-bin， REN Rui-e

(SchoolofChemicalandEnvironmentalEngineering,NorthUniversityofChina,Taiyuan030051,China)

The killing and injury effects of gas explosion shock wave on mouse in an open space pipeline is tested experimentally. When the methane volume fraction is 10%, the maximum explosion pressure is 0.264 MPa and the injury is the most serious. Specially, some designed obstacles put in the open space pipeline are conducive to producing more stronger gas explosion shock wave. Accordingly, the injury effect of methane explosion on mouse is enhanced under obstacles condition.When the methane volume fraction is 10%, the maximum explosion pressure can reach 0.298 MPa under obstacles condition. It can be concluded that to reduce explosive accident impact, the obstacles in coal mine should be avoided. With the explosions increasing, the death pressure of mouse decreases.

mouse; animal injury; methane; gas explosion

Gas explosion is a kind of serious injury accident to life and property safety of mankind. To prevent gas explosion and reduce its injury to human, it is very necessary to research killing and injury effects of gas explosion shock wave on people or animals.

The explosion sources of shock wave to kill and injury animals are usually dynamite and detonator. Experimental study is performed mostly in an open space. Many researchers have done similar work, but there is little research on injury effects of gas explosion on animals in a close space. For example, Stuhmiller J H[1]outlined the biological effects of impact injury. Chavko M, et al.[2]measured the damage degree of shock wave to animal brain using a micro pressure sensor. Jaffin J H[3]established the damage model of explosion over pressure to lung. SUN Yan-fu[4]studied the explosion shock wave variation of standard TNT under different equivalent conditions in the free field. ZHOU Jie[5]applied computational fluid dynamics in analysis of damage effect of the shock wave on animals. However, the research on the injury effect of gas explosion wave on animals is less. CHEN Hai-bin[6]simulated the injury of three different periods of shock wave to animals’ lung. HU Qing-wu[7]used animals to test the injury of shock wave to human body. But for the injury effects of gas explosion on animals, only FAN Xiao-tao[8]simulated the injury of different gas volume to the rats with the experiment tube in an open space.

In this article, the killing and injury effects of gas explosion shock wave on mouse in an open pipeline is tested experimentally. Specially, some designed obstacles is put in the open pipeline to produce stronger gas explosion shock wave. Under these conditions, the killing and injury effects of gas explosion shock wave to mouse are studied.

1 Test principle

To reckon human injury value caused by gas explosion shock wave, the killing and injury effects of gas explosion shock wave on mouse are tested experimentally, because the visceral structure of mouse is similar to that of human. The injury of gas explosion shock wave mainly includes burn, blast injury, noxious gas injury and mechanical injury[9]. Before being tested, mouse is fixed in a small cage, as shown in Fig.1. During testing, it is put in the pipeline with designed obstacles. The last procedure is as follows: the mixture of methane gas and air is filled in the pipeline with the volume fraction of methane of 10%; when the mixture gas is well distributed, the mixture is ignited. As a result, explosion shock wave will produce and react on the mouse in the pipeline.

Fig.1 Mouse in a small cage

The explosion pressure only lasts for hundreds of milliseconds, therefore not the impulse of explosion shock but the peak pressure is the main reason of mouse death[10]. Over-pressure damage effects on mouse organs are different. The lung injury is the most serious[11], thus lung is chosen to do anatomic analysis. The lesion morphology of lung mainly includes congestion, angiectasis blood stasis, hematoma, punctiform, plaque and flaky bleeding, and organ rupture.

2 Test process

2.1 Test apparatus

The pipeline explosion apparatus used for the test is composed of blast pipes, ignition system, distribution system and data acquisition system[12]. The ignition system consists of ignition electrode, power and high voltage transformer; Gas distribution system mainly includes air compressor, vacuum pump, methane tank and vacuum pressure gauge; Data acquisition system consists of sensor, charge amplifier and dynamic data analyzer.

The blast pipe is put horizontally for the experiment under normal temperature and pressure. The inner diameter of the pipe is 139 mm and the wall thickness is 10 mm. The total length of the pipe is 3.1 m, consistsing of three seamless steel pipes connected by flange, two of which are 1.2 m and the other one of which is 0.7 m. The end of the pipe is closed by a blind flange. The maximum pressure resistance is 6.4 MPa. The experimental set-up is shown in Fig.2.

Fig.2 Experimental set-up

2.2 Experimental test

The mice are from Kunming city. They are male and have similar physiological states. According to weight, the mice are divided into two groups. Group 1 is (220±5) g, and group 2 is (20±5) g. The mice are fixed in the cages and put on the upper layer or the lower layer. Every mouse is numbered. Before igniting combustible mixture gas, the cages are put in the pipe. The mice are all no anesthesia treatment. After gas explosion, the lung injuries of the mice go through anatomic analysis.

2.2.1 Mice injury tests at different methane volume fractions

The methane explosion pressure at different volume fractions (6%,8%,10%,2% and 4%) are tested before mice injury tests.The representative explosion peak pressure at methane volume fraction of 10% reaches 0.264 MPa, as shown in Fig.3.

Fig.3 Explosion pressure at methane volume fraction of 10%

The distance of the mice from the ignition source is 2.05 m in the pipeline. The tests are done ten to twelve times. The experimental results and the mice’ vital signs are shown in Table 1.

Table 1 Mice vital signs after methane explosion

The bleeding in lung is shown in Fig.4. The dead mouse with smaller body is shown in Fig.5.

Fig.4 Bleeding in lung

Fig.5 Dead mouse and its smaller body

It can be seen from Table 1 that with the increase of methane concentration, the injury degree of the mouse changes from serious to mitigated. When methane volume fraction is 10%, the mouse injury is the most serious. Then the injury degree to the mouse decreases with the decrease of methane concentration because volume fraction 10% of methane is its chemical equivalent. At this point, the value of explosion peak pressure is the highest. It can be concluded that the greater the pressure is, the greater injury effect on the mouse is. According to mechanical and biological effects, the injury mechanism can be summarized as follows: explosion causes hydrodynamic change in animals, fragmentation effect in animals, implosion effect of gas on liquid contained organizations, inertia effect on animal body and inside pressure imbalance caused by the rapid change of external pressure, therefore all these effects lead to organ injury.

2.2.2 Mice injury tests with obstacles in pipeline

In order to enhance gas explosion pressure, a ring type obstacle is put in the pipeline, as marked in Fig.1. The obstacle blocking ratio is 60%. The mice are still placed away from the ignition source 2.05 m. The tests are done ten to twelve times. The experimental results and the mice’ vital signs are presented in Table 2. The explosion peak pressure value is 0.298 MPa. The lung micro-structure of normal mouse is shown in Fig.6. The lung micro-structure of the injuried mouse is shown in Fig.7.

Table 2 Mice injuries after explosion with obstacles in pipeline

Comparing the injury effects of the methane explosion with obstacles and that without obstacles at the same concentration shown in Table 1, it can be found that the injury effect of methane explosion on mouse is enhanced under obstacles condition. The reason is that, on the one hand, the presence of obstacles intensifies the strength of pressure field and turbulent field and promotes the combustion reaction, on the other hand, the obstacle makes the narrow flame front stretch to larger width after it passes through the obstacle. Furthermore, the flame front is divided into a plurality of continuous waves or zigzag flame surfaces, which makes the contact area of unburned gas increase and the flame propagation velocity accelerate. As a result, the turbulence effects are enhanced and the explosion pressure is increased.

Fig.6 Lung micro-structure of normal mouse

Fig.7 Lung micro-structure of injuried mouse

2.2.3 Mice injury tests at different numbers of explosions

The pipe is filled with methane-air mixed gas and the methane concentration is 8%, the mice are away from the ignition source 2.05 m. From Table 1, we known that the peak pressure is 0.135 MPa. Only the mouse in group 1 is used to do this test. The explosion numbers are 1, 2, 4 and 7. Table 3 shows the relation between the explosion number and the mice vital signs.

Table 3 Mice injury at different explosion numbers

It can be seen from Table 3 that the injury degree of mouse increases with the increase of the explosions.

3 Conclusions

1) With the increase of methane concentration, mouse injury degree gets serious first and then mitigated. When the methane volume fraction is 10%, the maximum explosion pressure is 0.264 MPa and the injury is the most serious. The higher the pressure is, the greater the death rate is. In coal mine underground roadway, the methane concentration should be strictly controlled and explosion suppression and protective measures should be taken.

2) The injury effect of methane explosion on mouse is enhanced under obstacles condition.When the methane volume fraction is 10%, the maximum explosion pressure is 0.298 MPa. In order to reduce accident impact, the obstacles in coal mine, such as trolley, control box, etc., should be avoided.

3) With the increase of explosions, the death pressure of mouse decreases. Therefore, it is necessary to prevent the occurrence of the second explosion in coal mine.

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氣體爆炸對白鼠殺傷作用的實驗研究

譚迎新， 王海賓， 任瑞娥

(中北大學(xué) 化工與環(huán)境工程學(xué)院， 山西 太原 030051)

通過實驗測試了管道式氣體爆炸沖擊波對置于管道內(nèi)的白鼠的殺傷作用， 當(dāng)甲烷體積分數(shù)為10%時， 爆炸產(chǎn)生的最大壓力為0.264 MPa， 白鼠受傷最嚴重。 將一些特制的障礙物置于管道可產(chǎn)生更強的沖擊波， 這有助于增強甲烷爆炸對白鼠的殺傷作用。 當(dāng)甲烷體積分數(shù)為10%時， 有障礙物條件下的最大爆炸壓力可達到0.298 MPa。 由此可知， 為減小煤礦中事故沖擊力， 應(yīng)盡量避免障礙物的存在； 隨爆炸次數(shù)增加， 白鼠致死壓力減小。

白鼠； 動物殺傷； 甲烷； 氣體爆炸

TAN Ying-xin， WANG Hai-bin， REN Rui-e. Experimental study on gas explosion to kill and injury mouse. Journal of Measurement Science and Instrumentation, 2015, 6(4)： 322-326.

10.3969/j.issn.1674-8042.2015.04.003

TAN Ying-xin (13934240901@163.com)

1674-8042(2015)04-0322-05 doi： 10.3969/j.issn.1674-8042.2015.04.003

Received date： 2015-08-09

CLD number： X932, TD712 Document code： A