The pure SF6 gas is colorless, odorless and nonflammable. It’s with the stable chemical properties at room temperature and belongs to the inert gas. But in the power industry, because of the SF6 gas is mainly used as insulation and arc extinguishing medium is widely used in high voltage switch and circuit breaker and GIS equipment, in the operation process, while the influence of the arc and corona and spark discharge and partial discharge, higher temperature and other factors, SF6 gas will decompose it decomposition of encounter water will become corrosive electrolyte. In particular, there are some highly toxic compounds, such as the SF4, S2F2, S2F10, SOF2, HF and SO2, which will stimulate the skin, eyes and mucous membranes. If inhaled, it can cause dizziness and pulmonary edema, and even cause the death.

SF6 gas leakage harm

The installation of SF6 high voltage equipment of indoor space is generally closed, once SF6 gas leakage, the air circulation is extremely slow, toxic decomposition in the indoor deposition, not easy eduction, resulting in great danger when the staff enter into the SF6 switch room. Also because of the SF6 gas with the higher proportion than Oxygen, when SF6 gas leakage occurs, the SF6 gas will accumulate in the low layer space, will cause the local hypoxia and makes people suffocating. On the other hand, if the SF6 gas leakage will not be easy to be detected, which also will increase the potential risk of the leakage into the field personnel, seriously threatening the safety and health of people, even causing the malignant accidents.

SF6 gas safe concentration

According to the related research, under the environment existing the pure SF6 gas, if the skin expose to the SF6 gas for 8hours continuously, the human can bear the highest concentration is 1000ppm. If less than this level, will not cause the danger to human.

Protective measures

1. Reduce the SF6 gas emissions amount and increase the gas recovery rate. The SF6 gas in the equipment shall not be discharged into the atmosphere. It should be recovered by the purification device and should be used properly after the treatment is qualified.

2. The workers should not enter into the GIS room at random. When the staff need to enter into the GIS room, the air should be discharged for 20 minutes, and the equipment is not allowed to stay near the explosion proof film. The Oxygen gas and SF6 gas concentration must be measured before entering into the cable trench or low level area.

3. In case of emergency, all ventilation systems should be opened immediately for ventilation. When the explosion rupture of the equipment is occurred, the power should be cut off. SF6 electrical equipment installation should be isolated with the main control room, in order to prevent the gas leakage into the main control room. Equipment installation room should have a good exhaust system, ventilation holes should be installed in the lower part of the room, the bottom should be installed with the SF6 gas detector, connect with the ventilating fan, when the SF6 gas concentration up to the alarm value, the fan will be opened to decrease the gas concentration.