Myth of nichrome pests
Although winter is over, scary stories about open spiral spirals are quite popular. And they burn oxygen, and emit everything and air dry ... Only fearless sellers from home appliances stores stand between them and humanity!
Of course, everything is not so scary. Not at all, to be honest. Consider the three components of the myth in more detail.
We should start with the fact that oxygen can be burned, from a chemical point of view, only by halogens, and even then not by everyone. The remaining elements themselves are burning in oxygen.
It must be assumed that this statement means that dust and the spiral itself burn in the open spiral, thereby reducing the amount of oxygen in the air. Let's check the calculations.
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In the beginning we will determine how much oxygen the middle room contains. The volume of the middle room is 3 * 3 * 2.5 = 22.5 m 3 . To ensure that all nuances are taken into account, for example, a suspended ceiling, a wardrobe, a sofa, a person, etc., we will assume that it is the air in the room that occupies two thirds of the volume - 15 m 3 .
This is 15,000 liters.
Of these, oxygen is approximately 15,000 liters * 0.21 = 3,150 liters.
This is 140.625 mol or 4501.35 g.
The amount of this is much more significant than it seems. Most people do not have any physical understanding of the meaning of this quantity. What should be burned to use it?
Of course, all the oxygen is overkill. For a tangible effect, the concentration should fall somewhere up to 14%, that is, you need to spend "just something" 1700 g of oxygen. If you burn dust, you need about half a kilogram, if you consider it to be pure carbon.
Thus, it turns out that “burning out” a heater with a significant amount of oxygen in a room is not a trivial task. We must constantly pour on it all the garbage.
Highlight does not exactly highlight. Nichrome cannot emit carbon monoxide, except in some exotic experiments. But maybe it burns dust, which, when burned, releases this very gas?
MPC CO c is 20 mg / m 3 . But this is the MPC, some significant consequences for a person begin with the content of 0.019% when inhaled for six hours. For our average room it is 285 liters or 380 g. If we assume that we burn pure carbon and the CO output is 100%, then we will have to burn 153 g. This is about a glass of dust.
Also not a realistic situation. Even if we reduce it 20 times, we get about a tablespoon of dust. It is difficult to imagine a situation in which so much garbage gets into the heater, and not just into the heater namely on the spiral.
Suppose a heater stood in a forgotten tomb and the dust covered it for centuries. The spiral is packed with dust and the necessary mass has gathered. Let us return to the CO exit in the combustion process. In the absence of another source, you can see data on the combustion of coal. In the worst cases, CO can be about five percent of the combustion products.
As we can see, even our silent killer cannot really even highlight carbon monoxide.
Here, unfortunately, is true. But any air heaters dry the air.
This happens because of the laws of physics. The relative humidity of the air is critical for the human body. It is called relative because it shows not only how much water is in the air, but how much water is in it from the possible maximum. This figure is much more effective than the absolute. In fact, it shows how quickly water will evaporate in such conditions.
The maximum possible mass fraction of water vapor in the air is proportional to temperature. The hotter the air, the more water it can contain. Here comes into effect the heater.
For example, 1 m 3 of air contained 1 g of water, a possible maximum content of 2 g, and a relative humidity of 50%. The heater heated the air, the water in it was still 1 g, the limit of the water content increased to 3 g, so the relative humidity dropped to 33.3%. The air has become dry, the person has a sore throat, and the cat starts to sparkle when stroking.
Kota, by the way, can be considered a good indicator of humidity. Static electricity begins to be produced by a cat at a humidity of no more than 45%, for a person a range of 40% -60% is considered comfortable.
Unfortunately, the use of cats of different models as a sensor in the circuits of automation is unpromising due to their active resistance.
Oddly enough, open coil heaters can actually cause you to feel unwell. Only thing is not at all in burnt oxygen.
Despite all the above calculations, some strange dirty trick can get on the spiral, the smoke from which will cause an allergic reaction or even poisoning. But in this respect, the usual stove chances to cause problems no less.
Unfortunately, an open coil in a household heater with a 90% probability indicates that this product is of extremely poor quality. A good heating element is quite expensive, and if you decide to save on it, then the rest is not up to standard.
The case of such a heater will be designed to work in ideal conditions - no more than a couple of hours without interruption and at a distance of a meter from any object. As a result, it will be very hot in the real world. What aromas will emit secondary plastic body is impossible to predict.
Airflow device presents its surprises. The fan of such a device will also match the quality. Although it seems that in the fan, there certainly cannot be any threat to health, this is not so. A motor, especially poorly manufactured and unbalanced, is a source of vibrations and noise, perhaps even infra-sound and ultrasound. Both factors may well cause headaches.
All conventional arguments against open spirals are just a myth, generated not by illiteracy or marketing. Heaters with an open helix and in fact can damage health, these cases are quite rare and require confluence of rather strange circumstances.
If you intend to use such a heater in an average apartment, where there are no invasions of insects and dust storms, then you will not have any problems. Provided that the device is made of high quality, of course.
Heaters with an open coil are more fire hazardous and can cause burns, but do not cause oxygen starvation and do not emit carbon monoxide. The difference in price between them and more sophisticated models can be several thousand rubles.
The cold Russian spring and the optimism of public utilities are likely to force us to use the heater more than once in the near future. Someone wants a disposable device for a rented apartment, the safety of a child is important to someone, aesthetics is important to someone. If you suddenly need to buy a heater, evaluate the ratio of ease of use and price, and do not believe the scary stories of sales assistants.
Of course, everything is not so scary. Not at all, to be honest. Consider the three components of the myth in more detail.
Burn oxygen
We should start with the fact that oxygen can be burned, from a chemical point of view, only by halogens, and even then not by everyone. The remaining elements themselves are burning in oxygen.
It must be assumed that this statement means that dust and the spiral itself burn in the open spiral, thereby reducing the amount of oxygen in the air. Let's check the calculations.
')
In the beginning we will determine how much oxygen the middle room contains. The volume of the middle room is 3 * 3 * 2.5 = 22.5 m 3 . To ensure that all nuances are taken into account, for example, a suspended ceiling, a wardrobe, a sofa, a person, etc., we will assume that it is the air in the room that occupies two thirds of the volume - 15 m 3 .
This is 15,000 liters.
Of these, oxygen is approximately 15,000 liters * 0.21 = 3,150 liters.
This is 140.625 mol or 4501.35 g.
The amount of this is much more significant than it seems. Most people do not have any physical understanding of the meaning of this quantity. What should be burned to use it?
- Nichrome (an alloy from which spirals are usually made) ~ 10 kg. To get this amount you need to burn without the rest of the spiral of hundreds of heaters.
- Coal (pure carbon) ~ 1.687 kg.
- Firewood ~ 6 kg, excluding own oxygen
- Galoshes - at least 3 pieces and maybe all 4 (with a pair weight of 700 g)
- Giordano Bruno - about 0.5 J. B.Why so much?Galoshes consist of rubber, almost do not contain oxygen, water contains trace amounts, so they burn almost 100%. The human body consists on average of 60% of water, 34% of organic matter, 6% of inorganic (for different ages, the relations given vary). The main chemical elements that form organic substances are carbon (~ 18%), oxygen (~ 65%), hydrogen (~ 10%) and nitrogen (~ 2%); in addition, phosphorus (~ 1% ) and sulfur (~ 0,25%).
The average weight of an adult male is about 70 kg. According to rough estimates, approximately 145 g of external oxygen is required to burn a kilogram of a great scientist. But, as you understand, the figure is given as a joke. Good thing you can't hurt the feelings of astronomers, right?
Of course, all the oxygen is overkill. For a tangible effect, the concentration should fall somewhere up to 14%, that is, you need to spend "just something" 1700 g of oxygen. If you burn dust, you need about half a kilogram, if you consider it to be pure carbon.
Thus, it turns out that “burning out” a heater with a significant amount of oxygen in a room is not a trivial task. We must constantly pour on it all the garbage.
Emit carbon monoxide
Highlight does not exactly highlight. Nichrome cannot emit carbon monoxide, except in some exotic experiments. But maybe it burns dust, which, when burned, releases this very gas?
MPC CO c is 20 mg / m 3 . But this is the MPC, some significant consequences for a person begin with the content of 0.019% when inhaled for six hours. For our average room it is 285 liters or 380 g. If we assume that we burn pure carbon and the CO output is 100%, then we will have to burn 153 g. This is about a glass of dust.
Also not a realistic situation. Even if we reduce it 20 times, we get about a tablespoon of dust. It is difficult to imagine a situation in which so much garbage gets into the heater, and not just into the heater namely on the spiral.
Suppose a heater stood in a forgotten tomb and the dust covered it for centuries. The spiral is packed with dust and the necessary mass has gathered. Let us return to the CO exit in the combustion process. In the absence of another source, you can see data on the combustion of coal. In the worst cases, CO can be about five percent of the combustion products.
As we can see, even our silent killer cannot really even highlight carbon monoxide.
UPDATE: As olehorg rightly pointed out, here I was counted two orders of magnitude. Not 285 and 2.85. That is, it is necessary to burn 1.53 g. Sleep with ashes on my head.
Though I was dishonored on all Habr, the sense of the section will all the same remain, though will not be so indicative. I promise in the future to be more careful with the calculations.
Air dry
Here, unfortunately, is true. But any air heaters dry the air.
This happens because of the laws of physics. The relative humidity of the air is critical for the human body. It is called relative because it shows not only how much water is in the air, but how much water is in it from the possible maximum. This figure is much more effective than the absolute. In fact, it shows how quickly water will evaporate in such conditions.
The maximum possible mass fraction of water vapor in the air is proportional to temperature. The hotter the air, the more water it can contain. Here comes into effect the heater.
For example, 1 m 3 of air contained 1 g of water, a possible maximum content of 2 g, and a relative humidity of 50%. The heater heated the air, the water in it was still 1 g, the limit of the water content increased to 3 g, so the relative humidity dropped to 33.3%. The air has become dry, the person has a sore throat, and the cat starts to sparkle when stroking.
Kota, by the way, can be considered a good indicator of humidity. Static electricity begins to be produced by a cat at a humidity of no more than 45%, for a person a range of 40% -60% is considered comfortable.
Unfortunately, the use of cats of different models as a sensor in the circuits of automation is unpromising due to their active resistance.
The probable causes of the myth
Oddly enough, open coil heaters can actually cause you to feel unwell. Only thing is not at all in burnt oxygen.
Despite all the above calculations, some strange dirty trick can get on the spiral, the smoke from which will cause an allergic reaction or even poisoning. But in this respect, the usual stove chances to cause problems no less.
Unfortunately, an open coil in a household heater with a 90% probability indicates that this product is of extremely poor quality. A good heating element is quite expensive, and if you decide to save on it, then the rest is not up to standard.
The case of such a heater will be designed to work in ideal conditions - no more than a couple of hours without interruption and at a distance of a meter from any object. As a result, it will be very hot in the real world. What aromas will emit secondary plastic body is impossible to predict.
Airflow device presents its surprises. The fan of such a device will also match the quality. Although it seems that in the fan, there certainly cannot be any threat to health, this is not so. A motor, especially poorly manufactured and unbalanced, is a source of vibrations and noise, perhaps even infra-sound and ultrasound. Both factors may well cause headaches.
Conclusion
All conventional arguments against open spirals are just a myth, generated not by illiteracy or marketing. Heaters with an open helix and in fact can damage health, these cases are quite rare and require confluence of rather strange circumstances.
If you intend to use such a heater in an average apartment, where there are no invasions of insects and dust storms, then you will not have any problems. Provided that the device is made of high quality, of course.
Heaters with an open coil are more fire hazardous and can cause burns, but do not cause oxygen starvation and do not emit carbon monoxide. The difference in price between them and more sophisticated models can be several thousand rubles.
The cold Russian spring and the optimism of public utilities are likely to force us to use the heater more than once in the near future. Someone wants a disposable device for a rented apartment, the safety of a child is important to someone, aesthetics is important to someone. If you suddenly need to buy a heater, evaluate the ratio of ease of use and price, and do not believe the scary stories of sales assistants.
Source: https://habr.com/ru/post/443272/
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