Sulphur Hexafluoride - Safety

Toxicity New SF6 Pure sulphur hexafluoride is absolutely non-toxic. The by-products arising during production of the gas are completely removed during subsequent purification operations. Solvay sulphur hexafluoride is constantly tested for the presence of toxic constituents using the test decribed in IEC 376. In places where work involving large quantities of sulphur hexafluoride in containers and in enclosed areas is carried out, the safety regulations should take into account the potential asphyxiation hazard arising from oxygen deficiency, as, due to its high density, the gas can displace air from lower-lying regions of enclosed areas (pits, sumps etc). This hazard can, however, be easily countered by the provision of adequate ventilation. Measuring instruments functioning on the principles of thermal conductivity can be installed to check the SF6 content of air. The existing TLV in the Federal Republic of Germany for sulphur hexafluoride is 6000 mg / m³ = 1000 ppm. Contaminated SF6 As mentioned previously, electrical discharges (e.g. switching processes, fault electric arcs) lead to the formation of gaseous decomposition products and dusty metal compounds. Gaseous decomposition products of SF6 exhibit very characteristic warning signs even at low concentrations. These warning signs are for example pungent or unpleasant odours (like 'rotten eggs'), or irritation of nose, mouth and eyes. Such irritation occurs within seconds, well in advance of any danger arising from poisoning. When handling contaminated SF6 care must be taken not to breathe in gaseous or dusty decomposition products. In case this cannot be achieved by technical safety measures, i.e. ventilation, personal protective equipment must be worn. Personal protective equipment consists of items of protection for the eyes, body and breathing. More detailed information on handling SF6 is given in the information leaflet BGI 753 'SF6 plant' (Trade Association for Precision Mechanics and Electrical Engineering) and in the DIN Standard IEC 60 480 and VDE 0373, Part 2 / 4.80.   Back