China News Service, Taiyuan, July 10 (Reporter Lu Qiguo) Recently, gas explosion accidents occurred in many places in China, causing great losses to the safety of people's lives and property.
On the issue of how to use gas safely, professionals pointed out that the key is "leak prevention".
In June this year, gas explosions occurred in Changsha City, Hunan Province, Hohhot City, Inner Mongolia Autonomous Region, Tai'an City, Shandong Province, Baodi District, Tianjin City, Tonghua City, Jilin Province, Sanhe City, Hebei Province, and Shenyang City, Liaoning Province. people are injured.
The common topic of gas safety has once again attracted the attention of all sectors of society.
On July 10, Ma Yin, a staff member of Huaxin Gas Group City Gas Company, and Wang Yong, a safety officer of Shanxi Jinzhong Ningxin Liquefied Gas Co., Ltd., were interviewed by reporters from Chinanews.com, respectively, on the matters needing attention in the safe use of pipeline natural gas and liquefied petroleum gas. to interpret.
The staff of Huaxin Gas Group City Gas Company demonstrated the connection method of natural gas pipeline and self-closing valve.
Photo by Wang Huilin
Reporter: Why did the gas explosion accident cause great loss of life and property?
Ma Yin: The main component of natural gas is methane.
According to statistics, the energy released when 1 cubic meter of methane is completely burned is about 55.5 MJ, while the energy released after 1 kg of TNT explosive explodes is 4.2 MJ.
Therefore, once natural gas explodes, its power is no less than that of TNT explosives.
Moreover, the gas explosion is often only 0.5 seconds from the beginning to the end, and the parties have no time to respond at all. This is what we often call "flash explosion".
Wang Yong: The energy of complete combustion of 1 kg of liquefied petroleum gas is approximately equal to the energy released by the explosion of 10 kg of TNT explosives.
The explosion limit of natural gas is 5%-15%, and the explosion limit of liquefied petroleum gas is 1.5%-9.5%.
Comparing the two, it is not difficult to see that LPG is more likely to explode.
The service life of stainless steel corrugated hose is 8-10 years, and the safety is obviously better than that of ordinary rubber hose.
Photo by Wang Huilin
Reporter: Whether pipeline natural gas or liquefied petroleum gas, a hose is required to connect to the stove.
Excuse me, how do end users choose gas hoses?
Ma Yin: In the past, most end-users used rubber hoses. The disadvantage is that it is easy to loosen, fall off, break, and age. Therefore, relevant functional departments are promoting the use of metal hoses, and stainless steel corrugated hoses are more common.
This kind of hose has the characteristics of high temperature resistance, good flexibility, etc., and it uses a threaded port, so there is no gas leakage under normal circumstances.
Wang Yong: Ordinary rubber hose is the "favorite" of mice.
The stainless steel corrugated hose can effectively prevent the hidden danger of mice gnawing.
Reporter: Is there any regulation on the length of the gas hose?
Ma Yin: According to the "Code for Design of Urban Gas" (GB50028), when the gas hose is connected to a household gas appliance, its length should not exceed 2 meters, and there should be no interface in the middle.
Reporter: How often should the gas hose be replaced?
Ma Yin: The general service life of gas rubber hose is 18 months, and the service life of stainless steel corrugated hose is 8-10 years.
Reporter: What is the function of the gas self-closing valve?
Ma Yin: The gas self-closing valve is installed on the low-pressure gas system pipeline. When the gas supply pressure of the pipeline is under-pressure or over-pressure, it can be closed automatically without electricity or other external power and needs to be reset and opened manually to prevent gas leakage. situation arises.
Therefore, it is very important to install a self-closing valve on the gas pipeline.
Wang Yong: According to the new "Liquefied Gas Cylinder Valve" (GB/T7512-20178), for LPG cylinders produced after 2019, the valve outlet structure must have a self-closing device.
This self-closing device can only be opened automatically after it is connected to the pressure reducing valve; if the pressure reducing valve is removed, the valve will automatically close.
When the gas supply pressure in the pipeline is underpressure or overpressure, the gas self-closing valve can be automatically closed without electricity or other external power.
Photo by Wang Huilin
Reporter: Is it important to install a flammable gas alarm in the kitchen?
Where should it be installed?
Ma Yin: It is very important to install a combustible gas alarm in the kitchen, which can issue a gas leakage alarm in time.
Because the density of natural gas is less than that of air, and it floats upward after leakage, ordinary pipeline natural gas users can install the combustible gas alarm on the top of the kitchen.
Wang Yong: The density of liquefied petroleum gas is greater than that of air. After a leak occurs, it will drill wherever it is lower.
Therefore, users of liquefied petroleum gas should install the flammable gas alarm at a distance of about 30 cm from the ground.
Reporter: What is the danger of dumping the liquefied gas residue?
Wang Yong: Absolutely not.
In daily life, some users dump the liquefied petroleum gas residue into the sewers by themselves, which is easy to cause the liquefied gas to remain in the sewers for a long time. In case someone throws a cigarette butt into the well, or encounters sparks in the exhaust of the car, it will cause an explosion.
Therefore, the dumping of liquefied petroleum gas residue must be strictly followed by professionals in designated places.
Reporter: Some users turn the tank upside down or lay the tank horizontally in order to use up the LPG in the cylinder. What is the harm of this behavior?
Wang Yong: Extremely dangerous.
When the cylinder is used upside down or lying down, it is easy to cause the outflow of liquid gas, which will expand more than 250 times in an instant, which will cause an explosion.
Reporter: Why should residents pay attention to ventilation when using gas?
Ma Yin: When gas burns, it needs oxygen in the air to help it burn.
If the indoor ventilation is poor, the oxygen content in the air will gradually decrease, and the lack of oxygen will lead to incomplete combustion of the gas and produce a large amount of harmful gases such as carbon monoxide, which will cause people to be poisoned or suffocated due to lack of oxygen.
Therefore, during the use of gas, windows should be opened as much as possible for ventilation, especially in winter.
LPG users can install the flammable gas alarm at a distance of about 30 cm from the ground.
Photo by Wang Huilin
Reporter: If there is a gas leak, what should the end user do?
Ma Yin: Close the valve quickly and open the doors and windows for ventilation.
At the same time, it is absolutely forbidden to use open flames, switch on and off any electrical appliances, and use no means of communication. People inside the building must be evacuated to a safe area as soon as possible.
In addition, when gas leaks are found in winter, residents wearing sweaters and nylon clothes should remember not to run quickly, so as not to generate static sparks and cause gas explosions.
Reporter: Is it important for end users to close the valve after using gas?
Ma Yin: Even if a self-closing valve is installed, it cannot completely replace the closing valve.
Pipeline natural gas users should pay attention to closing the valve in front of the gas pipeline stove; if the gas is not used for a long time, the valve in front of the meter should also be closed.
Wang Yong: LPG users should develop a good habit of closing the main valve above the cylinder easily.
Reporter: Is it terrible for LPG cylinders to breathe fire?
How should it be handled?
Wang Yong: The most terrifying thing about gas leakage is that it only leaks and does not catch fire. In this case, an explosion may occur at any time.
If the liquefied petroleum gas cylinder valve has spewed fire, it means that it has been burning steadily, and the danger is less.
If the fire breathing time is not long and the valve is not damaged, you can use a fire blanket or wet towel to protect your hands, and tighten the valve directly to the right to put out the fire; The gas continued to leak after the fire was extinguished. In this case, it is best to call 119 for help.
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