Incorrect operation of heating devices

In the mountains, where they often have to trek through treeless areas, tourists are forced to use flammable gases, kerosene or gasoline as fuel.

Liquefied gases

Recently, gas kitchens have been increasingly used as heating appliances. The following types of liquefied gases are used as fuel:

—technical propane, consisting mainly of propane and propylene (average calorie content 11050 kcal/kg, maximum flame temperature about 2200°C);

—technical butane, consisting of butane and butylene (average calorie content 10930 kcal/kg, maximum flame temperature about 2130°C);

— a mixture of technical propane and technical butane.

In mountain travel, as a rule, only technical propane is used, which evaporates well over a wide temperature range (from -35 to +45°C). At subzero temperatures, typical for high-altitude travel, technical butane evaporates poorly due to a decrease in pressure.

Of course, using gas heating appliances if the rules are followed does not pose any danger. However, disregard for these rules can lead to cases of serious injury.

The fire hazard of liquefied gases is determined by the high temperature of the flame, the release of a significant amount of heat, and low flammability and explosion limits.

Combustion of liquefied gases requires a certain amount of air. Both with insufficient concentration of these gases in the mixture with air and with excessive concentration, combustion of the gas-air mixture is impossible.

In the event of a gas leak, as its concentration increases, the gas-air mixture reaches a lower ignition threshold. However, this mixture, even at the most dangerous concentration (at normal ambient temperature), does not ignite on its own. But it is enough to warm it up with some heat source with a temperature exceeding the ignition temperature of the gas, and the mixture will flare up and uncontrolled combustion of liquefied gas (fire) will occur. If a gas-air mixture forms in a confined space, an explosion will occur.

The flammability (explosive) limits of the gas-air mixture are shown in the following table.

Table 5

The ignition temperature of these gases is only 490-580°C, that is, the slightest source of open flame, an electric or mechanical spark, is enough to ignite. The maximum explosion pressure is 8.58 kgm/cm² or 8580 kes/m³, and many building structures cannot withstand such pressure.

In addition to direct burns and injuries, fire and explosion have a serious psychological impact on others, causing panic, which can even lead to death due to slipping on steep areas or falling into glacier crevasses.

In order to prevent uncontrolled ignition (explosion) of the gas-air mixture or leakage of liquefied gas, it is necessary:

—prevent the possibility of ignition of the mixture;

— find out the location and cause of the gas leak;

— stop gas leakage;

— remove people from the danger zone;

—Take measures to disperse the gas if the leak occurs inside a tent, snow hut or cave.

In order to easily detect the leak of flammable gases, an odorant is added to them - a substance that gives the gas a specific unpleasant odor. This smell is clearly felt when the gas concentration in the air is only 0.5%, that is, long before the formation of a fire-hazardous flammable mixture. A significant gas leak can be detected by sound. Evaporation of the liquid phase is accompanied by heat consumption, that is, a decrease in temperature. This causes cooling of the pipeline or cylinder body, condensation and freezing of moisture on them with the formation of a snow “coat”, the appearance of which is one of the signs of a gas leak.

To prevent cases of gas leakage, it is necessary to reduce the number of pipeline connections on threads and flanges to a minimum (if possible, replacing them with welded connections), use high-quality oil-gasoline-resistant packing in the stuffing box seals and gaskets in flange connections, regularly monitor the tightness of the entire system, especially after long-term transportation, a fall of a participant carrying a gas stove or cylinders, or pulling out backpacks using a rope on steep slopes. rocky and ice areas.

Combustible gases: butane, propane, butylene, propylene, ethane and ethylene are very slightly soluble in the blood and therefore have almost no toxic (poisonous) effect. Their effect on the human body lies primarily in the fact that when they enter the air and mix with it, they displace other gases, including oxygen, reducing the content of the latter (in the case of an open space) in the air or reducing its partial pressure (in the case of a closed space). In both the first and second cases, a person will experience oxygen starvation. Thus, two minutes of inhaling air with a 10% content of flammable gases causes dizziness. At significant concentrations of gases, a person can die from suffocation.

In addition to the above, propylene and butylene have a narcotic effect. For example, when inhaling air containing 15% propylene, loss of consciousness occurs after 30 minutes, with 24% - after 3 minutes, and with 35% - after 20 seconds.

For domestic needs, technical propane and butane, as well as their mixture, are used. These mixtures already have a certain toxicity, since they contain a small amount of hydrogen sulfide, a gas that has a negative effect on the nervous system. If the air contains 0.2 mg of hydrogen sulfide per liter, then after a few hours a person will develop symptoms of mild poisoning; at 0.3 mg/l, severe irritation of the eyes, mucous membrane of the nose and throat appears in 5-10 minutes, and at a concentration of more than 1.5 mg/l, rapid fatal poisoning can occur.

All these gases are heavier than air and, when leaking, spread along the ground. Therefore, it is prohibited to leave cylinders and a gas kitchen overnight in tents, snow huts, that is, in those places where tourists sleep.

When gas is incompletely burned, carbon monoxide is formed - CO, which is a potent poisonous gas. The nature of the effect of carbon monoxide on the human body at various concentrations in the air is shown in the table below.

Table 6

In case of carbon monoxide poisoning, the victim should be taken out into fresh air as soon as possible, eliminate everything that interferes with breathing, take measures to warm up (insulate a sleeping bag, a heating pad, if the victim is conscious - hot strong tea or coffee), give ammonia to sniff every 1-2 minutes, and if breathing is weak and shallow or stops, perform artificial respiration.

Since the air contains up to 78% nitrogen, the combustion products of liquefied gases also contain carbon dioxide - CC>2, which has a narcotic effect and can cause irritation of the skin and mucous surfaces;

In connection with the above, all flammable gases considered are included in the list of substances harmful to the human body.

To prevent the release of excess amounts of carbon monoxide during gas combustion, the pressure regime should be strictly monitored: do not allow the flame to separate from the burner nozzle or allow the flame to partially disappear into the burner. The position of the nozzle, the displacement of the axes of the nozzle and the burner mixer must not be disturbed. When changing the design of the plate, in no case should you arbitrarily change the diameter of the nozzle and its opening angle.

One of the most dangerous violations of safety rules is overfilling liquefied gas cylinders beyond established standards. The fact is that when the temperature increases by the same amount, propane expands 16 times more than water, and 3.2 times more than kerosene (butane, respectively, 11 and 2.2 times). Calculated data say that the pressure in a cylinder filled with liquefied gas increases by an average of 7 kgf/cm² when the gas is heated at the gas station. Thus, a temperature difference from +20 to +35°C leads to an increase in pressure by 105 kgf/cm², which will inevitably cause inflation and then rupture of the cylinder, the material of which has a tensile strength of only 38–40 kgf/cm² (that is, approximately designed for a 2.5-fold reserve compared to? working pressure not exceeding 16 kgf/cm²).

Therefore, the cylinders are not filled completely, but with some volume left for liquefied gas vapors. In the presence of such an air cushion (vapor phase), the expansion of liquefied gases (liquid phase) will not cause stresses dangerous to the walls of the cylinder, but will only lead to a decrease in the volume (compression) of this cushion.

The degree of filling of cylinders depends on the density of the liquefied gas and the difference in its temperatures during filling and during subsequent use (storage). Existing safety rules determine the maximum filling of the cylinder depending on the difference between the specified temperatures within 80-90%. from its capacity. The standards for filling cylinders with a specific type of liquefied gas are:

Table 7

When a cylinder ruptures, even if the gas-air mixture does not ignite, the liquefied gas, falling on surrounding objects, intensively evaporates and cools them. The boiling point of propane is -42°C. Therefore, the contact of the liquid phase on open areas of the human body causes frostbite of the skin, which in its results is similar to a burn: blisters form, the blisters burst, and wound healing continues for a long time.

It is recommended to transport liquefied gas cylinders in a vertical position, since in the event of accidental impacts, dynamic loads are absorbed mainly not by the cylinder body, but by its shoe, which evenly transfers these loads to the body in all directions.

Liquefied gases can dissolve a certain amount of water. In the liquid phase, the water content is significantly less than in the vapor phase. For example, at a temperature of +10°C, the vapor phase contains 7.1 times more water than the liquid phase. As the temperature decreases, this ratio increases even more.

When using gas in cold weather, the pressure inside the cylinder decreases. Since the decrease in pressure is associated with the extraction of heat, when the liquefied gas evaporates, the temperature both inside the cylinder and at the outlet of the pressure regulator may become lower than the ambient temperature. In this case, in the area where the vapor phase is located inside the cylinder (usually in the area where the regulator is located), as well as on the outside of the regulator in the area where the liquefied gas evaporates, partial condensation of vapor occurs, depositing on the regulator in the form of ice. Subsequently, when the pressure regulator operates under such conditions, ice crystals grow until the throttle device becomes clogged and the regulator ceases to function normally. This leads to temporary failure of the installation due to interruption of the gas supply.

A measure to prevent this phenomenon should be to carefully remove all traces of moisture from the cylinder before filling it with liquefied gas. Under no circumstances should a cylinder covered with ice be heated with heat sources (primus stove, alcohol lamp, fire, etc.). A sharp increase in pressure, as well as local overheating of the metal, can lead to rupture of the cylinder.

Petrol

Tourists, as a rule, stock up on gasoline from oncoming drivers, not paying much attention to the fact that this gasoline is leaded, that is, it contains 0.1-0.3% tetraethyl lead. Gasoline itself, and even more so tetraethyl lead, are generally toxic poisons and can cause severe poisoning of the body.

Tetraethyl lead (TEL) and gasoline evaporate already at a temperature of +16-18°C. Therefore, the main route of entry of poisons into the body is the lungs. However, having the ability to dissolve fats well, TES and gasoline can penetrate the body through skin, even without scratches. When charging Primus stoves from a canister through a straw, gasoline may enter the mouth at the moment of suction. Poisoning due to frequent use of this technique (during repeated duty) by the same person is most typical for ski trips. In winter, water for cooking is obtained by melting snow. Therefore, to obtain hot dishes, the amount of gasoline consumed doubles compared to summer conditions. Due to the small capacity of the fuel tank for kerosene stoves of the “Tourist” type, the number of refuelings for such stoves also doubles. Consequently, the possibility of gasoline entering the human body increases.

Prolonged mishandling of gasoline (even unleaded) under the influence of frequently repeated small doses can cause poisoning. Since gasoline is a general toxic poison, it mainly causes disruption of the central nervous system. With small doses of poison, the disease develops slowly. There is increasing severe weakness, fatigue, lethargy, loss of appetite, sleep disturbance is especially characteristic. There is often an obsessive sensation of a foreign body in the mouth (for example, a hair), and severe itching of the skin.

In acute poisoning, mental agitation, unsteady (“drunk”) gait, violent laughter, dizziness, and sometimes vomiting are observed.

To prevent possible poisoning, food preparation must be done outside the tent (in a separate hole dug in the snow, in the vestibule between the tents), storage of canisters of gasoline should also be organized outside the tent (gasoline vapors are heavier than air, and therefore they, concentrating in the lower layer of still air in the tent, will freely penetrate into the body of a sleeping tourist). When charging a kerosene stove, you must use either a funnel, or use a small rubber bulb to suck in gasoline (when using a straw). Do not suck gasoline into your mouth under any circumstances. You should be aware that sometimes gasoline penetrates the lungs and causes direct damage to the lung tissue. In such cases, after 3-6 hours the temperature rises sharply, pain in the side and cough appear, exactly reproducing the symptoms of lobar pneumonia. With timely measures taken (rest, warmth, cardiovascular medications, gastric lavage with a 2% soda solution in an amount of up to 5-10 liters), poisoning goes away within 4-5 days.

In addition to the above, gasoline also has a number of other dangers listed in the previous section “Liquefied gases”. This is a fire and explosion hazard, the content of carbon monoxide (CO) and carbon dioxide (CO₂) in combustion products.