Do you know about sulfur hexafluoride?

2024-10-29

Sulfur hexafluorideis an inorganic Compound with the chemical formulaSF6. It is a colorless, tasteless, odorless, non-toxic, non-combustible gas at room temperature and pressure. Its molecular weight is 146.06 and its density is 6.139 g/L, which is about 5 times that of air. It is one of the best known chemically stable substances, and its inertness is similar to that of nitrogen.

It has excellent thermal stability and does not decompose in pure state even at temperatures above 500°C. The melting point of sulfur hexafluoride is -50.8°C, and it can be used as a special refrigerant in the temperature range of -45-0°C. Because of its good heat resistance, it is a stable high-temperature heat carrier.

Sulfur hexafluoride has good electrical insulation properties and excellent arc extinguishing performance. Under the same conditions, its electrical strength is 2.5 times that of ammonia, its breakdown voltage is 2.5 times that of air, and its arc extinguishing ability is 100 times that of air. It is a new generation of ultra-high voltage insulating dielectric material that is superior to air and oil. Due to the above and other excellent properties, sulfur hexafluoride has been widely used in the power, electronic and electrical industries, laser, medical, meteorological, refrigeration, fire protection, chemical, military, aerospace, non-ferrous metallurgy, physical research and other fields in recent years.

However, when using sulfur hexafluoride, you need to pay attention to the following points:

First, bottled sulfur hexafluoride is a high-pressure liquefied gas and should be stored, transported and used in strict accordance with the "Gas Cylinder Safety Supervision Regulations" promulgated by the State Administration of Labor.

Second, the cylinder valve should be fully opened when in use, and the pressure and flow should be controlled by a pressure reducing valve so that the gas can be filled into the equipment in a gaseous state. After use, the valve should be closed tightly and a protective cap should be worn. The material in the cylinder should not be used up, and the residual pressure in the cylinder should not be less than 0.2MPa at room temperature.

Third, sulfur hexafluoride gas cylinders are not allowed to be used in an environment above 45°C. The storage and use places should be well ventilated and the gas cylinders must be prevented from leaking.

Fourth, sulfur hexafluoride is physiologically inactive and pharmacologically considered a non-toxic gas. However, when it contains impurities such as SE, it becomes a toxic substance. When inhaling high concentrations of SF6, suffocation symptoms such as difficulty breathing, wheezing, blue skin and mucous membranes, and whole body convulsions may occur. If these conditions occur, move quickly to fresh air.

Fifth, liquid sulfur hexafluoride has a rapid freezing effect. Do not allow it to come into contact with eyes, skin or clothing to avoid frostbite.

Last, gas-using devices can be tested for leaks with soap solution. SF6 is non-corrosive and can be filled in containers made of common materials such as stainless steel, copper, and aluminum. In case of fire, water and sand can be used to extinguish the fire. Leaking gas can be treated by introducing it into a mixed solution of caustic soda and slaked lime, or by placing the leaking gas cylinder in a fume hood.