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Basic Statements on SF6

Atmosphere
  1. SF6 does not contribute to the ozone hole.
  2. Although SF6 is a greenhouse gas, it is only used in such small quantity that its contribution to global warming remains negligible.
  3. The use of SF6 in electric power equipment is contained. Only a small fraction needs to be released by leakage and at handling operations.
  4. The SF6 in electric power equipment is recyclable. Most of the gas can be reused on-site. Only a small fraction is contaminated to the extent that additional processing will be necessary to make it reusable. For details contact the equipment manufacturer.
  5. SF6 can be removed from the ecocycle, if necessary by a thermal process which retransforms it into the natural substances fluorspar and gypsum.
  6. At present, only about one third of the SF6 produced worldwide is used by the manufacturers of electrical power equipment. Most of this gas is filled into newly installed equipment.
  7. SF6 leakage rates from operating equipment can be kept below 0.2%/year with current technology. Leakage can therefore be kept so low that also future contribution of “electrical“ SF6 to the greenhouse effect remains negligible.
  8. The total environmental impact of power equipment can be assessed by environmental lifecycle analysis (LCA) according to ISO 14000. It shows that the use of SF6 allows to minimize the integral environmental load of equipment. This is because the savings of other materials and their associated environmental load quantitatively overcompensate the impact caused by SF6 losses.

Recycling
  1. The deliberate release of SF6 into the atmosphere must be avoided.
  2. SF6 should only be applied where it can be reused and recycled.
  3. In SF6-insulated electric power equipment, the SF6 can be systematically recycled and reused on-site.
  4. Purity standards for the reuse of recycled SF6 have been proposed by international committees (CIGRE, IEC) and will be included in a revised IEC standard in the near future.
  5. Commercial SF6 recycling equipment is available for all requirements.
  6. Only a very small fraction of the SF6 is contaminated to such a degree that it can not be reused on site. This gas can be rendered reusable by specialized recycling enterprises (e.g. SF6 producers).
  7. SF6 can be completely removed from the ecocycle, if necessary by a thermal process which retransforms it into the natural substances flourspar and gypsum.
  8. SF6 equipment manufactured by ABB is appropriately labelled.

Safety
  1. After more than 30 years of successful practical experience, the handling of SF6 in gas-insulated electric power equipment is an established technology.
  2. SF6 is non-toxic and biologically inert.
  3. Similar to CO2, SF6 is heavier than air and may accumulate if released into unventilated rooms. It may thereby replace oxygen. This normally does not constitute a suffocation hazard because the SF6 quantities contained in electric power equipment are too small to cause dangerously high concentrations in the air. Only where very large SF6 quantities are released into small rooms, ventilation should be provided for security.
  4. SF6 decomposition products caused by electrical discharges in normally operating equipment do not constitute a health hazard because they are removed by absorbers.
  5. Toxic decomposition may be generated in electrical discharges. However, they are in high quantity only in the rare event of heavy failure arcing (switchgear failure or internal arcing) when released they are diluted and chemically transformed into less toxic products. They produce a smell warning already at concentrations which are not yet health-risk relevant. With proper safety precautions and personnel instruction, no health risk is incurred.
  6. Highly toxic SF6-decomposition products like S2F10 do not constitute any health risk at all because they are only produced in extremely low quantity and are decomposed on the walls.

Substitutes
  1. Concerns presently being expressed on SF6 in electrical power equipment are not based on rational and quantitative reasoning. They are driven by sensational journalism, competitive sales argumentation and funding interest of research institutions.
  2. There is no technical, no ecological and no safety reason to substitute SF6 in electric power equipment.
  3. Because of a unique combination of physico-chemical properties, SF6 exhibits optimal performance both as arc quenching and insulation medium.
  4. In spite of two decades of expensive research, no equivalent gases have been found, neither for arc quenching nor for insulation. Hence, unlike other fluorinated substances (such as CFC), SF6 cannot be replaced by an environmentally more favorable gas.
  5. If SF6 did not exist, arc quenching in HV switchgear could only be achieved by going back to historical technologies (compressed air blast or minimum oil) which were phased out decades ago due to reliability, cost, security and environmental reasons.
  6. If SF6 did not exist, compact high-voltage insulation could only be achieved by compressed nitrogen or air at much higher pressure. This would result in a much lower performance-to-cost ratio, worse safety feature due to the higher pressure required and lower environmental life-cycle performance because of higher pressure tequired and lower environmental life-cycle performance because of the higher demand of enclosure materials.
  7. If SF6 did not exist, the integral environmental impact of electric power equipment (as assessed by environmental life cycle analysis, according to ISO 14000) would increase due to much higher quantities of materials needed in order to produce same function with a gas of much lower performance.

Last edited 2003-04-24
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