Explosion of a gas cylinder in a fire. Why gas cylinders explode: main reasons and preventive measures. Foreign impurities in gas
Agree, the news that a gas cylinder exploded somewhere, which we, unfortunately, sometimes hear on TV or from friends, makes us think about our own safety. And there is no place for complacency that this will not happen to us in this situation.
The consequences that such an explosion and the fire caused by it lead to can be the most tragic, and not only for property, but also for the health and life of people nearby. We will help you understand why gas cylinders can explode and how, without sacrificing the convenience of their use, you can protect yourself from big troubles.
To do this, we conducted a study of the features of existing types of household gas vessels, analyzed the reasons why explosions occurred in a number of real cases, and studied the competent opinions of experienced users about this. The proposed article can be presented as a compilation of sets of rules, presented in an understandable form, that allow, in practice, the correct and safe use of gas in cylinders.
The indispensability of gas cylinders in everyday life can be confidently confirmed by a significant part of the Russian population.
For many people, the use of liquefied gas cylinders is not just an opportunity to have additional amenities in the country, but the only available option for gasifying their residential building
At the state level, Rostechnadzor has identified general problems with the use of gas vessels that you need to be aware of, as they are related to their safe use:
- outdated fleet - about 90% of all cylinders are not protected from overfilling during refueling;
- lack of clear government regulation in the field of circulation of cylinders on the market, which includes the presence of illegal refills;
- the need to improve and bring technical parameters to international standards.
In addition to knowing the general problems, to make it easier to imagine the reasons leading to an explosion and the conditions that can contribute to this, it will be useful to know what cylinders exist, understand the device, and understand some of the nuances of the physics of explosion and combustion of the mixture used in them.
Types of gas vessels
Depending on the area of application, the filler used and connection methods, they may differ both structurally and in the material from which the housing is made.
Heating or cooling the walls of the vessel
The propane-butane mixture, having a large expansion coefficient, greatly increases in volume even with a slight increase in its temperature.
The danger of increasing the pressure of the mixture on the walls of the flask also exists in a cylinder installed next to a heat source.
In addition to heating, a number of dangers are also fraught with the negative effects of negative temperatures. The first is an increase in the fragility of the metal. And secondly, it is necessary to remember forever that under no circumstances should a vessel that has been exposed to the cold for a long time be brought into a warm room. A sharp increase in the temperature of the hydrocarbon mixture is unsafe.
Impacts and falls of cylinders
Damage and ignition of a container with gas can be caused by sudden mechanical impacts on its walls, especially when the reservoir is in conditions of low or, conversely, extremely high temperatures.
When using a cylinder in abnormally cold conditions, the mechanical properties of the metal change - the impact strength of the steel decreases.
For this reason, a strong blow to the cylinder or its hard fall can damage the seal of the vessel and contribute to the release of gas, which, when mixed with oxygen and in contact with a spark, will lead to detonation of the gas-air mixture
In the second case, increasing the temperature and heating the gas contained in the flask, as was said, sharply increases its pressure, which, with additional shock effects on the vessel, can rupture it.
Foreign impurities in gas
The danger of explosion lurks when water and hydrogen sulfide enter a vessel with liquid gas. Their high content in the tank contributes to the appearance of delaminations and bulges on the inner metal surface of the shell.
Such vascular defects occur when there is 0.3% or more hydrogen sulfide in propane, and can be observed after only two years of using the cylinder.
Weld defect
Less common, but encountered, are problems associated with depressurization of gas vessels in the heat-affected zone.
If a weld is defective, a weakening of its working section may occur, stress concentration and, as a result, opening of the longitudinal or circumferential seam
The overall integrity of the shell may be preserved when a defective weld ruptures.
Scenarios for the consequences of a cylinder explosion
The above reasons for the explosion or fire of gas vessels can, in various ways, provoke the following dangerous scenarios.
Cylinder rupture and flame emission
Explosion of a cylinder and ignition of propane-butane are dangerous due to the following factors:
- a column of strong flame, quickly increasing the area of the fire;
- high temperature of fire at the source of the explosion;
- toxicity of combustion products.
Damage can also occur from suffocation, due to a significant decrease in oxygen with a sharp concentration of harmful gases.
Conducted studies have shown that the sealing of a 50-liter gas vessel with liquefied gas in a fire is broken in less than 5 minutes. As a result, a fire-flash with the release of a “fireball” reaching a diameter of 10 m
Typically, a vessel ruptures along its side.
Secondary damaging effects from the explosion
Secondary, but no less serious, damaging consequences of a cylinder explosion are:
- valve separation;
- impact of a compression wave or shock wave;
- damage from fragments of shell elements.
Fragments from the cylinder and its detached elements can fly very far, causing damage within a radius of up to 250 m, and rise to a height of thirty meters.
Danger of gas leakage
The danger of propane leaking from a damaged container is that an explosive concentration of a mixture of hydrocarbon and oxygen is created very quickly and in large volumes in the room - much faster than with leaks of liquid flammable substances.
A strong leak of the mixture from a flask or faulty shut-off valve can be detected by smell or hearing - the sound is similar to what we hear when a balloon is quickly deflated.
If you suspect a gas leak or in order to control its absence, it will be enough to apply a soap solution to the cylinder with a sponge and determine the location of the depressurization by the bubbles that form
If there is a gas leak, then it is necessary to cover the leakage area with a wet rag, carefully take the vessel outside and call the gas workers.
Since 2016, technical regulations have provided for the mandatory installation of gas alarms in new houses. For previously built housing, this standard is advisory in nature, but the benefits of this device, especially in houses that use bottled gas, are undoubted.
The fact is that the density of the hydrocarbon mixture is greater than the density of air. If the sealing of the flask, shut-off equipment or connecting hose is broken, gas begins to accumulate at the bottom, and its odor may not be immediately detectable. This is why a propane mixture released into the air from a damaged gas cylinder often explodes in houses from any spark without being noticed.
Basics of safe cylinder handling
Before installing the cylinder and
Only certified cylinders supplied by specialized organizations, having a paper passport for all cycles of operation and appropriate markings applied by impact stamping will be used.
The main technical requirements that must be observed when operating cylinders include:
- All cylinders, with the exception of one (five-liter for connecting to a gas stove) must be installed in outbuildings outside buildings and at a distance no closer than 5 m from the entrance to them.
- Avoid storing cylinders in living rooms, basements and attics.
- Do not place cylinders closer than 1 m from heating devices and 5 m from open fire.
Obvious, but often forgotten safety measures when using vessels with gas include and must be strictly followed:
- Do not bring a lit match or lighter to the cylinder to check for gas leaks.
- Strictly exclude the use of open flames to heat the gearbox or valve. For these purposes, only hot water can be used.
- If gas is detected in the room, do not turn on any electrical appliances, including lights, or turn them off. The temperature of a spark in a socket or switch can reach up to a thousand degrees.
- Do not try to repair shut-off valves and other structural elements of the cylinder yourself.
In addition, you must strictly follow the time frame for using the cylinders prescribed by the manufacturer. Vessels manufactured before December 2014 can be used for 40 years.
In the absence of information about the permitted period of use of gas cylinders produced after this date and without accompanying documentation, Rostechnadzor recommends taking 20 years as the shelf life of the cylinder.
It is strictly forbidden to carry gas cylinders using the valve as a holding device. This may cause depressurization or breakage of the locking device.
A safe alternative to steel gas cylinders are more modern polymer-composite vessels - Eurocylinders. Their flasks are protected by a plastic casing and do not accumulate static electricity. The explosion safety of composite cylinders is ensured by equipping them with new generation safety devices - a fusible link and a non-return valve for releasing high pressure.
Conclusions and useful video on the topic
The reasons for explosions of gas cylinders using examples of real facts, and what can and cannot be done when using them:
How to properly use gas cylinders at home, and what requirements they must meet:
With all the existing risk factors that accompany the operation of gas equipment, there is no reason to succumb to fear and refuse the convenience of using them in everyday life.
Theoretical knowledge of the causes and conditions accompanying the explosion of household gas cylinders is intended to help overcome such fear. And compliance with the given set of standards for their safe use will serve as reliable insurance against the serious consequences of a gas explosion and fire.
If you have valuable information that can complement our material, please share it with other site visitors - leave your comments in the block below. There you can ask questions about the topic of the article.
Experts continue to find out the cause of the tragedy at the children's tent camp
Investigators continue to find out. Schoolchildren who went on a camping trip suffered from the explosion of a gas cylinder, which they took with them for cooking.
A consultant and technologist from a specialized store told MK about the conditions under which depressurization can occur in a gas cylinder and an explosion can occur. And also how hunters have fun buying whole boxes of them.
Photo courtesy of the press service of the Ministry of Emergency Situations
It is already known that a gas cylinder with a volume of 530 milliliters exploded during a camping trip. These are used by tourists and fishermen to cook food on gas burners.
-Are these small 230 and 530 gram gas cylinders produced in Korea?
They used to come from Korea. They were produced there under the Pathfinder brand. As soon as the exchange rate of the dollar and euro rose, one of the enterprises in Novosibirsk began producing them under the same brand. I can’t say more precisely.
How could the can ignite, since it contains a very high degree of protection? The product is certified, there is a GOST, the bottle itself, as they say, is sealed, like a “lunar rover”.
Its operating temperature is from -20 °C to +35 °C. Or he was in the open sun for a long time, and the maximum permissible pressure was exceeded. Or there was exposure to open fire.
There was a message that the tragedy happened during the hike. An autonomous group of children left the camp along a certain route. An eyewitness said they were sitting by the fire when they heard a loud bang. Some children's hair was severely singed and one girl was carried in her arms to the ambulance. She is now in intensive care with 20-25% burns to her body.
The guys could run, play, and someone could accidentally push or move the cylinder towards the fire. The other thing is unclear. Why did they need to light a fire if they took a gas cylinder with them for cooking? Probably making a fire was part of the curriculum. Children are taught to make a fire with one or two matches. But I know one thing: under the right operating conditions, gas cylinders do not spontaneously explode. But our people love to have fun in nature. Many people, after using up the gas in the cylinder, throw it into the fire to get a big “boom.” Even an empty cylinder explodes with a loud bang. Our hunters take whole boxes of these cylinders, they are cheap. Then they have fun in the evening, lying “in ambush”, even throwing full gas cylinders into the fire. Or they shoot out cylinders from guns. Surprisingly, there have been no accidents so far.
A source in law enforcement agencies said that, according to a preliminary version, the cause of the explosion could have been the depressurization of a cylinder, which was refilled using a makeshift method. Is this possible or is it still a one-time use?
They can refill, although this is strictly prohibited. They do this to save money. There are craftsmen who take appropriate orders. To do this, they buy special adapters and fill them from a large gas cylinder. A small factory cylinder weighs 230 grams; those who fill cylinders, as they say, for themselves, and know that they will not keep them under the scorching rays of the sun, pump more gas into them - 250 - 260 grams. Accordingly, this is an additional load on the walls of the metal vessel. And even with short exposure to sunlight, rupture is possible. Therefore, those who refill cylinders at home place them on sensitive scales. Here it is very important not to upload too much; you need clear control.
-You still need to choose the right gas composition.
It's already been selected. Take a 50-liter cylinder and fill it from it. There are three base hydrocarbon gases mixed there: 30% propane, 11% butane and 56% isobutane.
Gas cylinders are not the safest products, but in some cases they are the only possible way to obtain heating, cook food, etc.
Although modern polymer composite cylinders are much safer than outdated metal ones, many people are still wary of them. It must be said that their fears are not unfounded. Gas cylinders do sometimes explode, although much less frequently than it might seem.
The explosion of a gas cylinder in a car or apartment is an emergency that can lead to very serious consequences, especially if there are other products near the exploded vessel. Such an emergency can lead not only to the destruction of property, but also to human casualties. Therefore, if you have to deal with gas cylinders, you should know why this happens.
The main reason for such incidents is violation of the rules for storing and operating cylinders. If the valve is not closed well enough, gas begins to escape and fill the room. Any accidental spark leads to an explosion and fire in the room.
Another option is to bring the cylinder in from the cold. If you bring a container from outside where it has been at a low temperature for a long time, a sudden change in temperature will cause the gas to expand and increase the risk of leakage.
Therefore, under no circumstances should you place a gas cylinder near a heat source. The build-up of pressure inside the balloon, which is created by the expanding gas, increases the risk of rupture of the vessel.
Microcracks or corrosion of the metal cylinder can form over time. Such damage may not be noticeable from the outside, but from the inside it creates a great danger.
This is another reason not to bring the cylinder from the cold into a very warm room - condensation forms on its surface, which also increases the risk of corrosion and a subsequent accident. If the cylinder is not made of metal, there is no such danger, but this does not mean that the gas cylinder can be handled carelessly.
Dependence of explosion on temperature
Winter is the most dangerous time of year for gas cylinders. As mentioned above, sudden temperature changes are one of the main enemies of such containers. The gas, which has the strongest destructive power, almost as good as TNT, can destroy an entire apartment, and the explosion can put people's lives in great danger. Not only the residents of the apartment, but also their neighbors and even just passersby, who at the time of the incident will be in close proximity to the explosion, can be exposed to danger.
If the cylinder was left in the cold, the gas in it is in a liquefied state. If you bring the cylinder into the heat immediately, the gas it contains will quickly turn into a gaseous state and expand greatly. The increased pressure can rupture the container, and since the gas ignites easily, it may not even require additional contact with the flame.
The problem with metal cylinders is that it is extremely difficult to control the gas level in them. An explosion is also caused by the fact that the ratio of gas in the cylinder does not meet the standards. An incorrectly filled cylinder, when exposed to a higher temperature, will certainly be ruptured by gas, which, when expanding, will simply have nowhere to go.
But the simplest and one of the most common causes of explosions is an insufficiently closed valve. The gas is heavier than air - when it comes out of the cylinder, it accumulates at the bottom near the floor, so at human height the leak may be detected too late. Even the smallest spark, static electricity or the contact of two solid objects can cause it to ignite.
How often do cylinders explode?
Every year in our country there are about three hundred accidents caused by the explosion of gas containers. According to statistics, such incidents occur much more often in the cold season due to refueling at low temperatures and subsequent transfer of the cylinder to a warm room.
The drop itself is not so dangerous. The cylinders can withstand a fairly wide range of temperatures - from minus 40 to plus 50 degrees Celsius. The temperature difference is only a “trigger” of an emergency situation.
Among the most common causes of explosions, statistics highlight the following:
- The cylinders did not undergo inspection (testing and pressure testing).
- Refueling at gas stations that evaluate the filling of a cylinder not by the pressure in it, but by the weight of the container being filled.
- Placing gas cylinders in residential premises or other premises in common use.
Consequences of a gas cylinder explosion
The consequences of an explosion in a house can include significant damage and destruction of property, as well as harm to human health and even death. The explosion also causes a fire, which increases its destructive power and makes such an incident even more dangerous for people.
During an explosion in an apartment, as a rule, windows and doors are knocked out, walls and partitions, including load-bearing structures, can be destroyed. Access to oxygen increases the area of fire.
How to avoid an explosion
There are two ways to avoid such an incident as a gas cylinder explosion:
- Follow the safety regulations and operation of gas cylinders.
- Refuse metal containers in favor of modern composite-polymer products.
Composite polymer cylinders are not afraid of corrosion, and the walls of the container can become gas permeable as the temperature rises. In this case, the gas slowly leaves the cylinder and dissipates, without reaching such a concentration that a fire occurs. But the main thing is extreme caution when handling gas cylinders.