What is the purity of SF6 IEC standards?

The purity requirements of SF6 are clearly specified in the IEC 60376:2018 standard, which classifies SF6 into pure gas and gas for mixtures, with different purity thresholds for each category. The specific requirements are as follows:

1.Pure SF6 gas: The purity (by volume fraction) shall be greater than 98.5%. Although this threshold seems not extremely high, it is the basic requirement to ensure that pure SF6 can exert its insulation and arc - extinguishing performance in electrical equipment.

2.SF6 gas for mixed gases: The purity (by volume fraction) shall be greater than 99.7%. The higher purity requirement is because when SF6 is mixed with other gases (such as nitrogen, carbon tetrafluoride) for use in electrical equipment, impurities in SF6 will more easily affect the overall insulation and arc - quenching effect of the mixed gas, so stricter control is needed.

In addition to the purity indicators, this IEC standard also defines strict limits on impurities in SF6, such as oxygen, nitrogen, carbon tetrafluoride, etc. For example, the content of oxygen and nitrogen in pure SF6 should be less than 10000 μL/L, and the content of carbon tetrafluoride should be less than 4000 μL/L. These supporting indicators cooperate with the purity requirements to jointly ensure the stable operation of SF6 in high - voltage electrical equipment.