1. Three kinds of flame with different properties of neutral flame, oxide flame and carbonization flame can be obtained by adjusting the mixing ratio of oxygen and acetylene gas by gas welding flame, as shown in the following figure:

1) neutral flame oxygen and acetylene are fully burned, the mixing ratio is 1.1~1.2, there is no excess oxygen and acetylene, the internal flame has a certain reduction, the CO2 and CO generated by the combustion has a protective effect on the melting pool, the color is blue and white.The highest temperature is 3050~3150℃.When welding, flame core terminal melting pool 3 ~ 5mm. Mainly used for welding low carbon steel, low alloy steel, high chromium steel, stainless steel, copper, tin bronze, aluminum and its alloys.

2) the mixing ratio of oxygen and acetylene in the flame of oxidation is greater than 1.2. The oxygen is over the flame and has oxidizability.Maximum temperature 3100~3300℃.Mainly used for welding brass, bronze, etc.

3) carbonization flame mixing ratio is less than 1.1, excessive acetylene, with a strong reduction, the flame has free state of carbon and too much hydrogen, welding will increase the amount of hydrogen weld, welding low carbon steel carburizing phenomenon, the flame is light white.The highest temperature is 2700~3000℃.When welding, the flame core from melting pool 3 ~ 5mm. Mainly used for welding or welding of high carbon steel, high speed steel, hard alloy, aluminum, bronze and cast iron.

2. Gas welding equipment

1) the oxygen cylinder has a capacity of 40L and a working pressure of 15MPa.Prevent contamination with oil stains during storage and use;It must be placed in a stable and reliable manner and should not be mixed with other cylinders.Do not expose to the sun, fire or knock in case of explosion.When using oxygen, do not use up all the oxygen in the bottle, at least 100~200kPa should be left, in order to blow off dust and avoid mixing other gases when reloading oxygen.

2) the acetylene bottle has a capacity of 40L and a working pressure of 1.5mpa. The surface is white with red paint "acetylene" and "no fire".A porous filler impregnated in the bottle makes acetylene stable and safe to be stored in the bottle.When using acetylene cylinder, in addition to the use of oxygen cylinder should comply with the requirements, should also pay attention to: the temperature of the cylinder body should not exceed 30~40℃;When handling, loading, unloading, storage and use, it should be erected and put firmly. It is strictly prohibited to lie down on the ground and use directly. Once the recumbent acetylene bottle is used, it must be erected first and then static for 20min, and then connected to the acetylene decompression device for use;Do not suffer from severe vibration, etc.

3) regulator for reducing high pressure gas to low pressure gas.For different nature of the gas, must choose to meet the requirements of their own special pressure reducer. Generally, the required working pressure during gas welding is generally relatively low, such as oxygen pressure is generally 0.2~0.4MPa, the highest acetylene pressure is not more than 0.15MPa.The role of the pressure reducer is to reduce the gas pressure, and make the gas pressure sent to the torch stable and unchanged, to ensure that the flame can be stable combustion.The pressure reducer shall be firmly installed on the dedicated cylinder.Pressure reducer for all kinds of gases, do not replace or replace.