Sf6 Cylinder
SF6 gas (sulphur hexafluoride) is an inorganic substance that, under standard conditions, is a nearly colorless, odorless and tasteless, non-toxic, non-combustible, very heavy gas (it is 5 times heavier than air) (the chemical formula is SF6). It is very weakly soluble in water, chemically inert: it does not interact with alkalis, acids, oxidizing agents, reductants, is resistant to the action of molten sodium, does not react with molten aluminum and magnesium, protects them from atmospheric oxygen. Industrial-scale sulphur hexafluoride is produced by direct interaction of fluorine with liquid or gaseous sulphur (combustion of sulphur in the flow of fluorine) with subsequent purification of impurities and condensation. Under laboratory conditions, small amounts of SF6 gas can be produced by reacting fluorine with sulphur tetrafluoride (SF4) in the presence of a catalyst, by fluorinating sulphur compounds, such as carbon oxysulfide (COS), by thermal decomposition of fluorochloride (SF5Cl) at temperatures between 200 and 300 °C.
APPLICATION:< / strong>< / p>< / p> • in high-voltage electrical engineering as the basic insulation for complete switchgears, high-voltage current and voltage measuring transformers; • as an arc-quenching medium in high-voltage circuit breakers; • as a technological medium in the electronic and metallurgical industries; • in gas fire suppression systems as an extinguishing agent; • to improve sound insulation in insulating glass units; • in the semiconductor industry for plasma chemical etching of silicon • as a refrigerant due to its high heat capacity, low thermal conductivity and low viscosity. Requirements for transportation, storage and use of cylinders for sulphur hexafluoride are established by the Federal standards and regulations in the field of industrial safety "Regulations of industrial safety for hazardous facilities using equipment operating under excessive pressure", GOST R 54426-2011 "Guidelines for checking and processing of sulphur hexafluoride (SF6) taken from electrical equipment, and technical requirements for its reuse", TU 6-02-1249-83 "Sulphur hexafluoride of high purity. Amendments 1-6", fire safety standards, as well as other laws and regulations and international agreements in force on the territory of the Russian Federation.
Cylinders are not hazardous cargo until they are taken into use, but in any case they should be transported in conditions that exclude mechanical damage. Cylinders filled with SF6 gas shall be transported by all modes of transport in accordance with cargo carriage regulations applicable to this mode of transport, as well as safety rules for transportation of dangerous goods by rail. Cylinders may be transported in special containers, as well as without containers in an upright position, always with spacers between them and secured against possible falling. The cylinders must be transported with caps screwed on.
Cylinders designed for storage and transportation of SF6 gas must not be used for storage and transportation of other gases, and it is prohibited to perform any operations that may contaminate their internal surface and degrade the physical and chemical properties of the gas. It is forbidden to make any modifications to the cylinder bodies using welding or mechanical tools, which can lead to damage to the integrity or appearance of defects that degrade the technical characteristics of the cylinders. When using SF6 gas cylinders it is not allowed to install them in the places of people passage, movement of goods and passage of vehicles. Cylinders must be located at least 1 m away from radiators and other heating devices and at least 5 m from heat sources with open flame. Cylinders designed for storage and transportation of SF6 gas are filled at the rate of 1.04 kg of the product per 1 dm3 of the cylinder capacity. The maximum permissible concentration of sulphur hexafluoride vapor in the air of the working area of production facilities is 5000 mg/m3. A mixture consisting of 20 % oxygen and 80 % sulphur hexafluoride does not cause adverse effects on the respiratory organs and the body, but when the oxygen content in the air drops to 16 % or lower, there will be a risk of suffocation for personnel. The rooms in which SF6 gas is handled must be equipped with devices that signalize the unacceptable concentration of sulphur hexafluoride and must provide the supply and exhaust ventilation. Special measures must be taken when working with SF6 gas to prevent the risk of exposure of personnel to mechanical damage to the body of the equipment, to reduce the risk of serious frostbite of body parts, protective clothing and eye protection must be used. The gas in the cylinders must not be completely consumed when in use. The residual gas pressure in the cylinder must be at least 0.05 MPa (0.5 kgf/cm2).
Cylinders with SF6 gas can be stored both in special rooms and in the open air, in the latter case they must be protected from atmospheric precipitation and sunlight. Cylinders filled with SF6 gas may be stored in open areas together with other gases, provided that the storage areas are separated from each other by non-combustible barriers with a height of 1.5 m, joint storage with cylinders filled with combustible gases is also allowed, provided that the storage areas are separated from each other by non-combustible protective walls not less than 2.5 m high. Storage of cylinders should be carried out with the caps screwed on.