Solder flame temperature performance indicators

The current generation of "left-handed" rarely uses a blowtorch, preferring an industrial electric hair dryer or gas burner, which is much easier and safer to use. But even 40-50 years ago the blowtorch was practically in every home workshop of a mechanic or a car enthusiast, since it was the only tool capable of heating various materials to the required temperature.


The blowtorch burns gasoline in the nozzle, producing a fairly large jet of open flame.

But it’s still not worthwhile to take a blowtorch for scrap in our age of scientific and technological progress. For example, a gas burner in the bitter cold is almost impossible to ignite. With an industrial dryer, the situation is no better: for his work, a constant source of electricity is needed. And an old blowtorch doesn’t care about all these difficulties.

The principle of burning in a blowtorch

Device blowtorch

Device blowtorch.

A blowtorch is a liquid-fuel heater. Its peculiarity is that in the working tool, the burner, fumes of fuel filled into the lamp burn, but not the fuel itself. Acting at high speed into the burner, a jet of such vapors sucks in itself the air around the burner, thereby providing itself with enough oxygen.

Such self-sufficiency is very important, because for complete combustion of 1 kg of liquid fuel based on hydrocarbons, a certain amount of oxygen is needed. In this case, complete combustion will be achieved, after which only carbon dioxide and water will remain from the fuel.

But if you just ignite the liquid fuel, such as gasoline, in an open container, it will not completely burn. This is indicated by the orange-red flame of similar burning foci, besides with a fair amount of soot. But if artificially injecting air into such a burning center, the flame from the orange-red will turn blue, practically without soot, and its temperature will increase significantly. The reason for these changes will be the oxygen in the air.

Temperature controllers for the soldering iron tip

Schemes of temperature controls of the soldering tip.

It is the principle of artificial enrichment of the flame with air, borrowed from gas lamps (so-called horn), that is the basis of the work of a blowtorch. Moreover, such an air supply is regulated spontaneously: fuel vapors enter the burner, and the higher the supply, the more powerful the jet will be and, accordingly, the more air will be drawn into it.

Sometimes it happens that the jet draws in too much air, and the oxygen does not have time to completely burn out. In this case, the burning temperature decreases markedly, since the excess air passing through the burner cools it. However, this happens only when using low-quality fuel. During normal filling of the burner with fuel vapors, it is impossible to draw in excess air in it for purely physical reasons.

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Fuel for soldering lamps

Refinement soldering tip

Refinement soldering tip.

The universality of a blowtorch is that it can work on almost any fire capable liquid fuel: alcohol, kerosene, gasoline, diesel oil, and oil. But this does not mean that you can pour anything into each blowtorch.

Fuel must be of high quality. In addition, it must be borne in mind that an inappropriate type of fuel will very quickly clog the nozzle with its fumes. Today soldering lamps come in three forms:

  • kerosene;
  • petrol;
  • alcohol.

The principle of the blowtorch has been preserved in the gas burner as well; therefore, some specialized sources also refer to this device as a blowtorch, distinguishing it with a separate, fourth, appearance.

Filling the lamp with another type of fuel that does not comply with its design is strictly prohibited by the safety instructions. And this rule must be strictly observed. After all, kerosene poured into the gasoline "soldering iron" will make it a tool like a flamethrower. Getting into the burner, he will not have time to completely evaporate, therefore, not the fumes will burn, but the kerosene itself. Such a tool will not work normally.

Even more dangerous in a kerosene blowtorch pour gasoline. Gasoline evaporates much faster than kerosene, and the pressure of its vapor in the burner will be 6 times higher than the calculated value. When you try to ignite a couple will explode, turning a useful tool into a dangerous bomb. Therefore, if you use a kerosene blowtorch, you need to fill it only with pure kerosene, without any impurities, without using mixtures of kerosene with gasoline or other fuel.

Soldering Soldering Tip

Soldering soldering tip.

The same situation with a gasoline blowtorch. It needs to be filled with pure gasoline only. At the same time, the octane number of gasoline has practically no effect on the operation of the instrument: neither the speed of ignition, nor the burning time, nor the flame temperature. But when choosing a gasoline brand, one should not forget that low-octane grades of various additives and impurities are much smaller, therefore, during operation, the nozzle will be contaminated much less.

In alcohol soldering lamps a small volume of the reservoir (only 200-300 ml), respectively, its burning is very limited in time, so today instead of them the masters prefer to use gas burners.

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Flame temperature

There is a conviction among a significant part of users that it is impossible to perform high-quality soldering with a blowtorch and that it is suitable only for heating frozen plumbing and sewage pipes, warming up the engine at low temperatures and for other similar works.

Such a reputation arose because of a lack of attention to the technical characteristics of the instrument or a lack of understanding of the principle of operation. The maximum temperature that the flame coming out of the blowtorch can produce is 1100º C. Therefore, trying to melt iron, nickel or chrome with a blowtorch is hopeless. At the same time, its temperature is quite enough to melt lead, zinc, tin or aluminum.

In order not to waste time, it is better to have on hand data of melting metals:

Soldering iron

A soldering iron is needed for small repairs of electronic devices, but at home it is rarely used, so it is not profitable to buy it, you can use its substitutes.

  • tin - 230ºС;
  • bismuth - 270ºС;
  • lead - 330ºС;
  • Zinc - 420ºС;
  • magnesium - 650ºС;
  • aluminum - 660ºС;
  • bronze - 830ºС;
  • brass - 890ºС;
  • silver - 960ºС;
  • neodymium 1030ºС;
  • gold - 1060ºС;
  • copper - 1080ºС;
  • Nickel - 1450ºС:
  • iron - 1540ºС;
  • titanium - 1,660ºС;
  • platinum - 1770ºС;
  • chrome - 1900ºС;
  • molybdenum - 2620ºС.

Based on these data, it is easy to determine, working with which metal with a blowtorch can be carried out without difficulty, with which it is possible, but with difficulty, and it is useless to work with what.

But it is also possible that even work with light-melting metals is unsuccessful. The reason for all the improper use of the lamp, or rather the lack of understanding of the physical properties of the flame. After all, the flame coming out of the burner is not equal in its physical components.

Depending on the excess or lack of oxygen in it, it can have different temperatures.

Experts distinguish three types of flame: reductive or normal; oxidizing, formed with an excess of oxygen in the mixture and contributing to the oxidation of metals, and carburizing, when there is an excess of fuel gases in the mixture. When metal is processed last, its surface is saturated with carbon, which leads to a significant increase in its hardness, but at the same time brittleness.

By itself, even the maximum temperature of the flame cannot guarantee the quality of the work done with the help of a blowtorch. When working with this tool, knowledge of the basics of soldering and especially work experience are very important. If you do not possess neither the first nor the second, then it is better to ask for help from a more experienced comrade. After all, no matter how easy to use the lamp, due to the use of flammable explosive liquids in its work, it was and remains a source of increased danger.

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